\input texinfo @c -*-texinfo-*-
@c %**start of header
@setfilename gfortran.info
-@set copyrights-gfortran 1999-2006
+@set copyrights-gfortran 1999-2007
@include gcc-common.texi
@syncodeindex pg cp
@syncodeindex tp cp
+@c TODO: The following "Part" definitions are included here temporarily
+@c until they are incorporated into the official Texinfo distribution.
+@c They borrow heavily from Texinfo's \unnchapentry definitions.
+
+@tex
+\gdef\part#1#2{%
+ \pchapsepmacro
+ \gdef\thischapter{}
+ \begingroup
+ \vglue\titlepagetopglue
+ \titlefonts \rm
+ \leftline{Part #1:@* #2}
+ \vskip4pt \hrule height 4pt width \hsize \vskip4pt
+ \endgroup
+ \writetocentry{part}{#2}{#1}
+}
+\gdef\blankpart{%
+ \writetocentry{blankpart}{}{}
+}
+% Part TOC-entry definition for summary contents.
+\gdef\dosmallpartentry#1#2#3#4{%
+ \vskip .5\baselineskip plus.2\baselineskip
+ \begingroup
+ \let\rm=\bf \rm
+ \tocentry{Part #2: #1}{\doshortpageno\bgroup#4\egroup}
+ \endgroup
+}
+\gdef\dosmallblankpartentry#1#2#3#4{%
+ \vskip .5\baselineskip plus.2\baselineskip
+}
+% Part TOC-entry definition for regular contents. This has to be
+% equated to an existing entry to not cause problems when the PDF
+% outline is created.
+\gdef\dopartentry#1#2#3#4{%
+ \unnchapentry{Part #2: #1}{}{#3}{#4}
+}
+\gdef\doblankpartentry#1#2#3#4{}
+@end tex
+
@c %**end of header
@c Use with @@smallbook.
@center The gfortran team
@page
@vskip 0pt plus 1filll
-For the @value{version-GCC} Version*
+For the @value{version-GCC} Version
@sp 1
-Published by the Free Software Foundation @*
+Published by the Free Software Foundation@*
51 Franklin Street, Fifth Floor@*
Boston, MA 02110-1301, USA@*
@c Last printed ??ber, 19??.@*
@sp 1
@insertcopying
@end titlepage
+
+@c TODO: The following "Part" definitions are included here temporarily
+@c until they are incorporated into the official Texinfo distribution.
+
+@tex
+\global\let\partentry=\dosmallpartentry
+\global\let\blankpartentry=\dosmallblankpartentry
+@end tex
@summarycontents
+
+@tex
+\global\let\partentry=\dopartentry
+\global\let\blankpartentry=\doblankpartentry
+@end tex
@contents
+
@page
+@c ---------------------------------------------------------------------
+@c TexInfo table of contents.
+@c ---------------------------------------------------------------------
+
+@ifnottex
@node Top
@top Introduction
@cindex Introduction
@comment better formatting.
@comment
@menu
-* Getting Started:: What you should know about GNU Fortran.
-* GNU Fortran and GCC:: You can compile Fortran, C, or other programs.
-* GNU Fortran and G77:: Why we chose to start from scratch.
+* Introduction::
+
+Part I: Invoking GNU Fortran
* Invoking GNU Fortran:: Command options supported by @command{gfortran}.
-* Project Status:: Status of GNU Fortran, roadmap, proposed extensions.
-* Contributing:: How you can help.
-* Standards:: Standards supported by GNU Fortran.
* Runtime:: Influencing runtime behavior with environment variables.
+
+Part II: Language Reference
+* Fortran 2003 status:: Fortran 2003 features supported by GNU Fortran.
* Extensions:: Language extensions implemented by GNU Fortran.
* Intrinsic Procedures:: Intrinsic procedures supported by GNU Fortran.
+
+* Contributing:: How you can help.
* Copying:: GNU General Public License says
how you can copy and share GNU Fortran.
* GNU Free Documentation License::
* Funding:: How to help assure continued work for free software.
* Index:: Index of this documentation.
@end menu
-
-
+@end ifnottex
@c ---------------------------------------------------------------------
-@c Getting Started
+@c Introduction
@c ---------------------------------------------------------------------
-@node Getting Started
-@chapter Getting Started
+@node Introduction
+@chapter Introduction
+
+@c The following duplicates the text on the TexInfo table of contents.
+@iftex
+This manual documents the use of @command{gfortran}, the GNU Fortran
+compiler. You can find in this manual how to invoke @command{gfortran},
+as well as its features and incompatibilities.
+
+@ifset DEVELOPMENT
+@emph{Warning:} This document, and the compiler it describes, are still
+under development. While efforts are made to keep it up-to-date, it
+might not accurately reflect the status of the most recent GNU Fortran
+compiler.
+@end ifset
+@end iftex
The GNU Fortran compiler front end was
designed initially as a free replacement for,
or alternative to, the unix @command{f95} command;
@command{gfortran} is the command you'll use to invoke the compiler.
+@menu
+* About GNU Fortran:: What you should know about the GNU Fortran compiler.
+* GNU Fortran and GCC:: You can compile Fortran, C, or other programs.
+* GNU Fortran and G77:: Why we chose to start from scratch.
+* Project Status:: Status of GNU Fortran, roadmap, proposed extensions.
+* Standards:: Standards supported by GNU Fortran.
+@end menu
+
+
+@c ---------------------------------------------------------------------
+@c About GNU Fortran
+@c ---------------------------------------------------------------------
+
+@node About GNU Fortran
+@section About GNU Fortran
+
The GNU Fortran compiler is still in an early state of development.
It can generate code for most constructs and expressions,
but much work remains to be done.
@item
Read a user's program,
stored in a file and containing instructions written
-in Fortran 77, Fortran 90 or Fortran 95.
+in Fortran 77, Fortran 90, Fortran 95 or Fortran 2003.
This file contains @dfn{source code}.
@item
@end itemize
-
@c ---------------------------------------------------------------------
@c GNU Fortran and GCC
@c ---------------------------------------------------------------------
@node GNU Fortran and GCC
-@chapter GNU Fortran and GCC
+@section GNU Fortran and GCC
@cindex GNU Compiler Collection
-
-GCC used to be the GNU ``C'' Compiler,
-but is now known as the @dfn{GNU Compiler Collection}.
-GCC provides the GNU system with a very versatile
-compiler middle end (shared optimization passes),
-and back ends (code generators) for many different
-computer architectures and operating systems.
-The code of the middle end and back end are shared by all
-compiler front ends that are in the GNU Compiler Collection.
-
-A GCC front end is essentially a source code parser
-and an intermediate code generator. The code generator translates the
-semantics of the source code into a language independent form called
-@dfn{GENERIC}.
-
-The parser takes a source file written in a
-particular computer language, reads and parses it,
-and tries to make sure that the source code conforms to
-the language rules.
-Once the correctness of a program has been established,
-the compiler will build a data structure known as the
-@dfn{Abstract Syntax tree},
-or just @dfn{AST} or ``tree'' for short.
-This data structure represents the whole program
-or a subroutine or a function.
-The ``tree'' is passed to the GCC middle end,
-which will perform optimization passes on it. The optimized AST is then
-handed off too the back end which assembles the program unit.
-
-Different phases in this translation process can be,
-and in fact @emph{are} merged in many compiler front ends.
-GNU Fortran has a strict separation between the
-parser and code generator.
-
-The goal of the GNU Fortran project is to build a new front end for GCC.
-Specifically, a Fortran 95 front end.
-In a non-@command{gfortran} installation,
-@command{gcc} will not be able to compile Fortran source code
-(only the ``C'' front end has to be compiled if you want to build GCC,
-all other languages are optional).
-If you build GCC with @command{gfortran}, @command{gcc} will recognize
-@file{.f/.f90/.f95} source files and accepts Fortran specific
-command line options.
-
+@cindex GCC
+
+GNU Fortran is a part of GCC, the @dfn{GNU Compiler Collection}. GCC
+consists of a collection of front ends for various languages, which
+translate the source code into a language-independent form called
+@dfn{GENERIC}. This is then processed by a common middle end which
+provides optimization, and then passed to one of a collection of back
+ends which generate code for different computer architectures and
+operating systems.
+
+Functionally, this is implemented with a driver program (@command{gcc})
+which provides the command-line interface for the compiler. It calls
+the relevant compiler front-end program (e.g., @command{f951} for
+Fortran) for each file in the source code, and then calls the assembler
+and linker as appropriate to produce the compiled output. In a copy of
+GCC which has been compiled with Fortran language support enabled,
+@command{gcc} will recognize files with @file{.f}, @file{.f90}, @file{.f95},
+and @file{.f03} extensions as Fortran source code, and compile it
+accordingly. A @command{gfortran} driver program is also provided,
+which is identical to @command{gcc} except that it automatically links
+the Fortran runtime libraries into the compiled program.
+
+This manual specifically documents the Fortran front end, which handles
+the programming language's syntax and semantics. The aspects of GCC
+which relate to the optimization passes and the back-end code generation
+are documented in the GCC manual; see
+@ref{Top,,Introduction,gcc,Using the GNU Compiler Collection (GCC)}.
+The two manuals together provide a complete reference for the GNU
+Fortran compiler.
@c ---------------------------------------------------------------------
@c ---------------------------------------------------------------------
@node GNU Fortran and G77
-@chapter GNU Fortran and G77
+@section GNU Fortran and G77
@cindex Fortran 77
@cindex G77
develop ourselves than to do a major overhaul of @command{g77} first,
and then build a Fortran 95 compiler out of it.
-@include invoke.texi
@c ---------------------------------------------------------------------
@c Project Status
@c ---------------------------------------------------------------------
@node Project Status
-@chapter Project Status
+@section Project Status
@quotation
As soon as @command{gfortran} can parse all of the statements correctly,
(even though Andy had already been working on it for a while,
of course).
-@menu
-* Compiler and Library Status::
-* Proposed Extensions::
-@end menu
-
-@node Compiler and Library Status
-@section Compiler and Library Status
-
The GNU Fortran compiler is able to compile nearly all
standard-compliant Fortran 95, Fortran 90, and Fortran 77 programs,
including a number of standard and non-standard extensions, and can be
@uref{http://mysite.verizon.net/serveall/moene.pdf, the HIRLAM
weather-forecasting code} and
@uref{http://www.theochem.uwa.edu.au/tonto/, the Tonto quantum
-chemistry package}.
+chemistry package}; see @url{http://gcc.gnu.org/wiki/GfortranApps} for an
+extended list.
Among other things, the GNU Fortran compiler is intended as a replacement
for G77. At this point, nearly all programs that could be compiled with
categories: bug fixing (primarily regarding the treatment of invalid code
and providing useful error messages), improving the compiler optimizations
and the performance of compiled code, and extending the compiler to support
-future standards -- in particular, Fortran 2003.
-
-
-@node Proposed Extensions
-@section Proposed Extensions
-
-Here's a list of proposed extensions for the GNU Fortran compiler, in no particular
-order. Most of these are necessary to be fully compatible with
-existing Fortran compilers, but they are not part of the official
-J3 Fortran 95 standard.
-
-@subsection Compiler extensions:
-@itemize @bullet
-@item
-User-specified alignment rules for structures.
-
-@item
-Flag to generate @code{Makefile} info.
-
-@item
-Automatically extend single precision constants to double.
-
-@item
-Compile code that conserves memory by dynamically allocating common and
-module storage either on stack or heap.
-
-@item
-Compile flag to generate code for array conformance checking (suggest -CC).
-
-@item
-User control of symbol names (underscores, etc).
-
-@item
-Compile setting for maximum size of stack frame size before spilling
-parts to static or heap.
-
-@item
-Flag to force local variables into static space.
-
-@item
-Flag to force local variables onto stack.
+future standards---in particular, Fortran 2003.
-@item
-Flag for maximum errors before ending compile.
-
-@item
-Option to initialize otherwise uninitialized integer and floating
-point variables.
-@end itemize
-
-
-@subsection Environment Options
-@itemize @bullet
-@item
-Pluggable library modules for random numbers, linear algebra.
-LA should use BLAS calling conventions.
-@item
-Environment variables controlling actions on arithmetic exceptions like
-overflow, underflow, precision loss -- Generate NaN, abort, default.
-action.
-
-@item
-Set precision for fp units that support it (i387).
-
-@item
-Variable for setting fp rounding mode.
+@c ---------------------------------------------------------------------
+@c Standards
+@c ---------------------------------------------------------------------
-@item
-Variable to fill uninitialized variables with a user-defined bit
-pattern.
+@node Standards
+@section Standards
+@cindex Standards
-@item
-Environment variable controlling filename that is opened for that unit
-number.
+The GNU Fortran compiler implements
+ISO/IEC 1539:1997 (Fortran 95). As such, it can also compile essentially all
+standard-compliant Fortran 90 and Fortran 77 programs. It also supports
+the ISO/IEC TR-15581 enhancements to allocatable arrays, and
+the @uref{http://www.openmp.org/drupal/mp-documents/spec25.pdf,
+OpenMP Application Program Interface v2.5} specification.
-@item
-Environment variable to clear/trash memory being freed.
+In the future, the GNU Fortran compiler may also support other standard
+variants of and extensions to the Fortran language. These include
+ISO/IEC 1539-1:2004 (Fortran 2003).
-@item
-Environment variable to control tracing of allocations and frees.
-@item
-Environment variable to display allocated memory at normal program end.
+@c =====================================================================
+@c PART I: INVOCATION REFERENCE
+@c =====================================================================
-@item
-Environment variable for filename for * IO-unit.
+@tex
+\part{I}{Invoking GNU Fortran}
+@end tex
-@item
-Environment variable for temporary file directory.
-
-@item
-Environment variable forcing standard output to be line buffered (unix).
+@c ---------------------------------------------------------------------
+@c Compiler Options
+@c ---------------------------------------------------------------------
-@end itemize
+@include invoke.texi
@c ---------------------------------------------------------------------
@node GFORTRAN_DEFAULT_RECL
@section @env{GFORTRAN_DEFAULT_RECL}---Default record length for new files
-This environment variable specifies the default record length for
-files which are opened without a @code{RECL} tag in the @code{OPEN}
-statement. This must be a positive integer. The default value is
-1073741824.
+This environment variable specifies the default record length, in
+bytes, for files which are opened without a @code{RECL} tag in the
+@code{OPEN} statement. This must be a positive integer. The
+default value is 1073741824 bytes (1 GB).
@node GFORTRAN_LIST_SEPARATOR
@section @env{GFORTRAN_LIST_SEPARATOR}---Separator for list output
@smallexample
$ GFORTRAN_LIST_SEPARATOR=' , ' ./a.out
@end smallexample
-when @code{a.out} is the compiled Fortran program that you want to run.
+when @command{a.out} is the compiled Fortran program that you want to run.
Default is a single space.
@node GFORTRAN_CONVERT_UNIT
@item @code{BIG_ENDIAN} Use the big-endian format for unformatted files.
@end itemize
A missing mode for an exception is taken to mean @code{BIG_ENDIAN}.
-Examples of values for @code{GFORTRAN_CONVERT_UNIT} are:
+Examples of values for @env{GFORTRAN_CONVERT_UNIT} are:
@itemize @w{}
@item @code{'big_endian'} Do all unformatted I/O in big_endian mode.
@item @code{'little_endian;native:10-20,25'} Do all unformatted I/O
@end itemize
Setting the environment variables should be done on the command
-line or via the @code{export}
-command for @code{sh}-compatible shells and via @code{setenv}
-for @code{csh}-compatible shells.
+line or via the @command{export}
+command for @command{sh}-compatible shells and via @command{setenv}
+for @command{csh}-compatible shells.
-Example for @code{sh}:
+Example for @command{sh}:
@smallexample
$ gfortran foo.f90
$ GFORTRAN_CONVERT_UNIT='big_endian;native:10-20' ./a.out
@end smallexample
-Example code for @code{csh}:
+Example code for @command{csh}:
@smallexample
% gfortran foo.f90
% setenv GFORTRAN_CONVERT_UNIT 'big_endian;native:10-20'
@xref{CONVERT specifier}, for an alternative way to specify the
data representation for unformatted files. @xref{Runtime Options}, for
setting a default data representation for the whole program. The
-@code{CONVERT} specifier overrides the @code{-fconvert} compile options.
+@code{CONVERT} specifier overrides the @option{-fconvert} compile options.
+
+
+@c =====================================================================
+@c PART II: LANGUAGE REFERENCE
+@c =====================================================================
+
+@tex
+\part{II}{Language Reference}
+@end tex
+
+@c ---------------------------------------------------------------------
+@c Fortran 2003 Status
+@c ---------------------------------------------------------------------
+
+@node Fortran 2003 status
+@chapter Fortran 2003 Status
+
+Although GNU Fortran focuses on implementing the Fortran 95
+standard for the time being, a few Fortran 2003 features are currently
+available.
+
+@itemize
+@item
+Intrinsics @code{command_argument_count}, @code{get_command},
+@code{get_command_argument}, @code{get_environment_variable}, and
+@code{move_alloc}.
+
+@item
+@cindex Array constructors
+@cindex @code{[...]}
+Array constructors using square brackets. That is, @code{[...]} rather
+than @code{(/.../)}.
+
+@item
+@cindex @code{FLUSH} statement
+@code{FLUSH} statement.
+
+@item
+@cindex @code{IOMSG=} specifier
+@code{IOMSG=} specifier for I/O statements.
+
+@item
+@cindex @code{ENUM} statement
+@cindex @code{ENUMERATOR} statement
+@cindex @code{-fshort-enums} option
+Support for the declaration of enumeration constants via the
+@code{ENUM} and @code{ENUMERATOR} statements. Interoperability with
+@command{gcc} is guaranteed also for the case where the
+@command{-fshort-enums} command line option is given.
+
+@item
+@cindex TR 15581
+TR 15581:
+@itemize
+@item
+@cindex @code{ALLOCATABLE} dummy arguments
+@code{ALLOCATABLE} dummy arguments.
+@item
+@cindex @code{ALLOCATABLE} function results
+@code{ALLOCATABLE} function results
+@item
+@cindex @code{ALLOCATABLE} components of derived types
+@code{ALLOCATABLE} components of derived types
+@end itemize
+
+@item
+@cindex @code{STREAM} I/O
+@cindex @code{ACCESS='STREAM'} I/O
+The @code{OPEN} statement supports the @code{ACCESS='STREAM'} specifier,
+allowing I/O without any record structure.
+
+@item
+Namelist input/output for internal files.
+
+@item
+@cindex @code{PROTECTED}
+The @code{PROTECTED} statement and attribute.
+
+@item
+@cindex @code{VALUE}
+The @code{VALUE} statement and attribute.
+
+@item
+@cindex @code{VOLATILE}
+The @code{VOLATILE} statement and attribute.
+
+@item
+@cindex @code{IMPORT}
+The @code{IMPORT} statement, allowing to import
+host-associated derived types.
+
+@item
+@cindex @code{USE, INTRINSIC}
+@cindex @code{ISO_FORTRAN_ENV}
+@code{USE} statement with @code{INTRINSIC} and @code{NON_INTRINSIC}
+attribute; supported intrinsic modules: @code{ISO_FORTRAN_ENV},
+@code{OMP_LIB} and @code{OMP_LIB_KINDS}.
+
+@end itemize
+
@c ---------------------------------------------------------------------
@c Extensions
* Old-style kind specifications::
* Old-style variable initialization::
* Extensions to namelist::
-* X format descriptor::
+* X format descriptor without count field::
* Commas in FORMAT specifications::
* Missing period in FORMAT specifications::
* I/O item lists::
-* Hexadecimal constants::
+* BOZ literal constants::
* Real array indices::
* Unary operators::
-* Implicitly interconvert LOGICAL and INTEGER::
+* Implicitly convert LOGICAL and INTEGER values::
* Hollerith constants support::
* Cray pointers::
* CONVERT specifier::
@section Old-style kind specifications
@cindex Kind specifications
-GNU Fortran allows old-style kind specifications in
-declarations. These look like:
+GNU Fortran allows old-style kind specifications in declarations. These
+look like:
@smallexample
- TYPESPEC*k x,y,z
+ TYPESPEC*size x,y,z
@end smallexample
-where @code{TYPESPEC} is a basic type, and where @code{k} is a valid kind
-number for that type. The statement then declares @code{x}, @code{y}
-and @code{z} to be of type @code{TYPESPEC} with kind @code{k}. In
-other words, it is equivalent to the standard conforming declaration
+where @code{TYPESPEC} is a basic type (@code{INTEGER}, @code{REAL},
+etc.), and where @code{size} is a byte count corresponding to a valid
+kind for that type. The statement then declares @code{x}, @code{y} and
+@code{z} to be of type @code{TYPESPEC} with the appropriate kind. This
+is equivalent to the standard conforming declaration
@smallexample
TYPESPEC(k) x,y,z
@end smallexample
+where @code{k} is equal to @code{size} for most types, but is equal to
+@code{size/2} for the @code{COMPLEX} type.
@node Old-style variable initialization
@section Old-style variable initialization
GNU Fortran allows old-style initialization of variables of the
form:
@smallexample
- INTEGER*4 i/1/,j/2/
- REAL*8 x(2,2) /3*0.,1./
+ INTEGER i/1/,j/2/
+ REAL x(2,2) /3*0.,1./
@end smallexample
-These are only allowed in declarations without double colons
-(@code{::}), as these were introduced in Fortran 90 which also
-introduced a new syntax for variable initializations. The syntax for
-the individual initializers is as for the @code{DATA} statement, but
+The syntax for the initializers is as for the @code{DATA} statement, but
unlike in a @code{DATA} statement, an initializer only applies to the
-variable immediately preceding. In other words, something like
-@code{INTEGER I,J/2,3/} is not valid.
-
-Examples of standard conforming code equivalent to the above example, are:
+variable immediately preceding the initialization. In other words,
+something like @code{INTEGER I,J/2,3/} is not valid. This style of
+initialization is only allowed in declarations without double colons
+(@code{::}); the double colons were introduced in Fortran 90, which also
+introduced a standard syntax for initializing variables in type
+declarations.
+
+Examples of standard-conforming code equivalent to the above example
+are:
@smallexample
! Fortran 90
- INTEGER(4) :: i = 1, j = 2
- REAL(8) :: x(2,2) = RESHAPE((/0.,0.,0.,1./),SHAPE(x))
+ INTEGER :: i = 1, j = 2
+ REAL :: x(2,2) = RESHAPE((/0.,0.,0.,1./),SHAPE(x))
! Fortran 77
- INTEGER i, j
- DOUBLE PRECISION x(2,2)
- DATA i,j,x /1,2,3*0.,1./
+ INTEGER i, j
+ REAL x(2,2)
+ DATA i/1/, j/2/, x/3*0.,1./
@end smallexample
-Note that variables initialized in type declarations
-automatically acquire the @code{SAVE} attribute.
+Note that variables which are explicitly initialized in declarations
+or in @code{DATA} statements automatically acquire the @code{SAVE}
+attribute.
@node Extensions to namelist
@section Extensions to namelist
output has all names in upper case and indentation to column 1 after the
namelist name. Two extensions are permitted:
-Old-style use of $ instead of &
+Old-style use of @samp{$} instead of @samp{&}
@smallexample
$MYNML
X(:)%Y(2) = 1.0 2.0 3.0
$END
@end smallexample
-It should be noticed that the default terminator is / rather than &END.
+It should be noted that the default terminator is @samp{/} rather than
+@samp{&END}.
Querying of the namelist when inputting from stdin. After at least
-one space, entering ? sends to stdout the namelist name and the names of
+one space, entering @samp{?} sends to stdout the namelist name and the names of
the variables in the namelist:
@smallexample
-?
+ ?
&mynml
x
&end
@end smallexample
-Entering =? outputs the namelist to stdout, as if WRITE (*,NML = mynml)
-had been called:
+Entering @samp{=?} outputs the namelist to stdout, as if
+@code{WRITE(*,NML = mynml)} had been called:
@smallexample
=?
@end smallexample
To aid this dialog, when input is from stdin, errors send their
-messages to stderr and execution continues, even if IOSTAT is set.
+messages to stderr and execution continues, even if @code{IOSTAT} is set.
-PRINT namelist is permitted. This causes an error if -std=f95 is used.
+@code{PRINT} namelist is permitted. This causes an error if
+@option{-std=f95} is used.
@smallexample
PROGRAM test_print
REAL, dimension (4) :: x = (/1.0, 2.0, 3.0, 4.0/)
END PROGRAM test_print
@end smallexample
-Expanded namelist reads are permitted. This causes an error if -std=f95
-is used. In the following example, the first element of the array will be
-given the value 0.00 and succeeding elements will be 1.00 and 2.00.
+Expanded namelist reads are permitted. This causes an error if
+@option{-std=f95} is used. In the following example, the first element
+of the array will be given the value 0.00 and the two succeeding
+elements will be given the values 1.00 and 2.00.
@smallexample
&MYNML
X(1,1) = 0.00 , 1.00 , 2.00
/
@end smallexample
-@node X format descriptor
-@section X format descriptor
-@cindex X format descriptor
+@node X format descriptor without count field
+@section @code{X} format descriptor without count field
+@cindex @code{X} format descriptor without count field
-To support legacy codes, GNU Fortran permits the count field
-of the X edit descriptor in FORMAT statements to be omitted. When
-omitted, the count is implicitly assumed to be one.
+To support legacy codes, GNU Fortran permits the count field of the
+@code{X} edit descriptor in @code{FORMAT} statements to be omitted.
+When omitted, the count is implicitly assumed to be one.
@smallexample
PRINT 10, 2, 3
@end smallexample
@node Commas in FORMAT specifications
-@section Commas in FORMAT specifications
-@cindex Commas in FORMAT specifications
+@section Commas in @code{FORMAT} specifications
+@cindex Commas in @code{FORMAT} specifications
To support legacy codes, GNU Fortran allows the comma separator
to be omitted immediately before and after character string edit
-descriptors in FORMAT statements.
+descriptors in @code{FORMAT} statements.
@smallexample
PRINT 10, 2, 3
@node Missing period in FORMAT specifications
-@section Missing period in FORMAT specifications
-@cindex Missing period in FORMAT specifications
+@section Missing period in @code{FORMAT} specifications
+@cindex Missing period in @code{FORMAT} specifications
To support legacy codes, GNU Fortran allows missing periods in format
-specifications if and only if -std=legacy is given on the command line. This
-is considered non-conforming code and is discouraged.
+specifications if and only if @option{-std=legacy} is given on the
+command line. This is considered non-conforming code and is
+discouraged.
@smallexample
REAL :: value
@cindex I/O item lists
To support legacy codes, GNU Fortran allows the input item list
-of the READ statement, and the output item lists of the WRITE and PRINT
-statements to start with a comma.
+of the @code{READ} statement, and the output item lists of the
+@code{WRITE} and @code{PRINT} statements, to start with a comma.
-@node Hexadecimal constants
-@section Hexadecimal constants
-@cindex Hexadecimal constants
+@node BOZ literal constants
+@section BOZ literal constants
+@cindex BOZ literal constants
-As an extension, GNU Fortran allows hexadecimal constants to
+As an extension, GNU Fortran allows hexadecimal BOZ literal constants to
be specified using the X prefix, in addition to the standard Z prefix.
-BOZ literal constants can also be specified by adding a suffix to the string.
-For example, @code{Z'ABC'} and @code{'ABC'Z} are the same constant.
-
-The Fortran standard restricts the appearance of a BOZ literal constant to
-the @code{DATA} statement, and it is expected to be assigned to an
-@code{INTEGER} variable. GNU Fortran permits a BOZ literal to appear
-in any initialization expression as well as assignment statements.
-
-Attempts to use a BOZ literal constant to do a bitwise initialization of a
-variable can lead to confusion. A BOZ literal constant is converted to an
-@code{INTEGER} value with the kind type with the largest decimal representation,
-and this value is then converted numerically to the type and kind of the
-variable in question. Thus, one should not expect a bitwise copy of the BOZ
-literal constant to be assigned to a @code{REAL} variable.
-
-Similarly, initializing an @code{INTEGER} variable with a statement such as
-@code{DATA i/Z'FFFFFFFF'/} will produce an integer overflow rather than the
-desired result of @math{-1} when @code{i} is a 32-bit integer on a system that
-supports 64-bit integers. The @samp{-fno-range-check} option can be used as
-a workaround for legacy code that initializes integers in this manner.
-
+BOZ literal constants can also be specified by adding a suffix to the
+string. For example, @code{Z'ABC'} and @code{'ABC'Z} are equivalent.
+
+The Fortran standard restricts the appearance of a BOZ literal constant
+to the @code{DATA} statement, and it is expected to be assigned to an
+@code{INTEGER} variable. GNU Fortran permits a BOZ literal to appear in
+any initialization expression as well as assignment statements.
+
+Attempts to use a BOZ literal constant to do a bitwise initialization of
+a variable can lead to confusion. A BOZ literal constant is converted
+to an @code{INTEGER} value with the kind type with the largest decimal
+representation, and this value is then converted numerically to the type
+and kind of the variable in question. Thus, one should not expect a
+bitwise copy of the BOZ literal constant to be assigned to a @code{REAL}
+variable.
+
+Similarly, initializing an @code{INTEGER} variable with a statement such
+as @code{DATA i/Z'FFFFFFFF'/} will produce an integer overflow rather
+than the desired result of @math{-1} when @code{i} is a 32-bit integer
+on a system that supports 64-bit integers. The @samp{-fno-range-check}
+option can be used as a workaround for legacy code that initializes
+integers in this manner.
@node Real array indices
@section Real array indices
@cindex Real array indices
-As an extension, GNU Fortran allows arrays to be indexed using
-real types, whose values are implicitly converted to integers.
+As an extension, GNU Fortran allows the use of @code{REAL} expressions
+or variables as array indices.
@node Unary operators
@section Unary operators
@cindex Unary operators
-As an extension, GNU Fortran allows unary plus and unary
-minus operators to appear as the second operand of binary arithmetic
-operators without the need for parenthesis.
+As an extension, GNU Fortran allows unary plus and unary minus operators
+to appear as the second operand of binary arithmetic operators without
+the need for parenthesis.
@smallexample
X = Y * -Z
@end smallexample
-@node Implicitly interconvert LOGICAL and INTEGER
-@section Implicitly interconvert LOGICAL and INTEGER
-@cindex Implicitly interconvert LOGICAL and INTEGER
+@node Implicitly convert LOGICAL and INTEGER values
+@section Implicitly convert @code{LOGICAL} and @code{INTEGER} values
+@cindex Implicitly convert @code{LOGICAL} and @code{INTEGER} values
-As an extension for backwards compatibility with other compilers,
-GNU Fortran allows the implicit conversion of LOGICALs to INTEGERs
-and vice versa. When converting from a LOGICAL to an INTEGER, the numeric
-value of @code{.FALSE.} is zero, and that of @code{.TRUE.} is one. When
-converting from INTEGER to LOGICAL, the value zero is interpreted as
+As an extension for backwards compatibility with other compilers, GNU
+Fortran allows the implicit conversion of @code{LOGICAL} values to
+@code{INTEGER} values and vice versa. When converting from a
+@code{LOGICAL} to an @code{INTEGER}, @code{.FALSE.} is interpreted as
+zero, and @code{.TRUE.} is interpreted as one. When converting from
+@code{INTEGER} to @code{LOGICAL}, the value zero is interpreted as
@code{.FALSE.} and any nonzero value is interpreted as @code{.TRUE.}.
@smallexample
- INTEGER*4 i
- i = .FALSE.
+ INTEGER :: i = 1
+ IF (i) PRINT *, 'True'
@end smallexample
@node Hollerith constants support
@section Hollerith constants support
@cindex Hollerith constants
-A Hollerith constant is a string of characters preceded by the letter @samp{H}
-or @samp{h}, and there must be an literal, unsigned, nonzero default integer
-constant indicating the number of characters in the string. Hollerith constants
-are stored as byte strings, one character per byte.
-
-GNU Fortran supports Hollerith constants. They can be used as the right
-hands in the @code{DATA} statement and @code{ASSIGN} statement, also as the
-arguments. The left hands can be of Integer, Real, Complex and Logical type.
-The constant will be padded or truncated to fit the size of left hand.
+GNU Fortran supports Hollerith constants in assignments, function
+arguments, and @code{DATA} and @code{ASSIGN} statements. A Hollerith
+constant is written as a string of characters preceded by an integer
+constant indicating the character count, and the letter @code{H} or
+@code{h}, and stored in bytewise fashion in a numeric (@code{INTEGER},
+@code{REAL}, or @code{complex}) or @code{LOGICAL} variable. The
+constant will be padded or truncated to fit the size of the variable in
+which it is stored.
-Valid Hollerith constants examples:
+Examples of valid uses of Hollerith constants:
@smallexample
-complex*16 x(2)
-data x /16Habcdefghijklmnop, 16Hqrstuvwxyz012345/
-call foo (4H abc)
-x(1) = 16Habcdefghijklmnop
+ complex*16 x(2)
+ data x /16Habcdefghijklmnop, 16Hqrstuvwxyz012345/
+ x(1) = 16HABCDEFGHIJKLMNOP
+ call foo (4h abc)
@end smallexample
Invalid Hollerith constants examples:
@smallexample
-integer*4 a
-a = 8H12345678 ! The Hollerith constant is too long. It will be truncated.
-a = 0H ! At least one character needed.
+ integer*4 a
+ a = 8H12345678 ! Valid, but the Hollerith constant will be truncated.
+ a = 0H ! At least one character is needed.
@end smallexample
+In general, Hollerith constants were used to provide a rudimentary
+facility for handling character strings in early Fortran compilers,
+prior to the introduction of @code{CHARACTER} variables in Fortran 77;
+in those cases, the standard-compliant equivalent is to convert the
+program to use proper character strings. On occasion, there may be a
+case where the intent is specifically to initialize a numeric variable
+with a given byte sequence. In these cases, the same result can be
+obtained by using the @code{TRANSFER} statement, as in this example.
+@smallexample
+ INTEGER(KIND=4) :: a
+ a = TRANSFER ("abcd", a) ! equivalent to: a = 4Habcd
+@end smallexample
+
+
@node Cray pointers
@section Cray pointers
@cindex Cray pointers
@end smallexample
The pointer is an integer that is intended to hold a memory address.
The pointee may be an array or scalar. A pointee can be an assumed
-size array -- that is, the last dimension may be left unspecified by
-using a '*' in place of a value -- but a pointee cannot be an assumed
-shape array. No space is allocated for the pointee.
+size array---that is, the last dimension may be left unspecified by
+using a @code{*} in place of a value---but a pointee cannot be an
+assumed shape array. No space is allocated for the pointee.
The pointee may have its type declared before or after the pointer
statement, and its array specification (if any) may be declared
ipt = loc (target)
ipt = ipt + 1
@end smallexample
-The last statement does not set ipt to the address of
-@code{target(1)}, as one familiar with C pointer arithmetic might
-expect. Adding 1 to ipt just adds one byte to the address stored in
-ipt.
+The last statement does not set @code{ipt} to the address of
+@code{target(1)}, as it would in C pointer arithmetic. Adding @code{1}
+to @code{ipt} just adds one byte to the address stored in @code{ipt}.
Any expression involving the pointee will be translated to use the
value stored in the pointer as the base address.
To get the address of elements, this extension provides an intrinsic
-function loc(), loc() is essentially the C '&' operator, except the
-address is cast to an integer type:
+function @code{LOC()}. The @code{LOC()} function is equivalent to the
+@code{&} operator in C, except the address is cast to an integer type:
@smallexample
real ar(10)
pointer(ipt, arpte(10))
pointer (ipt, iarr)
ipt = loc(target)
@end smallexample
-As long as ipt remains unchanged, iarr is now an alias for target.
-The optimizer, however, will not detect this aliasing, so it is unsafe
-to use iarr and target simultaneously. Using a pointee in any way
-that violates the Fortran aliasing rules or assumptions is illegal.
-It is the user's responsibility to avoid doing this; the compiler
-works under the assumption that no such aliasing occurs.
-
-Cray pointers will work correctly when there is no aliasing (i.e.,
-when they're used to access a dynamically allocated block of memory),
-and also in any routine where a pointee is used, but any variable with
-which it shares storage is not used. Code that violates these rules
-may not run as the user intends. This is not a bug in the optimizer;
-any code that violates the aliasing rules is illegal. (Note that this
-is not unique to GNU Fortran; any Fortran compiler that supports Cray
-pointers will ``incorrectly'' optimize code with illegal aliasing.)
-
-There are a number of restrictions on the attributes that can be
-applied to Cray pointers and pointees. Pointees may not have the
-attributes ALLOCATABLE, INTENT, OPTIONAL, DUMMY, TARGET,
-INTRINSIC, or POINTER. Pointers may not have the attributes
-DIMENSION, POINTER, TARGET, ALLOCATABLE, EXTERNAL, or INTRINSIC.
+As long as @code{ipt} remains unchanged, @code{iarr} is now an alias for
+@code{target}. The optimizer, however, will not detect this aliasing, so
+it is unsafe to use @code{iarr} and @code{target} simultaneously. Using
+a pointee in any way that violates the Fortran aliasing rules or
+assumptions is illegal. It is the user's responsibility to avoid doing
+this; the compiler works under the assumption that no such aliasing
+occurs.
+
+Cray pointers will work correctly when there is no aliasing (i.e., when
+they are used to access a dynamically allocated block of memory), and
+also in any routine where a pointee is used, but any variable with which
+it shares storage is not used. Code that violates these rules may not
+run as the user intends. This is not a bug in the optimizer; any code
+that violates the aliasing rules is illegal. (Note that this is not
+unique to GNU Fortran; any Fortran compiler that supports Cray pointers
+will ``incorrectly'' optimize code with illegal aliasing.)
+
+There are a number of restrictions on the attributes that can be applied
+to Cray pointers and pointees. Pointees may not have the
+@code{ALLOCATABLE}, @code{INTENT}, @code{OPTIONAL}, @code{DUMMY},
+@code{TARGET}, @code{INTRINSIC}, or @code{POINTER} attributes. Pointers
+may not have the @code{DIMENSION}, @code{POINTER}, @code{TARGET},
+@code{ALLOCATABLE}, @code{EXTERNAL}, or @code{INTRINSIC} attributes.
Pointees may not occur in more than one pointer statement. A pointee
cannot be a pointer. Pointees cannot occur in equivalence, common, or
data statements.
-A Cray pointer may point to a function or a subroutine. For example,
-the following excerpt is valid:
+A Cray pointer may also point to a function or a subroutine. For
+example, the following excerpt is valid:
@smallexample
implicit none
external sub
on IEEE systems of kinds 4 and 8. Conversion between different
``extended double'' types on different architectures such as
m68k and x86_64, which GNU Fortran
-supports as @code{REAL(KIND=10)}, will probably not work.
+supports as @code{REAL(KIND=10)} and @code{REAL(KIND=16)}, will
+probably not work.
@emph{Note that the values specified via the GFORTRAN_CONVERT_UNIT
environment variable will override the CONVERT specifier in the
open statement}. This is to give control over data formats to
-a user who does not have the source code of his program available.
+users who do not have the source code of their program available.
Using anything but the native representation for unformatted data
carries a significant speed overhead. If speed in this area matters
@cindex OpenMP
GNU Fortran attempts to be OpenMP Application Program Interface v2.5
-compatible when invoked with the @code{-fopenmp} option. GNU Fortran
+compatible when invoked with the @option{-fopenmp} option. GNU Fortran
then generates parallelized code according to the OpenMP directives
used in the source. The OpenMP Fortran runtime library
-routines are provided both in a form of Fortran 90 module named
+routines are provided both in a form of a Fortran 90 module named
@code{omp_lib} and in a form of a Fortran @code{include} file named
-@code{omp_lib.h}.
+@file{omp_lib.h}.
For details refer to the actual
@uref{http://www.openmp.org/drupal/mp-documents/spec25.pdf,
OpenMP Application Program Interface v2.5} specification.
@c ---------------------------------------------------------------------
-@include intrinsic.texi
+@c Intrinsic Procedures
@c ---------------------------------------------------------------------
+@include intrinsic.texi
+
+
+@tex
+\blankpart
+@end tex
+
@c ---------------------------------------------------------------------
@c Contributing
@c ---------------------------------------------------------------------
@node Contributing
-@chapter Contributing
+@unnumbered Contributing
@cindex Contributing
Free software is only possible if people contribute to efforts
@menu
* Contributors::
* Projects::
+* Proposed Extensions::
@end menu
@c TODO: email!
-@c ---------------------------------------------------------------------
-@c Standards
-@c ---------------------------------------------------------------------
+@node Proposed Extensions
+@section Proposed Extensions
-@node Standards
-@chapter Standards
-@cindex Standards
+Here's a list of proposed extensions for the GNU Fortran compiler, in no particular
+order. Most of these are necessary to be fully compatible with
+existing Fortran compilers, but they are not part of the official
+J3 Fortran 95 standard.
-The GNU Fortran compiler aims to be a conforming implementation of
-ISO/IEC 1539:1997 (Fortran 95).
+@subsection Compiler extensions:
+@itemize @bullet
+@item
+User-specified alignment rules for structures.
-In the future it may also support other variants of and extensions to
-the Fortran language. These include ANSI Fortran 77, ISO Fortran 90,
-ISO Fortran 2003 and OpenMP.
+@item
+Flag to generate @code{Makefile} info.
-@menu
-* Fortran 2003 status::
-@end menu
+@item
+Automatically extend single precision constants to double.
-@node Fortran 2003 status
-@section Fortran 2003 status
+@item
+Compile code that conserves memory by dynamically allocating common and
+module storage either on stack or heap.
-Although GNU Fortran focuses on implementing the Fortran 95
-standard for the time being, a few Fortran 2003 features are currently
-available.
+@item
+Compile flag to generate code for array conformance checking (suggest -CC).
-@itemize
-@item
-Intrinsics @code{command_argument_count}, @code{get_command},
-@code{get_command_argument}, @code{get_environment_variable}, and
-@code{move_alloc}.
+@item
+User control of symbol names (underscores, etc).
-@item
-@cindex Array constructors
-@cindex @code{[...]}
-Array constructors using square brackets. That is, @code{[...]} rather
-than @code{(/.../)}.
+@item
+Compile setting for maximum size of stack frame size before spilling
+parts to static or heap.
@item
-@cindex @code{FLUSH} statement
-@code{FLUSH} statement.
+Flag to force local variables into static space.
@item
-@cindex @code{IOMSG=} specifier
-@code{IOMSG=} specifier for I/O statements.
+Flag to force local variables onto stack.
@item
-@cindex @code{ENUM} statement
-@cindex @code{ENUMERATOR} statement
-@cindex @command{-fshort-enums}
-Support for the declaration of enumeration constants via the
-@code{ENUM} and @code{ENUMERATOR} statements. Interoperability with
-@command{gcc} is guaranteed also for the case where the
-@command{-fshort-enums} command line option is given.
+Flag for maximum errors before ending compile.
@item
-@cindex TR 15581
-TR 15581:
-@itemize
+Option to initialize otherwise uninitialized integer and floating
+point variables.
+@end itemize
+
+
+@subsection Environment Options
+@itemize @bullet
@item
-@cindex @code{ALLOCATABLE} dummy arguments
-@code{ALLOCATABLE} dummy arguments.
+Pluggable library modules for random numbers, linear algebra.
+LA should use BLAS calling conventions.
+
@item
-@cindex @code{ALLOCATABLE} function results
-@code{ALLOCATABLE} function results
+Environment variables controlling actions on arithmetic exceptions like
+overflow, underflow, precision loss---Generate NaN, abort, default.
+action.
+
@item
-@cindex @code{ALLOCATABLE} components of derived types
-@code{ALLOCATABLE} components of derived types
-@end itemize
+Set precision for fp units that support it (i387).
@item
-@cindex @code{STREAM} I/O
-@cindex @code{ACCESS='STREAM'} I/O
-The @code{OPEN} statement supports the @code{ACCESS='STREAM'} specifier,
-allowing I/O without any record structure.
+Variable for setting fp rounding mode.
+
+@item
+Variable to fill uninitialized variables with a user-defined bit
+pattern.
+@item
+Environment variable controlling filename that is opened for that unit
+number.
+@item
+Environment variable to clear/trash memory being freed.
+
+@item
+Environment variable to control tracing of allocations and frees.
+
+@item
+Environment variable to display allocated memory at normal program end.
+
+@item
+Environment variable for filename for * IO-unit.
+
+@item
+Environment variable for temporary file directory.
+
+@item
+Environment variable forcing standard output to be line buffered (unix).
@end itemize
OSDN Git Service
