@c o
@c G N A T _ RM o
@c o
-@c Copyright (C) 1995-2004 Free Software Foundation o
-@c o
-@c o
@c GNAT is maintained by Ada Core Technologies Inc (http://www.gnat.com). o
@c o
@c oooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo
@setfilename gnat_rm.info
+
+@copying
+Copyright @copyright{} 1995-2008, Free Software Foundation, Inc.
+
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.2 or
+any later version published by the Free Software Foundation; with no
+Invariant Sections, with the Front-Cover Texts being ``GNAT Reference
+Manual'', and with no Back-Cover Texts. A copy of the license is
+included in the section entitled ``GNU Free Documentation License''.
+@end copying
+
+@set EDITION GNAT
+@set DEFAULTLANGUAGEVERSION Ada 2005
+@set NONDEFAULTLANGUAGEVERSION Ada 95
+
@settitle GNAT Reference Manual
+
@setchapternewpage odd
@syncodeindex fn cp
* GNAT Reference Manual: (gnat_rm). Reference Manual for GNU Ada tools.
@end direntry
-@copying
-Copyright @copyright{} 1995-2004, Free Software Foundation
-
-Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.2
-or any later version published by the Free Software Foundation;
-with the Invariant Sections being ``GNU Free Documentation License'',
-with the Front-Cover Texts being ``GNAT Reference Manual'', and with
-no Back-Cover Texts. A copy of the license is included in the section
-entitled ``GNU Free Documentation License''.
-@end copying
-
@titlepage
-
@title GNAT Reference Manual
-@subtitle GNAT, The GNU Ada 95 Compiler
-@subtitle GCC version @value{version-GCC}
-@author Ada Core Technologies, Inc.
-
+@subtitle GNAT, The GNU Ada Compiler
+@versionsubtitle
+@author AdaCore
@page
@vskip 0pt plus 1filll
GNAT Reference Manual
@noindent
-GNAT, The GNU Ada 95 Compiler@*
+GNAT, The GNU Ada Compiler@*
GCC version @value{version-GCC}@*
@noindent
-Ada Core Technologies, Inc.
+AdaCore
@menu
* About This Guide::
* Specialized Needs Annexes::
* Implementation of Specific Ada Features::
* Project File Reference::
+* Obsolescent Features::
* GNU Free Documentation License::
* Index::
* Pragma Abort_Defer::
* Pragma Ada_83::
* Pragma Ada_95::
+* Pragma Ada_05::
+* Pragma Ada_2005::
* Pragma Annotate::
* Pragma Assert::
+* Pragma Assume_No_Invalid_Values::
* Pragma Ast_Entry::
* Pragma C_Pass_By_Copy::
+* Pragma Check::
+* Pragma Check_Name::
+* Pragma Check_Policy::
* Pragma Comment::
* Pragma Common_Object::
+* Pragma Compile_Time_Error::
* Pragma Compile_Time_Warning::
+* Pragma Compiler_Unit::
+* Pragma Complete_Representation::
* Pragma Complex_Representation::
* Pragma Component_Alignment::
* Pragma Convention_Identifier::
* Pragma CPP_Virtual::
* Pragma CPP_Vtable::
* Pragma Debug::
+* Pragma Debug_Policy::
+* Pragma Detect_Blocking::
* Pragma Elaboration_Checks::
* Pragma Eliminate::
* Pragma Export_Exception::
* Pragma Extend_System::
* Pragma External::
* Pragma External_Name_Casing::
+* Pragma Fast_Math::
+* Pragma Favor_Top_Level::
* Pragma Finalize_Storage_Only::
* Pragma Float_Representation::
* Pragma Ident::
+* Pragma Implemented_By_Entry::
+* Pragma Implicit_Packing::
* Pragma Import_Exception::
* Pragma Import_Function::
* Pragma Import_Object::
* Pragma License::
* Pragma Link_With::
* Pragma Linker_Alias::
+* Pragma Linker_Constructor::
+* Pragma Linker_Destructor::
* Pragma Linker_Section::
* Pragma Long_Float::
* Pragma Machine_Attribute::
+* Pragma Main::
* Pragma Main_Storage::
+* Pragma No_Body::
* Pragma No_Return::
+* Pragma No_Strict_Aliasing ::
* Pragma Normalize_Scalars::
* Pragma Obsolescent::
+* Pragma Optimize_Alignment::
* Pragma Passive::
+* Pragma Persistent_BSS::
* Pragma Polling::
-* Pragma Propagate_Exceptions::
+* Pragma Postcondition::
+* Pragma Precondition::
+* Pragma Profile (Ravenscar)::
+* Pragma Profile (Restricted)::
* Pragma Psect_Object::
* Pragma Pure_Function::
-* Pragma Ravenscar::
-* Pragma Restricted_Run_Time::
* Pragma Restriction_Warnings::
+* Pragma Shared::
+* Pragma Short_Circuit_And_Or::
* Pragma Source_File_Name::
* Pragma Source_File_Name_Project::
* Pragma Source_Reference::
* Pragma Stream_Convert::
* Pragma Style_Checks::
* Pragma Subtitle::
+* Pragma Suppress::
* Pragma Suppress_All::
* Pragma Suppress_Exception_Locations::
* Pragma Suppress_Initialization::
* Pragma Task_Info::
* Pragma Task_Name::
* Pragma Task_Storage::
-* Pragma Thread_Body::
+* Pragma Thread_Local_Storage::
* Pragma Time_Slice::
* Pragma Title::
* Pragma Unchecked_Union::
* Pragma Unimplemented_Unit::
+* Pragma Universal_Aliasing ::
* Pragma Universal_Data::
+* Pragma Unmodified::
* Pragma Unreferenced::
+* Pragma Unreferenced_Objects::
* Pragma Unreserve_All_Interrupts::
* Pragma Unsuppress::
* Pragma Use_VADS_Size::
* Pragma Volatile::
* Pragma Warnings::
* Pragma Weak_External::
+* Pragma Wide_Character_Encoding::
Implementation Defined Attributes
* AST_Entry::
* Bit::
* Bit_Position::
+* Compiler_Version::
* Code_Address::
* Default_Bit_Order::
* Elaborated::
* Elab_Body::
* Elab_Spec::
* Emax::
+* Enabled::
* Enum_Rep::
+* Enum_Val::
* Epsilon::
* Fixed_Value::
+* Has_Access_Values::
* Has_Discriminants::
* Img::
* Integer_Value::
+* Invalid_Value::
* Large::
* Machine_Size::
* Mantissa::
* Mechanism_Code::
* Null_Parameter::
* Object_Size::
+* Old::
* Passed_By_Reference::
+* Pool_Address::
* Range_Length::
+* Result::
* Safe_Emax::
* Safe_Large::
* Small::
* Storage_Unit::
+* Stub_Type::
* Target_Name::
* Tick::
* To_Address::
* Sequential_IO::
* Text_IO::
* Wide_Text_IO::
+* Wide_Wide_Text_IO::
* Stream_IO::
+* Text Translation::
* Shared Files::
+* Filenames encoding::
* Open Modes::
* Operations on C Streams::
* Interfacing to C Streams::
* Ada.Characters.Latin_9 (a-chlat9.ads)::
* Ada.Characters.Wide_Latin_1 (a-cwila1.ads)::
* Ada.Characters.Wide_Latin_9 (a-cwila9.ads)::
-* Ada.Command_Line.Remove (a-colire.ads)::
+* Ada.Characters.Wide_Wide_Latin_1 (a-chzla1.ads)::
+* Ada.Characters.Wide_Wide_Latin_9 (a-chzla9.ads)::
* Ada.Command_Line.Environment (a-colien.ads)::
+* Ada.Command_Line.Remove (a-colire.ads)::
+* Ada.Command_Line.Response_File (a-clrefi.ads)::
* Ada.Direct_IO.C_Streams (a-diocst.ads)::
* Ada.Exceptions.Is_Null_Occurrence (a-einuoc.ads)::
+* Ada.Exceptions.Last_Chance_Handler (a-elchha.ads)::
* Ada.Exceptions.Traceback (a-exctra.ads)::
* Ada.Sequential_IO.C_Streams (a-siocst.ads)::
* Ada.Streams.Stream_IO.C_Streams (a-ssicst.ads)::
* Ada.Strings.Unbounded.Text_IO (a-suteio.ads)::
* Ada.Strings.Wide_Unbounded.Wide_Text_IO (a-swuwti.ads)::
+* Ada.Strings.Wide_Wide_Unbounded.Wide_Wide_Text_IO (a-szuzti.ads)::
* Ada.Text_IO.C_Streams (a-tiocst.ads)::
+* Ada.Text_IO.Reset_Standard_Files (a-tirsfi.ads)::
+* Ada.Wide_Characters.Unicode (a-wichun.ads)::
* Ada.Wide_Text_IO.C_Streams (a-wtcstr.ads)::
+* Ada.Wide_Text_IO.Reset_Standard_Files (a-wrstfi.ads)::
+* Ada.Wide_Wide_Characters.Unicode (a-zchuni.ads)::
+* Ada.Wide_Wide_Text_IO.C_Streams (a-ztcstr.ads)::
+* Ada.Wide_Wide_Text_IO.Reset_Standard_Files (a-zrstfi.ads)::
+* GNAT.Altivec (g-altive.ads)::
+* GNAT.Altivec.Conversions (g-altcon.ads)::
+* GNAT.Altivec.Vector_Operations (g-alveop.ads)::
+* GNAT.Altivec.Vector_Types (g-alvety.ads)::
+* GNAT.Altivec.Vector_Views (g-alvevi.ads)::
* GNAT.Array_Split (g-arrspl.ads)::
* GNAT.AWK (g-awk.ads)::
* GNAT.Bounded_Buffers (g-boubuf.ads)::
* GNAT.Bubble_Sort (g-bubsor.ads)::
* GNAT.Bubble_Sort_A (g-busora.ads)::
* GNAT.Bubble_Sort_G (g-busorg.ads)::
+* GNAT.Byte_Order_Mark (g-byorma.ads)::
+* GNAT.Byte_Swapping (g-bytswa.ads)::
* GNAT.Calendar (g-calend.ads)::
* GNAT.Calendar.Time_IO (g-catiio.ads)::
* GNAT.Case_Util (g-casuti.ads)::
* GNAT.Current_Exception (g-curexc.ads)::
* GNAT.Debug_Pools (g-debpoo.ads)::
* GNAT.Debug_Utilities (g-debuti.ads)::
+* GNAT.Decode_String (g-decstr.ads)::
+* GNAT.Decode_UTF8_String (g-deutst.ads)::
* GNAT.Directory_Operations (g-dirope.ads)::
+* GNAT.Directory_Operations.Iteration (g-diopit.ads)::
* GNAT.Dynamic_HTables (g-dynhta.ads)::
* GNAT.Dynamic_Tables (g-dyntab.ads)::
+* GNAT.Encode_String (g-encstr.ads)::
+* GNAT.Encode_UTF8_String (g-enutst.ads)::
* GNAT.Exception_Actions (g-excact.ads)::
* GNAT.Exception_Traces (g-exctra.ads)::
* GNAT.Exceptions (g-except.ads)::
* GNAT.Memory_Dump (g-memdum.ads)::
* GNAT.Most_Recent_Exception (g-moreex.ads)::
* GNAT.OS_Lib (g-os_lib.ads)::
-* GNAT.Perfect_Hash.Generators (g-pehage.ads)::
+* GNAT.Perfect_Hash_Generators (g-pehage.ads)::
+* GNAT.Random_Numbers (g-rannum.ads)::
* GNAT.Regexp (g-regexp.ads)::
* GNAT.Registry (g-regist.ads)::
* GNAT.Regpat (g-regpat.ads)::
* GNAT.Secondary_Stack_Info (g-sestin.ads)::
* GNAT.Semaphores (g-semaph.ads)::
+* GNAT.Serial_Communications (g-sercom.ads)::
+* GNAT.SHA1 (g-sha1.ads)::
+* GNAT.SHA224 (g-sha224.ads)::
+* GNAT.SHA256 (g-sha256.ads)::
+* GNAT.SHA384 (g-sha384.ads)::
+* GNAT.SHA512 (g-sha512.ads)::
* GNAT.Signals (g-signal.ads)::
* GNAT.Sockets (g-socket.ads)::
* GNAT.Source_Info (g-souinf.ads)::
-* GNAT.Spell_Checker (g-speche.ads)::
+* GNAT.Spelling_Checker (g-speche.ads)::
+* GNAT.Spelling_Checker_Generic (g-spchge.ads)::
* GNAT.Spitbol.Patterns (g-spipat.ads)::
* GNAT.Spitbol (g-spitbo.ads)::
* GNAT.Spitbol.Table_Boolean (g-sptabo.ads)::
* GNAT.Spitbol.Table_Integer (g-sptain.ads)::
* GNAT.Spitbol.Table_VString (g-sptavs.ads)::
+* GNAT.SSE (g-sse.ads)::
+* GNAT.SSE.Vector_Types (g-ssvety.ads)::
* GNAT.Strings (g-string.ads)::
* GNAT.String_Split (g-strspl.ads)::
* GNAT.Table (g-table.ads)::
* GNAT.Task_Lock (g-tasloc.ads)::
* GNAT.Threads (g-thread.ads)::
+* GNAT.Time_Stamp (g-timsta.ads)::
* GNAT.Traceback (g-traceb.ads)::
* GNAT.Traceback.Symbolic (g-trasym.ads)::
+* GNAT.UTF_32 (g-utf_32.ads)::
+* GNAT.UTF_32_Spelling_Checker (g-u3spch.ads)::
+* GNAT.Wide_Spelling_Checker (g-wispch.ads)::
* GNAT.Wide_String_Split (g-wistsp.ads)::
+* GNAT.Wide_Wide_Spelling_Checker (g-zspche.ads)::
+* GNAT.Wide_Wide_String_Split (g-zistsp.ads)::
* Interfaces.C.Extensions (i-cexten.ads)::
* Interfaces.C.Streams (i-cstrea.ads)::
* Interfaces.CPP (i-cpp.ads)::
-* Interfaces.Os2lib (i-os2lib.ads)::
-* Interfaces.Os2lib.Errors (i-os2err.ads)::
-* Interfaces.Os2lib.Synchronization (i-os2syn.ads)::
-* Interfaces.Os2lib.Threads (i-os2thr.ads)::
* Interfaces.Packed_Decimal (i-pacdec.ads)::
* Interfaces.VxWorks (i-vxwork.ads)::
* Interfaces.VxWorks.IO (i-vxwoio.ads)::
* System.Assertions (s-assert.ads)::
* System.Memory (s-memory.ads)::
* System.Partition_Interface (s-parint.ads)::
+* System.Pool_Global (s-pooglo.ads)::
+* System.Pool_Local (s-pooloc.ads)::
* System.Restrictions (s-restri.ads)::
* System.Rident (s-rident.ads)::
+* System.Strings.Stream_Ops (s-ststop.ads)::
* System.Task_Info (s-tasinf.ads)::
* System.Wch_Cnv (s-wchcnv.ads)::
* System.Wch_Con (s-wchcon.ads)::
* Wide_Text_IO Stream Pointer Positioning::
* Wide_Text_IO Reading and Writing Non-Regular Files::
+Wide_Wide_Text_IO
+
+* Wide_Wide_Text_IO Stream Pointer Positioning::
+* Wide_Wide_Text_IO Reading and Writing Non-Regular Files::
+
Interfacing to Other Languages
* Interfacing to C::
* GNAT Implementation of Tasking::
* GNAT Implementation of Shared Passive Packages::
* Code Generation for Array Aggregates::
+* The Size of Discriminated Records with Default Discriminants::
+* Strict Conformance to the Ada Reference Manual::
Project File Reference
+Obsolescent Features
+
GNU Free Documentation License
Index
@noindent
This manual contains useful information in writing programs using the
-GNAT compiler. It includes information on implementation dependent
-characteristics of GNAT, including all the information required by Annex
-M of the standard.
-
-Ada 95 is designed to be highly portable.
+@value{EDITION} compiler. It includes information on implementation dependent
+characteristics of @value{EDITION}, including all the information required by
+Annex M of the Ada language standard.
+
+@value{EDITION} implements Ada 95 and Ada 2005, and it may also be invoked in
+Ada 83 compatibility mode.
+By default, @value{EDITION} assumes @value{DEFAULTLANGUAGEVERSION},
+but you can override with a compiler switch
+to explicitly specify the language version.
+(Please refer to @ref{Compiling Different Versions of Ada,,, gnat_ugn,
+@value{EDITION} User's Guide}, for details on these switches.)
+Throughout this manual, references to ``Ada'' without a year suffix
+apply to both the Ada 95 and Ada 2005 versions of the language.
+
+Ada is designed to be highly portable.
In general, a program will have the same effect even when compiled by
different compilers on different platforms.
-However, since Ada 95 is designed to be used in a
+However, since Ada is designed to be used in a
wide variety of applications, it also contains a number of system
dependent features to be used in interfacing to the external world.
@cindex Implementation-dependent features
isolate and clearly document any sections of your program that make use
of these features in a non-portable manner.
+@ifset PROEDITION
+For ease of exposition, ``GNAT Pro'' will be referred to simply as
+``GNAT'' in the remainder of this document.
+@end ifset
+
@menu
* What This Reference Manual Contains::
* Conventions::
@ref{Project File Reference}, presents the syntax and semantics
of project files.
+@item
+@ref{Obsolescent Features} documents implementation dependent features,
+including pragmas and attributes, which are considered obsolescent, since
+there are other preferred ways of achieving the same results. These
+obsolescent forms are retained for backwards compatibility.
+
@end itemize
-@cindex Ada 95 ISO/ANSI Standard
+@cindex Ada 95 Language Reference Manual
+@cindex Ada 2005 Language Reference Manual
@noindent
-This reference manual assumes that you are familiar with Ada 95
-language, as described in the International Standard
-ANSI/ISO/IEC-8652:1995, Jan 1995.
+This reference manual assumes a basic familiarity with the Ada 95 language, as
+described in the International Standard ANSI/ISO/IEC-8652:1995,
+January 1995.
+It does not require knowledge of the new features introduced by Ada 2005,
+(officially known as ISO/IEC 8652:1995 with Technical Corrigendum 1
+and Amendment 1).
+Both reference manuals are included in the GNAT documentation
+package.
@node Conventions
@unnumberedsec Conventions
@code{Option flags}
@item
-@file{File Names}, @samp{button names}, and @samp{field names}.
+@file{File names}, @samp{button names}, and @samp{field names}.
@item
-@code{Variables}.
+@code{Variables}, @env{environment variables}, and @var{metasyntactic
+variables}.
@item
@emph{Emphasis}.
@itemize @bullet
@item
-@cite{GNAT User's Guide}, which provides information on how to use
-the GNAT compiler system.
+@xref{Top, @value{EDITION} User's Guide, About This Guide, gnat_ugn,
+@value{EDITION} User's Guide}, which provides information on how to use the
+GNAT compiler system.
@item
@cite{Ada 95 Reference Manual}, which contains all reference
@item
@cite{Ada 95 Annotated Reference Manual}, which is an annotated version
-of the standard reference manual cited above. The annotations describe
+of the Ada 95 standard. The annotations describe
detailed aspects of the design decision, and in particular contain useful
sections on Ada 83 compatibility.
@item
+@cite{Ada 2005 Reference Manual}, which contains all reference
+material for the Ada 2005 programming language.
+
+@item
+@cite{Ada 2005 Annotated Reference Manual}, which is an annotated version
+of the Ada 2005 standard. The annotations describe
+detailed aspects of the design decision, and in particular contain useful
+sections on Ada 83 and Ada 95 compatibility.
+
+@item
@cite{DEC Ada, Technical Overview and Comparison on DIGITAL Platforms},
which contains specific information on compatibility between GNAT and
DEC Ada 83 systems.
@chapter Implementation Defined Pragmas
@noindent
-Ada 95 defines a set of pragmas that can be used to supply additional
+Ada defines a set of pragmas that can be used to supply additional
information to the compiler. These language defined pragmas are
-implemented in GNAT and work as described in the Ada 95 Reference
-Manual.
+implemented in GNAT and work as described in the Ada Reference Manual.
-In addition, Ada 95 allows implementations to define additional pragmas
+In addition, Ada allows implementations to define additional pragmas
whose meaning is defined by the implementation. GNAT provides a number
-of these implementation-dependent pragmas which can be used to extend
+of these implementation-defined pragmas, which can be used to extend
and enhance the functionality of the compiler. This section of the GNAT
Reference Manual describes these additional pragmas.
-Note that any program using these pragmas may not be portable to other
+Note that any program using these pragmas might not be portable to other
compilers (although GNAT implements this set of pragmas on all
platforms). Therefore if portability to other compilers is an important
consideration, the use of these pragmas should be minimized.
* Pragma Abort_Defer::
* Pragma Ada_83::
* Pragma Ada_95::
+* Pragma Ada_05::
+* Pragma Ada_2005::
* Pragma Annotate::
* Pragma Assert::
+* Pragma Assume_No_Invalid_Values::
* Pragma Ast_Entry::
* Pragma C_Pass_By_Copy::
+* Pragma Check::
+* Pragma Check_Name::
+* Pragma Check_Policy::
* Pragma Comment::
* Pragma Common_Object::
+* Pragma Compile_Time_Error::
* Pragma Compile_Time_Warning::
+* Pragma Compiler_Unit::
+* Pragma Complete_Representation::
* Pragma Complex_Representation::
* Pragma Component_Alignment::
* Pragma Convention_Identifier::
* Pragma CPP_Virtual::
* Pragma CPP_Vtable::
* Pragma Debug::
+* Pragma Debug_Policy::
+* Pragma Detect_Blocking::
* Pragma Elaboration_Checks::
* Pragma Eliminate::
* Pragma Export_Exception::
* Pragma Extend_System::
* Pragma External::
* Pragma External_Name_Casing::
+* Pragma Fast_Math::
+* Pragma Favor_Top_Level::
* Pragma Finalize_Storage_Only::
* Pragma Float_Representation::
* Pragma Ident::
+* Pragma Implemented_By_Entry::
+* Pragma Implicit_Packing::
* Pragma Import_Exception::
* Pragma Import_Function::
* Pragma Import_Object::
* Pragma License::
* Pragma Link_With::
* Pragma Linker_Alias::
+* Pragma Linker_Constructor::
+* Pragma Linker_Destructor::
* Pragma Linker_Section::
* Pragma Long_Float::
* Pragma Machine_Attribute::
+* Pragma Main::
* Pragma Main_Storage::
+* Pragma No_Body::
* Pragma No_Return::
+* Pragma No_Strict_Aliasing::
* Pragma Normalize_Scalars::
* Pragma Obsolescent::
+* Pragma Optimize_Alignment::
* Pragma Passive::
+* Pragma Persistent_BSS::
* Pragma Polling::
-* Pragma Propagate_Exceptions::
+* Pragma Postcondition::
+* Pragma Precondition::
+* Pragma Profile (Ravenscar)::
+* Pragma Profile (Restricted)::
* Pragma Psect_Object::
* Pragma Pure_Function::
-* Pragma Ravenscar::
-* Pragma Restricted_Run_Time::
* Pragma Restriction_Warnings::
+* Pragma Shared::
+* Pragma Short_Circuit_And_Or::
* Pragma Source_File_Name::
* Pragma Source_File_Name_Project::
* Pragma Source_Reference::
* Pragma Stream_Convert::
* Pragma Style_Checks::
* Pragma Subtitle::
+* Pragma Suppress::
* Pragma Suppress_All::
* Pragma Suppress_Exception_Locations::
* Pragma Suppress_Initialization::
* Pragma Task_Info::
* Pragma Task_Name::
* Pragma Task_Storage::
-* Pragma Thread_Body::
+* Pragma Thread_Local_Storage::
* Pragma Time_Slice::
* Pragma Title::
* Pragma Unchecked_Union::
* Pragma Unimplemented_Unit::
+* Pragma Universal_Aliasing ::
* Pragma Universal_Data::
+* Pragma Unmodified::
* Pragma Unreferenced::
+* Pragma Unreferenced_Objects::
* Pragma Unreserve_All_Interrupts::
* Pragma Unsuppress::
* Pragma Use_VADS_Size::
* Pragma Volatile::
* Pragma Warnings::
* Pragma Weak_External::
+* Pragma Wide_Character_Encoding::
@end menu
@node Pragma Abort_Defer
which it applies, regardless of the mode set by the command line
switches. In Ada 83 mode, GNAT attempts to be as compatible with
the syntax and semantics of Ada 83, as defined in the original Ada
-83 Reference Manual as possible. In particular, the new Ada 95
-keywords are not recognized, optional package bodies are allowed,
+83 Reference Manual as possible. In particular, the keywords added by Ada 95
+and Ada 2005 are not recognized, optional package bodies are allowed,
and generics may name types with unknown discriminants without using
the @code{(<>)} notation. In addition, some but not all of the additional
restrictions of Ada 83 are enforced.
Ada 83 mode is intended for two purposes. Firstly, it allows existing
-legacy Ada 83 code to be compiled and adapted to GNAT with less effort.
+Ada 83 code to be compiled and adapted to GNAT with less effort.
Secondly, it aids in keeping code backwards compatible with Ada 83.
However, there is no guarantee that code that is processed correctly
by GNAT in Ada 83 mode will in fact compile and execute with an Ada
itself uses Ada 95 features, but which is intended to be usable from
either Ada 83 or Ada 95 programs.
+@node Pragma Ada_05
+@unnumberedsec Pragma Ada_05
+@findex Ada_05
+@noindent
+Syntax:
+@smallexample @c ada
+pragma Ada_05;
+@end smallexample
+
+@noindent
+A configuration pragma that establishes Ada 2005 mode for the unit to which
+it applies, regardless of the mode set by the command line switches.
+This mode is set automatically for the @code{Ada} and @code{System}
+packages and their children, so you need not specify it in these
+contexts. This pragma is useful when writing a reusable component that
+itself uses Ada 2005 features, but which is intended to be usable from
+either Ada 83 or Ada 95 programs.
+
+@node Pragma Ada_2005
+@unnumberedsec Pragma Ada_2005
+@findex Ada_2005
+@noindent
+Syntax:
+@smallexample @c ada
+pragma Ada_2005;
+@end smallexample
+
+@noindent
+This configuration pragma is a synonym for pragma Ada_05 and has the
+same syntax and effect.
+
@node Pragma Annotate
@unnumberedsec Pragma Annotate
@findex Annotate
@noindent
Syntax:
@smallexample @c ada
-pragma Annotate (IDENTIFIER @{, ARG@});
+pragma Annotate (IDENTIFIER [,IDENTIFIER] @{, ARG@});
ARG ::= NAME | EXPRESSION
@end smallexample
@noindent
This pragma is used to annotate programs. @var{identifier} identifies
-the type of annotation. GNAT verifies this is an identifier, but does
-not otherwise analyze it. The @var{arg} argument
-can be either a string literal or an
-expression. String literals are assumed to be of type
-@code{Standard.String}. Names of entities are simply analyzed as entity
-names. All other expressions are analyzed as expressions, and must be
+the type of annotation. GNAT verifies that it is an identifier, but does
+not otherwise analyze it. The second optional identifier is also left
+unanalyzed, and by convention is used to control the action of the tool to
+which the annotation is addressed. The remaining @var{arg} arguments
+can be either string literals or more generally expressions.
+String literals are assumed to be either of type
+@code{Standard.String} or else @code{Wide_String} or @code{Wide_Wide_String}
+depending on the character literals they contain.
+All other kinds of arguments are analyzed as expressions, and must be
unambiguous.
The analyzed pragma is retained in the tree, but not otherwise processed
@smallexample @c ada
pragma Assert (
boolean_EXPRESSION
- [, static_string_EXPRESSION]);
+ [, string_EXPRESSION]);
@end smallexample
@noindent
type of the expression is either @code{Standard.Boolean}, or any type derived
from this standard type.
-If assertions are disabled (switch @code{-gnata} not used), then there
-is no effect (and in particular, any side effects from the expression
-are suppressed). More precisely it is not quite true that the pragma
-has no effect, since the expression is analyzed, and may cause types
-to be frozen if they are mentioned here for the first time.
+If assertions are disabled (switch @option{-gnata} not used), then there
+is no run-time effect (and in particular, any side effects from the
+expression will not occur at run time). (The expression is still
+analyzed at compile time, and may cause types to be frozen if they are
+mentioned here for the first time).
If assertions are enabled, then the given expression is tested, and if
it is @code{False} then @code{System.Assertions.Raise_Assert_Failure} is called
which results in the raising of @code{Assert_Failure} with the given message.
-If the boolean expression has side effects, these side effects will turn
-on and off with the setting of the assertions mode, resulting in
-assertions that have an effect on the program. You should generally
-avoid side effects in the expression arguments of this pragma. However,
-the expressions are analyzed for semantic correctness whether or not
-assertions are enabled, so turning assertions on and off cannot affect
-the legality of a program.
+You should generally avoid side effects in the expression arguments of
+this pragma, because these side effects will turn on and off with the
+setting of the assertions mode, resulting in assertions that have an
+effect on the program. However, the expressions are analyzed for
+semantic correctness whether or not assertions are enabled, so turning
+assertions on and off cannot affect the legality of a program.
+
+@node Pragma Assume_No_Invalid_Values
+@unnumberedsec Pragma Assume_No_Invalid_Values
+@findex Assume_No_Invalid_Values
+@cindex Invalid representations
+@cindex Invalid values
+@noindent
+Syntax:
+@smallexample @c ada
+pragma Assume_No_Invalid_Values (On | Off);
+@end smallexample
+
+@noindent
+This is a configuration pragma that controls the assumptions made by the
+compiler about the occurrence of invalid representations (invalid values)
+in the code.
+
+The default behavior (corresponding to an Off argument for this pragma), is
+to assume that values may in general be invalid unless the compiler can
+prove they are valid. Consider the following example:
+
+@smallexample @c ada
+V1 : Integer range 1 .. 10;
+V2 : Integer range 11 .. 20;
+...
+for J in V2 .. V1 loop
+ ...
+end loop;
+@end smallexample
+
+@noindent
+if V1 and V2 have valid values, then the loop is known at compile
+time not to execute since the lower bound must be greater than the
+upper bound. However in default mode, no such assumption is made,
+and the loop may execute. If @code{Assume_No_Invalid_Values (On)}
+is given, the compiler will assume that any occurrence of a variable
+other than in an explicit @code{'Valid} test always has a valid
+value, and the loop above will be optimized away.
+
+The use of @code{Assume_No_Invalid_Values (On)} is appropriate if
+you know your code is free of uninitialized variables and other
+possible sources of invalid representations, and may result in
+more efficient code. A program that accesses an invalid representation
+with this pragma in effect is erroneous, so no guarantees can be made
+about its behavior.
+
+It is peculiar though permissible to use this pragma in conjunction
+with validity checking (-gnatVa). In such cases, accessing invalid
+values will generally give an exception, though formally the program
+is erroneous so there are no guarantees that this will always be the
+case, and it is recommended that these two options not be used together.
@node Pragma Ast_Entry
@unnumberedsec Pragma Ast_Entry
@itemize @bullet
@item
-The size of the record type does not exceed@*@var{static_integer_expression}.
+The size of the record type does not exceed the value specified for
+@code{Max_Size}.
@item
The record type has @code{Convention C}.
@item
@code{Import} and @code{Export} pragmas, which allow specification of
passing mechanisms on a parameter by parameter basis.
+@node Pragma Check
+@unnumberedsec Pragma Check
+@cindex Assertions
+@cindex Named assertions
+@findex Check
+@noindent
+Syntax:
+@smallexample @c ada
+pragma Check (
+ [Name =>] Identifier,
+ [Check =>] Boolean_EXPRESSION
+ [, [Message =>] string_EXPRESSION] );
+@end smallexample
+
+@noindent
+This pragma is similar to the predefined pragma @code{Assert} except that an
+extra identifier argument is present. In conjunction with pragma
+@code{Check_Policy}, this can be used to define groups of assertions that can
+be independently controlled. The identifier @code{Assertion} is special, it
+refers to the normal set of pragma @code{Assert} statements. The identifiers
+@code{Precondition} and @code{Postcondition} correspond to the pragmas of these
+names, so these three names would normally not be used directly in a pragma
+@code{Check}.
+
+Checks introduced by this pragma are normally deactivated by default. They can
+be activated either by the command line option @option{-gnata}, which turns on
+all checks, or individually controlled using pragma @code{Check_Policy}.
+
+@node Pragma Check_Name
+@unnumberedsec Pragma Check_Name
+@cindex Defining check names
+@cindex Check names, defining
+@findex Check_Name
+@noindent
+Syntax:
+@smallexample @c ada
+pragma Check_Name (check_name_IDENTIFIER);
+@end smallexample
+
+@noindent
+This is a configuration pragma that defines a new implementation
+defined check name (unless IDENTIFIER matches one of the predefined
+check names, in which case the pragma has no effect). Check names
+are global to a partition, so if two or more configuration pragmas
+are present in a partition mentioning the same name, only one new
+check name is introduced.
+
+An implementation defined check name introduced with this pragma may
+be used in only three contexts: @code{pragma Suppress},
+@code{pragma Unsuppress},
+and as the prefix of a @code{Check_Name'Enabled} attribute reference. For
+any of these three cases, the check name must be visible. A check
+name is visible if it is in the configuration pragmas applying to
+the current unit, or if it appears at the start of any unit that
+is part of the dependency set of the current unit (e.g., units that
+are mentioned in @code{with} clauses).
+
+@node Pragma Check_Policy
+@unnumberedsec Pragma Check_Policy
+@cindex Controlling assertions
+@cindex Assertions, control
+@cindex Check pragma control
+@cindex Named assertions
+@findex Check
+@noindent
+Syntax:
+@smallexample @c ada
+pragma Check_Policy
+ ([Name =>] Identifier,
+ [Policy =>] POLICY_IDENTIFIER);
+
+POLICY_IDENTIFIER ::= On | Off | Check | Ignore
+@end smallexample
+
+@noindent
+This pragma is similar to the predefined pragma @code{Assertion_Policy},
+except that it controls sets of named assertions introduced using the
+@code{Check} pragmas. It can be used as a configuration pragma or (unlike
+@code{Assertion_Policy}) can be used within a declarative part, in which case
+it controls the status to the end of the corresponding construct (in a manner
+identical to pragma @code{Suppress)}.
+
+The identifier given as the first argument corresponds to a name used in
+associated @code{Check} pragmas. For example, if the pragma:
+
+@smallexample @c ada
+pragma Check_Policy (Critical_Error, Off);
+@end smallexample
+
+@noindent
+is given, then subsequent @code{Check} pragmas whose first argument is also
+@code{Critical_Error} will be disabled. The special identifier @code{Assertion}
+controls the behavior of normal @code{Assert} pragmas (thus a pragma
+@code{Check_Policy} with this identifier is similar to the normal
+@code{Assertion_Policy} pragma except that it can appear within a
+declarative part).
+
+The special identifiers @code{Precondition} and @code{Postcondition} control
+the status of preconditions and postconditions. If a @code{Precondition} pragma
+is encountered, it is ignored if turned off by a @code{Check_Policy} specifying
+that @code{Precondition} checks are @code{Off} or @code{Ignored}. Similarly use
+of the name @code{Postcondition} controls whether @code{Postcondition} pragmas
+are recognized.
+
+The check policy is @code{Off} to turn off corresponding checks, and @code{On}
+to turn on corresponding checks. The default for a set of checks for which no
+@code{Check_Policy} is given is @code{Off} unless the compiler switch
+@option{-gnata} is given, which turns on all checks by default.
+
+The check policy settings @code{Check} and @code{Ignore} are also recognized
+as synonyms for @code{On} and @code{Off}. These synonyms are provided for
+compatibility with the standard @code{Assertion_Policy} pragma.
+
@node Pragma Comment
@unnumberedsec Pragma Comment
@findex Comment
@smallexample @c ada
pragma Common_Object (
- [Internal =>] LOCAL_NAME,
+ [Internal =>] LOCAL_NAME
[, [External =>] EXTERNAL_SYMBOL]
[, [Size =>] EXTERNAL_SYMBOL] );
This pragma enables the shared use of variables stored in overlaid
linker areas corresponding to the use of @code{COMMON}
in Fortran. The single
-object @var{local_name} is assigned to the area designated by
+object @var{LOCAL_NAME} is assigned to the area designated by
the @var{External} argument.
You may define a record to correspond to a series
-of fields. The @var{size} argument
+of fields. The @var{Size} argument
is syntax checked in GNAT, but otherwise ignored.
@code{Common_Object} is not supported on all platforms. If no
indicating that the necessary attribute for implementation of this
pragma is not available.
-@node Pragma Compile_Time_Warning
-@unnumberedsec Pragma Compile_Time_Warning
-@findex Compile_Time_Warning
+@node Pragma Compile_Time_Error
+@unnumberedsec Pragma Compile_Time_Error
+@findex Compile_Time_Error
@noindent
Syntax:
@smallexample @c ada
-pragma Compile_Time_Warning
+pragma Compile_Time_Error
(boolean_EXPRESSION, static_string_EXPRESSION);
@end smallexample
@noindent
-This pragma can be used to generate additional compile time warnings. It
-is particularly useful in generics, where warnings can be issued for
+This pragma can be used to generate additional compile time
+error messages. It
+is particularly useful in generics, where errors can be issued for
specific problematic instantiations. The first parameter is a boolean
expression. The pragma is effective only if the value of this expression
is known at compile time, and has the value True. The set of expressions
whose values are known at compile time includes all static boolean
expressions, and also other values which the compiler can determine
-at compile time (e.g. the size of a record type set by an explicit
+at compile time (e.g., the size of a record type set by an explicit
size representation clause, or the value of a variable which was
initialized to a constant and is known not to have been modified).
-If these conditions are met, a warning message is generated using
+If these conditions are met, an error message is generated using
the value given as the second argument. This string value may contain
embedded ASCII.LF characters to break the message into multiple lines.
+@node Pragma Compile_Time_Warning
+@unnumberedsec Pragma Compile_Time_Warning
+@findex Compile_Time_Warning
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Compile_Time_Warning
+ (boolean_EXPRESSION, static_string_EXPRESSION);
+@end smallexample
+
+@noindent
+Same as pragma Compile_Time_Error, except a warning is issued instead
+of an error message. Note that if this pragma is used in a package that
+is with'ed by a client, the client will get the warning even though it
+is issued by a with'ed package (normally warnings in with'ed units are
+suppressed, but this is a special exception to that rule).
+
+One typical use is within a generic where compile time known characteristics
+of formal parameters are tested, and warnings given appropriately. Another use
+with a first parameter of True is to warn a client about use of a package,
+for example that it is not fully implemented.
+
+@node Pragma Compiler_Unit
+@unnumberedsec Pragma Compiler_Unit
+@findex Compiler_Unit
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Compiler_Unit;
+@end smallexample
+
+@noindent
+This pragma is intended only for internal use in the GNAT run-time library.
+It indicates that the unit is used as part of the compiler build. The effect
+is to disallow constructs (raise with message, conditional expressions etc)
+that would cause trouble when bootstrapping using an older version of GNAT.
+For the exact list of restrictions, see the compiler sources and references
+to Is_Compiler_Unit.
+
+@node Pragma Complete_Representation
+@unnumberedsec Pragma Complete_Representation
+@findex Complete_Representation
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Complete_Representation;
+@end smallexample
+
+@noindent
+This pragma must appear immediately within a record representation
+clause. Typical placements are before the first component clause
+or after the last component clause. The effect is to give an error
+message if any component is missing a component clause. This pragma
+may be used to ensure that a record representation clause is
+complete, and that this invariant is maintained if fields are
+added to the record in the future.
+
@node Pragma Complex_Representation
@unnumberedsec Pragma Complex_Representation
@findex Complex_Representation
@end table
@noindent
-If the @code{Name} parameter is present, @var{type_local_name} must
+If the @code{Name} parameter is present, @var{type_LOCAL_NAME} must
refer to a local record or array type, and the specified alignment
choice applies to the specified type. The use of
@code{Component_Alignment} together with a pragma @code{Pack} causes the
@end smallexample
@noindent
-The argument denotes an entity in the current declarative region
-that is declared as a tagged or untagged record type. It indicates that
-the type corresponds to an externally declared C++ class type, and is to
-be laid out the same way that C++ would lay out the type.
-
-If (and only if) the type is tagged, at least one component in the
-record must be of type @code{Interfaces.CPP.Vtable_Ptr}, corresponding
-to the C++ Vtable (or Vtables in the case of multiple inheritance) used
-for dispatching.
+The argument denotes an entity in the current declarative region that is
+declared as a record type. It indicates that the type corresponds to an
+externally declared C++ class type, and is to be laid out the same way
+that C++ would lay out the type. If the C++ class has virtual primitives
+then the record must be declared as a tagged record type.
Types for which @code{CPP_Class} is specified do not have assignment or
equality operators defined (such operations can be imported or declared
-as subprograms as required). Initialization is allowed only by
-constructor functions (see pragma @code{CPP_Constructor}).
+as subprograms as required). Initialization is allowed only by constructor
+functions (see pragma @code{CPP_Constructor}). Such types are implicitly
+limited if not explicitly declared as limited or derived from a limited
+type, and an error is issued in that case.
Pragma @code{CPP_Class} is intended primarily for automatic generation
using an automatic binding generator tool.
See @ref{Interfacing to C++} for related information.
+Note: Pragma @code{CPP_Class} is currently obsolete. It is supported
+for backward compatibility but its functionality is available
+using pragma @code{Import} with @code{Convention} = @code{CPP}.
+
@node Pragma CPP_Constructor
@unnumberedsec Pragma CPP_Constructor
@cindex Interfacing with C++
Syntax:
@smallexample @c ada
-pragma CPP_Constructor ([Entity =>] LOCAL_NAME);
+pragma CPP_Constructor ([Entity =>] LOCAL_NAME
+ [, [External_Name =>] static_string_EXPRESSION ]
+ [, [Link_Name =>] static_string_EXPRESSION ]);
@end smallexample
@noindent
This pragma identifies an imported function (imported in the usual way
-with pragma @code{Import}) as corresponding to a C++
-constructor. The argument is a name that must have been
-previously mentioned in a pragma @code{Import}
-with @code{Convention} = @code{CPP}, and must be of one of the following
-forms:
+with pragma @code{Import}) as corresponding to a C++ constructor. If
+@code{External_Name} and @code{Link_Name} are not specified then the
+@code{Entity} argument is a name that must have been previously mentioned
+in a pragma @code{Import} with @code{Convention} = @code{CPP}. Such name
+must be of one of the following forms:
+
+@itemize @bullet
+@item
+@code{function @var{Fname} return @var{T}}
@itemize @bullet
@item
@code{function @var{Fname} return @var{T}'Class}
@item
-@code{function @var{Fname} (@dots{}) return @var{T}'Class}
+@code{function @var{Fname} (@dots{}) return @var{T}}
@end itemize
-@noindent
-where @var{T} is a tagged type to which the pragma @code{CPP_Class} applies.
-
-The first form is the default constructor, used when an object of type
-@var{T} is created on the Ada side with no explicit constructor. Other
-constructors (including the copy constructor, which is simply a special
-case of the second form in which the one and only argument is of type
-@var{T}), can only appear in two contexts:
-
-@itemize @bullet
-@item
-On the right side of an initialization of an object of type @var{T}.
@item
-In an extension aggregate for an object of a type derived from @var{T}.
+@code{function @var{Fname} (@dots{}) return @var{T}'Class}
@end itemize
@noindent
-Although the constructor is described as a function that returns a value
-on the Ada side, it is typically a procedure with an extra implicit
-argument (the object being initialized) at the implementation
-level. GNAT issues the appropriate call, whatever it is, to get the
-object properly initialized.
-
-In the case of derived objects, you may use one of two possible forms
-for declaring and creating an object:
+where @var{T} is a limited record type imported from C++ with pragma
+@code{Import} and @code{Convention} = @code{CPP}.
-@itemize @bullet
-@item @code{New_Object : Derived_T}
-@item @code{New_Object : Derived_T := (@var{constructor-call with} @dots{})}
-@end itemize
-
-@noindent
-In the first case the default constructor is called and extension fields
-if any are initialized according to the default initialization
-expressions in the Ada declaration. In the second case, the given
-constructor is called and the extension aggregate indicates the explicit
-values of the extension fields.
+The first two forms import the default constructor, used when an object
+of type @var{T} is created on the Ada side with no explicit constructor.
+The latter two forms cover all the non-default constructors of the type.
+See the GNAT users guide for details.
If no constructors are imported, it is impossible to create any objects
-on the Ada side. If no default constructor is imported, only the
-initialization forms using an explicit call to a constructor are
-permitted.
+on the Ada side and the type is implicitly declared abstract.
Pragma @code{CPP_Constructor} is intended primarily for automatic generation
using an automatic binding generator tool.
See @ref{Interfacing to C++} for more related information.
+Note: The use of functions returning class-wide types for constructors is
+currently obsolete. They are supported for backward compatibility. The
+use of functions returning the type T leave the Ada sources more clear
+because the imported C++ constructors always return an object of type T;
+that is, they never return an object whose type is a descendant of type T.
+
@node Pragma CPP_Virtual
@unnumberedsec Pragma CPP_Virtual
@cindex Interfacing to C++
@findex CPP_Virtual
@noindent
-Syntax:
-
-@smallexample @c ada
-pragma CPP_Virtual
- [Entity =>] ENTITY,
- [, [Vtable_Ptr =>] vtable_ENTITY,]
- [, [Position =>] static_integer_EXPRESSION]);
-@end smallexample
-
-@noindent
-This pragma serves the same function as pragma @code{Import} in that
-case of a virtual function imported from C++. The @var{Entity} argument
-must be a
-primitive subprogram of a tagged type to which pragma @code{CPP_Class}
-applies. The @var{Vtable_Ptr} argument specifies
-the Vtable_Ptr component which contains the
-entry for this virtual function. The @var{Position} argument
-is the sequential number
-counting virtual functions for this Vtable starting at 1.
-
-The @code{Vtable_Ptr} and @code{Position} arguments may be omitted if
-there is one Vtable_Ptr present (single inheritance case) and all
-virtual functions are imported. In that case the compiler can deduce both
-these values.
+This pragma is now obsolete has has no effect because GNAT generates
+the same object layout than the G++ compiler.
-No @code{External_Name} or @code{Link_Name} arguments are required for a
-virtual function, since it is always accessed indirectly via the
-appropriate Vtable entry.
-
-Pragma @code{CPP_Virtual} is intended primarily for automatic generation
-using an automatic binding generator tool.
See @ref{Interfacing to C++} for related information.
@node Pragma CPP_Vtable
@cindex Interfacing with C++
@findex CPP_Vtable
@noindent
-Syntax:
-
-@smallexample @c ada
-pragma CPP_Vtable (
- [Entity =>] ENTITY,
- [Vtable_Ptr =>] vtable_ENTITY,
- [Entry_Count =>] static_integer_EXPRESSION);
-@end smallexample
-
-@noindent
-Given a record to which the pragma @code{CPP_Class} applies,
-this pragma can be specified for each component of type
-@code{CPP.Interfaces.Vtable_Ptr}.
-@var{Entity} is the tagged type, @var{Vtable_Ptr}
-is the record field of type @code{Vtable_Ptr}, and @var{Entry_Count} is
-the number of virtual functions on the C++ side. Not all of these
-functions need to be imported on the Ada side.
+This pragma is now obsolete has has no effect because GNAT generates
+the same object layout than the G++ compiler.
-You may omit the @code{CPP_Vtable} pragma if there is only one
-@code{Vtable_Ptr} component in the record and all virtual functions are
-imported on the Ada side (the default value for the entry count in this
-case is simply the total number of virtual functions).
-
-Pragma @code{CPP_Vtable} is intended primarily for automatic generation
-using an automatic binding generator tool.
See @ref{Interfacing to C++} for related information.
@node Pragma Debug
Syntax:
@smallexample @c ada
-pragma Debug (PROCEDURE_CALL_WITHOUT_SEMICOLON);
+pragma Debug ([CONDITION, ]PROCEDURE_CALL_WITHOUT_SEMICOLON);
PROCEDURE_CALL_WITHOUT_SEMICOLON ::=
PROCEDURE_NAME
@end smallexample
@noindent
-The argument has the syntactic form of an expression, meeting the
-syntactic requirements for pragmas.
+The procedure call argument has the syntactic form of an expression, meeting
+the syntactic requirements for pragmas.
+
+If debug pragmas are not enabled or if the condition is present and evaluates
+to False, this pragma has no effect. If debug pragmas are enabled, the
+semantics of the pragma is exactly equivalent to the procedure call statement
+corresponding to the argument with a terminating semicolon. Pragmas are
+permitted in sequences of declarations, so you can use pragma @code{Debug} to
+intersperse calls to debug procedures in the middle of declarations. Debug
+pragmas can be enabled either by use of the command line switch @option{-gnata}
+or by use of the configuration pragma @code{Debug_Policy}.
+
+@node Pragma Debug_Policy
+@unnumberedsec Pragma Debug_Policy
+@findex Debug_Policy
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Debug_Policy (CHECK | IGNORE);
+@end smallexample
+
+@noindent
+If the argument is @code{CHECK}, then pragma @code{DEBUG} is enabled.
+If the argument is @code{IGNORE}, then pragma @code{DEBUG} is ignored.
+This pragma overrides the effect of the @option{-gnata} switch on the
+command line.
+
+@node Pragma Detect_Blocking
+@unnumberedsec Pragma Detect_Blocking
+@findex Detect_Blocking
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Detect_Blocking;
+@end smallexample
-If assertions are not enabled on the command line, this pragma has no
-effect. If asserts are enabled, the semantics of the pragma is exactly
-equivalent to the procedure call statement corresponding to the argument
-with a terminating semicolon. Pragmas are permitted in sequences of
-declarations, so you can use pragma @code{Debug} to intersperse calls to
-debug procedures in the middle of declarations.
+@noindent
+This is a configuration pragma that forces the detection of potentially
+blocking operations within a protected operation, and to raise Program_Error
+if that happens.
@node Pragma Elaboration_Checks
@unnumberedsec Pragma Elaboration_Checks
Syntax:
@smallexample @c ada
-pragma Elaboration_Checks (RM | Static);
+pragma Elaboration_Checks (Dynamic | Static);
@end smallexample
@noindent
This is a configuration pragma that provides control over the
elaboration model used by the compilation affected by the
-pragma. If the parameter is RM, then the dynamic elaboration
+pragma. If the parameter is @code{Dynamic},
+then the dynamic elaboration
model described in the Ada Reference Manual is used, as though
-the @code{-gnatE} switch had been specified on the command
-line. If the parameter is Static, then the default GNAT static
+the @option{-gnatE} switch had been specified on the command
+line. If the parameter is @code{Static}, then the default GNAT static
model is used. This configuration pragma overrides the setting
of the command line. For full details on the elaboration models
-used by the GNAT compiler, see section ``Elaboration Order
-Handling in GNAT'' in the @cite{GNAT User's Guide}.
+used by the GNAT compiler, see @ref{Elaboration Order Handling in GNAT,,,
+gnat_ugn, @value{EDITION} User's Guide}.
@node Pragma Eliminate
@unnumberedsec Pragma Eliminate
Result_Type => result_SUBTYPE_NAME]
PARAMETER_TYPES ::= (SUBTYPE_NAME @{, SUBTYPE_NAME@})
-SUBTYPE_NAME ::= STRING_LITERAL
+SUBTYPE_NAME ::= STRING_VALUE
SOURCE_LOCATION ::= Source_Location => SOURCE_TRACE
-SOURCE_TRACE ::= STRING_LITERAL
+SOURCE_TRACE ::= STRING_VALUE
+
+STRING_VALUE ::= STRING_LITERAL @{& STRING_LITERAL@}
@end smallexample
@noindent
-
This pragma indicates that the given entity is not used outside the
-compilation unit it is defined in. The entity an explicitly declared
-subprogram, including subprogram declared by subprogram instantiations and
-subprograms declared in package instantiations.
+compilation unit it is defined in. The entity must be an explicitly declared
+subprogram; this includes generic subprogram instances and
+subprograms declared in generic package instances.
If the entity to be eliminated is a library level subprogram, then
the first form of pragma @code{Eliminate} is used with only a single argument.
Use PARAMETER_AND_RESULT_TYPE_PROFILE to specify the profile of the subprogram
to be eliminated in a manner similar to that used for the extended
@code{Import} and @code{Export} pragmas, except that the subtype names are
-always given as string literals. At the moment, this form of distinguishing
+always given as strings. At the moment, this form of distinguishing
overloaded subprograms is implemented only partially, so we do not recommend
using it for practical subprogram elimination.
-Note, that in case of a parameterless procedure its profile is represented
+Note that in case of a parameterless procedure its profile is represented
as @code{Parameter_Types => ("")}
Alternatively, the @code{Source_Location} parameter is used to specify
which overloaded alternative is to be eliminated by pointing to the
location of the DEFINING_PROGRAM_UNIT_NAME of this subprogram in the
-source text. The string literal submitted as SOURCE_TRACE should have
-the following format:
+source text. The string literal (or concatenation of string literals)
+given as SOURCE_TRACE must have the following format:
@smallexample @c ada
SOURCE_TRACE ::= SOURCE_LOCATION@{LBRACKET SOURCE_LOCATION RBRACKET@}
adding lines may make the set of Eliminate pragmas using SOURCE_LOCATION
parameter illegal.
+It is legal to use pragma Eliminate where the referenced entity is a
+dispatching operation, but it is not clear what this would mean, since
+in general the call does not know which entity is actually being called.
+Consequently, a pragma Eliminate for a dispatching operation is ignored.
+
@node Pragma Export_Exception
@unnumberedsec Pragma Export_Exception
@cindex OpenVMS
@smallexample @c ada
pragma Export_Exception (
- [Internal =>] LOCAL_NAME,
- [, [External =>] EXTERNAL_SYMBOL,]
+ [Internal =>] LOCAL_NAME
+ [, [External =>] EXTERNAL_SYMBOL]
[, [Form =>] Ada | VMS]
[, [Code =>] static_integer_EXPRESSION]);
@smallexample @c ada
pragma Export_Function (
- [Internal =>] LOCAL_NAME,
+ [Internal =>] LOCAL_NAME
[, [External =>] EXTERNAL_SYMBOL]
[, [Parameter_Types =>] PARAMETER_TYPES]
[, [Result_Type =>] result_SUBTYPE_MARK]
MECHANISM_NAME ::=
Value
| Reference
+| Descriptor [([Class =>] CLASS_NAME)]
+| Short_Descriptor [([Class =>] CLASS_NAME)]
+
+CLASS_NAME ::= ubs | ubsb | uba | s | sb | a
@end smallexample
@noindent
pragma applies. If more than one function name exists of this name in
the declarative part you must use the @code{Parameter_Types} and
@code{Result_Type} parameters is mandatory to achieve the required
-unique designation. @var{subtype_ mark}s in these parameters must
+unique designation. @var{subtype_mark}s in these parameters must
exactly match the subtypes in the corresponding function specification,
using positional notation to match parameters with subtype marks.
The form with an @code{'Access} attribute can be used to match an
@cindex OpenVMS
@cindex Passing by descriptor
-Note that passing by descriptor is not supported, even on the OpenVMS
-ports of GNAT@.
+Passing by descriptor is supported only on the OpenVMS ports of GNAT@.
+The default behavior for Export_Function is to accept either 64bit or
+32bit descriptors unless short_descriptor is specified, then only 32bit
+descriptors are accepted.
@cindex Suppressing external name
Special treatment is given if the EXTERNAL is an explicit null
@smallexample @c ada
pragma Export_Object
- [Internal =>] LOCAL_NAME,
+ [Internal =>] LOCAL_NAME
[, [External =>] EXTERNAL_SYMBOL]
[, [Size =>] EXTERNAL_SYMBOL]
MECHANISM_NAME ::=
Value
| Reference
+| Descriptor [([Class =>] CLASS_NAME)]
+| Short_Descriptor [([Class =>] CLASS_NAME)]
+
+CLASS_NAME ::= ubs | ubsb | uba | s | sb | a
@end smallexample
@noindent
@cindex OpenVMS
@cindex Passing by descriptor
-Note that passing by descriptor is not supported, even on the OpenVMS
-ports of GNAT@.
+Passing by descriptor is supported only on the OpenVMS ports of GNAT@.
+The default behavior for Export_Procedure is to accept either 64bit or
+32bit descriptors unless short_descriptor is specified, then only 32bit
+descriptors are accepted.
@cindex Suppressing external name
Special treatment is given if the EXTERNAL is an explicit null
MECHANISM_NAME ::=
Value
| Reference
+| Descriptor [([Class =>] CLASS_NAME)]
+| Short_Descriptor [([Class =>] CLASS_NAME)]
+
+CLASS_NAME ::= ubs | ubsb | uba | s | sb | a
@end smallexample
@noindent
This pragma is identical to @code{Export_Procedure} except that the
-first parameter of @var{local_name}, which must be present, must be of
+first parameter of @var{LOCAL_NAME}, which must be present, must be of
mode @code{OUT}, and externally the subprogram is treated as a function
with this parameter as the result of the function. GNAT provides for
this capability to allow the use of @code{OUT} and @code{IN OUT}
@cindex OpenVMS
@cindex Passing by descriptor
-Note that passing by descriptor is not supported, even on the OpenVMS
-ports of GNAT@.
+Passing by descriptor is supported only on the OpenVMS ports of GNAT@.
+The default behavior for Export_Valued_Procedure is to accept either 64bit or
+32bit descriptors unless short_descriptor is specified, then only 32bit
+descriptors are accepted.
@cindex Suppressing external name
Special treatment is given if the EXTERNAL is an explicit null
This pragma is used to provide backwards compatibility with other
implementations that extend the facilities of package @code{System}. In
GNAT, @code{System} contains only the definitions that are present in
-the Ada 95 RM@. However, other implementations, notably the DEC Ada 83
+the Ada RM@. However, other implementations, notably the DEC Ada 83
implementation, provide many extensions to package @code{System}.
For each such implementation accommodated by this pragma, GNAT provides a
definition. Note that such a package is a child of @code{System}
and thus is considered part of the implementation. To compile
it you will have to use the appropriate switch for compiling
-system units. See the GNAT User's Guide for details.
+system units. @xref{Top, @value{EDITION} User's Guide, About This
+Guide,, gnat_ugn, @value{EDITION} User's Guide}, for details.
@node Pragma External
@unnumberedsec Pragma External
@smallexample @c ada
pragma External (
[ Convention =>] convention_IDENTIFIER,
- [ Entity =>] local_NAME
+ [ Entity =>] LOCAL_NAME
[, [External_Name =>] static_string_EXPRESSION ]
[, [Link_Name =>] static_string_EXPRESSION ]);
@end smallexample
@table @asis
@item Implicit external names
Implicit external names are derived from identifiers. The most common case
-arises when a standard Ada 95 Import or Export pragma is used with only two
+arises when a standard Ada Import or Export pragma is used with only two
arguments, as in:
@smallexample @c ada
@end smallexample
@noindent
-Since Ada is a case insensitive language, the spelling of the identifier in
+Since Ada is a case-insensitive language, the spelling of the identifier in
the Ada source program does not provide any information on the desired
casing of the external name, and so a convention is needed. In GNAT the
default treatment is that such names are converted to all lower case
@item Explicit external names
Explicit external names are given as string literals. The most common case
-arises when a standard Ada 95 Import or Export pragma is used with three
+arises when a standard Ada Import or Export pragma is used with three
arguments, as in:
@smallexample @c ada
@noindent
to enforce the upper casing of all external symbols.
+@node Pragma Fast_Math
+@unnumberedsec Pragma Fast_Math
+@findex Fast_Math
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Fast_Math;
+@end smallexample
+
+@noindent
+This is a configuration pragma which activates a mode in which speed is
+considered more important for floating-point operations than absolutely
+accurate adherence to the requirements of the standard. Currently the
+following operations are affected:
+
+@table @asis
+@item Complex Multiplication
+The normal simple formula for complex multiplication can result in intermediate
+overflows for numbers near the end of the range. The Ada standard requires that
+this situation be detected and corrected by scaling, but in Fast_Math mode such
+cases will simply result in overflow. Note that to take advantage of this you
+must instantiate your own version of @code{Ada.Numerics.Generic_Complex_Types}
+under control of the pragma, rather than use the preinstantiated versions.
+@end table
+
+@node Pragma Favor_Top_Level
+@unnumberedsec Pragma Favor_Top_Level
+@findex Favor_Top_Level
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Favor_Top_Level (type_NAME);
+@end smallexample
+
+@noindent
+The named type must be an access-to-subprogram type. This pragma is an
+efficiency hint to the compiler, regarding the use of 'Access or
+'Unrestricted_Access on nested (non-library-level) subprograms. The
+pragma means that nested subprograms are not used with this type, or
+are rare, so that the generated code should be efficient in the
+top-level case. When this pragma is used, dynamically generated
+trampolines may be used on some targets for nested subprograms.
+See also the No_Implicit_Dynamic_Code restriction.
+
@node Pragma Finalize_Storage_Only
@unnumberedsec Pragma Finalize_Storage_Only
@findex Finalize_Storage_Only
Syntax:
@smallexample @c ada
-pragma Float_Representation (FLOAT_REP);
+pragma Float_Representation (FLOAT_REP[, float_type_LOCAL_NAME]);
FLOAT_REP ::= VAX_Float | IEEE_Float
@end smallexample
@noindent
-This pragma
+In the one argument form, this pragma is a configuration pragma which
allows control over the internal representation chosen for the predefined
floating point types declared in the packages @code{Standard} and
@code{System}. On all systems other than OpenVMS, the argument must
be @code{IEEE_Float} and the pragma has no effect. On OpenVMS, the
argument may be @code{VAX_Float} to specify the use of the VAX float
format for the floating-point types in Standard. This requires that
-the standard runtime libraries be recompiled. See the
-description of the @code{GNAT LIBRARY} command in the OpenVMS version
-of the GNAT Users Guide for details on the use of this command.
+the standard runtime libraries be recompiled. @xref{The GNAT Run-Time
+Library Builder gnatlbr,,, gnat_ugn, @value{EDITION} User's Guide
+OpenVMS}, for a description of the @code{GNAT LIBRARY} command.
+
+The two argument form specifies the representation to be used for
+the specified floating-point type. On all systems other than OpenVMS,
+the argument must
+be @code{IEEE_Float} and the pragma has no effect. On OpenVMS, the
+argument may be @code{VAX_Float} to specify the use of the VAX float
+format, as follows:
+
+@itemize @bullet
+@item
+For digits values up to 6, F float format will be used.
+@item
+For digits values from 7 to 9, G float format will be used.
+@item
+For digits values from 10 to 15, F float format will be used.
+@item
+Digits values above 15 are not allowed.
+@end itemize
@node Pragma Ident
@unnumberedsec Pragma Ident
maintain compatibility with this compiler, you should obey this length
limit.
-@node Pragma Import_Exception
-@unnumberedsec Pragma Import_Exception
-@cindex OpenVMS
-@findex Import_Exception
+@node Pragma Implemented_By_Entry
+@unnumberedsec Pragma Implemented_By_Entry
+@findex Implemented_By_Entry
@noindent
Syntax:
@smallexample @c ada
-pragma Import_Exception (
- [Internal =>] LOCAL_NAME,
- [, [External =>] EXTERNAL_SYMBOL,]
- [, [Form =>] Ada | VMS]
- [, [Code =>] static_integer_EXPRESSION]);
+pragma Implemented_By_Entry (LOCAL_NAME);
+@end smallexample
-EXTERNAL_SYMBOL ::=
- IDENTIFIER
-| static_string_EXPRESSION
+@noindent
+This is a representation pragma which applies to protected, synchronized and
+task interface primitives. If the pragma is applied to primitive operation Op
+of interface Iface, it is illegal to override Op in a type that implements
+Iface, with anything other than an entry.
+
+@smallexample @c ada
+type Iface is protected interface;
+procedure Do_Something (Object : in out Iface) is abstract;
+pragma Implemented_By_Entry (Do_Something);
+
+protected type P is new Iface with
+ procedure Do_Something; -- Illegal
+end P;
+
+task type T is new Iface with
+ entry Do_Something; -- Legal
+end T;
@end smallexample
@noindent
-This pragma is implemented only in the OpenVMS implementation of GNAT@.
-It allows OpenVMS conditions (for example, from OpenVMS system services or
-other OpenVMS languages) to be propagated to Ada programs as Ada exceptions.
-The pragma specifies that the exception associated with an exception
-declaration in an Ada program be defined externally (in non-Ada code).
-For further details on this pragma, see the
-DEC Ada Language Reference Manual, section 13.9a.3.1.
+NOTE: The pragma is still in its design stage by the Ada Rapporteur Group. It
+is intended to be used in conjunction with dispatching requeue statements as
+described in AI05-0030. Should the ARG decide on an official name and syntax,
+this pragma will become language-defined rather than GNAT-specific.
-@node Pragma Import_Function
-@unnumberedsec Pragma Import_Function
-@findex Import_Function
+@node Pragma Implicit_Packing
+@unnumberedsec Pragma Implicit_Packing
+@findex Implicit_Packing
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Implicit_Packing;
+@end smallexample
+
+@noindent
+This is a configuration pragma that requests implicit packing for packed
+arrays for which a size clause is given but no explicit pragma Pack or
+specification of Component_Size is present. It also applies to records
+where no record representation clause is present. Consider this example:
+
+@smallexample @c ada
+type R is array (0 .. 7) of Boolean;
+for R'Size use 8;
+@end smallexample
+
+@noindent
+In accordance with the recommendation in the RM (RM 13.3(53)), a Size clause
+does not change the layout of a composite object. So the Size clause in the
+above example is normally rejected, since the default layout of the array uses
+8-bit components, and thus the array requires a minimum of 64 bits.
+
+If this declaration is compiled in a region of code covered by an occurrence
+of the configuration pragma Implicit_Packing, then the Size clause in this
+and similar examples will cause implicit packing and thus be accepted. For
+this implicit packing to occur, the type in question must be an array of small
+components whose size is known at compile time, and the Size clause must
+specify the exact size that corresponds to the length of the array multiplied
+by the size in bits of the component type.
+@cindex Array packing
+
+Similarly, the following example shows the use in the record case
+
+@smallexample @c ada
+type r is record
+ a, b, c, d, e, f, g, h : boolean;
+ chr : character;
+end record;
+for r'size use 16;
+@end smallexample
+
+@noindent
+Without a pragma Pack, each Boolean field requires 8 bits, so the
+minimum size is 72 bits, but with a pragma Pack, 16 bits would be
+sufficient. The use of pragma Implciit_Packing allows this record
+declaration to compile without an explicit pragma Pack.
+@node Pragma Import_Exception
+@unnumberedsec Pragma Import_Exception
+@cindex OpenVMS
+@findex Import_Exception
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Import_Exception (
+ [Internal =>] LOCAL_NAME
+ [, [External =>] EXTERNAL_SYMBOL]
+ [, [Form =>] Ada | VMS]
+ [, [Code =>] static_integer_EXPRESSION]);
+
+EXTERNAL_SYMBOL ::=
+ IDENTIFIER
+| static_string_EXPRESSION
+@end smallexample
+
+@noindent
+This pragma is implemented only in the OpenVMS implementation of GNAT@.
+It allows OpenVMS conditions (for example, from OpenVMS system services or
+other OpenVMS languages) to be propagated to Ada programs as Ada exceptions.
+The pragma specifies that the exception associated with an exception
+declaration in an Ada program be defined externally (in non-Ada code).
+For further details on this pragma, see the
+DEC Ada Language Reference Manual, section 13.9a.3.1.
+
+@node Pragma Import_Function
+@unnumberedsec Pragma Import_Function
+@findex Import_Function
@noindent
Syntax:
Value
| Reference
| Descriptor [([Class =>] CLASS_NAME)]
+| Short_Descriptor [([Class =>] CLASS_NAME)]
CLASS_NAME ::= ubs | ubsb | uba | s | sb | a | nca
@end smallexample
@cindex OpenVMS
@cindex Passing by descriptor
Passing by descriptor is supported only on the OpenVMS ports of GNAT@.
+The default behavior for Import_Function is to pass a 64bit descriptor
+unless short_descriptor is specified, then a 32bit descriptor is passed.
@code{First_Optional_Parameter} applies only to OpenVMS ports of GNAT@.
It specifies that the designated parameter and all following parameters
@smallexample @c ada
pragma Import_Object
- [Internal =>] LOCAL_NAME,
- [, [External =>] EXTERNAL_SYMBOL],
+ [Internal =>] LOCAL_NAME
+ [, [External =>] EXTERNAL_SYMBOL]
[, [Size =>] EXTERNAL_SYMBOL]);
EXTERNAL_SYMBOL ::=
@smallexample @c ada
pragma Import_Procedure (
- [Internal =>] LOCAL_NAME,
+ [Internal =>] LOCAL_NAME
[, [External =>] EXTERNAL_SYMBOL]
[, [Parameter_Types =>] PARAMETER_TYPES]
[, [Mechanism =>] MECHANISM]
Value
| Reference
| Descriptor [([Class =>] CLASS_NAME)]
+| Short_Descriptor [([Class =>] CLASS_NAME)]
CLASS_NAME ::= ubs | ubsb | uba | s | sb | a | nca
@end smallexample
@smallexample @c ada
pragma Import_Valued_Procedure (
- [Internal =>] LOCAL_NAME,
+ [Internal =>] LOCAL_NAME
[, [External =>] EXTERNAL_SYMBOL]
[, [Parameter_Types =>] PARAMETER_TYPES]
[, [Mechanism =>] MECHANISM]
Value
| Reference
| Descriptor [([Class =>] CLASS_NAME)]
+| Short_Descriptor [([Class =>] CLASS_NAME)]
CLASS_NAME ::= ubs | ubsb | uba | s | sb | a | nca
@end smallexample
@noindent
This pragma is identical to @code{Import_Procedure} except that the
-first parameter of @var{local_name}, which must be present, must be of
+first parameter of @var{LOCAL_NAME}, which must be present, must be of
mode @code{OUT}, and externally the subprogram is treated as a function
with this parameter as the result of the function. The purpose of this
capability is to allow the use of @code{OUT} and @code{IN OUT}
whether the variable is initialized may also depend on whether the package
in which the type of the variable is declared is compiled with the pragma.
-The other important difference is that there is control over the value used
-for initializing scalar objects. At bind time, you can select whether to
-initialize with invalid values (like Normalize_Scalars), or with high or
+The other important difference is that you can control the value used
+for initializing scalar objects. At bind time, you can select several
+options for initialization. You can
+initialize with invalid values (similar to Normalize_Scalars, though for
+Initialize_Scalars it is not always possible to determine the invalid
+values in complex cases like signed component fields with non-standard
+sizes). You can also initialize with high or
low values, or with a specified bit pattern. See the users guide for binder
options for specifying these cases.
and if it does, then most likely you have an erroneous reference to an
uninitialized value.
+It is even possible to change the value at execution time eliminating even
+the need to rebind with a different switch using an environment variable.
+See the GNAT users guide for details.
+
Note that pragma @code{Initialize_Scalars} is particularly useful in
conjunction with the enhanced validity checking that is now provided
in GNAT, which checks for invalid values under more conditions.
-Using this feature (see description of the @code{-gnatV} flag in the
+Using this feature (see description of the @option{-gnatV} flag in the
users guide) in conjunction with pragma @code{Initialize_Scalars}
provides a powerful new tool to assist in the detection of problems
caused by uninitialized variables.
+Note: the use of @code{Initialize_Scalars} has a fairly extensive
+effect on the generated code. This may cause your code to be
+substantially larger. It may also cause an increase in the amount
+of stack required, so it is probably a good idea to turn on stack
+checking (see description of stack checking in the GNAT users guide)
+when using this pragma.
+
@node Pragma Inline_Always
@unnumberedsec Pragma Inline_Always
@findex Inline_Always
@noindent
Similar to pragma @code{Inline} except that inlining is not subject to
-the use of option @code{-gnatn} and the inlining happens regardless of
+the use of option @option{-gnatn} and the inlining happens regardless of
whether this option is used.
@node Pragma Inline_Generic
@smallexample @c ada
pragma Interface (
[Convention =>] convention_identifier,
- [Entity =>] local_name
- [, [External_Name =>] static_string_expression],
+ [Entity =>] local_NAME
+ [, [External_Name =>] static_string_expression]
[, [Link_Name =>] static_string_expression]);
@end smallexample
@noindent
This pragma is identical in syntax and semantics to
-the standard Ada 95 pragma @code{Import}. It is provided for compatibility
+the standard Ada pragma @code{Import}. It is provided for compatibility
with Ada 83. The definition is upwards compatible both with pragma
@code{Interface} as defined in the Ada 83 Reference Manual, and also
with some extended implementations of this pragma in certain Ada 83
Syntax:
@smallexample @c ada
-pragma Interrupt_State (Name => value, State => SYSTEM | RUNTIME | USER);
+pragma Interrupt_State
+ ([Name =>] value,
+ [State =>] SYSTEM | RUNTIME | USER);
@end smallexample
@noindent
Note that certain signals on many operating systems cannot be caught and
handled by applications. In such cases, the pragma is ignored. See the
operating system documentation, or the value of the array @code{Reserved}
-declared in the specification of package @code{System.OS_Interface}.
+declared in the spec of package @code{System.OS_Interface}.
Overriding the default state of signals used by the Ada runtime may interfere
with an application's runtime behavior in the cases of the synchronous signals,
This is used for a unit licensed under the GNAT modified GPL that includes
a special exception paragraph that specifically permits the inclusion of
the unit in programs without requiring the entire program to be released
-under the GPL@. This is the license used for the GNAT run-time which ensures
-that the run-time can be used freely in any program without GPL concerns.
+under the GPL@.
@item Restricted
This is used for a unit that is restricted in that it is not permitted to
@smallexample @c ada
pragma Linker_Alias (
- [Entity =>] LOCAL_NAME
- [Alias =>] static_string_EXPRESSION);
+ [Entity =>] LOCAL_NAME,
+ [Target =>] static_string_EXPRESSION);
+@end smallexample
+
+@noindent
+@var{LOCAL_NAME} must refer to an object that is declared at the library
+level. This pragma establishes the given entity as a linker alias for the
+given target. It is equivalent to @code{__attribute__((alias))} in GNU C
+and causes @var{LOCAL_NAME} to be emitted as an alias for the symbol
+@var{static_string_EXPRESSION} in the object file, that is to say no space
+is reserved for @var{LOCAL_NAME} by the assembler and it will be resolved
+to the same address as @var{static_string_EXPRESSION} by the linker.
+
+The actual linker name for the target must be used (e.g.@: the fully
+encoded name with qualification in Ada, or the mangled name in C++),
+or it must be declared using the C convention with @code{pragma Import}
+or @code{pragma Export}.
+
+Not all target machines support this pragma. On some of them it is accepted
+only if @code{pragma Weak_External} has been applied to @var{LOCAL_NAME}.
+
+@smallexample @c ada
+-- Example of the use of pragma Linker_Alias
+
+package p is
+ i : Integer := 1;
+ pragma Export (C, i);
+
+ new_name_for_i : Integer;
+ pragma Linker_Alias (new_name_for_i, "i");
+end p;
+@end smallexample
+
+@node Pragma Linker_Constructor
+@unnumberedsec Pragma Linker_Constructor
+@findex Linker_Constructor
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Linker_Constructor (procedure_LOCAL_NAME);
+@end smallexample
+
+@noindent
+@var{procedure_LOCAL_NAME} must refer to a parameterless procedure that
+is declared at the library level. A procedure to which this pragma is
+applied will be treated as an initialization routine by the linker.
+It is equivalent to @code{__attribute__((constructor))} in GNU C and
+causes @var{procedure_LOCAL_NAME} to be invoked before the entry point
+of the executable is called (or immediately after the shared library is
+loaded if the procedure is linked in a shared library), in particular
+before the Ada run-time environment is set up.
+
+Because of these specific contexts, the set of operations such a procedure
+can perform is very limited and the type of objects it can manipulate is
+essentially restricted to the elementary types. In particular, it must only
+contain code to which pragma Restrictions (No_Elaboration_Code) applies.
+
+This pragma is used by GNAT to implement auto-initialization of shared Stand
+Alone Libraries, which provides a related capability without the restrictions
+listed above. Where possible, the use of Stand Alone Libraries is preferable
+to the use of this pragma.
+
+@node Pragma Linker_Destructor
+@unnumberedsec Pragma Linker_Destructor
+@findex Linker_Destructor
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Linker_Destructor (procedure_LOCAL_NAME);
@end smallexample
@noindent
-This pragma establishes a linker alias for the given named entity. For
-further details on the exact effect, consult the GCC manual.
+@var{procedure_LOCAL_NAME} must refer to a parameterless procedure that
+is declared at the library level. A procedure to which this pragma is
+applied will be treated as a finalization routine by the linker.
+It is equivalent to @code{__attribute__((destructor))} in GNU C and
+causes @var{procedure_LOCAL_NAME} to be invoked after the entry point
+of the executable has exited (or immediately before the shared library
+is unloaded if the procedure is linked in a shared library), in particular
+after the Ada run-time environment is shut down.
+
+See @code{pragma Linker_Constructor} for the set of restrictions that apply
+because of these specific contexts.
@node Pragma Linker_Section
@unnumberedsec Pragma Linker_Section
@smallexample @c ada
pragma Linker_Section (
- [Entity =>] LOCAL_NAME
+ [Entity =>] LOCAL_NAME,
[Section =>] static_string_EXPRESSION);
@end smallexample
@noindent
-This pragma specifies the name of the linker section for the given entity.
-For further details on the exact effect, consult the GCC manual.
+@var{LOCAL_NAME} must refer to an object that is declared at the library
+level. This pragma specifies the name of the linker section for the given
+entity. It is equivalent to @code{__attribute__((section))} in GNU C and
+causes @var{LOCAL_NAME} to be placed in the @var{static_string_EXPRESSION}
+section of the executable (assuming the linker doesn't rename the section).
+
+The compiler normally places library-level objects in standard sections
+depending on their type: procedures and functions generally go in the
+@code{.text} section, initialized variables in the @code{.data} section
+and uninitialized variables in the @code{.bss} section.
+
+Other, special sections may exist on given target machines to map special
+hardware, for example I/O ports or flash memory. This pragma is a means to
+defer the final layout of the executable to the linker, thus fully working
+at the symbolic level with the compiler.
+
+Some file formats do not support arbitrary sections so not all target
+machines support this pragma. The use of this pragma may cause a program
+execution to be erroneous if it is used to place an entity into an
+inappropriate section (e.g.@: a modified variable into the @code{.text}
+section). See also @code{pragma Persistent_BSS}.
+
+@smallexample @c ada
+-- Example of the use of pragma Linker_Section
+
+package IO_Card is
+ Port_A : Integer;
+ pragma Volatile (Port_A);
+ pragma Linker_Section (Port_A, ".bss.port_a");
+
+ Port_B : Integer;
+ pragma Volatile (Port_B);
+ pragma Linker_Section (Port_B, ".bss.port_b");
+end IO_Card;
+@end smallexample
@node Pragma Long_Float
@unnumberedsec Pragma Long_Float
@code{digits} specified in the range 7 through 15.
For further details on this pragma, see the
@cite{DEC Ada Language Reference Manual}, section 3.5.7b. Note that to use
-this pragma, the standard runtime libraries must be recompiled. See the
-description of the @code{GNAT LIBRARY} command in the OpenVMS version
-of the GNAT User's Guide for details on the use of this command.
+this pragma, the standard runtime libraries must be recompiled.
+@xref{The GNAT Run-Time Library Builder gnatlbr,,, gnat_ugn,
+@value{EDITION} User's Guide OpenVMS}, for a description of the
+@code{GNAT LIBRARY} command.
@node Pragma Machine_Attribute
@unnumberedsec Pragma Machine_Attribute
@smallexample @c ada
pragma Machine_Attribute (
- [Attribute_Name =>] string_EXPRESSION,
- [Entity =>] LOCAL_NAME);
+ [Entity =>] LOCAL_NAME,
+ [Attribute_Name =>] static_string_EXPRESSION
+ [, [Info =>] static_EXPRESSION] );
@end smallexample
@noindent
-Machine dependent attributes can be specified for types and/or
-declarations. Currently only subprogram entities are supported. This
-pragma is semantically equivalent to
-@code{__attribute__((@var{string_expression}))} in GNU C,
-where @code{@var{string_expression}} is
-recognized by the GNU C macros @code{VALID_MACHINE_TYPE_ATTRIBUTE} and
-@code{VALID_MACHINE_DECL_ATTRIBUTE} which are defined in the
-configuration header file @file{tm.h} for each machine. See the GCC
-manual for further information.
+Machine-dependent attributes can be specified for types and/or
+declarations. This pragma is semantically equivalent to
+@code{__attribute__((@var{attribute_name}))} (if @var{info} is not
+specified) or @code{__attribute__((@var{attribute_name}(@var{info})))}
+in GNU C, where @code{@var{attribute_name}} is recognized by the
+compiler middle-end or the @code{TARGET_ATTRIBUTE_TABLE} machine
+specific macro. A string literal for the optional parameter @var{info}
+is transformed into an identifier, which may make this pragma unusable
+for some attributes. @xref{Target Attributes,, Defining target-specific
+uses of @code{__attribute__}, gccint, GNU Compiler Collection (GCC)
+Internals}, further information.
+
+@node Pragma Main
+@unnumberedsec Pragma Main
+@cindex OpenVMS
+@findex Main
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Main
+ (MAIN_OPTION [, MAIN_OPTION]);
+
+MAIN_OPTION ::=
+ [Stack_Size =>] static_integer_EXPRESSION
+| [Task_Stack_Size_Default =>] static_integer_EXPRESSION
+| [Time_Slicing_Enabled =>] static_boolean_EXPRESSION
+@end smallexample
+
+@noindent
+This pragma is provided for compatibility with OpenVMS VAX Systems. It has
+no effect in GNAT, other than being syntax checked.
@node Pragma Main_Storage
@unnumberedsec Pragma Main_Storage
MAIN_STORAGE_OPTION ::=
[WORKING_STORAGE =>] static_SIMPLE_EXPRESSION
| [TOP_GUARD =>] static_SIMPLE_EXPRESSION
-
@end smallexample
@noindent
no effect in GNAT, other than being syntax checked. Note that the pragma
also has no effect in DEC Ada 83 for OpenVMS Alpha Systems.
+@node Pragma No_Body
+@unnumberedsec Pragma No_Body
+@findex No_Body
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma No_Body;
+@end smallexample
+
+@noindent
+There are a number of cases in which a package spec does not require a body,
+and in fact a body is not permitted. GNAT will not permit the spec to be
+compiled if there is a body around. The pragma No_Body allows you to provide
+a body file, even in a case where no body is allowed. The body file must
+contain only comments and a single No_Body pragma. This is recognized by
+the compiler as indicating that no body is logically present.
+
+This is particularly useful during maintenance when a package is modified in
+such a way that a body needed before is no longer needed. The provision of a
+dummy body with a No_Body pragma ensures that there is no interference from
+earlier versions of the package body.
+
@node Pragma No_Return
@unnumberedsec Pragma No_Return
@findex No_Return
Syntax:
@smallexample @c ada
-pragma No_Return (procedure_LOCAL_NAME);
+pragma No_Return (procedure_LOCAL_NAME @{, procedure_LOCAL_NAME@});
@end smallexample
@noindent
-@var{procedure_local_NAME} must refer to one or more procedure
+Each @var{procedure_LOCAL_NAME} argument must refer to one or more procedure
declarations in the current declarative part. A procedure to which this
-pragma is applied may not contain any explicit @code{return} statements,
-and also may not contain any implicit return statements from falling off
-the end of a statement sequence. One use of this pragma is to identify
-procedures whose only purpose is to raise an exception.
-
-Another use of this pragma is to suppress incorrect warnings about
-missing returns in functions, where the last statement of a function
+pragma is applied may not contain any explicit @code{return} statements.
+In addition, if the procedure contains any implicit returns from falling
+off the end of a statement sequence, then execution of that implicit
+return will cause Program_Error to be raised.
+
+One use of this pragma is to identify procedures whose only purpose is to raise
+an exception. Another use of this pragma is to suppress incorrect warnings
+about missing returns in functions, where the last statement of a function
statement sequence is a call to such a procedure.
+Note that in Ada 2005 mode, this pragma is part of the language, and is
+identical in effect to the pragma as implemented in Ada 95 mode.
+
+@node Pragma No_Strict_Aliasing
+@unnumberedsec Pragma No_Strict_Aliasing
+@findex No_Strict_Aliasing
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma No_Strict_Aliasing [([Entity =>] type_LOCAL_NAME)];
+@end smallexample
+
+@noindent
+@var{type_LOCAL_NAME} must refer to an access type
+declaration in the current declarative part. The effect is to inhibit
+strict aliasing optimization for the given type. The form with no
+arguments is a configuration pragma which applies to all access types
+declared in units to which the pragma applies. For a detailed
+description of the strict aliasing optimization, and the situations
+in which it must be suppressed, see @ref{Optimization and Strict
+Aliasing,,, gnat_ugn, @value{EDITION} User's Guide}.
+
@node Pragma Normalize_Scalars
@unnumberedsec Pragma Normalize_Scalars
@findex Normalize_Scalars
@item Standard.Character
@noindent
Objects whose root type is Standard.Character are initialized to
-Character'Last. This will be out of range of the subtype only if
-the subtype range excludes this value.
+Character'Last unless the subtype range excludes NUL (in which case
+NUL is used). This choice will always generate an invalid value if
+one exists.
@item Standard.Wide_Character
@noindent
Objects whose root type is Standard.Wide_Character are initialized to
-Wide_Character'Last. This will be out of range of the subtype only if
-the subtype range excludes this value.
+Wide_Character'Last unless the subtype range excludes NUL (in which case
+NUL is used). This choice will always generate an invalid value if
+one exists.
-@item Integer types
+@item Standard.Wide_Wide_Character
@noindent
-Objects of an integer type are initialized to base_type'First, where
-base_type is the base type of the object type. This will be out of range
-of the subtype only if the subtype range excludes this value. For example,
-if you declare the subtype:
-
-@smallexample @c ada
-subtype Ityp is integer range 1 .. 10;
-@end smallexample
+Objects whose root type is Standard.Wide_Wide_Character are initialized to
+the invalid value 16#FFFF_FFFF# unless the subtype range excludes NUL (in
+which case NUL is used). This choice will always generate an invalid value if
+one exists.
+@item Integer types
@noindent
-then objects of type x will be initialized to Integer'First, a negative
-number that is certainly outside the range of subtype @code{Ityp}.
-
-@item Real types
-Objects of all real types (fixed and floating) are initialized to
-base_type'First, where base_Type is the base type of the object type.
-This will be out of range of the subtype only if the subtype range
-excludes this value.
+Objects of an integer type are treated differently depending on whether
+negative values are present in the subtype. If no negative values are
+present, then all one bits is used as the initial value except in the
+special case where zero is excluded from the subtype, in which case
+all zero bits are used. This choice will always generate an invalid
+value if one exists.
+
+For subtypes with negative values present, the largest negative number
+is used, except in the unusual case where this largest negative number
+is in the subtype, and the largest positive number is not, in which case
+the largest positive value is used. This choice will always generate
+an invalid value if one exists.
+
+@item Floating-Point Types
+Objects of all floating-point types are initialized to all 1-bits. For
+standard IEEE format, this corresponds to a NaN (not a number) which is
+indeed an invalid value.
+
+@item Fixed-Point Types
+Objects of all fixed-point types are treated as described above for integers,
+with the rules applying to the underlying integer value used to represent
+the fixed-point value.
@item Modular types
-Objects of a modular type are initialized to typ'Last. This will be out
-of range of the subtype only if the subtype excludes this value.
+Objects of a modular type are initialized to all one bits, except in
+the special case where zero is excluded from the subtype, in which
+case all zero bits are used. This choice will always generate an
+invalid value if one exists.
@item Enumeration types
Objects of an enumeration type are initialized to all one-bits, i.e.@: to
-the value @code{2 ** typ'Size - 1}. This will be out of range of the
-enumeration subtype in all cases except where the subtype contains
-exactly 2**8, 2**16, or 2**32 elements.
+the value @code{2 ** typ'Size - 1} unless the subtype excludes the literal
+whose Pos value is zero, in which case a code of zero is used. This choice
+will always generate an invalid value if one exists.
@end table
Syntax:
@smallexample @c ada
-pragma Obsolescent [(static_string_EXPRESSION)];
+pragma Obsolescent;
+
+pragma Obsolescent (
+ [Message =>] static_string_EXPRESSION
+[,[Version =>] Ada_05]]);
+
+pragma Obsolescent (
+ [Entity =>] NAME
+[,[Message =>] static_string_EXPRESSION
+[,[Version =>] Ada_05]] );
@end smallexample
@noindent
-This pragma must occur immediately following a subprogram
-declaration. It indicates that the associated function or procedure
+This pragma can occur immediately following a declaration of an entity,
+including the case of a record component. If no Entity argument is present,
+then this declaration is the one to which the pragma applies. If an Entity
+parameter is present, it must either match the name of the entity in this
+declaration, or alternatively, the pragma can immediately follow an enumeration
+type declaration, where the Entity argument names one of the enumeration
+literals.
+
+This pragma is used to indicate that the named entity
is considered obsolescent and should not be used. Typically this is
used when an API must be modified by eventually removing or modifying
-existing subprograms. The pragma can be used at an intermediate stage
-when the subprogram is still present, but will be removed later.
+existing subprograms or other entities. The pragma can be used at an
+intermediate stage when the entity is still present, but will be
+removed later.
+
+The effect of this pragma is to output a warning message on a reference to
+an entity thus marked that the subprogram is obsolescent if the appropriate
+warning option in the compiler is activated. If the Message parameter is
+present, then a second warning message is given containing this text. In
+addition, a reference to the eneity is considered to be a violation of pragma
+Restrictions (No_Obsolescent_Features).
+
+This pragma can also be used as a program unit pragma for a package,
+in which case the entity name is the name of the package, and the
+pragma indicates that the entire package is considered
+obsolescent. In this case a client @code{with}'ing such a package
+violates the restriction, and the @code{with} statement is
+flagged with warnings if the warning option is set.
+
+If the Version parameter is present (which must be exactly
+the identifier Ada_05, no other argument is allowed), then the
+indication of obsolescence applies only when compiling in Ada 2005
+mode. This is primarily intended for dealing with the situations
+in the predefined library where subprograms or packages
+have become defined as obsolescent in Ada 2005
+(e.g.@: in Ada.Characters.Handling), but may be used anywhere.
+
+The following examples show typical uses of this pragma:
+
+@smallexample @c ada
+package p is
+ pragma Obsolescent (p, Message => "use pp instead of p");
+end p;
+
+package q is
+ procedure q2;
+ pragma Obsolescent ("use q2new instead");
+
+ type R is new integer;
+ pragma Obsolescent
+ (Entity => R,
+ Message => "use RR in Ada 2005",
+ Version => Ada_05);
+
+ type M is record
+ F1 : Integer;
+ F2 : Integer;
+ pragma Obsolescent;
+ F3 : Integer;
+ end record;
+
+ type E is (a, bc, 'd', quack);
+ pragma Obsolescent (Entity => bc)
+ pragma Obsolescent (Entity => 'd')
+
+ function "+"
+ (a, b : character) return character;
+ pragma Obsolescent (Entity => "+");
+end;
+@end smallexample
+
+@noindent
+Note that, as for all pragmas, if you use a pragma argument identifier,
+then all subsequent parameters must also use a pragma argument identifier.
+So if you specify "Entity =>" for the Entity argument, and a Message
+argument is present, it must be preceded by "Message =>".
+
+@node Pragma Optimize_Alignment
+@unnumberedsec Pragma Optimize_Alignment
+@findex Optimize_Alignment
+@cindex Alignment, default settings
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Optimize_Alignment (TIME | SPACE | OFF);
+@end smallexample
+
+@noindent
+This is a configuration pragma which affects the choice of default alignments
+for types where no alignment is explicitly specified. There is a time/space
+trade-off in the selection of these values. Large alignments result in more
+efficient code, at the expense of larger data space, since sizes have to be
+increased to match these alignments. Smaller alignments save space, but the
+access code is slower. The normal choice of default alignments (which is what
+you get if you do not use this pragma, or if you use an argument of OFF),
+tries to balance these two requirements.
+
+Specifying SPACE causes smaller default alignments to be chosen in two cases.
+First any packed record is given an alignment of 1. Second, if a size is given
+for the type, then the alignment is chosen to avoid increasing this size. For
+example, consider:
+
+@smallexample @c ada
+ type R is record
+ X : Integer;
+ Y : Character;
+ end record;
+
+ for R'Size use 5*8;
+@end smallexample
+
+@noindent
+In the default mode, this type gets an alignment of 4, so that access to the
+Integer field X are efficient. But this means that objects of the type end up
+with a size of 8 bytes. This is a valid choice, since sizes of objects are
+allowed to be bigger than the size of the type, but it can waste space if for
+example fields of type R appear in an enclosing record. If the above type is
+compiled in @code{Optimize_Alignment (Space)} mode, the alignment is set to 1.
+
+Specifying TIME causes larger default alignments to be chosen in the case of
+small types with sizes that are not a power of 2. For example, consider:
+
+@smallexample @c ada
+ type R is record
+ A : Character;
+ B : Character;
+ C : Boolean;
+ end record;
+
+ pragma Pack (R);
+ for R'Size use 17;
+@end smallexample
+
+@noindent
+The default alignment for this record is normally 1, but if this type is
+compiled in @code{Optimize_Alignment (Time)} mode, then the alignment is set
+to 4, which wastes space for objects of the type, since they are now 4 bytes
+long, but results in more efficient access when the whole record is referenced.
-The effect of this pragma is to output a warning message that the
-subprogram is obsolescent if the appropriate warning option in the
-compiler is activated. If a parameter is present, then a second
-warning message is given containing this text.
+As noted above, this is a configuration pragma, and there is a requirement
+that all units in a partition be compiled with a consistent setting of the
+optimization setting. This would normally be achieved by use of a configuration
+pragma file containing the appropriate setting. The exception to this rule is
+that units with an explicit configuration pragma in the same file as the source
+unit are excluded from the consistency check, as are all predefined units. The
+latter are compiled by default in pragma Optimize_Alignment (Off) mode if no
+pragma appears at the start of the file.
@node Pragma Passive
@unnumberedsec Pragma Passive
Syntax:
@smallexample @c ada
-pragma Passive ([Semaphore | No]);
+pragma Passive [(Semaphore | No)];
@end smallexample
@noindent
optimized. GNAT does not attempt to optimize any tasks in this manner
(since protected objects are available in place of passive tasks).
+@node Pragma Persistent_BSS
+@unnumberedsec Pragma Persistent_BSS
+@findex Persistent_BSS
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Persistent_BSS [(LOCAL_NAME)]
+@end smallexample
+
+@noindent
+This pragma allows selected objects to be placed in the @code{.persistent_bss}
+section. On some targets the linker and loader provide for special
+treatment of this section, allowing a program to be reloaded without
+affecting the contents of this data (hence the name persistent).
+
+There are two forms of usage. If an argument is given, it must be the
+local name of a library level object, with no explicit initialization
+and whose type is potentially persistent. If no argument is given, then
+the pragma is a configuration pragma, and applies to all library level
+objects with no explicit initialization of potentially persistent types.
+
+A potentially persistent type is a scalar type, or a non-tagged,
+non-discriminated record, all of whose components have no explicit
+initialization and are themselves of a potentially persistent type,
+or an array, all of whose constraints are static, and whose component
+type is potentially persistent.
+
+If this pragma is used on a target where this feature is not supported,
+then the pragma will be ignored. See also @code{pragma Linker_Section}.
+
@node Pragma Polling
@unnumberedsec Pragma Polling
@findex Polling
@code{Poll} in this file makes a call to the appropriate runtime routine
to test for an abort condition.
-Note that polling can also be enabled by use of the @code{-gnatP} switch. See
-the @cite{GNAT User's Guide} for details.
+Note that polling can also be enabled by use of the @option{-gnatP} switch.
+@xref{Switches for gcc,,, gnat_ugn, @value{EDITION} User's Guide}, for
+details.
-@node Pragma Propagate_Exceptions
-@unnumberedsec Pragma Propagate_Exceptions
-@findex Propagate_Exceptions
-@cindex Zero Cost Exceptions
+@node Pragma Postcondition
+@unnumberedsec Pragma Postcondition
+@cindex Postconditions
+@cindex Checks, postconditions
+@findex Postconditions
@noindent
Syntax:
@smallexample @c ada
-pragma Propagate_Exceptions (subprogram_LOCAL_NAME);
+pragma Postcondition (
+ [Check =>] Boolean_Expression
+ [,[Message =>] String_Expression]);
@end smallexample
@noindent
-This pragma indicates that the given entity, which is the name of an
-imported foreign-language subprogram may receive an Ada exception,
-and that the exception should be propagated. It is relevant only if
-zero cost exception handling is in use, and is thus never needed if
-the alternative @code{longjmp} / @code{setjmp} implementation of
-exceptions is used (although it is harmless to use it in such cases).
+The @code{Postcondition} pragma allows specification of automatic
+postcondition checks for subprograms. These checks are similar to
+assertions, but are automatically inserted just prior to the return
+statements of the subprogram with which they are associated (including
+implicit returns at the end of procedure bodies and associated
+exception handlers).
+
+In addition, the boolean expression which is the condition which
+must be true may contain references to function'Result in the case
+of a function to refer to the returned value.
+
+@code{Postcondition} pragmas may appear either immediate following the
+(separate) declaration of a subprogram, or at the start of the
+declarations of a subprogram body. Only other pragmas may intervene
+(that is appear between the subprogram declaration and its
+postconditions, or appear before the postcondition in the
+declaration sequence in a subprogram body). In the case of a
+postcondition appearing after a subprogram declaration, the
+formal arguments of the subprogram are visible, and can be
+referenced in the postcondition expressions.
+
+The postconditions are collected and automatically tested just
+before any return (implicit or explicit) in the subprogram body.
+A postcondition is only recognized if postconditions are active
+at the time the pragma is encountered. The compiler switch @option{gnata}
+turns on all postconditions by default, and pragma @code{Check_Policy}
+with an identifier of @code{Postcondition} can also be used to
+control whether postconditions are active.
+
+The general approach is that postconditions are placed in the spec
+if they represent functional aspects which make sense to the client.
+For example we might have:
-The implementation of fast exceptions always properly propagates
-exceptions through Ada code, as described in the Ada Reference Manual.
-However, this manual is silent about the propagation of exceptions
-through foreign code. For example, consider the
-situation where @code{P1} calls
-@code{P2}, and @code{P2} calls @code{P3}, where
-@code{P1} and @code{P3} are in Ada, but @code{P2} is in C@.
-@code{P3} raises an Ada exception. The question is whether or not
-it will be propagated through @code{P2} and can be handled in
-@code{P1}.
+@smallexample @c ada
+ function Direction return Integer;
+ pragma Postcondition
+ (Direction'Result = +1
+ or else
+ Direction'Result = -1);
+@end smallexample
-For the @code{longjmp} / @code{setjmp} implementation of exceptions,
-the answer is always yes. For some targets on which zero cost exception
-handling is implemented, the answer is also always yes. However, there
-are some targets, notably in the current version all x86 architecture
-targets, in which the answer is that such propagation does not
-happen automatically. If such propagation is required on these
-targets, it is mandatory to use @code{Propagate_Exceptions} to
-name all foreign language routines through which Ada exceptions
-may be propagated.
+@noindent
+which serves to document that the result must be +1 or -1, and
+will test that this is the case at run time if postcondition
+checking is active.
+
+Postconditions within the subprogram body can be used to
+check that some internal aspect of the implementation,
+not visible to the client, is operating as expected.
+For instance if a square root routine keeps an internal
+counter of the number of times it is called, then we
+might have the following postcondition:
+
+@smallexample @c ada
+ Sqrt_Calls : Natural := 0;
+
+ function Sqrt (Arg : Float) return Float is
+ pragma Postcondition
+ (Sqrt_Calls = Sqrt_Calls'Old + 1);
+ ...
+ end Sqrt
+@end smallexample
-@node Pragma Psect_Object
-@unnumberedsec Pragma Psect_Object
-@findex Psect_Object
@noindent
-Syntax:
+As this example, shows, the use of the @code{Old} attribute
+is often useful in postconditions to refer to the state on
+entry to the subprogram.
+
+Note that postconditions are only checked on normal returns
+from the subprogram. If an abnormal return results from
+raising an exception, then the postconditions are not checked.
+
+If a postcondition fails, then the exception
+@code{System.Assertions.Assert_Failure} is raised. If
+a message argument was supplied, then the given string
+will be used as the exception message. If no message
+argument was supplied, then the default message has
+the form "Postcondition failed at file:line". The
+exception is raised in the context of the subprogram
+body, so it is possible to catch postcondition failures
+within the subprogram body itself.
+
+Within a package spec, normal visibility rules
+in Ada would prevent forward references within a
+postcondition pragma to functions defined later in
+the same package. This would introduce undesirable
+ordering constraints. To avoid this problem, all
+postcondition pragmas are analyzed at the end of
+the package spec, allowing forward references.
+
+The following example shows that this even allows
+mutually recursive postconditions as in:
@smallexample @c ada
-pragma Psect_Object (
- [Internal =>] LOCAL_NAME,
- [, [External =>] EXTERNAL_SYMBOL]
- [, [Size =>] EXTERNAL_SYMBOL]);
+package Parity_Functions is
+ function Odd (X : Natural) return Boolean;
+ pragma Postcondition
+ (Odd'Result =
+ (x = 1
+ or else
+ (x /= 0 and then Even (X - 1))));
+
+ function Even (X : Natural) return Boolean;
+ pragma Postcondition
+ (Even'Result =
+ (x = 0
+ or else
+ (x /= 1 and then Odd (X - 1))));
+
+end Parity_Functions;
+@end smallexample
-EXTERNAL_SYMBOL ::=
- IDENTIFIER
-| static_string_EXPRESSION
+@noindent
+There are no restrictions on the complexity or form of
+conditions used within @code{Postcondition} pragmas.
+The following example shows that it is even possible
+to verify performance behavior.
+
+@smallexample @c ada
+package Sort is
+
+ Performance : constant Float;
+ -- Performance constant set by implementation
+ -- to match target architecture behavior.
+
+ procedure Treesort (Arg : String);
+ -- Sorts characters of argument using N*logN sort
+ pragma Postcondition
+ (Float (Clock - Clock'Old) <=
+ Float (Arg'Length) *
+ log (Float (Arg'Length)) *
+ Performance);
+end Sort;
@end smallexample
@noindent
-This pragma is identical in effect to pragma @code{Common_Object}.
+Note: postcondition pragmas associated with subprograms that are
+marked as Inline_Always, or those marked as Inline with front-end
+inlining (-gnatN option set) are accepted and legality-checked
+by the compiler, but are ignored at run-time even if postcondition
+checking is enabled.
-@node Pragma Pure_Function
-@unnumberedsec Pragma Pure_Function
-@findex Pure_Function
+@node Pragma Precondition
+@unnumberedsec Pragma Precondition
+@cindex Preconditions
+@cindex Checks, preconditions
+@findex Preconditions
@noindent
Syntax:
@smallexample @c ada
-pragma Pure_Function ([Entity =>] function_LOCAL_NAME);
+pragma Precondition (
+ [Check =>] Boolean_Expression
+ [,[Message =>] String_Expression]);
@end smallexample
@noindent
-This pragma appears in the same declarative part as a function
-declaration (or a set of function declarations if more than one
-overloaded declaration exists, in which case the pragma applies
-to all entities). It specifies that the function @code{Entity} is
-to be considered pure for the purposes of code generation. This means
-that the compiler can assume that there are no side effects, and
-in particular that two calls with identical arguments produce the
-same result. It also means that the function can be used in an
-address clause.
+The @code{Precondition} pragma is similar to @code{Postcondition}
+except that the corresponding checks take place immediately upon
+entry to the subprogram, and if a precondition fails, the exception
+is raised in the context of the caller, and the attribute 'Result
+cannot be used within the precondition expression.
-Note that, quite deliberately, there are no static checks to try
-to ensure that this promise is met, so @code{Pure_Function} can be used
-with functions that are conceptually pure, even if they do modify
-global variables. For example, a square root function that is
-instrumented to count the number of times it is called is still
-conceptually pure, and can still be optimized, even though it
-modifies a global variable (the count). Memo functions are another
-example (where a table of previous calls is kept and consulted to
-avoid re-computation).
+Otherwise, the placement and visibility rules are identical to those
+described for postconditions. The following is an example of use
+within a package spec:
+
+@smallexample @c ada
+package Math_Functions is
+ ...
+ function Sqrt (Arg : Float) return Float;
+ pragma Precondition (Arg >= 0.0)
+ ...
+end Math_Functions;
+@end smallexample
+
+@noindent
+@code{Precondition} pragmas may appear either immediate following the
+(separate) declaration of a subprogram, or at the start of the
+declarations of a subprogram body. Only other pragmas may intervene
+(that is appear between the subprogram declaration and its
+postconditions, or appear before the postcondition in the
+declaration sequence in a subprogram body).
+
+Note: postcondition pragmas associated with subprograms that are
+marked as Inline_Always, or those marked as Inline with front-end
+inlining (-gnatN option set) are accepted and legality-checked
+by the compiler, but are ignored at run-time even if postcondition
+checking is enabled.
-@findex Pure
-Note: Most functions in a @code{Pure} package are automatically pure, and
-there is no need to use pragma @code{Pure_Function} for such functions. One
-exception is any function that has at least one formal of type
-@code{System.Address} or a type derived from it. Such functions are not
-considered pure by default, since the compiler assumes that the
-@code{Address} parameter may be functioning as a pointer and that the
-referenced data may change even if the address value does not.
-Similarly, imported functions are not considered to be pure by default,
-since there is no way of checking that they are in fact pure. The use
-of pragma @code{Pure_Function} for such a function will override these default
-assumption, and cause the compiler to treat a designated subprogram as pure
-in these cases.
-Note: If pragma @code{Pure_Function} is applied to a renamed function, it
-applies to the underlying renamed function. This can be used to
-disambiguate cases of overloading where some but not all functions
-in a set of overloaded functions are to be designated as pure.
-@node Pragma Ravenscar
-@unnumberedsec Pragma Ravenscar
+@node Pragma Profile (Ravenscar)
+@unnumberedsec Pragma Profile (Ravenscar)
@findex Ravenscar
@noindent
Syntax:
@smallexample @c ada
-pragma Ravenscar;
+pragma Profile (Ravenscar);
@end smallexample
@noindent
-A configuration pragma that establishes the following set of restrictions:
+A configuration pragma that establishes the following set of configuration
+pragmas:
+
+@table @code
+@item Task_Dispatching_Policy (FIFO_Within_Priorities)
+[RM D.2.2] Tasks are dispatched following a preemptive
+priority-ordered scheduling policy.
+
+@item Locking_Policy (Ceiling_Locking)
+[RM D.3] While tasks and interrupts execute a protected action, they inherit
+the ceiling priority of the corresponding protected object.
+@c
+@c @item Detect_Blocking
+@c This pragma forces the detection of potentially blocking operations within a
+@c protected operation, and to raise Program_Error if that happens.
+@end table
+@noindent
+
+plus the following set of restrictions:
@table @code
+@item Max_Entry_Queue_Length = 1
+Defines the maximum number of calls that are queued on a (protected) entry.
+Note that this restrictions is checked at run time. Violation of this
+restriction results in the raising of Program_Error exception at the point of
+the call. For the Profile (Ravenscar) the value of Max_Entry_Queue_Length is
+always 1 and hence no task can be queued on a protected entry.
+
+@item Max_Protected_Entries = 1
+[RM D.7] Specifies the maximum number of entries per protected type. The
+bounds of every entry family of a protected unit shall be static, or shall be
+defined by a discriminant of a subtype whose corresponding bound is static.
+For the Profile (Ravenscar) the value of Max_Protected_Entries is always 1.
+
+@item Max_Task_Entries = 0
+[RM D.7] Specifies the maximum number of entries
+per task. The bounds of every entry family
+of a task unit shall be static, or shall be
+defined by a discriminant of a subtype whose
+corresponding bound is static. A value of zero
+indicates that no rendezvous are possible. For
+the Profile (Ravenscar), the value of Max_Task_Entries is always
+0 (zero).
+
@item No_Abort_Statements
[RM D.7] There are no abort_statements, and there are
no calls to Task_Identification.Abort_Task.
-@item No_Select_Statements
-There are no select_statements.
+@item No_Asynchronous_Control
+There are no semantic dependences on the package
+Asynchronous_Task_Control.
-@item No_Task_Hierarchy
-[RM D.7] All (non-environment) tasks depend
-directly on the environment task of the partition.
+@item No_Calendar
+There are no semantic dependencies on the package Ada.Calendar.
-@item No_Task_Allocators
-[RM D.7] There are no allocators for task types
-or types containing task subcomponents.
+@item No_Dynamic_Attachment
+There is no call to any of the operations defined in package Ada.Interrupts
+(Is_Reserved, Is_Attached, Current_Handler, Attach_Handler, Exchange_Handler,
+Detach_Handler, and Reference).
@item No_Dynamic_Priorities
[RM D.7] There are no semantic dependencies on the package Dynamic_Priorities.
-@item No_Terminate_Alternatives
-[RM D.7] There are no selective_accepts with terminate_alternatives
-
-@item No_Dynamic_Interrupts
-There are no semantic dependencies on Ada.Interrupts.
-
@item No_Implicit_Heap_Allocations
-[RM D.7] No constructs are allowed to cause implicit heap allocation
-
-@item No_Protected_Type_Allocators
-There are no allocators for protected types or
-types containing protected subcomponents.
+[RM D.7] No constructs are allowed to cause implicit heap allocation.
@item No_Local_Protected_Objects
Protected objects and access types that designate
such objects shall be declared only at library level.
-@item No_Requeue_Statements
-Requeue statements are not allowed.
+@item No_Local_Timing_Events
+[RM D.7] All objects of type Ada.Timing_Events.Timing_Event are
+declared at the library level.
-@item No_Calendar
-There are no semantic dependencies on the package Ada.Calendar.
+@item No_Protected_Type_Allocators
+There are no allocators for protected types or
+types containing protected subcomponents.
@item No_Relative_Delay
-There are no delay_relative_statements.
+There are no delay_relative statements.
-@item No_Task_Attributes
-There are no semantic dependencies on the Ada.Task_Attributes package and
-there are no references to the attributes Callable and Terminated [RM 9.9].
+@item No_Requeue_Statements
+Requeue statements are not allowed.
-@item Boolean_Entry_Barriers
-Entry barrier condition expressions shall be boolean
-objects which are declared in the protected type
-which contains the entry.
+@item No_Select_Statements
+There are no select_statements.
-@item Max_Asynchronous_Select_Nesting = 0
-[RM D.7] Specifies the maximum dynamic nesting level of asynchronous_selects.
-A value of zero prevents the use of any asynchronous_select.
+@item No_Specific_Termination_Handlers
+[RM D.7] There are no calls to Ada.Task_Termination.Set_Specific_Handler
+or to Ada.Task_Termination.Specific_Handler.
-@item Max_Task_Entries = 0
-[RM D.7] Specifies the maximum number of entries
-per task. The bounds of every entry family
-of a task unit shall be static, or shall be
-defined by a discriminant of a subtype whose
-corresponding bound is static. A value of zero
-indicates that no rendezvous are possible. For
-the Ravenscar pragma, the value of Max_Task_Entries is always
-0 (zero).
+@item No_Task_Allocators
+[RM D.7] There are no allocators for task types
+or types containing task subcomponents.
-@item Max_Protected_Entries = 1
-[RM D.7] Specifies the maximum number of entries per
-protected type. The bounds of every entry family of
-a protected unit shall be static, or shall be defined
-by a discriminant of a subtype whose corresponding
-bound is static. For the Ravenscar pragma the value of
-Max_Protected_Entries is always 1.
+@item No_Task_Attributes_Package
+There are no semantic dependencies on the Ada.Task_Attributes package.
-@item Max_Select_Alternatives = 0
-[RM D.7] Specifies the maximum number of alternatives in a selective_accept.
-For the Ravenscar pragma the value is always 0.
+@item No_Task_Hierarchy
+[RM D.7] All (non-environment) tasks depend
+directly on the environment task of the partition.
@item No_Task_Termination
Tasks which terminate are erroneous.
-@item No_Entry_Queue
-No task can be queued on a protected entry. Note that this restrictions is
-checked at run time. The violation of this restriction generates a
-Program_Error exception.
+@item No_Unchecked_Conversion
+There are no semantic dependencies on the Ada.Unchecked_Conversion package.
+
+@item No_Unchecked_Deallocation
+There are no semantic dependencies on the Ada.Unchecked_Deallocation package.
+
+@item Simple_Barriers
+Entry barrier condition expressions shall be either static
+boolean expressions or boolean objects which are declared in
+the protected type which contains the entry.
@end table
@noindent
-This set of restrictions corresponds to the definition of the ``Ravenscar
-Profile'' for limited tasking, devised and published by the
-@cite{International Real-Time Ada Workshop}, 1997,
+This set of configuration pragmas and restrictions correspond to the
+definition of the ``Ravenscar Profile'' for limited tasking, devised and
+published by the @cite{International Real-Time Ada Workshop}, 1997,
and whose most recent description is available at
-@url{ftp://ftp.openravenscar.org/openravenscar/ravenscar00.pdf}.
+@url{http://www-users.cs.york.ac.uk/~burns/ravenscar.ps}.
+
+The original definition of the profile was revised at subsequent IRTAW
+meetings. It has been included in the ISO
+@cite{Guide for the Use of the Ada Programming Language in High
+Integrity Systems}, and has been approved by ISO/IEC/SC22/WG9 for inclusion in
+the next revision of the standard. The formal definition given by
+the Ada Rapporteur Group (ARG) can be found in two Ada Issues (AI-249 and
+AI-305) available at
+@url{http://www.ada-auth.org/cgi-bin/cvsweb.cgi/AIs/AI-00249.TXT} and
+@url{http://www.ada-auth.org/cgi-bin/cvsweb.cgi/AIs/AI-00305.TXT}
+respectively.
The above set is a superset of the restrictions provided by pragma
-@code{Restricted_Run_Time}, it includes five additional restrictions
-(@code{Boolean_Entry_Barriers}, @code{No_Select_Statements},
-@code{No_Calendar},
+@code{Profile (Restricted)}, it includes six additional restrictions
+(@code{Simple_Barriers}, @code{No_Select_Statements},
+@code{No_Calendar}, @code{No_Implicit_Heap_Allocations},
@code{No_Relative_Delay} and @code{No_Task_Termination}). This means
-that pragma @code{Ravenscar}, like the pragma @code{Restricted_Run_Time},
-automatically causes the use of a simplified, more efficient version
-of the tasking run-time system.
+that pragma @code{Profile (Ravenscar)}, like the pragma
+@code{Profile (Restricted)},
+automatically causes the use of a simplified,
+more efficient version of the tasking run-time system.
-@node Pragma Restricted_Run_Time
-@unnumberedsec Pragma Restricted_Run_Time
-@findex Restricted_Run_Time
+@node Pragma Profile (Restricted)
+@unnumberedsec Pragma Profile (Restricted)
+@findex Restricted Run Time
@noindent
Syntax:
@smallexample @c ada
-pragma Restricted_Run_Time;
+pragma Profile (Restricted);
@end smallexample
@noindent
@item No_Task_Allocators
@item No_Dynamic_Priorities
@item No_Terminate_Alternatives
-@item No_Dynamic_Interrupts
+@item No_Dynamic_Attachment
@item No_Protected_Type_Allocators
@item No_Local_Protected_Objects
@item No_Requeue_Statements
-@item No_Task_Attributes
+@item No_Task_Attributes_Package
@item Max_Asynchronous_Select_Nesting = 0
@item Max_Task_Entries = 0
@item Max_Protected_Entries = 1
version of the run time that provides improved performance for the
limited set of tasking functionality permitted by this set of restrictions.
+@node Pragma Psect_Object
+@unnumberedsec Pragma Psect_Object
+@findex Psect_Object
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Psect_Object (
+ [Internal =>] LOCAL_NAME,
+ [, [External =>] EXTERNAL_SYMBOL]
+ [, [Size =>] EXTERNAL_SYMBOL]);
+
+EXTERNAL_SYMBOL ::=
+ IDENTIFIER
+| static_string_EXPRESSION
+@end smallexample
+
+@noindent
+This pragma is identical in effect to pragma @code{Common_Object}.
+
+@node Pragma Pure_Function
+@unnumberedsec Pragma Pure_Function
+@findex Pure_Function
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Pure_Function ([Entity =>] function_LOCAL_NAME);
+@end smallexample
+
+@noindent
+This pragma appears in the same declarative part as a function
+declaration (or a set of function declarations if more than one
+overloaded declaration exists, in which case the pragma applies
+to all entities). It specifies that the function @code{Entity} is
+to be considered pure for the purposes of code generation. This means
+that the compiler can assume that there are no side effects, and
+in particular that two calls with identical arguments produce the
+same result. It also means that the function can be used in an
+address clause.
+
+Note that, quite deliberately, there are no static checks to try
+to ensure that this promise is met, so @code{Pure_Function} can be used
+with functions that are conceptually pure, even if they do modify
+global variables. For example, a square root function that is
+instrumented to count the number of times it is called is still
+conceptually pure, and can still be optimized, even though it
+modifies a global variable (the count). Memo functions are another
+example (where a table of previous calls is kept and consulted to
+avoid re-computation).
+
+@findex Pure
+Note: Most functions in a @code{Pure} package are automatically pure, and
+there is no need to use pragma @code{Pure_Function} for such functions. One
+exception is any function that has at least one formal of type
+@code{System.Address} or a type derived from it. Such functions are not
+considered pure by default, since the compiler assumes that the
+@code{Address} parameter may be functioning as a pointer and that the
+referenced data may change even if the address value does not.
+Similarly, imported functions are not considered to be pure by default,
+since there is no way of checking that they are in fact pure. The use
+of pragma @code{Pure_Function} for such a function will override these default
+assumption, and cause the compiler to treat a designated subprogram as pure
+in these cases.
+
+Note: If pragma @code{Pure_Function} is applied to a renamed function, it
+applies to the underlying renamed function. This can be used to
+disambiguate cases of overloading where some but not all functions
+in a set of overloaded functions are to be designated as pure.
+
+If pragma @code{Pure_Function} is applied to a library level function, the
+function is also considered pure from an optimization point of view, but the
+unit is not a Pure unit in the categorization sense. So for example, a function
+thus marked is free to @code{with} non-pure units.
+
@node Pragma Restriction_Warnings
@unnumberedsec Pragma Restriction_Warnings
@findex Restriction_Warnings
generates a warning message rather than an error message
if the restriction is violated.
+@node Pragma Shared
+@unnumberedsec Pragma Shared
+@findex Shared
+
+@noindent
+This pragma is provided for compatibility with Ada 83. The syntax and
+semantics are identical to pragma Atomic.
+
+@node Pragma Short_Circuit_And_Or
+@unnumberedsec Pragma Short_Circuit_And_Or
+@findex Short_Circuit_And_Or
+
+@noindent
+This configuration pragma causes any occurrence of the AND operator applied to
+operands of type Standard.Boolean to be short-circuited (i.e. the AND operator
+is treated as if it were AND THEN). Or is similarly treated as OR ELSE. This
+may be useful in the context of certification protocols requiring the use of
+short-circuited logical operators. If this configuration pragma occurs locally
+within the file being compiled, it applies only to the file being compiled.
+There is no requirement that all units in a partition use this option.
+
+semantics are identical to pragma Atomic.
@node Pragma Source_File_Name
@unnumberedsec Pragma Source_File_Name
@findex Source_File_Name
@smallexample @c ada
pragma Source_File_Name (
[Unit_Name =>] unit_NAME,
- Spec_File_Name => STRING_LITERAL);
+ Spec_File_Name => STRING_LITERAL,
+ [Index => INTEGER_LITERAL]);
pragma Source_File_Name (
[Unit_Name =>] unit_NAME,
- Body_File_Name => STRING_LITERAL);
+ Body_File_Name => STRING_LITERAL,
+ [Index => INTEGER_LITERAL]);
@end smallexample
@noindent
the second argument is required, and indicates whether this is the file
name for the spec or for the body.
+The optional Index argument should be used when a file contains multiple
+units, and when you do not want to use @code{gnatchop} to separate then
+into multiple files (which is the recommended procedure to limit the
+number of recompilations that are needed when some sources change).
+For instance, if the source file @file{source.ada} contains
+
+@smallexample @c ada
+package B is
+...
+end B;
+
+with B;
+procedure A is
+begin
+ ..
+end A;
+@end smallexample
+
+you could use the following configuration pragmas:
+
+@smallexample @c ada
+pragma Source_File_Name
+ (B, Spec_File_Name => "source.ada", Index => 1);
+pragma Source_File_Name
+ (A, Body_File_Name => "source.ada", Index => 2);
+@end smallexample
+
+Note that the @code{gnatname} utility can also be used to generate those
+configuration pragmas.
+
Another form of the @code{Source_File_Name} pragma allows
the specification of patterns defining alternative file naming schemes
to apply to all files.
@smallexample @c ada
pragma Source_File_Name
- (Spec_File_Name => STRING_LITERAL
- [,Casing => CASING_SPEC]
- [,Dot_Replacement => STRING_LITERAL]);
+ ( [Spec_File_Name =>] STRING_LITERAL
+ [,[Casing =>] CASING_SPEC]
+ [,[Dot_Replacement =>] STRING_LITERAL]);
pragma Source_File_Name
- (Body_File_Name => STRING_LITERAL
- [,Casing => CASING_SPEC]
- [,Dot_Replacement => STRING_LITERAL]);
+ ( [Body_File_Name =>] STRING_LITERAL
+ [,[Casing =>] CASING_SPEC]
+ [,[Dot_Replacement =>] STRING_LITERAL]);
pragma Source_File_Name
- (Subunit_File_Name => STRING_LITERAL
- [,Casing => CASING_SPEC]
- [,Dot_Replacement => STRING_LITERAL]);
+ ( [Subunit_File_Name =>] STRING_LITERAL
+ [,[Casing =>] CASING_SPEC]
+ [,[Dot_Replacement =>] STRING_LITERAL]);
CASING_SPEC ::= Lowercase | Uppercase | Mixedcase
@end smallexample
@ref{Pragma Source_File_Name_Project}.
For more details on the use of the @code{Source_File_Name} pragma,
-see the sections ``Using Other File Names'' and
-``Alternative File Naming Schemes'' in the @cite{GNAT User's Guide}.
+@xref{Using Other File Names,,, gnat_ugn, @value{EDITION} User's Guide},
+and @ref{Alternative File Naming Schemes,,, gnat_ugn, @value{EDITION}
+User's Guide}.
@node Pragma Source_File_Name_Project
@unnumberedsec Pragma Source_File_Name_Project
information). @var{string_literal} is a static string constant that
specifies the file name to be used in error messages and debugging
information. This is most notably used for the output of @code{gnatchop}
-with the @code{-r} switch, to make sure that the original unchopped
+with the @option{-r} switch, to make sure that the original unchopped
source file is the one referred to.
The second argument must be a string literal, it cannot be a static
@end smallexample
@noindent
-The specifications of the referenced functions, as given in the Ada 95
+The specifications of the referenced functions, as given in the Ada
Reference Manual are:
@smallexample @c ada
@end smallexample
@noindent
-The effect is that if the value of an unbounded string is written to a
-stream, then the representation of the item in the stream is in the same
-format used for @code{Standard.String}, and this same representation is
-expected when a value of this type is read from the stream.
+The effect is that if the value of an unbounded string is written to a stream,
+then the representation of the item in the stream is in the same format that
+would be used for @code{Standard.String'Output}, and this same representation
+is expected when a value of this type is read from the stream. Note that the
+value written always includes the bounds, even for Unbounded_String'Write,
+since Unbounded_String is not an array type.
@node Pragma Style_Checks
@unnumberedsec Pragma Style_Checks
The form with a string literal specifies which style options are to be
activated. These are additive, so they apply in addition to any previously
set style check options. The codes for the options are the same as those
-used in the @code{-gnaty} switch to @code{gcc} or @code{gnatmake}.
+used in the @option{-gnaty} switch to @command{gcc} or @command{gnatmake}.
For example the following two methods can be used to enable
layout checking:
@noindent
The form ALL_CHECKS activates all standard checks (its use is equivalent
-to the use of the @code{gnaty} switch with no options. See GNAT User's
-Guide for details.
+to the use of the @code{gnaty} switch with no options. @xref{Top,
+@value{EDITION} User's Guide, About This Guide, gnat_ugn,
+@value{EDITION} User's Guide}, for details.
The forms with @code{Off} and @code{On}
can be used to temporarily disable style checks
This pragma is recognized for compatibility with other Ada compilers
but is ignored by GNAT@.
+@node Pragma Suppress
+@unnumberedsec Pragma Suppress
+@findex Suppress
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Suppress (Identifier [, [On =>] Name]);
+@end smallexample
+
+@noindent
+This is a standard pragma, and supports all the check names required in
+the RM. It is included here because GNAT recognizes one additional check
+name: @code{Alignment_Check} which can be used to suppress alignment checks
+on addresses used in address clauses. Such checks can also be suppressed
+by suppressing range checks, but the specific use of @code{Alignment_Check}
+allows suppression of alignment checks without suppressing other range checks.
+
+Note that pragma Suppress gives the compiler permission to omit
+checks, but does not require the compiler to omit checks. The compiler
+will generate checks if they are essentially free, even when they are
+suppressed. In particular, if the compiler can prove that a certain
+check will necessarily fail, it will generate code to do an
+unconditional ``raise'', even if checks are suppressed. The compiler
+warns in this case.
+
+Of course, run-time checks are omitted whenever the compiler can prove
+that they will not fail, whether or not checks are suppressed.
+
@node Pragma Suppress_All
@unnumberedsec Pragma Suppress_All
@findex Suppress_All
aspects of tasking implementation, for example, the ability to map
tasks to specific processors. For details on the facilities available
for the version of GNAT that you are using, see the documentation
-in the specification of package System.Task_Info in the runtime
+in the spec of package System.Task_Info in the runtime
library.
@node Pragma Task_Name
@code{Storage_Size} attribute definition clause is allowed for a task
type.
-@node Pragma Thread_Body
-@unnumberedsec Pragma Thread_Body
-@findex Thread_Body
+@node Pragma Thread_Local_Storage
+@unnumberedsec Pragma Thread_Local_Storage
+@findex Thread_Local_Storage
+@cindex Task specific storage
+@cindex TLS (Thread Local Storage)
Syntax:
@smallexample @c ada
-pragma Thread_Body (
- [Entity =>] LOCAL_NAME,
- [[Secondary_Stack_Size =>] static_integer_EXPRESSION)];
+pragma Thread_Local_Storage ([Entity =>] LOCAL_NAME);
@end smallexample
@noindent
-This pragma specifies that the subprogram whose name is given as the
-@code{Entity} argument is a thread body, which will be activated
-by being called via its Address from foreign code. The purpose is
-to allow execution and registration of the foreign thread within the
-Ada run-time system.
-
-See the library unit @code{System.Threads} for details on the expansion of
-a thread body subprogram, including the calls made to subprograms
-within System.Threads to register the task. This unit also lists the
-targets and runtime systems for which this pragma is supported.
+This pragma specifies that the specified entity, which must be
+a variable declared in a library level package, is to be marked as
+"Thread Local Storage" (@code{TLS}). On systems supporting this (which
+include Solaris, GNU/Linux and VxWorks 6), this causes each thread
+(and hence each Ada task) to see a distinct copy of the variable.
-A thread body subprogram may not be called directly from Ada code, and
-it is not permitted to apply the Access (or Unrestricted_Access) attributes
-to such a subprogram. The only legitimate way of calling such a subprogram
-is to pass its Address to foreign code and then make the call from the
-foreign code.
+The variable may not have default initialization, and if there is
+an explicit initialization, it must be either @code{null} for an
+access variable, or a static expression for a scalar variable.
+This provides a low level mechanism similar to that provided by
+the @code{Ada.Task_Attributes} package, but much more efficient
+and is also useful in writing interface code that will interact
+with foreign threads.
-A thread body subprogram may have any parameters, and it may be a function
-returning a result. The convention of the thread body subprogram may be
-set in the usual manner using @code{pragma Convention}.
-
-The secondary stack size parameter, if given, is used to set the size
-of secondary stack for the thread. The secondary stack is allocated as
-a local variable of the expanded thread body subprogram, and thus is
-allocated out of the main thread stack size. If no secondary stack
-size parameter is present, the default size (from the declaration in
-@code{System.Secondary_Stack} is used.
+If this pragma is used on a system where @code{TLS} is not supported,
+then an error message will be generated and the program will be rejected.
@node Pragma Time_Slice
@unnumberedsec Pragma Time_Slice
@cindex Unions in C
@findex Unchecked_Union
@noindent
-Syntax:
-
-@smallexample @c ada
-pragma Unchecked_Union (first_subtype_LOCAL_NAME);
-@end smallexample
-
-@noindent
-This pragma is used to declare that the specified type should be represented
-in a manner
-equivalent to a C union type, and is intended only for use in
-interfacing with C code that uses union types. In Ada terms, the named
-type must obey the following rules:
-
-@itemize @bullet
-@item
-It is a non-tagged non-limited record type.
-@item
-It has a single discrete discriminant with a default value.
-@item
-The component list consists of a single variant part.
-@item
-Each variant has a component list with a single component.
-@item
-No nested variants are allowed.
-@item
-No component has an explicit default value.
-@item
-No component has a non-static constraint.
-@end itemize
-
-@noindent
-In addition, given a type that meets the above requirements, the
-following restrictions apply to its use throughout the program:
+Syntax:
-@itemize @bullet
-@item
-The discriminant name can be mentioned only in an aggregate.
-@item
-No subtypes may be created of this type.
-@item
-The type may not be constrained by giving a discriminant value.
-@item
-The type cannot be passed as the actual for a generic formal with a
-discriminant.
-@end itemize
+@smallexample @c ada
+pragma Unchecked_Union (first_subtype_LOCAL_NAME);
+@end smallexample
@noindent
-Equality and inequality operations on @code{unchecked_unions} are not
-available, since there is no discriminant to compare and the compiler
-does not even know how many bits to compare. It is implementation
-dependent whether this is detected at compile time as an illegality or
-whether it is undetected and considered to be an erroneous construct. In
-GNAT, a direct comparison is illegal, but GNAT does not attempt to catch
-the composite case (where two composites are compared that contain an
-unchecked union component), so such comparisons are simply considered
-erroneous.
-
-The layout of the resulting type corresponds exactly to a C union, where
-each branch of the union corresponds to a single variant in the Ada
-record. The semantics of the Ada program is not changed in any way by
-the pragma, i.e.@: provided the above restrictions are followed, and no
-erroneous incorrect references to fields or erroneous comparisons occur,
-the semantics is exactly as described by the Ada reference manual.
-Pragma @code{Suppress (Discriminant_Check)} applies implicitly to the
-type and the default convention is C.
+This pragma is used to specify a representation of a record type that is
+equivalent to a C union. It was introduced as a GNAT implementation defined
+pragma in the GNAT Ada 95 mode. Ada 2005 includes an extended version of this
+pragma, making it language defined, and GNAT fully implements this extended
+version in all language modes (Ada 83, Ada 95, and Ada 2005). For full
+details, consult the Ada 2005 Reference Manual, section B.3.3.
@node Pragma Unimplemented_Unit
@unnumberedsec Pragma Unimplemented_Unit
The abort only happens if code is being generated. Thus you can use
specs of unimplemented packages in syntax or semantic checking mode.
+@node Pragma Universal_Aliasing
+@unnumberedsec Pragma Universal_Aliasing
+@findex Universal_Aliasing
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Universal_Aliasing [([Entity =>] type_LOCAL_NAME)];
+@end smallexample
+
+@noindent
+@var{type_LOCAL_NAME} must refer to a type declaration in the current
+declarative part. The effect is to inhibit strict type-based aliasing
+optimization for the given type. In other words, the effect is as though
+access types designating this type were subject to pragma No_Strict_Aliasing.
+For a detailed description of the strict aliasing optimization, and the
+situations in which it must be suppressed, @xref{Optimization and Strict
+Aliasing,,, gnat_ugn, @value{EDITION} User's Guide}.
+
@node Pragma Universal_Data
@unnumberedsec Pragma Universal_Data
@findex Universal_Data
of this pragma is also available by applying the -univ switch on the
compilations of units where universal addressing of the data is desired.
+@node Pragma Unmodified
+@unnumberedsec Pragma Unmodified
+@findex Unmodified
+@cindex Warnings, unmodified
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Unmodified (LOCAL_NAME @{, LOCAL_NAME@});
+@end smallexample
+
+@noindent
+This pragma signals that the assignable entities (variables,
+@code{out} parameters, @code{in out} parameters) whose names are listed are
+deliberately not assigned in the current source unit. This
+suppresses warnings about the
+entities being referenced but not assigned, and in addition a warning will be
+generated if one of these entities is in fact assigned in the
+same unit as the pragma (or in the corresponding body, or one
+of its subunits).
+
+This is particularly useful for clearly signaling that a particular
+parameter is not modified, even though the spec suggests that it might
+be.
+
@node Pragma Unreferenced
@unnumberedsec Pragma Unreferenced
@findex Unreferenced
Syntax:
@smallexample @c ada
-pragma Unreferenced (local_Name @{, local_Name@});
+pragma Unreferenced (LOCAL_NAME @{, LOCAL_NAME@});
+pragma Unreferenced (library_unit_NAME @{, library_unit_NAME@});
@end smallexample
@noindent
objects declared only for their initialization or finalization side
effects.
-If @code{local_Name} identifies more than one matching homonym in the
+If @code{LOCAL_NAME} identifies more than one matching homonym in the
current scope, then the entity most recently declared is the one to which
-the pragma applies.
+the pragma applies. Note that in the case of accept formals, the pragma
+Unreferenced may appear immediately after the keyword @code{do} which
+allows the indication of whether or not accept formals are referenced
+or not to be given individually for each accept statement.
The left hand side of an assignment does not count as a reference for the
purpose of this pragma. Thus it is fine to assign to an entity for which
pragma Unreferenced is given.
+Note that if a warning is desired for all calls to a given subprogram,
+regardless of whether they occur in the same unit as the subprogram
+declaration, then this pragma should not be used (calls from another
+unit would not be flagged); pragma Obsolescent can be used instead
+for this purpose, see @xref{Pragma Obsolescent}.
+
+The second form of pragma @code{Unreferenced} is used within a context
+clause. In this case the arguments must be unit names of units previously
+mentioned in @code{with} clauses (similar to the usage of pragma
+@code{Elaborate_All}. The effect is to suppress warnings about unreferenced
+units and unreferenced entities within these units.
+
+@node Pragma Unreferenced_Objects
+@unnumberedsec Pragma Unreferenced_Objects
+@findex Unreferenced_Objects
+@cindex Warnings, unreferenced
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Unreferenced_Objects (local_subtype_NAME @{, local_subtype_NAME@});
+@end smallexample
+
+@noindent
+This pragma signals that for the types or subtypes whose names are
+listed, objects which are declared with one of these types or subtypes may
+not be referenced, and if no references appear, no warnings are given.
+
+This is particularly useful for objects which are declared solely for their
+initialization and finalization effect. Such variables are sometimes referred
+to as RAII variables (Resource Acquisition Is Initialization). Using this
+pragma on the relevant type (most typically a limited controlled type), the
+compiler will automatically suppress unwanted warnings about these variables
+not being referenced.
+
@node Pragma Unreserve_All_Interrupts
@unnumberedsec Pragma Unreserve_All_Interrupts
@findex Unreserve_All_Interrupts
a program can then handle the @code{SIGINT} interrupt as it chooses.
For a full list of the interrupts handled in a specific implementation,
-see the source code for the specification of @code{Ada.Interrupts.Names} in
+see the source code for the spec of @code{Ada.Interrupts.Names} in
file @file{a-intnam.ads}. This is a target dependent file that contains the
list of interrupts recognized for a given target. The documentation in
this file also specifies what interrupts are affected by the use of
This is a configuration pragma. In a unit to which it applies, any use
of the 'Size attribute is automatically interpreted as a use of the
'VADS_Size attribute. Note that this may result in incorrect semantic
-processing of valid Ada 95 programs. This is intended to aid in the
-handling of legacy code which depends on the interpretation of Size
+processing of valid Ada 95 or Ada 2005 programs. This is intended to aid in
+the handling of existing code which depends on the interpretation of Size
as implemented in the VADS compiler. See description of the VADS_Size
attribute for further details.
activated. The validity checks are first set to include only the default
reference manual settings, and then a string of letters in the string
specifies the exact set of options required. The form of this string
-is exactly as described for the @code{-gnatVx} compiler switch (see the
+is exactly as described for the @option{-gnatVx} compiler switch (see the
GNAT users guide for details). For example the following two methods
can be used to enable validity checking for mode @code{in} and
@code{in out} subprogram parameters:
Syntax:
@smallexample @c ada
-pragma Volatile (local_NAME);
+pragma Volatile (LOCAL_NAME);
@end smallexample
@noindent
-This pragma is defined by the Ada 95 Reference Manual, and the GNAT
+This pragma is defined by the Ada Reference Manual, and the GNAT
implementation is fully conformant with this definition. The reason it
is mentioned in this section is that a pragma of the same name was supplied
-in some Ada 83 compilers, including DEC Ada 83. The Ada 95 implementation
-of pragma Volatile is upwards compatible with the implementation in
-Dec Ada 83.
+in some Ada 83 compilers, including DEC Ada 83. The Ada 95 / Ada 2005
+implementation of pragma Volatile is upwards compatible with the
+implementation in DEC Ada 83.
@node Pragma Warnings
@unnumberedsec Pragma Warnings
Syntax:
@smallexample @c ada
-pragma Warnings (On | Off [, LOCAL_NAME]);
+pragma Warnings (On | Off);
+pragma Warnings (On | Off, LOCAL_NAME);
+pragma Warnings (static_string_EXPRESSION);
+pragma Warnings (On | Off, static_string_EXPRESSION);
@end smallexample
@noindent
pragma, then no warning messages are output, regardless of the
setting of the command line switches.
-The form with a single argument is a configuration pragma.
+The form with a single argument may be used as a configuration pragma.
-If the @var{local_name} parameter is present, warnings are suppressed for
+If the @var{LOCAL_NAME} parameter is present, warnings are suppressed for
the specified entity. This suppression is effective from the point where
it occurs till the end of the extended scope of the variable (similar to
the scope of @code{Suppress}).
+The form with a single static_string_EXPRESSION argument provides more precise
+control over which warnings are active. The string is a list of letters
+specifying which warnings are to be activated and which deactivated. The
+code for these letters is the same as the string used in the command
+line switch controlling warnings. For a brief summary, use the gnatmake
+command with no arguments, which will generate usage information containing
+the list of warnings switches supported. For
+full details see @ref{Warning Message Control,,, gnat_ugn, @value{EDITION}
+User's Guide}.
+
+@noindent
+The specified warnings will be in effect until the end of the program
+or another pragma Warnings is encountered. The effect of the pragma is
+cumulative. Initially the set of warnings is the standard default set
+as possibly modified by compiler switches. Then each pragma Warning
+modifies this set of warnings as specified. This form of the pragma may
+also be used as a configuration pragma.
+
+The fourth form, with an On|Off parameter and a string, is used to
+control individual messages, based on their text. The string argument
+is a pattern that is used to match against the text of individual
+warning messages (not including the initial "warning: " tag).
+
+The pattern may contain asterisks, which match zero or more characters in
+the message. For example, you can use
+@code{pragma Warnings (Off, "*bits of*unused")} to suppress the warning
+message @code{warning: 960 bits of "a" unused}. No other regular
+expression notations are permitted. All characters other than asterisk in
+these three specific cases are treated as literal characters in the match.
+
+There are two ways to use this pragma. The OFF form can be used as a
+configuration pragma. The effect is to suppress all warnings (if any)
+that match the pattern string throughout the compilation.
+
+The second usage is to suppress a warning locally, and in this case, two
+pragmas must appear in sequence:
+
+@smallexample @c ada
+pragma Warnings (Off, Pattern);
+@dots{} code where given warning is to be suppressed
+pragma Warnings (On, Pattern);
+@end smallexample
+
+@noindent
+In this usage, the pattern string must match in the Off and On pragmas,
+and at least one matching warning must be suppressed.
+
+Note: the debug flag -gnatd.i (@code{/NOWARNINGS_PRAGMAS} in VMS) can be
+used to cause the compiler to entirely ignore all WARNINGS pragmas. This can
+be useful in checking whether obsolete pragmas in existing programs are hiding
+real problems.
+
@node Pragma Weak_External
@unnumberedsec Pragma Weak_External
@findex Weak_External
@end smallexample
@noindent
-This pragma specifies that the given entity should be marked as a weak
-external (one that does not have to be resolved) for the linker. For
-further details, consult the GCC manual.
+@var{LOCAL_NAME} must refer to an object that is declared at the library
+level. This pragma specifies that the given entity should be marked as a
+weak symbol for the linker. It is equivalent to @code{__attribute__((weak))}
+in GNU C and causes @var{LOCAL_NAME} to be emitted as a weak symbol instead
+of a regular symbol, that is to say a symbol that does not have to be
+resolved by the linker if used in conjunction with a pragma Import.
+
+When a weak symbol is not resolved by the linker, its address is set to
+zero. This is useful in writing interfaces to external modules that may
+or may not be linked in the final executable, for example depending on
+configuration settings.
+
+If a program references at run time an entity to which this pragma has been
+applied, and the corresponding symbol was not resolved at link time, then
+the execution of the program is erroneous. It is not erroneous to take the
+Address of such an entity, for example to guard potential references,
+as shown in the example below.
+
+Some file formats do not support weak symbols so not all target machines
+support this pragma.
+
+@smallexample @c ada
+-- Example of the use of pragma Weak_External
+
+package External_Module is
+ key : Integer;
+ pragma Import (C, key);
+ pragma Weak_External (key);
+ function Present return boolean;
+end External_Module;
+
+with System; use System;
+package body External_Module is
+ function Present return boolean is
+ begin
+ return key'Address /= System.Null_Address;
+ end Present;
+end External_Module;
+@end smallexample
+
+@node Pragma Wide_Character_Encoding
+@unnumberedsec Pragma Wide_Character_Encoding
+@findex Wide_Character_Encoding
+@noindent
+Syntax:
+
+@smallexample @c ada
+pragma Wide_Character_Encoding (IDENTIFIER | CHARACTER_LITERAL);
+@end smallexample
+
+@noindent
+This pragma specifies the wide character encoding to be used in program
+source text appearing subsequently. It is a configuration pragma, but may
+also be used at any point that a pragma is allowed, and it is permissible
+to have more than one such pragma in a file, allowing multiple encodings
+to appear within the same file.
+
+The argument can be an identifier or a character literal. In the identifier
+case, it is one of @code{HEX}, @code{UPPER}, @code{SHIFT_JIS},
+@code{EUC}, @code{UTF8}, or @code{BRACKETS}. In the character literal
+case it is correspondingly one of the characters @samp{h}, @samp{u},
+@samp{s}, @samp{e}, @samp{8}, or @samp{b}.
+
+Note that when the pragma is used within a file, it affects only the
+encoding within that file, and does not affect withed units, specs,
+or subunits.
@node Implementation Defined Attributes
@chapter Implementation Defined Attributes
-Ada 95 defines (throughout the Ada 95 reference manual,
-summarized in annex K),
+Ada defines (throughout the Ada reference manual,
+summarized in Annex K),
a set of attributes that provide useful additional functionality in all
areas of the language. These language defined attributes are implemented
-in GNAT and work as described in the Ada 95 Reference Manual.
+in GNAT and work as described in the Ada Reference Manual.
-In addition, Ada 95 allows implementations to define additional
+In addition, Ada allows implementations to define additional
attributes whose meaning is defined by the implementation. GNAT provides
a number of these implementation-dependent attributes which can be used
to extend and enhance the functionality of the compiler. This section of
* AST_Entry::
* Bit::
* Bit_Position::
+* Compiler_Version::
* Code_Address::
* Default_Bit_Order::
* Elaborated::
* Elab_Body::
* Elab_Spec::
* Emax::
+* Enabled::
* Enum_Rep::
+* Enum_Val::
* Epsilon::
* Fixed_Value::
+* Has_Access_Values::
* Has_Discriminants::
* Img::
* Integer_Value::
+* Invalid_Value::
* Large::
* Machine_Size::
* Mantissa::
* Mechanism_Code::
* Null_Parameter::
* Object_Size::
+* Old::
* Passed_By_Reference::
+* Pool_Address::
* Range_Length::
+* Result::
* Safe_Emax::
* Safe_Large::
* Small::
* Storage_Unit::
+* Stub_Type::
* Target_Name::
* Tick::
* To_Address::
@var{C} and is independent of the alignment of
the containing record @var{R}.
+@node Compiler_Version
+@unnumberedsec Compiler_Version
+@findex Compiler_Version
+@noindent
+@code{Standard'Compiler_Version} (@code{Standard} is the only allowed
+prefix) yields a static string identifying the version of the compiler
+being used to compile the unit containing the attribute reference. A
+typical result would be something like "GNAT Pro 6.3.0w (20090221)".
+
@node Code_Address
@unnumberedsec Code_Address
@findex Code_Address
@cindex Address of subprogram code
@noindent
The @code{'Address}
-attribute may be applied to subprograms in Ada 95, but the
-intended effect from the Ada 95 reference manual seems to be to provide
+attribute may be applied to subprograms in Ada 95 and Ada 2005, but the
+intended effect seems to be to provide
an address value which can be used to call the subprogram by means of
an address clause as in the following example:
@noindent
A call to @code{L} is then expected to result in a call to @code{K}@.
In Ada 83, where there were no access-to-subprogram values, this was
-a common work around for getting the effect of an indirect call.
+a common work-around for getting the effect of an indirect call.
GNAT implements the above use of @code{Address} and the technique
illustrated by the example code works correctly.
@noindent
This attribute can only be applied to a program unit name. It returns
the entity for the corresponding elaboration procedure for elaborating
-the specification of the referenced unit. This is used in the main
+the spec of the referenced unit. This is used in the main
generated elaboration procedure by the binder and is not normally used
in any other context. However, there may be specialized situations in
which it is useful to be able to call this elaboration procedure from
the Ada 83 reference manual for an exact description of the semantics of
this attribute.
+@node Enabled
+@unnumberedsec Enabled
+@findex Enabled
+@noindent
+The @code{Enabled} attribute allows an application program to check at compile
+time to see if the designated check is currently enabled. The prefix is a
+simple identifier, referencing any predefined check name (other than
+@code{All_Checks}) or a check name introduced by pragma Check_Name. If
+no argument is given for the attribute, the check is for the general state
+of the check, if an argument is given, then it is an entity name, and the
+check indicates whether an @code{Suppress} or @code{Unsuppress} has been
+given naming the entity (if not, then the argument is ignored).
+
+Note that instantiations inherit the check status at the point of the
+instantiation, so a useful idiom is to have a library package that
+introduces a check name with @code{pragma Check_Name}, and then contains
+generic packages or subprograms which use the @code{Enabled} attribute
+to see if the check is enabled. A user of this package can then issue
+a @code{pragma Suppress} or @code{pragma Unsuppress} before instantiating
+the package or subprogram, controlling whether the check will be present.
+
@node Enum_Rep
@unnumberedsec Enum_Rep
@cindex Representation of enums
or integer types. Note that if @code{Enum_Rep} is used on a modular
type whose upper bound exceeds the upper bound of the largest signed
integer type, and the argument is a variable, so that the universal
-integer calculation is done at run-time, then the call to @code{Enum_Rep}
+integer calculation is done at run time, then the call to @code{Enum_Rep}
may raise @code{Constraint_Error}.
+@node Enum_Val
+@unnumberedsec Enum_Val
+@cindex Representation of enums
+@findex Enum_Val
+@noindent
+For every enumeration subtype @var{S}, @code{@var{S}'Enum_Rep} denotes a
+function with the following spec:
+
+@smallexample @c ada
+function @var{S}'Enum_Rep (Arg : @i{Universal_Integer)
+ return @var{S}'Base};
+@end smallexample
+
+@noindent
+The function returns the enumeration value whose representation matches the
+argument, or raises Constraint_Error if no enumeration literal of the type
+has the matching value.
+This will be equal to value of the @code{Val} attribute in the
+absence of an enumeration representation clause. This is a static
+attribute (i.e.@: the result is static if the argument is static).
+
@node Epsilon
@unnumberedsec Epsilon
@cindex Ada 83 attributes
This attribute is primarily intended for use in implementation of the
input-output functions for fixed-point values.
+@node Has_Access_Values
+@unnumberedsec Has_Access_Values
+@cindex Access values, testing for
+@findex Has_Access_Values
+@noindent
+The prefix of the @code{Has_Access_Values} attribute is a type. The result
+is a Boolean value which is True if the is an access type, or is a composite
+type with a component (at any nesting depth) that is an access type, and is
+False otherwise.
+The intended use of this attribute is in conjunction with generic
+definitions. If the attribute is applied to a generic private type, it
+indicates whether or not the corresponding actual type has access values.
+
@node Has_Discriminants
@unnumberedsec Has_Discriminants
@cindex Discriminants, testing for
This attribute is primarily intended for use in implementation of the
standard input-output functions for fixed-point values.
+@node Invalid_Value
+@unnumberedsec Invalid_Value
+@findex Invalid_Value
+@noindent
+For every scalar type S, S'Invalid_Value returns an undefined value of the
+type. If possible this value is an invalid representation for the type. The
+value returned is identical to the value used to initialize an otherwise
+uninitialized value of the type if pragma Initialize_Scalars is used,
+including the ability to modify the value with the binder -Sxx flag and
+relevant environment variables at run time.
+
@node Large
@unnumberedsec Large
@cindex Ada 83 attributes
integer field, and so the default size of record objects for this type
will be 64 (8 bytes).
-The @code{@var{type}'Object_Size} attribute
-has been added to GNAT to allow the
-default object size of a type to be easily determined. For example,
-@code{Natural'Object_Size} is 32, and
-@code{Rec'Object_Size} (for the record type in the above example) will be
-64. Note also that, unlike the situation with the
-@code{Size} attribute as defined in the Ada RM, the
-@code{Object_Size} attribute can be specified individually
-for different subtypes. For example:
+@node Old
+@unnumberedsec Old
+@cindex Capturing Old values
+@cindex Postconditions
+@noindent
+The attribute Prefix'Old can be used within a
+subprogram to refer to the value of the prefix on entry. So for
+example if you have an argument of a record type X called Arg1,
+you can refer to Arg1.Field'Old which yields the value of
+Arg1.Field on entry. The implementation simply involves generating
+an object declaration which captures the value on entry. Any
+prefix is allowed except one of a limited type (since limited
+types cannot be copied to capture their values) or a local variable
+(since it does not exist at subprogram entry time).
+
+The following example shows the use of 'Old to implement
+a test of a postcondition:
@smallexample @c ada
-type R is new Integer;
-subtype R1 is R range 1 .. 10;
-subtype R2 is R range 1 .. 10;
-for R2'Object_Size use 8;
+with Old_Pkg;
+procedure Old is
+begin
+ Old_Pkg.Incr;
+end Old;
+
+package Old_Pkg is
+ procedure Incr;
+end Old_Pkg;
+
+package body Old_Pkg is
+ Count : Natural := 0;
+
+ procedure Incr is
+ begin
+ ... code manipulating the value of Count
+
+ pragma Assert (Count = Count'Old + 1);
+ end Incr;
+end Old_Pkg;
@end smallexample
@noindent
-In this example, @code{R'Object_Size} and @code{R1'Object_Size} are both
-32 since the default object size for a subtype is the same as the object size
-for the parent subtype. This means that objects of type @code{R}
-or @code{R1} will
-by default be 32 bits (four bytes). But objects of type
-@code{R2} will be only
-8 bits (one byte), since @code{R2'Object_Size} has been set to 8.
+Note that it is allowed to apply 'Old to a constant entity, but this will
+result in a warning, since the old and new values will always be the same.
@node Passed_By_Reference
@unnumberedsec Passed_By_Reference
passed by copy in calls. For scalar types, the result is always @code{False}
and is static. For non-scalar types, the result is non-static.
+@node Pool_Address
+@unnumberedsec Pool_Address
+@cindex Parameters, when passed by reference
+@findex Pool_Address
+@noindent
+@code{@var{X}'Pool_Address} for any object @var{X} returns the address
+of X within its storage pool. This is the same as
+@code{@var{X}'Address}, except that for an unconstrained array whose
+bounds are allocated just before the first component,
+@code{@var{X}'Pool_Address} returns the address of those bounds,
+whereas @code{@var{X}'Address} returns the address of the first
+component.
+
+Here, we are interpreting ``storage pool'' broadly to mean ``wherever
+the object is allocated'', which could be a user-defined storage pool,
+the global heap, on the stack, or in a static memory area. For an
+object created by @code{new}, @code{@var{Ptr.all}'Pool_Address} is
+what is passed to @code{Allocate} and returned from @code{Deallocate}.
+
@node Range_Length
@unnumberedsec Range_Length
@findex Range_Length
applied to the index subtype of a one dimensional array always gives the
same result as @code{Range} applied to the array itself.
+@node Result
+@unnumberedsec Result
+@findex Result
+@noindent
+@code{@var{function}'Result} can only be used with in a Postcondition pragma
+for a function. The prefix must be the name of the corresponding function. This
+is used to refer to the result of the function in the postcondition expression.
+For a further discussion of the use of this attribute and examples of its use,
+see the description of pragma Postcondition.
+
@node Safe_Emax
@unnumberedsec Safe_Emax
@cindex Ada 83 attributes
@cindex Ada 83 attributes
@findex Small
@noindent
-The @code{Small} attribute is defined in Ada 95 only for fixed-point types.
+The @code{Small} attribute is defined in Ada 95 (and Ada 2005) only for
+fixed-point types.
GNAT also allows this attribute to be applied to floating-point types
for compatibility with Ada 83. See
the Ada 83 reference manual for an exact description of the semantics of
@code{Standard'Storage_Unit} (@code{Standard} is the only permissible
prefix) provides the same value as @code{System.Storage_Unit}.
+@node Stub_Type
+@unnumberedsec Stub_Type
+@findex Stub_Type
+@noindent
+The GNAT implementation of remote access-to-classwide types is
+organized as described in AARM section E.4 (20.t): a value of an RACW type
+(designating a remote object) is represented as a normal access
+value, pointing to a "stub" object which in turn contains the
+necessary information to contact the designated remote object. A
+call on any dispatching operation of such a stub object does the
+remote call, if necessary, using the information in the stub object
+to locate the target partition, etc.
+
+For a prefix @code{T} that denotes a remote access-to-classwide type,
+@code{T'Stub_Type} denotes the type of the corresponding stub objects.
+
+By construction, the layout of @code{T'Stub_Type} is identical to that of
+type @code{RACW_Stub_Type} declared in the internal implementation-defined
+unit @code{System.Partition_Interface}. Use of this attribute will create
+an implicit dependency on this unit.
+
@node Target_Name
@unnumberedsec Target_Name
@findex Target_Name
construction of values of the floating-point attributes from the file
@file{ttypef.ads}, but may also be used by user programs.
+For example, the following program prints the first 50 digits of pi:
+
+@smallexample @c ada
+with Text_IO; use Text_IO;
+with Ada.Numerics;
+procedure Pi is
+begin
+ Put (Ada.Numerics.Pi'Universal_Literal_String);
+end;
+@end smallexample
+
@node Unrestricted_Access
@unnumberedsec Unrestricted_Access
@cindex @code{Access}, unrestricted
other implementations, the use of static chains for inner level
subprograms means that @code{Unrestricted_Access} applied to a
subprogram yields a value that can be called as long as the subprogram
-is in scope (normal Ada 95 accessibility rules restrict this usage).
+is in scope (normal Ada accessibility rules restrict this usage).
It is possible to use @code{Unrestricted_Access} for any type, but care
-must be excercised if it is used to create pointers to unconstrained
+must be exercised if it is used to create pointers to unconstrained
objects. In this case, the resulting pointer has the same scope as the
context of the attribute, and may not be returned to some enclosing
scope. For instance, a function cannot use @code{Unrestricted_Access}
@node Implementation Advice
@chapter Implementation Advice
@noindent
-The main text of the Ada 95 Reference Manual describes the required
-behavior of all Ada 95 compilers, and the GNAT compiler conforms to
+The main text of the Ada Reference Manual describes the required
+behavior of all Ada compilers, and the GNAT compiler conforms to
these requirements.
-In addition, there are sections throughout the Ada 95
-reference manual headed
-by the phrase ``implementation advice''. These sections are not normative,
-i.e.@: they do not specify requirements that all compilers must
+In addition, there are sections throughout the Ada Reference Manual headed
+by the phrase ``Implementation advice''. These sections are not normative,
+i.e., they do not specify requirements that all compilers must
follow. Rather they provide advice on generally desirable behavior. You
may wonder why they are not requirements. The most typical answer is
that they describe behavior that seems generally desirable, but cannot
be provided on all systems, or which may be undesirable on some systems.
As far as practical, GNAT follows the implementation advice sections in
-the Ada 95 Reference Manual. This chapter contains a table giving the
+the Ada Reference Manual. This chapter contains a table giving the
reference manual section number, paragraph number and several keywords
for each advice. Each entry consists of the text of the advice followed
by the GNAT interpretation of this advice. Most often, this simply says
Affects semantics
@item CPP_Constructor
Affects semantics
-@item CPP_Virtual
-Affects semantics
-@item CPP_Vtable
-Affects semantics
@item Debug
Affects semantics
@item Interface_Name
the representation item is a name that statically denotes a constant
declared before the entity.
@end cartouche
-Followed. GNAT does not support non-static expressions in representation
-clauses unless they are constants declared before the entity. For
-example:
+Followed. In fact, GNAT goes beyond the recommended level of support
+by allowing nonstatic expressions in some representation clauses even
+without the need to declare constants initialized with the values of
+such expressions.
+For example:
@smallexample @c ada
-X : Some_Type;
-for X'Address use To_address (16#2000#);
+ X : Integer;
+ Y : Float;
+ for Y'Address use X'Address;>>
@end smallexample
-@noindent
-will be rejected, since the To_Address expression is non-static. Instead
-write:
-
-@smallexample @c ada
-X_Address : constant Address : = To_Address (16#2000#);
-X : Some_Type;
-for X'Address use X_Address;
-@end smallexample
@sp 1
@cartouche
@code{Size} clause on a composite subtype should not affect the
internal layout of components.
@end cartouche
-Followed.
+Followed. But note that this can be overridden by use of the implementation
+pragma Implicit_Packing in the case of packed arrays.
@sp 1
@cartouche
@end smallexample
@item
-Rebuild the GNAT run-time library as documented in the
-@cite{GNAT User's Guide}
+Rebuild the GNAT run-time library as documented in
+@ref{GNAT and Libraries,,, gnat_ugn, @value{EDITION} User's Guide}.
@end enumerate
@unnumberedsec A.1(52): Names of Predefined Numeric Types
the given hardware architecture should be provided directly in
@code{Interfaces}.
@end cartouche
-Followed. An additional package not defined
-in the Ada 95 Reference Manual is @code{Interfaces.CPP}, used
+Followed. An additional package not defined
+in the Ada Reference Manual is @code{Interfaces.CPP}, used
for interfacing to C++.
@sp 1
@end cartouche
GNAT currently takes advantage of these restrictions by providing an optimized
run time when the Ravenscar profile and the GNAT restricted run time set
-of restrictions are specified. See pragma @code{Ravenscar} and pragma
-@code{Restricted_Run_Time} for more details.
+of restrictions are specified. See pragma @code{Profile (Ravenscar)} and
+pragma @code{Profile (Restricted)} for more details.
@cindex Time, monotonic
@unnumberedsec D.8(47-49): Monotonic Time
@noindent
In addition to the implementation dependent pragmas and attributes, and
-the implementation advice, there are a number of other features of Ada
-95 that are potentially implementation dependent. These are mentioned
-throughout the Ada 95 Reference Manual, and are summarized in annex M@.
+the implementation advice, there are a number of other Ada features
+that are potentially implementation dependent. These are mentioned
+throughout the Ada Reference Manual, and are summarized in Annex M@.
A requirement for conforming Ada compilers is that they provide
documentation describing how the implementation deals with each of these
-issues. In this chapter, you will find each point in annex M listed
+issues. In this chapter, you will find each point in Annex M listed
followed by a description in italic font of how GNAT
@c SGI info:
@ignore
You can use this chapter as a guide to minimizing implementation
dependent features in your programs if portability to other compilers
and other operating systems is an important consideration. The numbers
-in each section below correspond to the paragraph number in the Ada 95
+in each section below correspond to the paragraph number in the Ada
Reference Manual.
@sp 1
length. See 2.2(15).
@end cartouche
@noindent
-The maximum line length is 255 characters an the maximum length of a
+The maximum line length is 255 characters and the maximum length of a
lexical element is also 255 characters.
@sp 1
@sp 1
@cartouche
@noindent
-@strong{27}. Whether or not two non overlapping parts of a composite
+@strong{27}. Whether or not two non-overlapping parts of a composite
object are independently addressable, in the case where packing, record
layout, or @code{Component_Size} is specified for the object. See
9.10(1).
@end cartouche
@noindent
A compilation is represented by a sequence of files presented to the
-compiler in a single invocation of the @code{gcc} command.
+compiler in a single invocation of the @command{gcc} command.
@sp 1
@cartouche
If the partition contains no main program, or if the main program is in
a language other than Ada, then GNAT
-provides the binder options @code{-z} and @code{-n} respectively, and in
+provides the binder options @option{-z} and @option{-n} respectively, and in
this case a list of units can be explicitly supplied to the binder for
inclusion in the partition (all units needed by these units will also
be included automatically). For full details on the use of these
-options, refer to the @cite{GNAT User's Guide} sections on Binding
-and Linking.
+options, refer to @ref{The GNAT Make Program gnatmake,,, gnat_ugn,
+@value{EDITION} User's Guide}.
@sp 1
@cartouche
@end cartouche
@noindent
The first constraint on ordering is that it meets the requirements of
-chapter 10 of the Ada 95 Reference Manual. This still leaves some
+Chapter 10 of the Ada Reference Manual. This still leaves some
implementation dependent choices, which are resolved by first
-elaborating bodies as early as possible (i.e.@: in preference to specs
+elaborating bodies as early as possible (i.e., in preference to specs
where there is a choice), and second by evaluating the immediate with
clauses of a unit to determine the probably best choice, and
third by elaborating in alphabetical order of unit names
@item
@code{ppp} is the Process Id value as a decimal integer (this line is
-present only if the Process Id is non-zero). Currently we are
+present only if the Process Id is nonzero). Currently we are
not making use of this field.
@item
@strong{42}. Implementation-defined check names. See 11.5(27).
@end cartouche
@noindent
-No implementation-defined check names are supported.
+The implementation defined check name Alignment_Check controls checking of
+address clause values for proper alignment (that is, the address supplied
+must be consistent with the alignment of the type).
+
+In addition, a user program can add implementation-defined check names
+by means of the pragma Check_Name.
@sp 1
@cartouche
@end cartouche
@noindent
Unchecked conversion between types of the same size
-and results in an uninterpreted transmission of the bits from one type
+results in an uninterpreted transmission of the bits from one type
to the other. If the types are of unequal sizes, then in the case of
discrete types, a shorter source is first zero or sign extended as
necessary, and a shorter target is simply truncated on the left.
to ensure that the alignment requirements of the target are met, then
a pointer is constructed to the source value, and the result is obtained
by dereferencing this pointer after converting it to be a pointer to the
-target type.
+target type. Unchecked conversions where the target subtype is an
+unconstrained array are not permitted. If the target alignment is
+greater than the source alignment, then a copy of the result is
+made with appropriate alignment
@sp 1
@cartouche
@table @code
-@item Boolean_Entry_Barriers
-@findex Boolean_Entry_Barriers
+@item Simple_Barriers
+@findex Simple_Barriers
This restriction ensures at compile time that barriers in entry declarations
-for protected types are restricted to references to simple boolean variables
-defined in the private part of the protected type. No other form of entry
-barriers is permitted. This is one of the restrictions of the Ravenscar
-profile for limited tasking (see also pragma @code{Ravenscar}).
-
-@item Max_Entry_Queue_Depth => Expr
-@findex Max_Entry_Queue_Depth
+for protected types are restricted to either static boolean expressions or
+references to simple boolean variables defined in the private part of the
+protected type. No other form of entry barriers is permitted. This is one
+of the restrictions of the Ravenscar profile for limited tasking (see also
+pragma @code{Profile (Ravenscar)}).
+
+@item Max_Entry_Queue_Length => Expr
+@findex Max_Entry_Queue_Length
This restriction is a declaration that any protected entry compiled in
the scope of the restriction has at most the specified number of
tasks waiting on the entry
This restriction ensures at compile time that there is no implicit or
explicit dependence on the package @code{Ada.Calendar}.
+@item No_Default_Initialization
+@findex No_Default_Initialization
+
+This restriction prohibits any instance of default initialization of variables.
+The binder implements a consistency rule which prevents any unit compiled
+without the restriction from with'ing a unit with the restriction (this allows
+the generation of initialization procedures to be skipped, since you can be
+sure that no call is ever generated to an initialization procedure in a unit
+with the restriction active). If used in conjunction with Initialize_Scalars or
+Normalize_Scalars, the effect is to prohibit all cases of variables declared
+without a specific initializer (including the case of OUT scalar parameters).
+
@item No_Direct_Boolean_Operators
@findex No_Direct_Boolean_Operators
-This restriction ensures that no logical (and/or/xor) or comparison
-operators are used on operands of type Boolean (or any type derived
+This restriction ensures that no logical (and/or/xor) are used on
+operands of type Boolean (or any type derived
from Boolean). This is intended for use in safety critical programs
where the certification protocol requires the use of short-circuit
(and then, or else) forms for all composite boolean operations.
-@item No_Dynamic_Interrupts
-@findex No_Dynamic_Interrupts
-This restriction ensures at compile time that there is no attempt to
-dynamically associate interrupts. Only static association is allowed.
+@item No_Dispatching_Calls
+@findex No_Dispatching_Calls
+This restriction ensures at compile time that the code generated by the
+compiler involves no dispatching calls. The use of this restriction allows the
+safe use of record extensions, classwide membership tests and other classwide
+features not involving implicit dispatching. This restriction ensures that
+the code contains no indirect calls through a dispatching mechanism. Note that
+this includes internally-generated calls created by the compiler, for example
+in the implementation of class-wide objects assignments. The
+membership test is allowed in the presence of this restriction, because its
+implementation requires no dispatching.
+This restriction is comparable to the official Ada restriction
+@code{No_Dispatch} except that it is a bit less restrictive in that it allows
+all classwide constructs that do not imply dispatching.
+The following example indicates constructs that violate this restriction.
+
+@smallexample
+package Pkg is
+ type T is tagged record
+ Data : Natural;
+ end record;
+ procedure P (X : T);
+
+ type DT is new T with record
+ More_Data : Natural;
+ end record;
+ procedure Q (X : DT);
+end Pkg;
+
+with Pkg; use Pkg;
+procedure Example is
+ procedure Test (O : T'Class) is
+ N : Natural := O'Size;-- Error: Dispatching call
+ C : T'Class := O; -- Error: implicit Dispatching Call
+ begin
+ if O in DT'Class then -- OK : Membership test
+ Q (DT (O)); -- OK : Type conversion plus direct call
+ else
+ P (O); -- Error: Dispatching call
+ end if;
+ end Test;
+
+ Obj : DT;
+begin
+ P (Obj); -- OK : Direct call
+ P (T (Obj)); -- OK : Type conversion plus direct call
+ P (T'Class (Obj)); -- Error: Dispatching call
+
+ Test (Obj); -- OK : Type conversion
+
+ if Obj in T'Class then -- OK : Membership test
+ null;
+ end if;
+end Example;
+@end smallexample
+
+@item No_Dynamic_Attachment
+@findex No_Dynamic_Attachment
+This restriction ensures that there is no call to any of the operations
+defined in package Ada.Interrupts.
@item No_Enumeration_Maps
@findex No_Enumeration_Maps
an immediate call to the last chance handler, a routine that the user
must define with the following profile:
- procedure Last_Chance_Handler
- (Source_Location : System.Address; Line : Integer);
- pragma Export (C, Last_Chance_Handler,
- "__gnat_last_chance_handler");
-
- The parameter is a C null-terminated string representing a message to be
- associated with the exception (typically the source location of the raise
- statement generated by the compiler). The Line parameter when non-zero
- represents the line number in the source program where the raise occurs.
+@smallexample @c ada
+procedure Last_Chance_Handler
+ (Source_Location : System.Address; Line : Integer);
+pragma Export (C, Last_Chance_Handler,
+ "__gnat_last_chance_handler");
+@end smallexample
-@item No_Exception_Streams
-@findex No_Exception_Streams
+The parameter is a C null-terminated string representing a message to be
+associated with the exception (typically the source location of the raise
+statement generated by the compiler). The Line parameter when nonzero
+represents the line number in the source program where the raise occurs.
+
+@item No_Exception_Propagation
+@findex No_Exception_Propagation
+This restriction guarantees that exceptions are never propagated to an outer
+subprogram scope). The only case in which an exception may be raised is when
+the handler is statically in the same subprogram, so that the effect of a raise
+is essentially like a goto statement. Any other raise statement (implicit or
+explicit) will be considered unhandled. Exception handlers are allowed, but may
+not contain an exception occurrence identifier (exception choice). In addition
+use of the package GNAT.Current_Exception is not permitted, and reraise
+statements (raise with no operand) are not permitted.
+
+@item No_Exception_Registration
+@findex No_Exception_Registration
This restriction ensures at compile time that no stream operations for
types Exception_Id or Exception_Occurrence are used. This also makes it
impossible to pass exceptions to or from a partition with this restriction
This restriction ensures that the generated code does not contain any
implicit conditionals, either by modifying the generated code where possible,
or by rejecting any construct that would otherwise generate an implicit
-conditional.
+conditional. Note that this check does not include run time constraint
+checks, which on some targets may generate implicit conditionals as
+well. To control the latter, constraint checks can be suppressed in the
+normal manner. Constructs generating implicit conditionals include comparisons
+of composite objects and the Max/Min attributes.
@item No_Implicit_Dynamic_Code
@findex No_Implicit_Dynamic_Code
+@cindex trampoline
This restriction prevents the compiler from building ``trampolines''.
This is a structure that is built on the stack and contains dynamic
-code to be executed at run time. A trampoline is needed to indirectly
-address a nested subprogram (that is a subprogram that is not at the
-library level). The restriction prevents the use of any of the
-attributes @code{Address}, @code{Access} or @code{Unrestricted_Access}
-being applied to a subprogram that is not at the library level.
+code to be executed at run time. On some targets, a trampoline is
+built for the following features: @code{Access},
+@code{Unrestricted_Access}, or @code{Address} of a nested subprogram;
+nested task bodies; primitive operations of nested tagged types.
+Trampolines do not work on machines that prevent execution of stack
+data. For example, on windows systems, enabling DEP (data execution
+protection) will cause trampolines to raise an exception.
+Trampolines are also quite slow at run time.
+
+On many targets, trampolines have been largely eliminated. Look at the
+version of system.ads for your target --- if it has
+Always_Compatible_Rep equal to False, then trampolines are largely
+eliminated. In particular, a trampoline is built for the following
+features: @code{Address} of a nested subprogram;
+@code{Access} or @code{Unrestricted_Access} of a nested subprogram,
+but only if pragma Favor_Top_Level applies, or the access type has a
+foreign-language convention; primitive operations of nested tagged
+types.
@item No_Implicit_Loops
@findex No_Implicit_Loops
implicit @code{for} loops, either by modifying
the generated code where possible,
or by rejecting any construct that would otherwise generate an implicit
-@code{for} loop.
+@code{for} loop. If this restriction is active, it is possible to build
+large array aggregates with all static components without generating an
+intermediate temporary, and without generating a loop to initialize individual
+components. Otherwise, a loop is created for arrays larger than about 5000
+scalar components.
@item No_Initialize_Scalars
@findex No_Initialize_Scalars
This restriction ensures at compile time no select statements of any kind
are permitted, that is the keyword @code{select} may not appear.
This is one of the restrictions of the Ravenscar
-profile for limited tasking (see also pragma @code{Ravenscar}).
+profile for limited tasking (see also pragma @code{Profile (Ravenscar)}).
@item No_Standard_Storage_Pools
@findex No_Standard_Storage_Pools
@item No_Streams
@findex No_Streams
-This restriction ensures at compile time that there are no implicit or
-explicit dependencies on the package @code{Ada.Streams}.
-
-@item No_Task_Attributes
-@findex No_Task_Attributes
+This restriction ensures at compile/bind time that there are no
+stream objects created and no use of stream attributes.
+This restriction does not forbid dependences on the package
+@code{Ada.Streams}. So it is permissible to with
+@code{Ada.Streams} (or another package that does so itself)
+as long as no actual stream objects are created and no
+stream attributes are used.
+
+Note that the use of restriction allows optimization of tagged types,
+since they do not need to worry about dispatching stream operations.
+To take maximum advantage of this space-saving optimization, any
+unit declaring a tagged type should be compiled with the restriction,
+though this is not required.
+
+@item No_Task_Attributes_Package
+@findex No_Task_Attributes_Package
This restriction ensures at compile time that there are no implicit or
explicit dependencies on the package @code{Ada.Task_Attributes}.
except that violations are caught at compile time and cause an error message
to be output either by the compiler or binder.
-@item No_Wide_Characters
-@findex No_Wide_Characters
-This restriction ensures at compile time that no uses of the types
-@code{Wide_Character} or @code{Wide_String}
-appear, and that no wide character literals
-appear in the program (that is literals representing characters not in
-type @code{Character}.
-
@item Static_Priorities
@findex Static_Priorities
This restriction ensures at compile time that all priority expressions
the case that preelaborable units will meet the restrictions, with
the exception of large aggregates initialized with an others_clause,
and exception declarations (which generate calls to a run-time
-registry procedure). Note that this restriction is enforced on
+registry procedure). This restriction is enforced on
a unit by unit basis, it need not be obeyed consistently
throughout a partition.
+In the case of aggregates with others, if the aggregate has a dynamic
+size, there is no way to eliminate the elaboration code (such dynamic
+bounds would be incompatible with @code{Preelaborate} in any case). If
+the bounds are static, then use of this restriction actually modifies
+the code choice of the compiler to avoid generating a loop, and instead
+generate the aggregate statically if possible, no matter how many times
+the data for the others clause must be repeatedly generated.
+
+It is not possible to precisely document
+the constructs which are compatible with this restriction, since,
+unlike most other restrictions, this is not a restriction on the
+source code, but a restriction on the generated object code. For
+example, if the source contains a declaration:
+
+@smallexample
+ Val : constant Integer := X;
+@end smallexample
+
+@noindent
+where X is not a static constant, it may be possible, depending
+on complex optimization circuitry, for the compiler to figure
+out the value of X at compile time, in which case this initialization
+can be done by the loader, and requires no initialization code. It
+is not possible to document the precise conditions under which the
+optimizer can figure this out.
+
+Note that this the implementation of this restriction requires full
+code generation. If it is used in conjunction with "semantics only"
+checking, then some cases of violations may be missed.
+
@item No_Entry_Queue
@findex No_Entry_Queue
This restriction is a declaration that any protected entry compiled in
@findex No_Implementation_Attributes
This restriction checks at compile time that no GNAT-defined attributes
are present. With this restriction, the only attributes that can be used
-are those defined in the Ada 95 Reference Manual.
+are those defined in the Ada Reference Manual.
@item No_Implementation_Pragmas
@findex No_Implementation_Pragmas
This restriction checks at compile time that no GNAT-defined pragmas
are present. With this restriction, the only pragmas that can be used
-are those defined in the Ada 95 Reference Manual.
+are those defined in the Ada Reference Manual.
@item No_Implementation_Restrictions
@findex No_Implementation_Restrictions
This restriction checks at compile time that no GNAT-defined restriction
identifiers (other than @code{No_Implementation_Restrictions} itself)
are present. With this restriction, the only other restriction identifiers
-that can be used are those defined in the Ada 95 Reference Manual.
+that can be used are those defined in the Ada Reference Manual.
+
+@item No_Wide_Characters
+@findex No_Wide_Characters
+This restriction ensures at compile time that no uses of the types
+@code{Wide_Character} or @code{Wide_String} or corresponding wide
+wide types
+appear, and that no wide or wide wide string or character literals
+appear in the program (that is literals representing characters not in
+type @code{Character}.
@end table
is to be passed by copy rather than reference.
@item COBOL
COBOL
-@item CPP
+@item C_Plus_Plus (or CPP)
C++
@item Default
Treated the same as C
@end cartouche
@noindent
The string passed to @code{Linker_Options} is presented uninterpreted as
-an argument to the link command, unless it contains Ascii.NUL characters.
+an argument to the link command, unless it contains ASCII.NUL characters.
NUL characters if they appear act as argument separators, so for example
@smallexample @c ada
-pragma Linker_Options ("-labc" & ASCII.Nul & "-ldef");
+pragma Linker_Options ("-labc" & ASCII.NUL & "-ldef");
@end smallexample
@noindent
causes two separate arguments @code{-labc} and @code{-ldef} to be passed to the
linker. The order of linker options is preserved for a given unit. The final
list of options passed to the linker is in reverse order of the elaboration
-order. For example, linker options fo a body always appear before the options
+order. For example, linker options for a body always appear before the options
from the corresponding package spec.
@sp 1
attribute. See C.7.1(7).
@end cartouche
@noindent
-The result of this attribute is an 8-digit hexadecimal string
-representing the virtual address of the task control block.
-
+The result of this attribute is a string that identifies
+the object or component that denotes a given task. If a variable @code{Var}
+has a task type, the image for this task will have the form @code{Var_@var{XXXXXXXX}},
+where the suffix
+is the hexadecimal representation of the virtual address of the corresponding
+task control block. If the variable is an array of tasks, the image of each
+task will have the form of an indexed component indicating the position of a
+given task in the array, e.g.@: @code{Group(5)_@var{XXXXXXX}}. If the task is a
+component of a record, the image of the task will have the form of a selected
+component. These rules are fully recursive, so that the image of a task that
+is a subcomponent of a composite object corresponds to the expression that
+designates this task.
+@noindent
+If a task is created by an allocator, its image depends on the context. If the
+allocator is part of an object declaration, the rules described above are used
+to construct its image, and this image is not affected by subsequent
+assignments. If the allocator appears within an expression, the image
+includes only the name of the task type.
+@noindent
+If the configuration pragma Discard_Names is present, or if the restriction
+No_Implicit_Heap_Allocation is in effect, the image reduces to
+the numeric suffix, that is to say the hexadecimal representation of the
+virtual address of the control block of the task.
@sp 1
@cartouche
@noindent
@noindent
The metrics information for GNAT depends on the performance of the
underlying operating system. The sources of the run-time for tasking
-implementation, together with the output from @code{-gnatG} can be
+implementation, together with the output from @option{-gnatG} can be
used to determine the exact sequence of operating systems calls made
to implement various tasking constructs. Together with appropriate
information on the performance of the underlying operating system,
@noindent
@c SGI info:
@ignore
-Tasks map to IRIX threads, and the dispatching policy is as defied by
+Tasks map to IRIX threads, and the dispatching policy is as defined by
the IRIX implementation of threads.
@end ignore
The policy is the same as that of the underlying threads implementation.
@end cartouche
@noindent
The ceiling priority of protected objects of the type
-@code{System.Interrupt_Priority'Last} as described in the Ada 95
+@code{System.Interrupt_Priority'Last} as described in the Ada
Reference Manual D.3(10),
@sp 1
@strong{101}. Implementation-defined queuing policies. See D.4(1).
@end cartouche
@noindent
-There are no implementation-defined queueing policies.
+There are no implementation-defined queuing policies.
@sp 1
@cartouche
result type is @code{False}. See G.2.1(13).
@end cartouche
@noindent
-Infinite and Nan values are produced as dictated by the IEEE
+Infinite and NaN values are produced as dictated by the IEEE
floating-point standard.
+Note that on machines that are not fully compliant with the IEEE
+floating-point standard, such as Alpha, the @option{-mieee} compiler flag
+must be used for achieving IEEE confirming behavior (although at the cost
+of a significant performance penalty), so infinite and NaN values are
+properly generated.
+
@sp 1
@cartouche
@noindent
@section Rotate_Left
@cindex Rotate_Left
@noindent
-In standard Ada 95, the @code{Rotate_Left} function is available only
+In standard Ada, the @code{Rotate_Left} function is available only
for the predefined modular types in package @code{Interfaces}. However, in
GNAT it is possible to define a Rotate_Left function for a user
defined modular type or any signed integer type as in this example:
@item @emph{Records}.
For the normal non-packed case, the alignment of a record is equal to
the maximum alignment of any of its components. For tagged records, this
-includes the implicit access type used for the tag. If a pragma @code{Pack} is
-used and all fields are packable (see separate section on pragma @code{Pack}),
-then the resulting alignment is 1.
+includes the implicit access type used for the tag. If a pragma @code{Pack}
+is used and all components are packable (see separate section on pragma
+@code{Pack}), then the resulting alignment is 1, unless the layout of the
+record makes it profitable to increase it.
A special case is when:
@itemize @bullet
@end itemize
@noindent
-An alignment clause may
-always specify a larger alignment than the default value, up to some
-maximum value dependent on the target (obtainable by using the
-attribute reference @code{Standard'Maximum_Alignment}).
-The only case where
-it is permissible to specify a smaller alignment than the default value
-is for a record with a record representation clause.
-In this case, packable fields for which a component clause is
-given still result in a default alignment corresponding to the original
-type, but this may be overridden, since these components in fact only
-require an alignment of one byte. For example, given
+An alignment clause may specify a larger alignment than the default value
+up to some maximum value dependent on the target (obtainable by using the
+attribute reference @code{Standard'Maximum_Alignment}). It may also specify
+a smaller alignment than the default value for enumeration, integer and
+fixed point types, as well as for record types, for example
@smallexample @c ada
type V is record
A : Integer;
end record;
- for V use record
- A at 0 range 0 .. 31;
- end record;
-
for V'alignment use 1;
@end smallexample
@noindent
@cindex Alignment, default
The default alignment for the type @code{V} is 4, as a result of the
-Integer field in the record, but since this field is placed with a
-component clause, it is permissible, as shown, to override the default
-alignment of the record with a smaller value.
+Integer field in the record, but it is permissible, as shown, to
+override the default alignment of the record with a smaller value.
@node Size Clauses
@section Size Clauses
(@code{Rec'Size} = @code{Rec'Value_Size} = 40), but
the alignment is 4, so objects of this type will have
their size increased to 64 bits so that it is a multiple
-of the alignment (in bits). The reason for this decision, which is
+of the alignment (in bits). This decision is
in accordance with the specific Implementation Advice in RM 13.3(43):
@quotation
@noindent
Then @code{Default_Stack_Size} can be defined in a global package, and
-modified as required. Any tasks requiring stack sizes different from the
+modified as required. Any tasks requiring stack sizes different from the
default can have an appropriate alternative reference in the pragma.
+You can also use the @option{-d} binder switch to modify the default stack
+size.
+
For access types, the @code{Storage_Size} clause specifies the maximum
space available for allocation of objects of the type. If this space is
exceeded then @code{Storage_Error} will be raised by an allocation attempt.
@cindex Size, of objects
@noindent
-In Ada 95, @code{T'Size} for a type @code{T} is the minimum number of bits
-required to hold values of type @code{T}. Although this interpretation was
-allowed in Ada 83, it was not required, and this requirement in practice
-can cause some significant difficulties. For example, in most Ada 83
-compilers, @code{Natural'Size} was 32. However, in Ada 95,
+In Ada 95 and Ada 2005, @code{T'Size} for a type @code{T} is the minimum
+number of bits required to hold values of type @code{T}.
+Although this interpretation was allowed in Ada 83, it was not required,
+and this requirement in practice can cause some significant difficulties.
+For example, in most Ada 83 compilers, @code{Natural'Size} was 32.
+However, in Ada 95 and Ada 2005,
@code{Natural'Size} is
typically 31. This means that code may change in behavior when moving
-from Ada 83 to Ada 95. For example, consider:
+from Ada 83 to Ada 95 or Ada 2005. For example, consider:
@smallexample @c ada
type Rec is record;
@noindent
In the above code, since the typical size of @code{Natural} objects
is 32 bits and @code{Natural'Size} is 31, the above code can cause
-unexpected inefficient packing in Ada 95, and in general there are
-cases where the fact that the object size can exceed the
+unexpected inefficient packing in Ada 95 and Ada 2005, and in general
+there are cases where the fact that the object size can exceed the
size of the type causes surprises.
To help get around this problem GNAT provides two implementation
@end smallexample
@noindent
-Note: the entries marked ``3*'' are not actually specified by the Ada 95 RM,
-but it seems in the spirit of the RM rules to allocate the minimum number
-of bits (here 3, given the range for @code{x2})
+Note: the entries marked ``3*'' are not actually specified by the Ada
+Reference Manual, but it seems in the spirit of the RM rules to allocate
+the minimum number of bits (here 3, given the range for @code{x2})
known to be large enough to hold the given range of values.
So far, so good, but GNAT has to obey the RM rules, so the question is
require four-byte alignment, and the Y component will be one byte. In this
case @code{R'Value_Size} will be 40 (bits) since this is the minimum size
required to store a value of this type, and for example, it is permissible
-to have a component of type R in an outer record whose component size is
+to have a component of type R in an outer array whose component size is
specified to be 48 bits. However, @code{R'Object_Size} will be 64 (bits),
since it must be rounded up so that this value is a multiple of the
alignment (4 bytes = 32 bits).
@cindex Component_Size Clause
@noindent
-Normally, the value specified in a component clause must be consistent
+Normally, the value specified in a component size clause must be consistent
with the subtype of the array component with regard to size and alignment.
In other words, the value specified must be at least equal to the size
of this subtype, and must be a multiple of the alignment value.
In addition, component size clauses are allowed which cause the array
-to be packed, by specifying a smaller value. The cases in which this
-is allowed are for component size values in the range 1 through 63. The value
-specified must not be smaller than the Size of the subtype. GNAT will
-accurately honor all packing requests in this range. For example, if
-we have:
+to be packed, by specifying a smaller value. A first case is for
+component size values in the range 1 through 63. The value specified
+must not be smaller than the Size of the subtype. GNAT will accurately
+honor all packing requests in this range. For example, if we have:
@smallexample @c ada
type r is array (1 .. 8) of Natural;
then the resulting array has a length of 31 bytes (248 bits = 8 * 31).
Of course access to the components of such an array is considerably
less efficient than if the natural component size of 32 is used.
+A second case is when the subtype of the component is a record type
+padded because of its default alignment. For example, if we have:
+
+@smallexample @c ada
+type r is record
+ i : Integer;
+ j : Integer;
+ b : Boolean;
+end record;
+
+type a is array (1 .. 8) of r;
+for a'Component_Size use 72;
+@end smallexample
+
+@noindent
+then the resulting array has a length of 72 bytes, instead of 96 bytes
+if the alignment of the record (4) was obeyed.
+
+Note that there is no point in giving both a component size clause
+and a pragma Pack for the same array type. if such duplicate
+clauses are given, the pragma Pack will be ignored.
@node Bit_Order Clauses
@section Bit_Order Clauses
Since the misconception that Bit_Order automatically deals with all
endian-related incompatibilities is a common one, the specification of
a component field that is an integral number of bytes will always
-generate a warning. This warning may be suppressed using
-@code{pragma Suppress} if desired. The following section contains additional
+generate a warning. This warning may be suppressed using @code{pragma
+Warnings (Off)} if desired. The following section contains additional
details regarding the issue of byte ordering.
@node Effect of Bit_Order on Byte Ordering
Any type whose size is specified with a size clause
@item
Any packed array type with a static size
+@item
+Any record type padded because of its default alignment
@end itemize
@noindent
and the size of the array @code{ar} will be exactly 40 bits.
Note that in some cases this rather fierce approach to packing can produce
-unexpected effects. For example, in Ada 95, type Natural typically has a
-size of 31, meaning that if you pack an array of Natural, you get 31-bit
+unexpected effects. For example, in Ada 95 and Ada 2005,
+subtype @code{Natural} typically has a size of 31, meaning that if you
+pack an array of @code{Natural}, you get 31-bit
close packing, which saves a few bits, but results in far less efficient
access. Since many other Ada compilers will ignore such a packing request,
GNAT will generate a warning on some uses of pragma @code{Pack} that it guesses
since typically @code{Natural'Size} is 32 in Ada 83, and in any case most
Ada 83 compilers did not attempt 31 bit packing.
-In Ada 95, @code{Natural'Size} is required to be 31. Furthermore, GNAT really
-does pack 31-bit subtype to 31 bits. This may result in a substantial
-unintended performance penalty when porting legacy Ada 83 code. To help
-prevent this, GNAT generates a warning in such cases. If you really want 31
-bit packing in a case like this, you can set the component size explicitly:
+In Ada 95 and Ada 2005, @code{Natural'Size} is required to be 31. Furthermore,
+GNAT really does pack 31-bit subtype to 31 bits. This may result in a
+substantial unintended performance penalty when porting legacy Ada 83 code.
+To help prevent this, GNAT generates a warning in such cases. If you really
+want 31 bit packing in a case like this, you can set the component size
+explicitly:
@smallexample @c ada
type Arr is array (1 .. 32) of Natural;
then a component clause for a component of type R may start on any
specified bit boundary, and may specify a value of 49 bits or greater.
-The rules for other types are different for GNAT 3 and GNAT 5 versions
-(based on GCC 2 and GCC 3 respectively). In GNAT 5, larger components
-may also be placed on arbitrary boundaries, so for example, the following
-is permitted:
+For packed bit arrays that are longer than 64 bits, there are two
+cases. If the component size is a power of 2 (1,2,4,8,16,32 bits),
+including the important case of single bits or boolean values, then
+there are no limitations on placement of such components, and they
+may start and end at arbitrary bit boundaries.
+
+If the component size is not a power of 2 (e.g.@: 3 or 5), then
+an array of this type longer than 64 bits must always be placed on
+on a storage unit (byte) boundary and occupy an integral number
+of storage units (bytes). Any component clause that does not
+meet this requirement will be rejected.
+
+Any aliased component, or component of an aliased type, must
+have its normal alignment and size. A component clause that
+does not meet this requirement will be rejected.
+
+The tag field of a tagged type always occupies an address sized field at
+the start of the record. No component clause may attempt to overlay this
+tag. When a tagged type appears as a component, the tag field must have
+proper alignment
+
+In the case of a record extension T1, of a type T, no component clause applied
+to the type T1 can specify a storage location that would overlap the first
+T'Size bytes of the record.
+
+For all other component types, including non-bit-packed arrays,
+the component can be placed at an arbitrary bit boundary,
+so for example, the following is permitted:
@smallexample @c ada
- type R is array (1 .. 79) of Boolean;
- pragma Pack (R);
- for R'Size use 79;
+ type R is array (1 .. 10) of Boolean;
+ for R'Size use 80;
type Q is record
G, H : Boolean;
for Q use record
G at 0 range 0 .. 0;
H at 0 range 1 .. 1;
- L at 0 range 2 .. 80;
- R at 0 range 81 .. 159;
+ L at 0 range 2 .. 81;
+ R at 0 range 82 .. 161;
end record;
@end smallexample
@noindent
+Note: the above rules apply to recent releases of GNAT 5.
In GNAT 3, there are more severe restrictions on larger components.
For non-primitive types, including packed arrays with a size greater than
64 bits, component clauses must respect the alignment requirement of the
type, in particular, always starting on a byte boundary, and the length
must be a multiple of the storage unit.
-The following rules regarding tagged types are enforced in both GNAT 3 and
-GNAT 5:
-
-The tag field of a tagged type always occupies an address sized field at
-the start of the record. No component clause may attempt to overlay this
-tag.
-
-In the case of a record extension T1, of a type T, no component clause applied
-to the type T1 can specify a storage location that would overlap the first
-T'Size bytes of the record.
-
@node Enumeration Clauses
@section Enumeration Clauses
@end smallexample
@noindent
-For the unsigned case, where all values are non negative, the values must
+For the unsigned case, where all values are nonnegative, the values must
be in the range:
@smallexample @c ada
checks (at compile time if possible, generating a warning, or at execution
time with a run-time check) that the alignment is appropriate. If the
run-time check fails, then @code{Program_Error} is raised. This run-time
-check is suppressed if range checks are suppressed, or if
+check is suppressed if range checks are suppressed, or if the special GNAT
+check Alignment_Check is suppressed, or if
@code{pragma Restrictions (No_Elaboration_Code)} is in effect.
+Finally, GNAT does not permit overlaying of objects of controlled types or
+composite types containing a controlled component. In most cases, the compiler
+can detect an attempt at such overlays and will generate a warning at compile
+time and a Program_Error exception at run time.
+
@findex Export
An address clause cannot be given for an exported object. More
understandably the real restriction is that objects with an address
and @code{B} become aliased to one another via the
address clause. This use of address clauses to overlay
variables, achieving an effect similar to unchecked
-conversion was erroneous in Ada 83, but in Ada 95
+conversion was erroneous in Ada 83, but in Ada 95 and Ada 2005
the effect is implementation defined. Furthermore, the
-Ada 95 RM specifically recommends that in a situation
+Ada RM specifically recommends that in a situation
like this, @code{B} should be subject to the following
implementation advice (RM 13.3(19)):
consistent with C@. This means that specifying convention C (for example)
has no effect.
-There are three exceptions to this general rule:
+There are four exceptions to this general rule:
@itemize @bullet
Ada enumeration type, then the size is modified as necessary (usually to
32 bits) to be consistent with the C convention for enum values.
+Note that this treatment applies only to types. If Convention C is given for
+an enumeration object, where the enumeration type is not Convention C, then
+Object_Size bits are allocated. For example, for a normal enumeration type,
+with less than 256 elements, only 8 bits will be allocated for the object.
+Since this may be a surprise in terms of what C expects, GNAT will issue a
+warning in this situation. The warning can be suppressed by giving an explicit
+size clause specifying the desired size.
+
@item Convention C/Fortran and Boolean types
In C, the usual convention for boolean values, that is values used for
conditions, is that zero represents false, and nonzero values represent
values generated by GNAT, the conventional value 1 will be used for True, but
when one of these values is read, any nonzero value is treated as True.
+@item Access types on OpenVMS
+For 64-bit OpenVMS systems, access types (other than those for unconstrained
+arrays) are 64-bits long. An exception to this rule is for the case of
+C-convention access types where there is no explicit size clause present (or
+inherited for derived types). In this case, GNAT chooses to make these
+pointers 32-bits, which provides an easier path for migration of 32-bit legacy
+code. size clause specifying 64-bits must be used to obtain a 64-bit pointer.
+
@end itemize
@node Determining the Representations chosen by GNAT
@section Determining the Representations chosen by GNAT
@cindex Representation, determination of
-@cindex @code{-gnatR} switch
+@cindex @option{-gnatR} switch
@noindent
Although the descriptions in this section are intended to be complete, it is
used to answer the second question, but it is often easier to just see
what the compiler does.
-For this purpose, GNAT provides the option @code{-gnatR}. If you compile
+For this purpose, GNAT provides the option @option{-gnatR}. If you compile
with this option, then the compiler will output information on the actual
representations chosen, in a format similar to source representation
clauses. For example, if we compile the package:
@end smallexample
@noindent
-using the switch @code{-gnatR} we obtain the following output:
+using the switch @option{-gnatR} we obtain the following output:
@smallexample
Representation information for unit q
@chapter Standard Library Routines
@noindent
-The Ada 95 Reference Manual contains in Annex A a full description of an
+The Ada Reference Manual contains in Annex A a full description of an
extensive set of standard library routines that can be used in any Ada
program, and which must be provided by all Ada compilers. They are
analogous to the standard C library used by C programs.
GNAT implements all of the facilities described in annex A, and for most
-purposes the description in the Ada 95
-reference manual, or appropriate Ada
+purposes the description in the Ada Reference Manual, or appropriate Ada
text book, will be sufficient for making use of these facilities.
-In the case of the input-output facilities, @xref{The Implementation of
-Standard I/O}, gives details on exactly how GNAT interfaces to the
-file system. For the remaining packages, the Ada 95 reference manual
+In the case of the input-output facilities,
+@xref{The Implementation of Standard I/O},
+gives details on exactly how GNAT interfaces to the
+file system. For the remaining packages, the Ada Reference Manual
should be sufficient. The following is a list of the packages included,
together with a brief description of the functionality that is provided.
For completeness, references are included to other predefined library
-routines defined in other sections of the Ada 95 reference manual (these are
-cross-indexed from annex A).
+routines defined in other sections of the Ada Reference Manual (these are
+cross-indexed from Annex A).
@table @code
@item Ada (A.2)
@item Ada.Decimal (F.2)
This package provides constants describing the range of decimal numbers
implemented, and also a decimal divide routine (analogous to the COBOL
-verb DIVIDE .. GIVING .. REMAINDER ..)
+verb DIVIDE @dots{} GIVING @dots{} REMAINDER @dots{})
@item Ada.Direct_IO (A.8.4)
This package provides input-output using a model of a set of records of
@item Float
@code{Ada.Numerics.Complex_Elementary_Functions}
@item Long_Float
-@code{Ada.Numerics.
- Long_Complex_Elementary_Functions}
+@code{Ada.Numerics.Long_Complex_Elementary_Functions}
@end table
@item Ada.Numerics.Generic_Complex_Types
@code{Wide_String} and @code{Wide_Character} instead of @code{String}
and @code{Character}.
+@item Ada.Strings.Wide_Wide_Bounded (A.4.7)
+@itemx Ada.Strings.Wide_Wide_Fixed (A.4.7)
+@itemx Ada.Strings.Wide_Wide_Maps (A.4.7)
+@itemx Ada.Strings.Wide_Wide_Maps.Constants (A.4.7)
+@itemx Ada.Strings.Wide_Wide_Unbounded (A.4.7)
+These packages provide analogous capabilities to the corresponding
+packages without @samp{Wide_} in the name, but operate with the types
+@code{Wide_Wide_String} and @code{Wide_Wide_Character} instead
+of @code{String} and @code{Character}.
+
@item Ada.Synchronous_Task_Control (D.10)
This package provides some standard facilities for controlling task
communication in a synchronous manner.
A pointer other than a pointer to an unconstrained array type may be
converted to and from System.Address. Such usage is common in Ada 83
programs, but note that Ada.Address_To_Access_Conversions is the
-preferred method of performing such conversions in Ada 95. Neither
+preferred method of performing such conversions in Ada 95 and Ada 2005.
+Neither
unchecked conversion nor Ada.Address_To_Access_Conversions should be
used in conjunction with pointers to unconstrained objects, since
the bounds information cannot be handled correctly in this case.
-@item Ada.Unchecked_Deallocation (13.11.2)
-This generic package allows explicit freeing of storage previously
-allocated by use of an allocator.
+@item Ada.Unchecked_Deallocation (13.11.2)
+This generic package allows explicit freeing of storage previously
+allocated by use of an allocator.
+
+@item Ada.Wide_Text_IO (A.11)
+This package is similar to @code{Ada.Text_IO}, except that the external
+file supports wide character representations, and the internal types are
+@code{Wide_Character} and @code{Wide_String} instead of @code{Character}
+and @code{String}. It contains generic subpackages listed next.
+
+@item Ada.Wide_Text_IO.Decimal_IO
+Provides input-output facilities for decimal fixed-point types
+
+@item Ada.Wide_Text_IO.Enumeration_IO
+Provides input-output facilities for enumeration types.
+
+@item Ada.Wide_Text_IO.Fixed_IO
+Provides input-output facilities for ordinary fixed-point types.
+
+@item Ada.Wide_Text_IO.Float_IO
+Provides input-output facilities for float types. The following
+predefined instantiations of this generic package are available:
+
+@table @code
+@item Short_Float
+@code{Short_Float_Wide_Text_IO}
+@item Float
+@code{Float_Wide_Text_IO}
+@item Long_Float
+@code{Long_Float_Wide_Text_IO}
+@end table
+
+@item Ada.Wide_Text_IO.Integer_IO
+Provides input-output facilities for integer types. The following
+predefined instantiations of this generic package are available:
+
+@table @code
+@item Short_Short_Integer
+@code{Ada.Short_Short_Integer_Wide_Text_IO}
+@item Short_Integer
+@code{Ada.Short_Integer_Wide_Text_IO}
+@item Integer
+@code{Ada.Integer_Wide_Text_IO}
+@item Long_Integer
+@code{Ada.Long_Integer_Wide_Text_IO}
+@item Long_Long_Integer
+@code{Ada.Long_Long_Integer_Wide_Text_IO}
+@end table
+
+@item Ada.Wide_Text_IO.Modular_IO
+Provides input-output facilities for modular (unsigned) types
+
+@item Ada.Wide_Text_IO.Complex_IO (G.1.3)
+This package is similar to @code{Ada.Text_IO.Complex_IO}, except that the
+external file supports wide character representations.
+
+@item Ada.Wide_Text_IO.Editing (F.3.4)
+This package is similar to @code{Ada.Text_IO.Editing}, except that the
+types are @code{Wide_Character} and @code{Wide_String} instead of
+@code{Character} and @code{String}.
+
+@item Ada.Wide_Text_IO.Streams (A.12.3)
+This package is similar to @code{Ada.Text_IO.Streams}, except that the
+types are @code{Wide_Character} and @code{Wide_String} instead of
+@code{Character} and @code{String}.
-@item Ada.Wide_Text_IO (A.11)
+@item Ada.Wide_Wide_Text_IO (A.11)
This package is similar to @code{Ada.Text_IO}, except that the external
file supports wide character representations, and the internal types are
@code{Wide_Character} and @code{Wide_String} instead of @code{Character}
and @code{String}. It contains generic subpackages listed next.
-@item Ada.Wide_Text_IO.Decimal_IO
+@item Ada.Wide_Wide_Text_IO.Decimal_IO
Provides input-output facilities for decimal fixed-point types
-@item Ada.Wide_Text_IO.Enumeration_IO
+@item Ada.Wide_Wide_Text_IO.Enumeration_IO
Provides input-output facilities for enumeration types.
-@item Ada.Wide_Text_IO.Fixed_IO
+@item Ada.Wide_Wide_Text_IO.Fixed_IO
Provides input-output facilities for ordinary fixed-point types.
-@item Ada.Wide_Text_IO.Float_IO
+@item Ada.Wide_Wide_Text_IO.Float_IO
Provides input-output facilities for float types. The following
predefined instantiations of this generic package are available:
@table @code
@item Short_Float
-@code{Short_Float_Wide_Text_IO}
+@code{Short_Float_Wide_Wide_Text_IO}
@item Float
-@code{Float_Wide_Text_IO}
+@code{Float_Wide_Wide_Text_IO}
@item Long_Float
-@code{Long_Float_Wide_Text_IO}
+@code{Long_Float_Wide_Wide_Text_IO}
@end table
-@item Ada.Wide_Text_IO.Integer_IO
+@item Ada.Wide_Wide_Text_IO.Integer_IO
Provides input-output facilities for integer types. The following
predefined instantiations of this generic package are available:
@table @code
@item Short_Short_Integer
-@code{Ada.Short_Short_Integer_Wide_Text_IO}
+@code{Ada.Short_Short_Integer_Wide_Wide_Text_IO}
@item Short_Integer
-@code{Ada.Short_Integer_Wide_Text_IO}
+@code{Ada.Short_Integer_Wide_Wide_Text_IO}
@item Integer
-@code{Ada.Integer_Wide_Text_IO}
+@code{Ada.Integer_Wide_Wide_Text_IO}
@item Long_Integer
-@code{Ada.Long_Integer_Wide_Text_IO}
+@code{Ada.Long_Integer_Wide_Wide_Text_IO}
@item Long_Long_Integer
-@code{Ada.Long_Long_Integer_Wide_Text_IO}
+@code{Ada.Long_Long_Integer_Wide_Wide_Text_IO}
@end table
-@item Ada.Wide_Text_IO.Modular_IO
+@item Ada.Wide_Wide_Text_IO.Modular_IO
Provides input-output facilities for modular (unsigned) types
-@item Ada.Wide_Text_IO.Complex_IO (G.1.3)
+@item Ada.Wide_Wide_Text_IO.Complex_IO (G.1.3)
This package is similar to @code{Ada.Text_IO.Complex_IO}, except that the
external file supports wide character representations.
-@item Ada.Wide_Text_IO.Editing (F.3.4)
+@item Ada.Wide_Wide_Text_IO.Editing (F.3.4)
This package is similar to @code{Ada.Text_IO.Editing}, except that the
types are @code{Wide_Character} and @code{Wide_String} instead of
@code{Character} and @code{String}.
-@item Ada.Wide_Text_IO.Streams (A.12.3)
+@item Ada.Wide_Wide_Text_IO.Streams (A.12.3)
This package is similar to @code{Ada.Text_IO.Streams}, except that the
types are @code{Wide_Character} and @code{Wide_String} instead of
@code{Character} and @code{String}.
@end table
+
+
@node The Implementation of Standard I/O
@chapter The Implementation of Standard I/O
@noindent
GNAT implements all the required input-output facilities described in
-A.6 through A.14. These sections of the Ada 95 reference manual describe the
+A.6 through A.14. These sections of the Ada Reference Manual describe the
required behavior of these packages from the Ada point of view, and if
you are writing a portable Ada program that does not need to know the
exact manner in which Ada maps to the outside world when it comes to
reading or writing external files, then you do not need to read this
chapter. As long as your files are all regular files (not pipes or
devices), and as long as you write and read the files only from Ada, the
-description in the Ada 95 reference manual is sufficient.
+description in the Ada Reference Manual is sufficient.
However, if you want to do input-output to pipes or other devices, such
as the keyboard or screen, or if the files you are dealing with are
* Sequential_IO::
* Text_IO::
* Wide_Text_IO::
+* Wide_Wide_Text_IO::
* Stream_IO::
+* Text Translation::
* Shared Files::
+* Filenames encoding::
* Open Modes::
* Operations on C Streams::
* Interfacing to C Streams::
@item
Ada.Text_IO.Complex_IO
@item
-Ada.Text_IO.Text_Streams,
+Ada.Text_IO.Text_Streams
@item
Ada.Wide_Text_IO
@item
-Ada.Wide_Text_IO.Complex_IO,
+Ada.Wide_Text_IO.Complex_IO
@item
Ada.Wide_Text_IO.Text_Streams
@item
+Ada.Wide_Wide_Text_IO
+@item
+Ada.Wide_Wide_Text_IO.Complex_IO
+@item
+Ada.Wide_Wide_Text_IO.Text_Streams
+@item
Ada.Stream_IO
@item
Ada.Sequential_IO
@end itemize
@noindent
-There is no internal buffering of any kind at the Ada library level. The
-only buffering is that provided at the system level in the
-implementation of the C library routines that support streams. This
-facilitates shared use of these streams by mixed language programs.
+There is no internal buffering of any kind at the Ada library level. The only
+buffering is that provided at the system level in the implementation of the
+library routines that support streams. This facilitates shared use of these
+streams by mixed language programs. Note though that system level buffering is
+explicitly enabled at elaboration of the standard I/O packages and that can
+have an impact on mixed language programs, in particular those using I/O before
+calling the Ada elaboration routine (e.g.@: adainit). It is recommended to call
+the Ada elaboration routine before performing any I/O or when impractical,
+flush the common I/O streams and in particular Standard_Output before
+elaborating the Ada code.
@node FORM Strings
@section FORM Strings
@noindent
where letters may be in upper or lower case, and there are no spaces
between values. The order of the entries is not important. Currently
-there are two keywords defined.
+the following keywords defined.
@smallexample
+TEXT_TRANSLATION=[YES|NO]
SHARED=[YES|NO]
-WCEM=[n|h|u|s\e]
+WCEM=[n|h|u|s|e|8|b]
+ENCODING=[UTF8|8BITS]
@end smallexample
@noindent
clearly incorrect, since there is only one element in the file, and that
element is the string @code{hello!}.
-In Ada 95, this kind of behavior can be legitimately achieved using
-Stream_IO, and this is the preferred mechanism. In particular, the above
-program fragment rewritten to use Stream_IO will work correctly.
+In Ada 95 and Ada 2005, this kind of behavior can be legitimately achieved
+using Stream_IO, and this is the preferred mechanism. In particular, the
+above program fragment rewritten to use Stream_IO will work correctly.
@node Text_IO
@section Text_IO
the file unless an explicit @code{New_Page} operation was performed
before closing the file.
-A canonical Text_IO file that is a regular file, i.e.@: not a device or a
-pipe, can be read using any of the routines in Text_IO@. The
-semantics in this case will be exactly as defined in the Ada 95 reference
-manual and all the routines in Text_IO are fully implemented.
+A canonical Text_IO file that is a regular file (i.e., not a device or a
+pipe) can be read using any of the routines in Text_IO@. The
+semantics in this case will be exactly as defined in the Ada Reference
+Manual, and all the routines in Text_IO are fully implemented.
A text file that does not meet the requirements for a canonical Text_IO
file has one of the following:
files @file{a-swuwti.ads} and @file{a-swuwti.adb} provides similar extended
@code{Wide_Text_IO} functionality for unbounded wide strings.
+The package @code{Ada.Strings.Wide_Wide_Unbounded.Wide_Wide_Text_IO} in library
+files @file{a-szuzti.ads} and @file{a-szuzti.adb} provides similar extended
+@code{Wide_Wide_Text_IO} functionality for unbounded wide wide strings.
+
@node Wide_Text_IO
@section Wide_Text_IO
@end smallexample
@noindent
-where the xxx bits correspond to the left-padded bits of the
+where the @var{xxx} bits correspond to the left-padded bits of the
16-bit character value. Note that all lower half ASCII characters
are represented as ASCII bytes and all upper half characters and
other wide characters are represented as sequences of upper-half
e.g.@: @code{["C1"]} for lower case a. However, on output, brackets notation
is only used for wide characters with a code greater than @code{16#FF#}.
+Note that brackets coding is not normally used in the context of
+Wide_Text_IO or Wide_Wide_Text_IO, since it is really just designed as
+a portable way of encoding source files. In the context of Wide_Text_IO
+or Wide_Wide_Text_IO, it can only be used if the file does not contain
+any instance of the left bracket character other than to encode wide
+character values using the brackets encoding method. In practice it is
+expected that some standard wide character encoding method such
+as UTF-8 will be used for text input output.
+
+If brackets notation is used, then any occurrence of a left bracket
+in the input file which is not the start of a valid wide character
+sequence will cause Constraint_Error to be raised. It is possible to
+encode a left bracket as ["5B"] and Wide_Text_IO and Wide_Wide_Text_IO
+input will interpret this as a left bracket.
+
+However, when a left bracket is output, it will be output as a left bracket
+and not as ["5B"]. We make this decision because for normal use of
+Wide_Text_IO for outputting messages, it is unpleasant to clobber left
+brackets. For example, if we write:
+
+@smallexample
+ Put_Line ("Start of output [first run]");
+@end smallexample
+
+@noindent
+we really do not want to have the left bracket in this message clobbered so
+that the output reads:
+
+@smallexample
+ Start of output ["5B"]first run]
+@end smallexample
+
+@noindent
+In practice brackets encoding is reasonably useful for normal Put_Line use
+since we won't get confused between left brackets and wide character
+sequences in the output. But for input, or when files are written out
+and read back in, it really makes better sense to use one of the standard
+encoding methods such as UTF-8.
+
@end table
@noindent
-For the coding schemes other than Hex and Brackets encoding,
+For the coding schemes other than UTF-8, Hex, or Brackets encoding,
not all wide character
values can be represented. An attempt to output a character that cannot
be represented using the encoding scheme for the file causes
@code{False}. Similarly, the end of file indication is not sticky, so
it is possible to read beyond an end of file.
+@node Wide_Wide_Text_IO
+@section Wide_Wide_Text_IO
+
+@noindent
+@code{Wide_Wide_Text_IO} is similar in most respects to Text_IO, except that
+both input and output files may contain special sequences that represent
+wide wide character values. The encoding scheme for a given file may be
+specified using a FORM parameter:
+
+@smallexample
+WCEM=@var{x}
+@end smallexample
+
+@noindent
+as part of the FORM string (WCEM = wide character encoding method),
+where @var{x} is one of the following characters
+
+@table @samp
+@item h
+Hex ESC encoding
+@item u
+Upper half encoding
+@item s
+Shift-JIS encoding
+@item e
+EUC Encoding
+@item 8
+UTF-8 encoding
+@item b
+Brackets encoding
+@end table
+
+@noindent
+The encoding methods match those that
+can be used in a source
+program, but there is no requirement that the encoding method used for
+the source program be the same as the encoding method used for files,
+and different files may use different encoding methods.
+
+The default encoding method for the standard files, and for opened files
+for which no WCEM parameter is given in the FORM string matches the
+wide character encoding specified for the main program (the default
+being brackets encoding if no coding method was specified with -gnatW).
+
+@table @asis
+
+@item UTF-8 Coding
+A wide character is represented using
+UCS Transformation Format 8 (UTF-8) as defined in Annex R of ISO
+10646-1/Am.2. Depending on the character value, the representation
+is a one, two, three, or four byte sequence:
+
+@smallexample
+16#000000#-16#00007f#: 2#0xxxxxxx#
+16#000080#-16#0007ff#: 2#110xxxxx# 2#10xxxxxx#
+16#000800#-16#00ffff#: 2#1110xxxx# 2#10xxxxxx# 2#10xxxxxx#
+16#010000#-16#10ffff#: 2#11110xxx# 2#10xxxxxx# 2#10xxxxxx# 2#10xxxxxx#
+@end smallexample
+
+@noindent
+where the @var{xxx} bits correspond to the left-padded bits of the
+21-bit character value. Note that all lower half ASCII characters
+are represented as ASCII bytes and all upper half characters and
+other wide characters are represented as sequences of upper-half
+characters.
+
+@item Brackets Coding
+In this encoding, a wide wide character is represented by the following eight
+character sequence if is in wide character range
+
+@smallexample
+[ " a b c d " ]
+@end smallexample
+
+and by the following ten character sequence if not
+
+@smallexample
+[ " a b c d e f " ]
+@end smallexample
+
+@noindent
+where @code{a}, @code{b}, @code{c}, @code{d}, @code{e}, and @code{f}
+are the four or six hexadecimal
+characters (using uppercase letters) of the wide wide character code. For
+example, @code{["01A345"]} is used to represent the wide wide character
+with code @code{16#01A345#}.
+
+This scheme is compatible with use of the full Wide_Wide_Character set.
+On input, brackets coding can also be used for upper half characters,
+e.g.@: @code{["C1"]} for lower case a. However, on output, brackets notation
+is only used for wide characters with a code greater than @code{16#FF#}.
+
+@end table
+
+@noindent
+If is also possible to use the other Wide_Character encoding methods,
+such as Shift-JIS, but the other schemes cannot support the full range
+of wide wide characters.
+An attempt to output a character that cannot
+be represented using the encoding scheme for the file causes
+Constraint_Error to be raised. An invalid wide character sequence on
+input also causes Constraint_Error to be raised.
+
+@menu
+* Wide_Wide_Text_IO Stream Pointer Positioning::
+* Wide_Wide_Text_IO Reading and Writing Non-Regular Files::
+@end menu
+
+@node Wide_Wide_Text_IO Stream Pointer Positioning
+@subsection Stream Pointer Positioning
+
+@noindent
+@code{Ada.Wide_Wide_Text_IO} is similar to @code{Ada.Text_IO} in its handling
+of stream pointer positioning (@pxref{Text_IO}). There is one additional
+case:
+
+If @code{Ada.Wide_Wide_Text_IO.Look_Ahead} reads a character outside the
+normal lower ASCII set (i.e.@: a character in the range:
+
+@smallexample @c ada
+Wide_Wide_Character'Val (16#0080#) .. Wide_Wide_Character'Val (16#10FFFF#)
+@end smallexample
+
+@noindent
+then although the logical position of the file pointer is unchanged by
+the @code{Look_Ahead} call, the stream is physically positioned past the
+wide character sequence. Again this is to avoid the need for buffering
+or backup, and all @code{Wide_Wide_Text_IO} routines check the internal
+indication that this situation has occurred so that this is not visible
+to a normal program using @code{Wide_Wide_Text_IO}. However, this discrepancy
+can be observed if the wide text file shares a stream with another file.
+
+@node Wide_Wide_Text_IO Reading and Writing Non-Regular Files
+@subsection Reading and Writing Non-Regular Files
+
+@noindent
+As in the case of Text_IO, when a non-regular file is read, it is
+assumed that the file contains no page marks (any form characters are
+treated as data characters), and @code{End_Of_Page} always returns
+@code{False}. Similarly, the end of file indication is not sticky, so
+it is possible to read beyond an end of file.
+
@node Stream_IO
@section Stream_IO
@noindent
A stream file is a sequence of bytes, where individual elements are
-written to the file as described in the Ada 95 reference manual. The type
+written to the file as described in the Ada Reference Manual. The type
@code{Stream_Element} is simply a byte. There are two ways to read or
write a stream file.
manner described for stream attributes.
@end itemize
+@node Text Translation
+@section Text Translation
+
+@noindent
+@samp{Text_Translation=@var{xxx}} may be used as the Form parameter
+passed to Text_IO.Create and Text_IO.Open:
+@samp{Text_Translation=@var{Yes}} is the default, which means to
+translate LF to/from CR/LF on Windows systems.
+@samp{Text_Translation=@var{No}} disables this translation; i.e. it
+uses binary mode. For output files, @samp{Text_Translation=@var{No}}
+may be used to create Unix-style files on
+Windows. @samp{Text_Translation=@var{xxx}} has no effect on Unix
+systems.
+
@node Shared Files
@section Shared Files
@noindent
-Section A.14 of the Ada 95 Reference Manual allows implementations to
+Section A.14 of the Ada Reference Manual allows implementations to
provide a wide variety of behavior if an attempt is made to access the
same external file with two or more internal files.
If the form parameter @samp{shared=yes} appears in the form string for
each of two or more files opened using the same full name, the same
stream is shared between these files, and the semantics are as described
-in Ada 95 Reference Manual, Section A.14.
+in Ada Reference Manual, Section A.14.
@end itemize
@noindent
One common use of file sharing in Ada 83 is the use of instantiations of
Sequential_IO on the same file with different types, to achieve
heterogeneous input-output. Although this approach will work in GNAT if
-@samp{shared=yes} is specified, it is preferable in Ada 95 to use Stream_IO
+@samp{shared=yes} is specified, it is preferable in Ada to use Stream_IO
for this purpose (using the stream attributes)
+@node Filenames encoding
+@section Filenames encoding
+
+@noindent
+An encoding form parameter can be used to specify the filename
+encoding @samp{encoding=@var{xxx}}.
+
+@itemize @bullet
+@item
+If the form parameter @samp{encoding=utf8} appears in the form string, the
+filename must be encoded in UTF-8.
+
+@item
+If the form parameter @samp{encoding=8bits} appears in the form
+string, the filename must be a standard 8bits string.
+@end itemize
+
+In the absence of a @samp{encoding=@var{xxx}} form parameter, the
+encoding is controlled by the @samp{GNAT_CODE_PAGE} environment
+variable. And if not set @samp{utf8} is assumed.
+
+@table @samp
+@item CP_ACP
+The current system Windows ANSI code page.
+@item CP_UTF8
+UTF-8 encoding
+@end table
+
+This encoding form parameter is only supported on the Windows
+platform. On the other Operating Systems the run-time is supporting
+UTF-8 natively.
+
@node Open Modes
@section Open Modes
-- If text_translation_required is true, then the following
-- functions may be used to dynamically switch a file from
-- binary to text mode or vice versa. These functions have
- -- no effect if text_translation_required is false (i.e. in
+ -- no effect if text_translation_required is false (i.e.@: in
-- normal UNIX mode). Use fileno to get a stream handle.
procedure set_binary_mode (handle : int);
procedure set_text_mode (handle : int);
Form : in String := "");
end Ada.Wide_Text_IO.C_Streams;
+ with Interfaces.C_Streams;
+ package Ada.Wide_Wide_Text_IO.C_Streams is
+ function C_Stream (F : File_Type)
+ return Interfaces.C_Streams.FILEs;
+ procedure Open
+ (File : in out File_Type;
+ Mode : in File_Mode;
+ C_Stream : in Interfaces.C_Streams.FILEs;
+ Form : in String := "");
+ end Ada.Wide_Wide_Text_IO.C_Streams;
+
with Interfaces.C_Streams;
package Ada.Stream_IO.C_Streams is
function C_Stream (F : File_Type)
@end smallexample
@noindent
-In each of these five packages, the @code{C_Stream} function obtains the
+In each of these six packages, the @code{C_Stream} function obtains the
@code{FILE} pointer from a currently opened Ada file. It is then
possible to use the @code{Interfaces.C_Streams} package to operate on
this stream, or the stream can be passed to a C program which can
* Ada.Characters.Latin_9 (a-chlat9.ads)::
* Ada.Characters.Wide_Latin_1 (a-cwila1.ads)::
* Ada.Characters.Wide_Latin_9 (a-cwila9.ads)::
-* Ada.Command_Line.Remove (a-colire.ads)::
+* Ada.Characters.Wide_Wide_Latin_1 (a-chzla1.ads)::
+* Ada.Characters.Wide_Wide_Latin_9 (a-chzla9.ads)::
* Ada.Command_Line.Environment (a-colien.ads)::
+* Ada.Command_Line.Remove (a-colire.ads)::
+* Ada.Command_Line.Response_File (a-clrefi.ads)::
* Ada.Direct_IO.C_Streams (a-diocst.ads)::
* Ada.Exceptions.Is_Null_Occurrence (a-einuoc.ads)::
+* Ada.Exceptions.Last_Chance_Handler (a-elchha.ads)::
* Ada.Exceptions.Traceback (a-exctra.ads)::
* Ada.Sequential_IO.C_Streams (a-siocst.ads)::
* Ada.Streams.Stream_IO.C_Streams (a-ssicst.ads)::
* Ada.Strings.Unbounded.Text_IO (a-suteio.ads)::
* Ada.Strings.Wide_Unbounded.Wide_Text_IO (a-swuwti.ads)::
+* Ada.Strings.Wide_Wide_Unbounded.Wide_Wide_Text_IO (a-szuzti.ads)::
* Ada.Text_IO.C_Streams (a-tiocst.ads)::
+* Ada.Text_IO.Reset_Standard_Files (a-tirsfi.ads)::
+* Ada.Wide_Characters.Unicode (a-wichun.ads)::
* Ada.Wide_Text_IO.C_Streams (a-wtcstr.ads)::
+* Ada.Wide_Text_IO.Reset_Standard_Files (a-wrstfi.ads)::
+* Ada.Wide_Wide_Characters.Unicode (a-zchuni.ads)::
+* Ada.Wide_Wide_Text_IO.C_Streams (a-ztcstr.ads)::
+* Ada.Wide_Wide_Text_IO.Reset_Standard_Files (a-zrstfi.ads)::
+* GNAT.Altivec (g-altive.ads)::
+* GNAT.Altivec.Conversions (g-altcon.ads)::
+* GNAT.Altivec.Vector_Operations (g-alveop.ads)::
+* GNAT.Altivec.Vector_Types (g-alvety.ads)::
+* GNAT.Altivec.Vector_Views (g-alvevi.ads)::
* GNAT.Array_Split (g-arrspl.ads)::
* GNAT.AWK (g-awk.ads)::
* GNAT.Bounded_Buffers (g-boubuf.ads)::
* GNAT.Bubble_Sort (g-bubsor.ads)::
* GNAT.Bubble_Sort_A (g-busora.ads)::
* GNAT.Bubble_Sort_G (g-busorg.ads)::
+* GNAT.Byte_Order_Mark (g-byorma.ads)::
+* GNAT.Byte_Swapping (g-bytswa.ads)::
* GNAT.Calendar (g-calend.ads)::
* GNAT.Calendar.Time_IO (g-catiio.ads)::
-* GNAT.CRC32 (g-crc32.ads)::
* GNAT.Case_Util (g-casuti.ads)::
* GNAT.CGI (g-cgi.ads)::
* GNAT.CGI.Cookie (g-cgicoo.ads)::
* GNAT.Command_Line (g-comlin.ads)::
* GNAT.Compiler_Version (g-comver.ads)::
* GNAT.Ctrl_C (g-ctrl_c.ads)::
+* GNAT.CRC32 (g-crc32.ads)::
* GNAT.Current_Exception (g-curexc.ads)::
* GNAT.Debug_Pools (g-debpoo.ads)::
* GNAT.Debug_Utilities (g-debuti.ads)::
+* GNAT.Decode_String (g-decstr.ads)::
+* GNAT.Decode_UTF8_String (g-deutst.ads)::
* GNAT.Directory_Operations (g-dirope.ads)::
+* GNAT.Directory_Operations.Iteration (g-diopit.ads)::
* GNAT.Dynamic_HTables (g-dynhta.ads)::
* GNAT.Dynamic_Tables (g-dyntab.ads)::
+* GNAT.Encode_String (g-encstr.ads)::
+* GNAT.Encode_UTF8_String (g-enutst.ads)::
* GNAT.Exception_Actions (g-excact.ads)::
* GNAT.Exception_Traces (g-exctra.ads)::
* GNAT.Exceptions (g-except.ads)::
* GNAT.Memory_Dump (g-memdum.ads)::
* GNAT.Most_Recent_Exception (g-moreex.ads)::
* GNAT.OS_Lib (g-os_lib.ads)::
-* GNAT.Perfect_Hash.Generators (g-pehage.ads)::
+* GNAT.Perfect_Hash_Generators (g-pehage.ads)::
+* GNAT.Random_Numbers (g-rannum.ads)::
* GNAT.Regexp (g-regexp.ads)::
* GNAT.Registry (g-regist.ads)::
* GNAT.Regpat (g-regpat.ads)::
* GNAT.Secondary_Stack_Info (g-sestin.ads)::
* GNAT.Semaphores (g-semaph.ads)::
+* GNAT.Serial_Communications (g-sercom.ads)::
+* GNAT.SHA1 (g-sha1.ads)::
+* GNAT.SHA224 (g-sha224.ads)::
+* GNAT.SHA256 (g-sha256.ads)::
+* GNAT.SHA384 (g-sha384.ads)::
+* GNAT.SHA512 (g-sha512.ads)::
* GNAT.Signals (g-signal.ads)::
* GNAT.Sockets (g-socket.ads)::
* GNAT.Source_Info (g-souinf.ads)::
-* GNAT.Spell_Checker (g-speche.ads)::
+* GNAT.Spelling_Checker (g-speche.ads)::
+* GNAT.Spelling_Checker_Generic (g-spchge.ads)::
* GNAT.Spitbol.Patterns (g-spipat.ads)::
* GNAT.Spitbol (g-spitbo.ads)::
* GNAT.Spitbol.Table_Boolean (g-sptabo.ads)::
* GNAT.Spitbol.Table_Integer (g-sptain.ads)::
* GNAT.Spitbol.Table_VString (g-sptavs.ads)::
+* GNAT.SSE (g-sse.ads)::
+* GNAT.SSE.Vector_Types (g-ssvety.ads)::
* GNAT.Strings (g-string.ads)::
* GNAT.String_Split (g-strspl.ads)::
* GNAT.Table (g-table.ads)::
* GNAT.Task_Lock (g-tasloc.ads)::
* GNAT.Threads (g-thread.ads)::
+* GNAT.Time_Stamp (g-timsta.ads)::
* GNAT.Traceback (g-traceb.ads)::
* GNAT.Traceback.Symbolic (g-trasym.ads)::
+* GNAT.UTF_32 (g-utf_32.ads)::
+* GNAT.UTF_32_Spelling_Checker (g-u3spch.ads)::
+* GNAT.Wide_Spelling_Checker (g-wispch.ads)::
* GNAT.Wide_String_Split (g-wistsp.ads)::
+* GNAT.Wide_Wide_Spelling_Checker (g-zspche.ads)::
+* GNAT.Wide_Wide_String_Split (g-zistsp.ads)::
* Interfaces.C.Extensions (i-cexten.ads)::
* Interfaces.C.Streams (i-cstrea.ads)::
* Interfaces.CPP (i-cpp.ads)::
-* Interfaces.Os2lib (i-os2lib.ads)::
-* Interfaces.Os2lib.Errors (i-os2err.ads)::
-* Interfaces.Os2lib.Synchronization (i-os2syn.ads)::
-* Interfaces.Os2lib.Threads (i-os2thr.ads)::
* Interfaces.Packed_Decimal (i-pacdec.ads)::
* Interfaces.VxWorks (i-vxwork.ads)::
* Interfaces.VxWorks.IO (i-vxwoio.ads)::
* System.Assertions (s-assert.ads)::
* System.Memory (s-memory.ads)::
* System.Partition_Interface (s-parint.ads)::
+* System.Pool_Global (s-pooglo.ads)::
+* System.Pool_Local (s-pooloc.ads)::
* System.Restrictions (s-restri.ads)::
* System.Rident (s-rident.ads)::
+* System.Strings.Stream_Ops (s-ststop.ads)::
* System.Task_Info (s-tasinf.ads)::
* System.Wch_Cnv (s-wchcnv.ads)::
* System.Wch_Con (s-wchcon.ads)::
few modifications required for @code{Latin-9}
The provision of such a package
is specifically authorized by the Ada Reference Manual
-(RM A.3(27)).
+(RM A.3.3(27)).
@node Ada.Characters.Wide_Latin_1 (a-cwila1.ads)
@section @code{Ada.Characters.Wide_Latin_1} (@file{a-cwila1.ads})
types of the constants being @code{Wide_Character}
instead of @code{Character}. The provision of such a package
is specifically authorized by the Ada Reference Manual
-(RM A.3(27)).
+(RM A.3.3(27)).
@node Ada.Characters.Wide_Latin_9 (a-cwila9.ads)
@section @code{Ada.Characters.Wide_Latin_9} (@file{a-cwila1.ads})
types of the constants being @code{Wide_Character}
instead of @code{Character}. The provision of such a package
is specifically authorized by the Ada Reference Manual
-(RM A.3(27)).
+(RM A.3.3(27)).
+
+@node Ada.Characters.Wide_Wide_Latin_1 (a-chzla1.ads)
+@section @code{Ada.Characters.Wide_Wide_Latin_1} (@file{a-chzla1.ads})
+@cindex @code{Ada.Characters.Wide_Wide_Latin_1} (@file{a-chzla1.ads})
+@cindex Latin_1 constants for Wide_Wide_Character
+
+@noindent
+This child of @code{Ada.Characters}
+provides a set of definitions corresponding to those in the
+RM-defined package @code{Ada.Characters.Latin_1} but with the
+types of the constants being @code{Wide_Wide_Character}
+instead of @code{Character}. The provision of such a package
+is specifically authorized by the Ada Reference Manual
+(RM A.3.3(27)).
+
+@node Ada.Characters.Wide_Wide_Latin_9 (a-chzla9.ads)
+@section @code{Ada.Characters.Wide_Wide_Latin_9} (@file{a-chzla9.ads})
+@cindex @code{Ada.Characters.Wide_Wide_Latin_9} (@file{a-chzla9.ads})
+@cindex Latin_9 constants for Wide_Wide_Character
+
+@noindent
+This child of @code{Ada.Characters}
+provides a set of definitions corresponding to those in the
+GNAT defined package @code{Ada.Characters.Latin_9} but with the
+types of the constants being @code{Wide_Wide_Character}
+instead of @code{Character}. The provision of such a package
+is specifically authorized by the Ada Reference Manual
+(RM A.3.3(27)).
+
+@node Ada.Command_Line.Environment (a-colien.ads)
+@section @code{Ada.Command_Line.Environment} (@file{a-colien.ads})
+@cindex @code{Ada.Command_Line.Environment} (@file{a-colien.ads})
+@cindex Environment entries
+
+@noindent
+This child of @code{Ada.Command_Line}
+provides a mechanism for obtaining environment values on systems
+where this concept makes sense.
@node Ada.Command_Line.Remove (a-colire.ads)
@section @code{Ada.Command_Line.Remove} (@file{a-colire.ads})
to further calls on the subprograms in @code{Ada.Command_Line} will not
see the removed argument.
-@node Ada.Command_Line.Environment (a-colien.ads)
-@section @code{Ada.Command_Line.Environment} (@file{a-colien.ads})
-@cindex @code{Ada.Command_Line.Environment} (@file{a-colien.ads})
-@cindex Environment entries
+@node Ada.Command_Line.Response_File (a-clrefi.ads)
+@section @code{Ada.Command_Line.Response_File} (@file{a-clrefi.ads})
+@cindex @code{Ada.Command_Line.Response_File} (@file{a-clrefi.ads})
+@cindex Response file for command line
+@cindex Command line, response file
+@cindex Command line, handling long command lines
@noindent
-This child of @code{Ada.Command_Line}
-provides a mechanism for obtaining environment values on systems
-where this concept makes sense.
+This child of @code{Ada.Command_Line} provides a mechanism facilities for
+getting command line arguments from a text file, called a "response file".
+Using a response file allow passing a set of arguments to an executable longer
+than the maximum allowed by the system on the command line.
@node Ada.Direct_IO.C_Streams (a-diocst.ads)
@section @code{Ada.Direct_IO.C_Streams} (@file{a-diocst.ads})
exception occurrence (@code{Null_Occurrence}) without raising
an exception.
+@node Ada.Exceptions.Last_Chance_Handler (a-elchha.ads)
+@section @code{Ada.Exceptions.Last_Chance_Handler} (@file{a-elchha.ads})
+@cindex @code{Ada.Exceptions.Last_Chance_Handler} (@file{a-elchha.ads})
+@cindex Null_Occurrence, testing for
+
+@noindent
+This child subprogram is used for handling otherwise unhandled
+exceptions (hence the name last chance), and perform clean ups before
+terminating the program. Note that this subprogram never returns.
+
@node Ada.Exceptions.Traceback (a-exctra.ads)
@section @code{Ada.Exceptions.Traceback} (@file{a-exctra.ads})
@cindex @code{Ada.Exceptions.Traceback} (@file{a-exctra.ads})
wide strings, avoiding the necessity for an intermediate operation
with ordinary wide strings.
+@node Ada.Strings.Wide_Wide_Unbounded.Wide_Wide_Text_IO (a-szuzti.ads)
+@section @code{Ada.Strings.Wide_Wide_Unbounded.Wide_Wide_Text_IO} (@file{a-szuzti.ads})
+@cindex @code{Ada.Strings.Wide_Wide_Unbounded.Wide_Wide_Text_IO} (@file{a-szuzti.ads})
+@cindex @code{Unbounded_Wide_Wide_String}, IO support
+@cindex @code{Text_IO}, extensions for unbounded wide wide strings
+
+@noindent
+This package provides subprograms for Text_IO for unbounded
+wide wide strings, avoiding the necessity for an intermediate operation
+with ordinary wide wide strings.
+
@node Ada.Text_IO.C_Streams (a-tiocst.ads)
@section @code{Ada.Text_IO.C_Streams} (@file{a-tiocst.ads})
@cindex @code{Ada.Text_IO.C_Streams} (@file{a-tiocst.ads})
extracted from a file opened on the Ada side, and an Ada file
can be constructed from a stream opened on the C side.
+@node Ada.Text_IO.Reset_Standard_Files (a-tirsfi.ads)
+@section @code{Ada.Text_IO.Reset_Standard_Files} (@file{a-tirsfi.ads})
+@cindex @code{Ada.Text_IO.Reset_Standard_Files} (@file{a-tirsfi.ads})
+@cindex @code{Text_IO} resetting standard files
+
+@noindent
+This procedure is used to reset the status of the standard files used
+by Ada.Text_IO. This is useful in a situation (such as a restart in an
+embedded application) where the status of the files may change during
+execution (for example a standard input file may be redefined to be
+interactive).
+
+@node Ada.Wide_Characters.Unicode (a-wichun.ads)
+@section @code{Ada.Wide_Characters.Unicode} (@file{a-wichun.ads})
+@cindex @code{Ada.Wide_Characters.Unicode} (@file{a-wichun.ads})
+@cindex Unicode categorization, Wide_Character
+
+@noindent
+This package provides subprograms that allow categorization of
+Wide_Character values according to Unicode categories.
+
@node Ada.Wide_Text_IO.C_Streams (a-wtcstr.ads)
@section @code{Ada.Wide_Text_IO.C_Streams} (@file{a-wtcstr.ads})
@cindex @code{Ada.Wide_Text_IO.C_Streams} (@file{a-wtcstr.ads})
extracted from a file opened on the Ada side, and an Ada file
can be constructed from a stream opened on the C side.
+@node Ada.Wide_Text_IO.Reset_Standard_Files (a-wrstfi.ads)
+@section @code{Ada.Wide_Text_IO.Reset_Standard_Files} (@file{a-wrstfi.ads})
+@cindex @code{Ada.Wide_Text_IO.Reset_Standard_Files} (@file{a-wrstfi.ads})
+@cindex @code{Wide_Text_IO} resetting standard files
+
+@noindent
+This procedure is used to reset the status of the standard files used
+by Ada.Wide_Text_IO. This is useful in a situation (such as a restart in an
+embedded application) where the status of the files may change during
+execution (for example a standard input file may be redefined to be
+interactive).
+
+@node Ada.Wide_Wide_Characters.Unicode (a-zchuni.ads)
+@section @code{Ada.Wide_Wide_Characters.Unicode} (@file{a-zchuni.ads})
+@cindex @code{Ada.Wide_Wide_Characters.Unicode} (@file{a-zchuni.ads})
+@cindex Unicode categorization, Wide_Wide_Character
+
+@noindent
+This package provides subprograms that allow categorization of
+Wide_Wide_Character values according to Unicode categories.
+
+@node Ada.Wide_Wide_Text_IO.C_Streams (a-ztcstr.ads)
+@section @code{Ada.Wide_Wide_Text_IO.C_Streams} (@file{a-ztcstr.ads})
+@cindex @code{Ada.Wide_Wide_Text_IO.C_Streams} (@file{a-ztcstr.ads})
+@cindex C Streams, Interfacing with @code{Wide_Wide_Text_IO}
+
+@noindent
+This package provides subprograms that allow interfacing between
+C streams and @code{Wide_Wide_Text_IO}. The stream identifier can be
+extracted from a file opened on the Ada side, and an Ada file
+can be constructed from a stream opened on the C side.
+
+@node Ada.Wide_Wide_Text_IO.Reset_Standard_Files (a-zrstfi.ads)
+@section @code{Ada.Wide_Wide_Text_IO.Reset_Standard_Files} (@file{a-zrstfi.ads})
+@cindex @code{Ada.Wide_Wide_Text_IO.Reset_Standard_Files} (@file{a-zrstfi.ads})
+@cindex @code{Wide_Wide_Text_IO} resetting standard files
+
+@noindent
+This procedure is used to reset the status of the standard files used
+by Ada.Wide_Wide_Text_IO. This is useful in a situation (such as a
+restart in an embedded application) where the status of the files may
+change during execution (for example a standard input file may be
+redefined to be interactive).
+
+@node GNAT.Altivec (g-altive.ads)
+@section @code{GNAT.Altivec} (@file{g-altive.ads})
+@cindex @code{GNAT.Altivec} (@file{g-altive.ads})
+@cindex AltiVec
+
+@noindent
+This is the root package of the GNAT AltiVec binding. It provides
+definitions of constants and types common to all the versions of the
+binding.
+
+@node GNAT.Altivec.Conversions (g-altcon.ads)
+@section @code{GNAT.Altivec.Conversions} (@file{g-altcon.ads})
+@cindex @code{GNAT.Altivec.Conversions} (@file{g-altcon.ads})
+@cindex AltiVec
+
+@noindent
+This package provides the Vector/View conversion routines.
+
+@node GNAT.Altivec.Vector_Operations (g-alveop.ads)
+@section @code{GNAT.Altivec.Vector_Operations} (@file{g-alveop.ads})
+@cindex @code{GNAT.Altivec.Vector_Operations} (@file{g-alveop.ads})
+@cindex AltiVec
+
+@noindent
+This package exposes the Ada interface to the AltiVec operations on
+vector objects. A soft emulation is included by default in the GNAT
+library. The hard binding is provided as a separate package. This unit
+is common to both bindings.
+
+@node GNAT.Altivec.Vector_Types (g-alvety.ads)
+@section @code{GNAT.Altivec.Vector_Types} (@file{g-alvety.ads})
+@cindex @code{GNAT.Altivec.Vector_Types} (@file{g-alvety.ads})
+@cindex AltiVec
+
+@noindent
+This package exposes the various vector types part of the Ada binding
+to AltiVec facilities.
+
+@node GNAT.Altivec.Vector_Views (g-alvevi.ads)
+@section @code{GNAT.Altivec.Vector_Views} (@file{g-alvevi.ads})
+@cindex @code{GNAT.Altivec.Vector_Views} (@file{g-alvevi.ads})
+@cindex AltiVec
+
+@noindent
+This package provides public 'View' data types from/to which private
+vector representations can be converted via
+GNAT.Altivec.Conversions. This allows convenient access to individual
+vector elements and provides a simple way to initialize vector
+objects.
+
@node GNAT.Array_Split (g-arrspl.ads)
@section @code{GNAT.Array_Split} (@file{g-arrspl.ads})
@cindex @code{GNAT.Array_Split} (@file{g-arrspl.ads})
if the procedures can be inlined, at the expense of duplicating code for
multiple instantiations.
+@node GNAT.Byte_Order_Mark (g-byorma.ads)
+@section @code{GNAT.Byte_Order_Mark} (@file{g-byorma.ads})
+@cindex @code{GNAT.Byte_Order_Mark} (@file{g-byorma.ads})
+@cindex UTF-8 representation
+@cindex Wide characte representations
+
+@noindent
+Provides a routine which given a string, reads the start of the string to
+see whether it is one of the standard byte order marks (BOM's) which signal
+the encoding of the string. The routine includes detection of special XML
+sequences for various UCS input formats.
+
+@node GNAT.Byte_Swapping (g-bytswa.ads)
+@section @code{GNAT.Byte_Swapping} (@file{g-bytswa.ads})
+@cindex @code{GNAT.Byte_Swapping} (@file{g-bytswa.ads})
+@cindex Byte swapping
+@cindex Endian
+
+@noindent
+General routines for swapping the bytes in 2-, 4-, and 8-byte quantities.
+Machine-specific implementations are available in some cases.
+
@node GNAT.Calendar (g-calend.ads)
@section @code{GNAT.Calendar} (@file{g-calend.ads})
@cindex @code{GNAT.Calendar} (@file{g-calend.ads})
@cite{Communications of the ACM}, Vol.@: 31 No.@: 8, pp.@: 1008-1013,
Aug.@: 1988. Sarwate, D.V@.
-@noindent
-Provides an extended capability for formatted output of time values with
-full user control over the format. Modeled on the GNU Date specification.
-
@node GNAT.Case_Util (g-casuti.ads)
@section @code{GNAT.Case_Util} (@file{g-casuti.ads})
@cindex @code{GNAT.Case_Util} (@file{g-casuti.ads})
@noindent
Provides access to information on the current exception that has been raised
-without the need for using the Ada-95 exception choice parameter specification
-syntax. This is particularly useful in simulating typical facilities for
+without the need for using the Ada 95 / Ada 2005 exception choice parameter
+specification syntax.
+This is particularly useful in simulating typical facilities for
obtaining information about exceptions provided by Ada 83 compilers.
@node GNAT.Debug_Pools (g-debpoo.ads)
@noindent
Provide a debugging storage pools that helps tracking memory corruption
-problems. See section ``Finding memory problems with GNAT Debug Pool'' in
-the @cite{GNAT User's Guide}.
+problems. @xref{The GNAT Debug Pool Facility,,, gnat_ugn,
+@value{EDITION} User's Guide}.
@node GNAT.Debug_Utilities (g-debuti.ads)
@section @code{GNAT.Debug_Utilities} (@file{g-debuti.ads})
to and from string images of address values. Supports both C and Ada formats
for hexadecimal literals.
+@node GNAT.Decode_String (g-decstr.ads)
+@section @code{GNAT.Decode_String} (@file{g-decstr.ads})
+@cindex @code{GNAT.Decode_String} (@file{g-decstr.ads})
+@cindex Decoding strings
+@cindex String decoding
+@cindex Wide character encoding
+@cindex UTF-8
+@cindex Unicode
+
+@noindent
+A generic package providing routines for decoding wide character and wide wide
+character strings encoded as sequences of 8-bit characters using a specified
+encoding method. Includes validation routines, and also routines for stepping
+to next or previous encoded character in an encoded string.
+Useful in conjunction with Unicode character coding. Note there is a
+preinstantiation for UTF-8. See next entry.
+
+@node GNAT.Decode_UTF8_String (g-deutst.ads)
+@section @code{GNAT.Decode_UTF8_String} (@file{g-deutst.ads})
+@cindex @code{GNAT.Decode_UTF8_String} (@file{g-deutst.ads})
+@cindex Decoding strings
+@cindex Decoding UTF-8 strings
+@cindex UTF-8 string decoding
+@cindex Wide character decoding
+@cindex UTF-8
+@cindex Unicode
+
+@noindent
+A preinstantiation of GNAT.Decode_Strings for UTF-8 encoding.
+
@node GNAT.Directory_Operations (g-dirope.ads)
-@section @code{GNAT.Directory_Operations} (g-dirope.ads)
-@cindex @code{GNAT.Directory_Operations} (g-dirope.ads)
+@section @code{GNAT.Directory_Operations} (@file{g-dirope.ads})
+@cindex @code{GNAT.Directory_Operations} (@file{g-dirope.ads})
@cindex Directory operations
@noindent
the current directory, making new directories, and scanning the files in a
directory.
+@node GNAT.Directory_Operations.Iteration (g-diopit.ads)
+@section @code{GNAT.Directory_Operations.Iteration} (@file{g-diopit.ads})
+@cindex @code{GNAT.Directory_Operations.Iteration} (@file{g-diopit.ads})
+@cindex Directory operations iteration
+
+@noindent
+A child unit of GNAT.Directory_Operations providing additional operations
+for iterating through directories.
+
@node GNAT.Dynamic_HTables (g-dynhta.ads)
@section @code{GNAT.Dynamic_HTables} (@file{g-dynhta.ads})
@cindex @code{GNAT.Dynamic_HTables} (@file{g-dynhta.ads})
dynamic instances of the table, while an instantiation of
@code{GNAT.Table} creates a single instance of the table type.
+@node GNAT.Encode_String (g-encstr.ads)
+@section @code{GNAT.Encode_String} (@file{g-encstr.ads})
+@cindex @code{GNAT.Encode_String} (@file{g-encstr.ads})
+@cindex Encoding strings
+@cindex String encoding
+@cindex Wide character encoding
+@cindex UTF-8
+@cindex Unicode
+
+@noindent
+A generic package providing routines for encoding wide character and wide
+wide character strings as sequences of 8-bit characters using a specified
+encoding method. Useful in conjunction with Unicode character coding.
+Note there is a preinstantiation for UTF-8. See next entry.
+
+@node GNAT.Encode_UTF8_String (g-enutst.ads)
+@section @code{GNAT.Encode_UTF8_String} (@file{g-enutst.ads})
+@cindex @code{GNAT.Encode_UTF8_String} (@file{g-enutst.ads})
+@cindex Encoding strings
+@cindex Encoding UTF-8 strings
+@cindex UTF-8 string encoding
+@cindex Wide character encoding
+@cindex UTF-8
+@cindex Unicode
+
+@noindent
+A preinstantiation of GNAT.Encode_Strings for UTF-8 encoding.
+
@node GNAT.Exception_Actions (g-excact.ads)
@section @code{GNAT.Exception_Actions} (@file{g-excact.ads})
@cindex @code{GNAT.Exception_Actions} (@file{g-excact.ads})
including a portable spawn procedure, and access to environment variables
and error return codes.
-@node GNAT.Perfect_Hash.Generators (g-pehage.ads)
-@section @code{GNAT.Perfect_Hash.Generators} (@file{g-pehage.ads})
-@cindex @code{GNAT.Perfect_Hash.Generators} (@file{g-pehage.ads})
+@node GNAT.Perfect_Hash_Generators (g-pehage.ads)
+@section @code{GNAT.Perfect_Hash_Generators} (@file{g-pehage.ads})
+@cindex @code{GNAT.Perfect_Hash_Generators} (@file{g-pehage.ads})
@cindex Hash functions
@noindent
probe (perfect property). The hash table size corresponds to the exact
size of the key set and no larger (minimal property). The key set has to
be know in advance (static property). The hash functions are also order
-preservering. If w2 is inserted after w1 in the generator, their
+preserving. If w2 is inserted after w1 in the generator, their
hashcode are in the same order. These hashing functions are very
convenient for use with realtime applications.
+@node GNAT.Random_Numbers (g-rannum.ads)
+@section @code{GNAT.Random_Numbers} (@file{g-rannum.ads})
+@cindex @code{GNAT.Random_Numbers} (@file{g-rannum.ads})
+@cindex Random number generation
+
+@noindent
+Provides random number capabilities which extend those available in the
+standard Ada library and are more convenient to use.
+
@node GNAT.Regexp (g-regexp.ads)
@section @code{GNAT.Regexp} (@file{g-regexp.ads})
@cindex @code{GNAT.Regexp} (@file{g-regexp.ads})
@noindent
Provides classic counting and binary semaphores using protected types.
+@node GNAT.Serial_Communications (g-sercom.ads)
+@section @code{GNAT.Serial_Communications} (@file{g-sercom.ads})
+@cindex @code{GNAT.Serial_Communications} (@file{g-sercom.ads})
+@cindex Serial_Communications
+
+@noindent
+Provides a simple interface to send and receive data over a serial
+port. This is only supported on GNU/Linux and Windows.
+
+@node GNAT.SHA1 (g-sha1.ads)
+@section @code{GNAT.SHA1} (@file{g-sha1.ads})
+@cindex @code{GNAT.SHA1} (@file{g-sha1.ads})
+@cindex Secure Hash Algorithm SHA-1
+
+@noindent
+Implements the SHA-1 Secure Hash Algorithm as described in FIPS PUB 180-3
+and RFC 3174.
+
+@node GNAT.SHA224 (g-sha224.ads)
+@section @code{GNAT.SHA224} (@file{g-sha224.ads})
+@cindex @code{GNAT.SHA224} (@file{g-sha224.ads})
+@cindex Secure Hash Algorithm SHA-224
+
+@noindent
+Implements the SHA-224 Secure Hash Algorithm as described in FIPS PUB 180-3.
+
+@node GNAT.SHA256 (g-sha256.ads)
+@section @code{GNAT.SHA256} (@file{g-sha256.ads})
+@cindex @code{GNAT.SHA256} (@file{g-sha256.ads})
+@cindex Secure Hash Algorithm SHA-256
+
+@noindent
+Implements the SHA-256 Secure Hash Algorithm as described in FIPS PUB 180-3.
+
+@node GNAT.SHA384 (g-sha384.ads)
+@section @code{GNAT.SHA384} (@file{g-sha384.ads})
+@cindex @code{GNAT.SHA384} (@file{g-sha384.ads})
+@cindex Secure Hash Algorithm SHA-384
+
+@noindent
+Implements the SHA-384 Secure Hash Algorithm as described in FIPS PUB 180-3.
+
+@node GNAT.SHA512 (g-sha512.ads)
+@section @code{GNAT.SHA512} (@file{g-sha512.ads})
+@cindex @code{GNAT.SHA512} (@file{g-sha512.ads})
+@cindex Secure Hash Algorithm SHA-512
+
+@noindent
+Implements the SHA-512 Secure Hash Algorithm as described in FIPS PUB 180-3.
+
@node GNAT.Signals (g-signal.ads)
@section @code{GNAT.Signals} (@file{g-signal.ads})
@cindex @code{GNAT.Signals} (@file{g-signal.ads})
Provides subprograms that give access to source code information known at
compile time, such as the current file name and line number.
-@node GNAT.Spell_Checker (g-speche.ads)
-@section @code{GNAT.Spell_Checker} (@file{g-speche.ads})
-@cindex @code{GNAT.Spell_Checker} (@file{g-speche.ads})
+@node GNAT.Spelling_Checker (g-speche.ads)
+@section @code{GNAT.Spelling_Checker} (@file{g-speche.ads})
+@cindex @code{GNAT.Spelling_Checker} (@file{g-speche.ads})
@cindex Spell checking
@noindent
Provides a function for determining whether one string is a plausible
near misspelling of another string.
+@node GNAT.Spelling_Checker_Generic (g-spchge.ads)
+@section @code{GNAT.Spelling_Checker_Generic} (@file{g-spchge.ads})
+@cindex @code{GNAT.Spelling_Checker_Generic} (@file{g-spchge.ads})
+@cindex Spell checking
+
+@noindent
+Provides a generic function that can be instantiated with a string type for
+determining whether one string is a plausible near misspelling of another
+string.
+
@node GNAT.Spitbol.Patterns (g-spipat.ads)
@section @code{GNAT.Spitbol.Patterns} (@file{g-spipat.ads})
@cindex @code{GNAT.Spitbol.Patterns} (@file{g-spipat.ads})
a variable length string type, giving an implementation of general
maps from strings to strings.
+@node GNAT.SSE (g-sse.ads)
+@section @code{GNAT.SSE} (@file{g-sse.ads})
+@cindex @code{GNAT.SSE} (@file{g-sse.ads})
+
+@noindent
+Root of a set of units aimed at offering Ada bindings to a subset of
+the Intel(r) Streaming SIMD Extensions with GNAT on the x86 family of
+targets. It exposes vector component types together with a general
+introduction to the binding contents and use.
+
+@node GNAT.SSE.Vector_Types (g-ssvety.ads)
+@section @code{GNAT.SSE.Vector_Types} (@file{g-ssvety.ads})
+@cindex @code{GNAT.SSE.Vector_Types} (@file{g-ssvety.ads})
+
+@noindent
+SSE vector types for use with SSE related intrinsics.
+
@node GNAT.Strings (g-string.ads)
@section @code{GNAT.Strings} (@file{g-string.ads})
@cindex @code{GNAT.Strings} (@file{g-string.ads})
@cindex String splitter
@noindent
-Useful string-manipulation routines: given a set of separators, split
+Useful string manipulation routines: given a set of separators, split
a string wherever the separators appear, and provide direct access
to the resulting slices. This package is instantiated from
@code{GNAT.Array_Split}.
single global task lock. Appropriate for use in situations where contention
between tasks is very rarely expected.
+@node GNAT.Time_Stamp (g-timsta.ads)
+@section @code{GNAT.Time_Stamp} (@file{g-timsta.ads})
+@cindex @code{GNAT.Time_Stamp} (@file{g-timsta.ads})
+@cindex Time stamp
+@cindex Current time
+
+@noindent
+Provides a simple function that returns a string YYYY-MM-DD HH:MM:SS.SS that
+represents the current date and time in ISO 8601 format. This is a very simple
+routine with minimal code and there are no dependencies on any other unit.
+
@node GNAT.Threads (g-thread.ads)
@section @code{GNAT.Threads} (@file{g-thread.ads})
@cindex @code{GNAT.Threads} (@file{g-thread.ads})
@cindex Threads, foreign
@noindent
-Provides facilities for creating and destroying threads with explicit calls.
-These threads are known to the GNAT run-time system. These subprograms are
-exported C-convention procedures intended to be called from foreign code.
-By using these primitives rather than directly calling operating systems
-routines, compatibility with the Ada tasking runt-time is provided.
+Provides facilities for dealing with foreign threads which need to be known
+by the GNAT run-time system. Consult the documentation of this package for
+further details if your program has threads that are created by a non-Ada
+environment which then accesses Ada code.
@node GNAT.Traceback (g-traceb.ads)
@section @code{GNAT.Traceback} (@file{g-traceb.ads})
@cindex @code{GNAT.Traceback.Symbolic} (@file{g-trasym.ads})
@cindex Trace back facilities
+@node GNAT.UTF_32 (g-utf_32.ads)
+@section @code{GNAT.UTF_32} (@file{g-table.ads})
+@cindex @code{GNAT.UTF_32} (@file{g-table.ads})
+@cindex Wide character codes
+
+@noindent
+This is a package intended to be used in conjunction with the
+@code{Wide_Character} type in Ada 95 and the
+@code{Wide_Wide_Character} type in Ada 2005 (available
+in @code{GNAT} in Ada 2005 mode). This package contains
+Unicode categorization routines, as well as lexical
+categorization routines corresponding to the Ada 2005
+lexical rules for identifiers and strings, and also a
+lower case to upper case fold routine corresponding to
+the Ada 2005 rules for identifier equivalence.
+
+@node GNAT.UTF_32_Spelling_Checker (g-u3spch.ads)
+@section @code{GNAT.Wide_Spelling_Checker} (@file{g-u3spch.ads})
+@cindex @code{GNAT.Wide_Spelling_Checker} (@file{g-u3spch.ads})
+@cindex Spell checking
+
+@noindent
+Provides a function for determining whether one wide wide string is a plausible
+near misspelling of another wide wide string, where the strings are represented
+using the UTF_32_String type defined in System.Wch_Cnv.
+
+@node GNAT.Wide_Spelling_Checker (g-wispch.ads)
+@section @code{GNAT.Wide_Spelling_Checker} (@file{g-wispch.ads})
+@cindex @code{GNAT.Wide_Spelling_Checker} (@file{g-wispch.ads})
+@cindex Spell checking
+
@noindent
-Provides symbolic traceback information that includes the subprogram
-name and line number information.
+Provides a function for determining whether one wide string is a plausible
+near misspelling of another wide string.
@node GNAT.Wide_String_Split (g-wistsp.ads)
@section @code{GNAT.Wide_String_Split} (@file{g-wistsp.ads})
@cindex Wide_String splitter
@noindent
-Useful wide_string-manipulation routines: given a set of separators, split
-a wide_string wherever the separators appear, and provide direct access
+Useful wide string manipulation routines: given a set of separators, split
+a wide string wherever the separators appear, and provide direct access
+to the resulting slices. This package is instantiated from
+@code{GNAT.Array_Split}.
+
+@node GNAT.Wide_Wide_Spelling_Checker (g-zspche.ads)
+@section @code{GNAT.Wide_Wide_Spelling_Checker} (@file{g-zspche.ads})
+@cindex @code{GNAT.Wide_Wide_Spelling_Checker} (@file{g-zspche.ads})
+@cindex Spell checking
+
+@noindent
+Provides a function for determining whether one wide wide string is a plausible
+near misspelling of another wide wide string.
+
+@node GNAT.Wide_Wide_String_Split (g-zistsp.ads)
+@section @code{GNAT.Wide_Wide_String_Split} (@file{g-zistsp.ads})
+@cindex @code{GNAT.Wide_Wide_String_Split} (@file{g-zistsp.ads})
+@cindex Wide_Wide_String splitter
+
+@noindent
+Useful wide wide string manipulation routines: given a set of separators, split
+a wide wide string wherever the separators appear, and provide direct access
to the resulting slices. This package is instantiated from
@code{GNAT.Array_Split}.
is primarily intended to be used in connection with automated tools
for the generation of C++ interfaces.
-@node Interfaces.Os2lib (i-os2lib.ads)
-@section @code{Interfaces.Os2lib} (@file{i-os2lib.ads})
-@cindex @code{Interfaces.Os2lib} (@file{i-os2lib.ads})
-@cindex Interfacing, to OS/2
-@cindex OS/2 interfacing
-
-@noindent
-This package provides interface definitions to the OS/2 library.
-It is a thin binding which is a direct translation of the
-various @file{<bse@.h>} files.
-
-@node Interfaces.Os2lib.Errors (i-os2err.ads)
-@section @code{Interfaces.Os2lib.Errors} (@file{i-os2err.ads})
-@cindex @code{Interfaces.Os2lib.Errors} (@file{i-os2err.ads})
-@cindex OS/2 Error codes
-@cindex Interfacing, to OS/2
-@cindex OS/2 interfacing
-
-@noindent
-This package provides definitions of the OS/2 error codes.
-
-@node Interfaces.Os2lib.Synchronization (i-os2syn.ads)
-@section @code{Interfaces.Os2lib.Synchronization} (@file{i-os2syn.ads})
-@cindex @code{Interfaces.Os2lib.Synchronization} (@file{i-os2syn.ads})
-@cindex Interfacing, to OS/2
-@cindex Synchronization, OS/2
-@cindex OS/2 synchronization primitives
-
-@noindent
-This is a child package that provides definitions for interfacing
-to the @code{OS/2} synchronization primitives.
-
-@node Interfaces.Os2lib.Threads (i-os2thr.ads)
-@section @code{Interfaces.Os2lib.Threads} (@file{i-os2thr.ads})
-@cindex @code{Interfaces.Os2lib.Threads} (@file{i-os2thr.ads})
-@cindex Interfacing, to OS/2
-@cindex Thread control, OS/2
-@cindex OS/2 thread interfacing
-
-@noindent
-This is a child package that provides definitions for interfacing
-to the @code{OS/2} thread primitives.
-
@node Interfaces.Packed_Decimal (i-pacdec.ads)
@section @code{Interfaces.Packed_Decimal} (@file{i-pacdec.ads})
@cindex @code{Interfaces.Packed_Decimal} (@file{i-pacdec.ads})
@node System.Partition_Interface (s-parint.ads)
@section @code{System.Partition_Interface} (@file{s-parint.ads})
@cindex @code{System.Partition_Interface} (@file{s-parint.ads})
-@cindex Partition intefacing functions
+@cindex Partition interfacing functions
@noindent
This package provides facilities for partition interfacing. It
is used primarily in a distribution context when using Annex E
with @code{GLADE}.
+@node System.Pool_Global (s-pooglo.ads)
+@section @code{System.Pool_Global} (@file{s-pooglo.ads})
+@cindex @code{System.Pool_Global} (@file{s-pooglo.ads})
+@cindex Storage pool, global
+@cindex Global storage pool
+
+@noindent
+This package provides a storage pool that is equivalent to the default
+storage pool used for access types for which no pool is specifically
+declared. It uses malloc/free to allocate/free and does not attempt to
+do any automatic reclamation.
+
+@node System.Pool_Local (s-pooloc.ads)
+@section @code{System.Pool_Local} (@file{s-pooloc.ads})
+@cindex @code{System.Pool_Local} (@file{s-pooloc.ads})
+@cindex Storage pool, local
+@cindex Local storage pool
+
+@noindent
+This package provides a storage pool that is intended for use with locally
+defined access types. It uses malloc/free for allocate/free, and maintains
+a list of allocated blocks, so that all storage allocated for the pool can
+be freed automatically when the pool is finalized.
+
@node System.Restrictions (s-restri.ads)
@section @code{System.Restrictions} (@file{s-restri.ads})
@cindex @code{System.Restrictions} (@file{s-restri.ads})
@cindex Run-time restrictions access
@noindent
-This package provides facilities for accessing at run-time
+This package provides facilities for accessing at run time
the status of restrictions specified at compile time for
the partition. Information is available both with regard
to actual restrictions specified, and with regard to
since the necessary instantiation is included in
package System.Restrictions.
+@node System.Strings.Stream_Ops (s-ststop.ads)
+@section @code{System.Strings.Stream_Ops} (@file{s-ststop.ads})
+@cindex @code{System.Strings.Stream_Ops} (@file{s-ststop.ads})
+@cindex Stream operations
+@cindex String stream operations
+
+@noindent
+This package provides a set of stream subprograms for standard string types.
+It is intended primarily to support implicit use of such subprograms when
+stream attributes are applied to string types, but the subprograms in this
+package can be used directly by application programs.
+
@node System.Task_Info (s-tasinf.ads)
@section @code{System.Task_Info} (@file{s-tasinf.ads})
@cindex @code{System.Task_Info} (@file{s-tasinf.ads})
@noindent
This package provides routines for converting between
-wide characters and a representation as a value of type
+wide and wide wide characters and a representation as a value of type
@code{Standard.String}, using a specified wide character
encoding method. It uses definitions in
package @code{System.Wch_Con}.
@node Interfacing to Other Languages
@chapter Interfacing to Other Languages
@noindent
-The facilities in annex B of the Ada 95 Reference Manual are fully
+The facilities in annex B of the Ada Reference Manual are fully
implemented in GNAT, and in addition, a full interface to C++ is
provided.
generator tool is supplied with GNAT though.
Using these pragmas it is possible to achieve complete
-inter-operability between Ada tagged types and C class definitions.
+inter-operability between Ada tagged types and C++ class definitions.
See @ref{Implementation Defined Pragmas}, for more details.
@table @code
-@item pragma CPP_Class ([Entity =>] @var{local_name})
+@item pragma CPP_Class ([Entity =>] @var{LOCAL_NAME})
The argument denotes an entity in the current declarative region that is
-declared as a tagged or untagged record type. It indicates that the type
+declared as a tagged or untagged record type. It indicates that the type
corresponds to an externally declared C++ class type, and is to be laid
out the same way that C++ would lay out the type.
-@item pragma CPP_Constructor ([Entity =>] @var{local_name})
+Note: Pragma @code{CPP_Class} is currently obsolete. It is supported
+for backward compatibility but its functionality is available
+using pragma @code{Import} with @code{Convention} = @code{CPP}.
+
+@item pragma CPP_Constructor ([Entity =>] @var{LOCAL_NAME})
This pragma identifies an imported function (imported in the usual way
with pragma @code{Import}) as corresponding to a C++ constructor.
-
-@item pragma CPP_Vtable @dots{}
-One @code{CPP_Vtable} pragma can be present for each component of type
-@code{CPP.Interfaces.Vtable_Ptr} in a record to which pragma @code{CPP_Class}
-applies.
@end table
@node Interfacing to COBOL
@noindent
Interfacing to COBOL is achieved as described in section B.4 of
-the Ada 95 reference manual.
+the Ada Reference Manual.
@node Interfacing to Fortran
@section Interfacing to Fortran
@noindent
Interfacing to Fortran is achieved as described in section B.5 of the
-reference manual. The pragma @code{Convention Fortran}, applied to a
+Ada Reference Manual. The pragma @code{Convention Fortran}, applied to a
multi-dimensional array causes the array to be stored in column-major
order as required for convenient interface to Fortran.
It is possible to specify the convention @code{Ada} in a pragma
@code{Import} or pragma @code{Export}. However this refers to
the calling conventions used by GNAT, which may or may not be
-similar enough to those used by some other Ada 83 or Ada 95
+similar enough to those used by some other Ada 83 / Ada 95 / Ada 2005
compiler to allow interoperation.
If arguments types are kept simple, and if the foreign compiler generally
@chapter Specialized Needs Annexes
@noindent
-Ada 95 defines a number of specialized needs annexes, which are not
+Ada 95 and Ada 2005 define a number of Specialized Needs Annexes, which are not
required in all implementations. However, as described in this chapter,
-GNAT implements all of these special needs annexes:
+GNAT implements all of these annexes:
@table @asis
@item Systems Programming (Annex C)
@item Numerics (Annex G)
The Numerics Annex is fully implemented.
-@item Safety and Security (Annex H)
-The Safety and Security annex is fully implemented.
+@item Safety and Security / High-Integrity Systems (Annex H)
+The Safety and Security Annex (termed the High-Integrity Systems Annex
+in Ada 2005) is fully implemented.
@end table
@node Implementation of Specific Ada Features
* GNAT Implementation of Tasking::
* GNAT Implementation of Shared Passive Packages::
* Code Generation for Array Aggregates::
+* The Size of Discriminated Records with Default Discriminants::
+* Strict Conformance to the Ada Reference Manual::
@end menu
@node Machine Code Insertions
@section Machine Code Insertions
+@cindex Machine Code insertions
@noindent
Package @code{Machine_Code} provides machine code support as described
-in the Ada 95 Reference Manual in two separate forms:
+in the Ada Reference Manual in two separate forms:
@itemize @bullet
@item
Machine code statements, consisting of qualified expressions that
The two features are similar, and both are closely related to the mechanism
provided by the asm instruction in the GNU C compiler. Full understanding
and use of the facilities in this package requires understanding the asm
-instruction as described in @cite{Using the GNU Compiler Collection (GCC)}
-by Richard Stallman. The relevant section is titled ``Extensions to the C
-Language Family'' -> ``Assembler Instructions with C Expression Operands''.
+instruction, see @ref{Extended Asm,, Assembler Instructions with C Expression
+Operands, gcc, Using the GNU Compiler Collection (GCC)}.
Calls to the function @code{Asm} and the procedure @code{Asm} have identical
semantic restrictions and effects as described below. Both are provided so
optimizations with respect to the instruction specified should be
suppressed, and that in particular, for an instruction that has outputs,
the instruction will still be generated, even if none of the outputs are
-used. See the full description in the GCC manual for further details.
+used. @xref{Extended Asm,, Assembler Instructions with C Expression Operands,
+gcc, Using the GNU Compiler Collection (GCC)}, for the full description.
+Generally it is strongly advisable to use Volatile for any ASM statement
+that is missing either input or output operands, or when two or more ASM
+statements appear in sequence, to avoid unwanted optimizations. A warning
+is generated if this advice is not followed.
The @code{Asm} subprograms may be used in two ways. First the procedure
forms can be used anywhere a procedure call would be valid, and
@cindex pragma @code{Shared_Passive}
the purpose of designating shared passive packages.
This allows the use of passive partitions in the
-context described in the Ada Reference Manual; i.e. for communication
+context described in the Ada Reference Manual; i.e., for communication
between separate partitions of a distributed application using the
features in Annex E.
@cindex Annex E
needed. The only requirement is that the two programs have a
common shared file system. It is even possible for programs
running on different machines with different architectures
-(e.g. different endianness) to communicate via the data in
+(e.g.@: different endianness) to communicate via the data in
a passive partition.
@item Persistence between program runs
@menu
* Static constant aggregates with static bounds::
-* Constant aggregates with an unconstrained nominal types::
+* Constant aggregates with unconstrained nominal types::
* Aggregates with static bounds::
* Aggregates with non-static bounds::
* Aggregates in assignment statements::
@end menu
@noindent
-Aggregate have a rich syntax and allow the user to specify the values of
+Aggregates have a rich syntax and allow the user to specify the values of
complex data structures by means of a single construct. As a result, the
code generated for aggregates can be quite complex and involve loops, case
statements and multiple assignments. In the simplest cases, however, the
compiler will recognize aggregates whose components and constraints are
fully static, and in those cases the compiler will generate little or no
executable code. The following is an outline of the code that GNAT generates
-for various aggregate constructs. For further details, the user will find it
+for various aggregate constructs. For further details, you will find it
useful to examine the output produced by the -gnatG flag to see the expanded
-source that is input to the code generator. The user will also want to examine
+source that is input to the code generator. You may also want to examine
the assembly code generated at various levels of optimization.
The code generated for aggregates depends on the context, the component values,
For the declarations:
@smallexample @c ada
type One_Dim is array (1..10) of integer;
- ar0 : constant One_Dim := ( 1, 2, 3, 4, 5, 6, 7, 8, 9, 0);
+ ar0 : constant One_Dim := (1, 2, 3, 4, 5, 6, 7, 8, 9, 0);
@end smallexample
@noindent
The same is true for constant aggregates with named associations:
@smallexample @c ada
- Cr1 : constant One_Dim := (4 => 16, 2 => 4, 3 => 9, 1=> 1);
+ Cr1 : constant One_Dim := (4 => 16, 2 => 4, 3 => 9, 1 => 1, 5 .. 10 => 0);
Cr3 : constant One_Dim := (others => 7777);
@end smallexample
Zero2: constant two_dim := (others => (others => 0));
@end smallexample
-@node Constant aggregates with an unconstrained nominal types
-@subsection Constant aggregates with an unconstrained nominal types
+@node Constant aggregates with unconstrained nominal types
+@subsection Constant aggregates with unconstrained nominal types
@noindent
In such cases the aggregate itself establishes the subtype, so that
object. The declarations
@smallexample @c ada
- Cr_Var1 : One_Dim := (2, 5, 7, 11);
+ Cr_Var1 : One_Dim := (2, 5, 7, 11, 0, 0, 0, 0, 0, 0);
Cr_Var2 : One_Dim := (others > -1);
@end smallexample
Cr_Var1 (4) := 11;
for I in Cr_Var2'range loop
- Cr_Var2 (I) := =-1;
+ Cr_Var2 (I) := -1;
end loop;
@end smallexample
a temporary (created either by the front-end or the code generator) and then
that temporary will be copied onto the target.
+
+@node The Size of Discriminated Records with Default Discriminants
+@section The Size of Discriminated Records with Default Discriminants
+
+@noindent
+If a discriminated type @code{T} has discriminants with default values, it is
+possible to declare an object of this type without providing an explicit
+constraint:
+
+@smallexample @c ada
+@group
+type Size is range 1..100;
+
+type Rec (D : Size := 15) is record
+ Name : String (1..D);
+end T;
+
+Word : Rec;
+@end group
+@end smallexample
+
+@noindent
+Such an object is said to be @emph{unconstrained}.
+The discriminant of the object
+can be modified by a full assignment to the object, as long as it preserves the
+relation between the value of the discriminant, and the value of the components
+that depend on it:
+
+@smallexample @c ada
+@group
+Word := (3, "yes");
+
+Word := (5, "maybe");
+
+Word := (5, "no"); -- raises Constraint_Error
+@end group
+@end smallexample
+
+@noindent
+In order to support this behavior efficiently, an unconstrained object is
+given the maximum size that any value of the type requires. In the case
+above, @code{Word} has storage for the discriminant and for
+a @code{String} of length 100.
+It is important to note that unconstrained objects do not require dynamic
+allocation. It would be an improper implementation to place on the heap those
+components whose size depends on discriminants. (This improper implementation
+was used by some Ada83 compilers, where the @code{Name} component above
+would have
+been stored as a pointer to a dynamic string). Following the principle that
+dynamic storage management should never be introduced implicitly,
+an Ada compiler should reserve the full size for an unconstrained declared
+object, and place it on the stack.
+
+This maximum size approach
+has been a source of surprise to some users, who expect the default
+values of the discriminants to determine the size reserved for an
+unconstrained object: ``If the default is 15, why should the object occupy
+a larger size?''
+The answer, of course, is that the discriminant may be later modified,
+and its full range of values must be taken into account. This is why the
+declaration:
+
+@smallexample
+@group
+type Rec (D : Positive := 15) is record
+ Name : String (1..D);
+end record;
+
+Too_Large : Rec;
+@end group
+@end smallexample
+
+@noindent
+is flagged by the compiler with a warning:
+an attempt to create @code{Too_Large} will raise @code{Storage_Error},
+because the required size includes @code{Positive'Last}
+bytes. As the first example indicates, the proper approach is to declare an
+index type of ``reasonable'' range so that unconstrained objects are not too
+large.
+
+One final wrinkle: if the object is declared to be @code{aliased}, or if it is
+created in the heap by means of an allocator, then it is @emph{not}
+unconstrained:
+it is constrained by the default values of the discriminants, and those values
+cannot be modified by full assignment. This is because in the presence of
+aliasing all views of the object (which may be manipulated by different tasks,
+say) must be consistent, so it is imperative that the object, once created,
+remain invariant.
+
+@node Strict Conformance to the Ada Reference Manual
+@section Strict Conformance to the Ada Reference Manual
+
+@noindent
+The dynamic semantics defined by the Ada Reference Manual impose a set of
+run-time checks to be generated. By default, the GNAT compiler will insert many
+run-time checks into the compiled code, including most of those required by the
+Ada Reference Manual. However, there are three checks that are not enabled
+in the default mode for efficiency reasons: arithmetic overflow checking for
+integer operations (including division by zero), checks for access before
+elaboration on subprogram calls, and stack overflow checking (most operating
+systems do not perform this check by default).
+
+Strict conformance to the Ada Reference Manual can be achieved by adding
+three compiler options for overflow checking for integer operations
+(@option{-gnato}), dynamic checks for access-before-elaboration on subprogram
+calls and generic instantiations (@option{-gnatE}), and stack overflow
+checking (@option{-fstack-check}).
+
+Note that the result of a floating point arithmetic operation in overflow and
+invalid situations, when the @code{Machine_Overflows} attribute of the result
+type is @code{False}, is to generate IEEE NaN and infinite values. This is the
+case for machines compliant with the IEEE floating-point standard, but on
+machines that are not fully compliant with this standard, such as Alpha, the
+@option{-mieee} compiler flag must be used for achieving IEEE confirming
+behavior (although at the cost of a significant performance penalty), so
+infinite and and NaN values are properly generated.
+
+
@node Project File Reference
@chapter Project File Reference
Project files specify the options to be used when building a system.
Project files can specify global settings for all tools,
as well as tool-specific settings.
-See the chapter on project files in the GNAT Users guide for examples of use.
+@xref{Examples of Project Files,,, gnat_ugn, @value{EDITION} User's Guide},
+for examples of use.
@menu
* Reserved Words::
* Lexical Elements::
* Declarations::
+* Empty declarations::
* Typed string declarations::
* Variables::
* Expressions::
@section Reserved Words
@noindent
-All Ada95 reserved words are reserved in project files, and cannot be used
+All Ada reserved words are reserved in project files, and cannot be used
as variable names or project names. In addition, the following are
also reserved in project files:
@section Lexical Elements
@noindent
-Rules for identifiers are the same as in Ada95. Identifiers
+Rules for identifiers are the same as in Ada. Identifiers
are case-insensitive. Strings are case sensitive, except where noted.
-Comments have the same form as in Ada95.
+Comments have the same form as in Ada.
@noindent
Syntax:
variable_declaration |
typed_variable_declaration |
attribute_declaration |
- case_construction
+ case_construction |
+ empty_declaration
+@end smallexample
+
+@node Empty declarations
+@section Empty declarations
+
+@smallexample
+empty_declaration ::=
+ @b{null} ;
@end smallexample
+An empty declaration is allowed anywhere a declaration is allowed.
+It has no effect.
+
@node Typed string declarations
@section Typed string declarations
A typed_variable can only be declare once.
@noindent
-a non typed variable can be declared multiple times.
+a non-typed variable can be declared multiple times.
@noindent
Before the completion of its first declaration, the value of variable
Expression must be a list of path names. The attribute
defines the directories in which the source files for the project are to be
found. If not specified, source files are found in the project directory.
+If a string in the list ends with "/**", then the directory that precedes
+"/**" and all of its subdirectories (recursively) are included in the list
+of source directories.
+
+@item Excluded_Source_Dirs
+Expression must be a list of strings. Each entry designates a directory that
+is not to be included in the list of source directories of the project.
+This is normally used when there are strings ending with "/**" in the value
+of attribute Source_Dirs.
@item Source_Files
Expression must be a list of file names. The attribute
information. If the project has no sources the attribute must be declared
explicitly with an empty list.
+@item Excluded_Source_Files (Locally_Removed_Files)
+Expression must be a list of strings that are legal file names.
+Each file name must designate a source that would normally be a source file
+in the source directories of the project or, if the project file is an
+extending project file, inherited by the current project file. It cannot
+designate an immediate source that is not inherited. Each of the source files
+in the list are not considered to be sources of the project file: they are not
+inherited. Attribute Locally_Removed_Files is obsolescent, attribute
+Excluded_Source_Files is preferred.
+
@item Source_List_File
Expression must a single path name. The attribute
defines a text file that contains a list of source file names to be used
Expression must be a path name. The attribute defines the
directory in which the sources of the interfaces of a Stand-alone Library will
be copied. The directory must exist, must be distinct from the project's
-object directory and source directories, and must be writable.
+object directory and source directories of all projects in the project tree,
+and must be writable.
+
+@item Library_Src_Dir
+Expression must be a path name. The attribute defines the
+directory in which the ALI files of a Library will
+be copied. The directory must exist, must be distinct from the project's
+object directory and source directories of all projects in the project tree,
+and must be writable.
+
+@item Library_Symbol_File
+Expression must be a single string. Its value is the single file name of a
+symbol file to be created when building a stand-alone library when the
+symbol policy is either "compliant", "controlled" or "restricted",
+on platforms that support symbol control, such as VMS. When symbol policy
+is "direct", then a file with this name must exist in the object directory.
+
+@item Library_Reference_Symbol_File
+Expression must be a single string. Its value is the path name of a
+reference symbol file that is read when the symbol policy is either
+"compliant" or "controlled", on platforms that support symbol control,
+such as VMS, when building a stand-alone library. The path may be an absolute
+path or a path relative to the project directory.
+
+@item Library_Symbol_Policy
+Expression must be a single string. Its case-insensitive value can only be
+"autonomous", "default", "compliant", "controlled", "restricted" or "direct".
+
+This attribute is not taken into account on all platforms. It controls the
+policy for exported symbols and, on some platforms (like VMS) that have the
+notions of major and minor IDs built in the library files, it controls
+the setting of these IDs.
+
+"autonomous" or "default": exported symbols are not controlled.
+
+"compliant": if attribute Library_Reference_Symbol_File is not defined, then
+it is equivalent to policy "autonomous". If there are exported symbols in
+the reference symbol file that are not in the object files of the interfaces,
+the major ID of the library is increased. If there are symbols in the
+object files of the interfaces that are not in the reference symbol file,
+these symbols are put at the end of the list in the newly created symbol file
+and the minor ID is increased.
+
+"controlled": the attribute Library_Reference_Symbol_File must be defined.
+The library will fail to build if the exported symbols in the object files of
+the interfaces do not match exactly the symbol in the symbol file.
+
+"restricted": The attribute Library_Symbol_File must be defined. The library
+will fail to build if there are symbols in the symbol file that are not in
+the exported symbols of the object files of the interfaces. Additional symbols
+in the object files are not added to the symbol file.
+
+"direct": The attribute Library_Symbol_File must be defined and must designate
+an existing file in the object directory. This symbol file is passed directly
+to the underlying linker without any symbol processing.
@item Main
Expression must be a list of strings that are legal file names.
If the gnatmake command does not include explicit file names, the executables
that are built correspond to the files specified by this attribute.
+@item Externally_Built
+Expression must be a single string. Its value must be either "true" of "false",
+case-insensitive. The default is "false". When the value of this attribute is
+"true", no attempt is made to compile the sources or to build the library,
+when the project is a library project.
+
@item Main_Language
This is a simple attribute. Its value is a string that specifies the
language of the main program.
Expression must be a string list. Each string designates
a programming language that is known to GNAT. The strings are case-insensitive.
-@item Locally_Removed_Files
-This attribute is legal only in a project file that extends another.
-Expression must be a list of strings that are legal file names.
-Each file name must designate a source that would normally be inherited
-by the current project file. It cannot designate an immediate source that is
-not inherited. Each of the source files in the list are not considered to
-be sources of the project file: they are not inherited.
@end table
@node Attribute References
@section Case Construction
@noindent
-A case construction supports attribute declarations that depend on the value of
-a previously declared variable.
+A case construction supports attribute and variable declarations that depend
+on the value of a previously declared variable.
Syntax:
@smallexample
case_item ::=
@b{when} discrete_choice_list =>
- @{case_construction | attribute_declaration@}
+ @{case_construction |
+ attribute_declaration |
+ variable_declaration |
+ empty_declaration@}
discrete_choice_list ::=
string_literal @{| string_literal@} |
@end smallexample
@noindent
+Inside a case construction, variable declarations must be for variables that
+have already been declared before the case construction.
+
All choices in a choice list must be distinct. The choice lists of two
distinct alternatives must be disjoint. Unlike Ada, the choice lists of all
alternatives do not need to include all values of the type. An @code{others}
@smallexample
package_declaration ::=
- package_specification | package_renaming
+ package_spec | package_renaming
-package_specification ::=
+package_spec ::=
@b{package} package_identifier @b{is}
@{simple_declarative_item@}
@b{end} package_identifier ;
package_identifier ::=
@code{Naming} | @code{Builder} | @code{Compiler} | @code{Binder} |
@code{Linker} | @code{Finder} | @code{Cross_Reference} |
- @code{gnatls} | @code{IDE} | @code{Pretty_Printer}
+ @code{gnatls} | @code{IDE} | @code{Pretty_Printer} | @code{Check}
@end smallexample
@subsection Package Naming
domain is a set of language names. Its range is a string list that
specifies the compilation options to be used when compiling a component
written in that language, for which no file-specific switches have been
-specified..
+specified.
@item Switches
This is an associative array attribute. Its domain is
a set of file names. Its range is a string list that specifies the
compilation options to be used when compiling the named file. If a file
is not specified in the Switches attribute, it is compiled with the
-settings specified by Default_Switches.
+options specified by Default_Switches of its language, if defined.
@item Local_Configuration_Pragmas.
This is a simple attribute, whose
value is a path name that designates a file containing configuration pragmas
to be used for all invocations of the compiler for immediate sources of the
project.
-
-@item Executable
-This is an associative array attribute. Its domain is
-a set of main source file names. Its range is a simple string that specifies
-the executable file name to be used when linking the specified main source.
-If a main source is not specified in the Executable attribute, the executable
-file name is deducted from the main source file name.
@end table
@subsection package Builder
@table @code
@item Default_Switches
-As above.
+This is an associative array attribute. Its
+domain is a set of language names. Its range is a string list that
+specifies options to be used when building a main
+written in that language, for which no file-specific switches have been
+specified.
@item Switches
-As above.
+This is an associative array attribute. Its domain is
+a set of file names. Its range is a string list that specifies
+options to be used when building the named main file. If a main file
+is not specified in the Switches attribute, it is built with the
+options specified by Default_Switches of its language, if defined.
@item Global_Configuration_Pragmas
This is a simple attribute, whose
to be used in every build of an executable. If both local and global
configuration pragmas are specified, a compilation makes use of both sets.
+
@item Executable
-This is an associative array attribute, defined over
-compilation unit names. The image is a string that is the name of the
-executable file corresponding to the main source file index.
+This is an associative array attribute. Its domain is
+a set of main source file names. Its range is a simple string that specifies
+the executable file name to be used when linking the specified main source.
+If a main source is not specified in the Executable attribute, the executable
+file name is deducted from the main source file name.
This attribute has no effect if its value is the empty string.
@item Executable_Suffix
-This is a simple attribute whose value is a suffix to be added to
+This is a simple attribute whose value is the suffix to be added to
the executables that don't have an attribute Executable specified.
@end table
@table @code
@item Switches
-As above.
+This is a single attribute with a string list value. Each nonempty string
+in the list is an option when invoking @code{gnatls}.
@end table
@subsection package Binder
@table @code
@item Default_Switches
-As above.
-@item Switches
-As above.
+This is an associative array attribute. Its
+domain is a set of language names. Its range is a string list that
+specifies options to be used when binding a main
+written in that language, for which no file-specific switches have been
+specified.
+
+@item Switches
+This is an associative array attribute. Its domain is
+a set of file names. Its range is a string list that specifies
+options to be used when binding the named main file. If a main file
+is not specified in the Switches attribute, it is bound with the
+options specified by Default_Switches of its language, if defined.
@end table
@subsection package Linker
@table @code
@item Default_Switches
-As above
-@item Switches
-As above.
+This is an associative array attribute. Its
+domain is a set of language names. Its range is a string list that
+specifies options to be used when linking a main
+written in that language, for which no file-specific switches have been
+specified.
+
+@item Switches
+This is an associative array attribute. Its domain is
+a set of file names. Its range is a string list that specifies
+options to be used when linking the named main file. If a main file
+is not specified in the Switches attribute, it is linked with the
+options specified by Default_Switches of its language, if defined.
+
+@item Linker_Options
+This is a string list attribute. Its value specifies additional options that
+be given to the linker when linking an executable. This attribute is not
+used in the main project, only in projects imported directly or indirectly.
+
@end table
@subsection package Cross_Reference
@table @code
@item Default_Switches
-As above.
-@item Switches
-As above.
+This is an associative array attribute. Its
+domain is a set of language names. Its range is a string list that
+specifies options to be used when calling @command{gnatxref} on a source
+written in that language, for which no file-specific switches have been
+specified.
+
+@item Switches
+This is an associative array attribute. Its domain is
+a set of file names. Its range is a string list that specifies
+options to be used when calling @command{gnatxref} on the named main source.
+If a source is not specified in the Switches attribute, @command{gnatxref} will
+be called with the options specified by Default_Switches of its language,
+if defined.
@end table
@subsection package Finder
@table @code
@item Default_Switches
-As above.
-@item Switches
-As above.
+This is an associative array attribute. Its
+domain is a set of language names. Its range is a string list that
+specifies options to be used when calling @command{gnatfind} on a source
+written in that language, for which no file-specific switches have been
+specified.
+
+@item Switches
+This is an associative array attribute. Its domain is
+a set of file names. Its range is a string list that specifies
+options to be used when calling @command{gnatfind} on the named main source.
+If a source is not specified in the Switches attribute, @command{gnatfind} will
+be called with the options specified by Default_Switches of its language,
+if defined.
+@end table
+
+@subsection package Check
+
+@noindent
+The attributes of package @code{Check}
+specify the checking rule options to be used
+when invoking the checking tool @command{gnatcheck}.
+The following attributes apply to package @code{Check}:
+
+@table @code
+@item Default_switches
+This is an associative array attribute. Its
+domain is a set of language names. Its range is a string list that
+specifies options to be used when calling @command{gnatcheck} on a source
+written in that language. The first string in the range should always be
+@code{"-rules"} to specify that all the other options belong to the
+@code{-rules} section of the parameters of @command{gnatcheck} call.
+
@end table
@subsection package Pretty_Printer
@table @code
@item Default_switches
-As above.
-@item Switches
-As above.
+This is an associative array attribute. Its
+domain is a set of language names. Its range is a string list that
+specifies options to be used when calling @command{gnatpp} on a source
+written in that language, for which no file-specific switches have been
+specified.
+
+@item Switches
+This is an associative array attribute. Its domain is
+a set of file names. Its range is a string list that specifies
+options to be used when calling @command{gnatpp} on the named main source.
+If a source is not specified in the Switches attribute, @command{gnatpp} will
+be called with the options specified by Default_Switches of its language,
+if defined.
+@end table
+
+@subsection package gnatstub
+
+@noindent
+The attributes of package @code{gnatstub}
+specify the tool options to be used
+when invoking the tool @command{gnatstub}.
+The following attributes apply to package @code{gnatstub}:
+
+@table @code
+@item Default_switches
+This is an associative array attribute. Its
+domain is a set of language names. Its range is a string list that
+specifies options to be used when calling @command{gnatstub} on a source
+written in that language, for which no file-specific switches have been
+specified.
+
+@item Switches
+This is an associative array attribute. Its domain is
+a set of file names. Its range is a string list that specifies
+options to be used when calling @command{gnatstub} on the named main source.
+If a source is not specified in the Switches attribute, @command{gnatpp} will
+be called with the options specified by Default_Switches of its language,
+if defined.
+@end table
+
+@subsection package Eliminate
+
+@noindent
+The attributes of package @code{Eliminate}
+specify the tool options to be used
+when invoking the tool @command{gnatelim}.
+The following attributes apply to package @code{Eliminate}:
+
+@table @code
+@item Default_switches
+This is an associative array attribute. Its
+domain is a set of language names. Its range is a string list that
+specifies options to be used when calling @command{gnatelim} on a source
+written in that language, for which no file-specific switches have been
+specified.
+
+@item Switches
+This is an associative array attribute. Its domain is
+a set of file names. Its range is a string list that specifies
+options to be used when calling @command{gnatelim} on the named main source.
+If a source is not specified in the Switches attribute, @command{gnatelim} will
+be called with the options specified by Default_Switches of its language,
+if defined.
+@end table
+
+@subsection package Metrics
+
+@noindent
+The attributes of package @code{Metrics}
+specify the tool options to be used
+when invoking the tool @command{gnatmetric}.
+The following attributes apply to package @code{Metrics}:
+
+@table @code
+@item Default_switches
+This is an associative array attribute. Its
+domain is a set of language names. Its range is a string list that
+specifies options to be used when calling @command{gnatmetric} on a source
+written in that language, for which no file-specific switches have been
+specified.
+
+@item Switches
+This is an associative array attribute. Its domain is
+a set of file names. Its range is a string list that specifies
+options to be used when calling @command{gnatmetric} on the named main source.
+If a source is not specified in the Switches attribute, @command{gnatmetric}
+will be called with the options specified by Default_Switches of its language,
+if defined.
@end table
@subsection package IDE
@item Communication_Protocol
This is a simple string attribute. Its value is the name of the protocol
to use to communicate with the target in a cross-compilation environment,
-e.g. @code{"wtx"} or @code{"vxworks"}.
+e.g.@: @code{"wtx"} or @code{"vxworks"}.
@item Compiler_Command
This is an associative array attribute, whose domain is a language name. Its
predefined path; e.g., @code{"gnatls"}, @code{"powerpc-wrs-vxworks-gnatls"}.
@item VCS_Kind
-This is a simple atribute. Is value is a string used to specify the
-Version Control System (VCS) to be used for this project, e.g CVS, RCS
+This is a simple attribute. Its value is a string used to specify the
+Version Control System (VCS) to be used for this project, e.g.@: CVS, RCS
ClearCase or Perforce.
@item VCS_File_Check
This is a simple attribute. Its value is a string that specifies
the command used by the VCS to check the validity of a log file.
+@item VCS_Repository_Root
+The VCS repository root path. This is used to create tags or branches
+of the repository. For subversion the value should be the @code{URL}
+as specified to check-out the working copy of the repository.
+
+@item VCS_Patch_Root
+The local root directory to use for building patch file. All patch chunks
+will be relative to this path. The root project directory is used if
+this value is not defined.
+
@end table
@node Package Renamings
attributes and variables in the project are then used to establish the
environment in which the gnat tool will execute.
+@node Obsolescent Features
+@chapter Obsolescent Features
+
+@noindent
+This chapter describes features that are provided by GNAT, but are
+considered obsolescent since there are preferred ways of achieving
+the same effect. These features are provided solely for historical
+compatibility purposes.
+
+@menu
+* pragma No_Run_Time::
+* pragma Ravenscar::
+* pragma Restricted_Run_Time::
+@end menu
+
+@node pragma No_Run_Time
+@section pragma No_Run_Time
+
+The pragma @code{No_Run_Time} is used to achieve an affect similar
+to the use of the "Zero Foot Print" configurable run time, but without
+requiring a specially configured run time. The result of using this
+pragma, which must be used for all units in a partition, is to restrict
+the use of any language features requiring run-time support code. The
+preferred usage is to use an appropriately configured run-time that
+includes just those features that are to be made accessible.
+
+@node pragma Ravenscar
+@section pragma Ravenscar
+
+The pragma @code{Ravenscar} has exactly the same effect as pragma
+@code{Profile (Ravenscar)}. The latter usage is preferred since it
+is part of the new Ada 2005 standard.
+
+@node pragma Restricted_Run_Time
+@section pragma Restricted_Run_Time
+
+The pragma @code{Restricted_Run_Time} has exactly the same effect as
+pragma @code{Profile (Restricted)}. The latter usage is
+preferred since the Ada 2005 pragma @code{Profile} is intended for
+this kind of implementation dependent addition.
+
@include fdl.texi
@c GNU Free Documentation License
@contents
@bye
-
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