\input texinfo @c -*-texinfo-*-
@c %**start of header
@setfilename gfortran.info
-@set copyrights-gfortran 1999-2005
+@set copyrights-gfortran 1999-2008
@include gcc-common.texi
-@settitle The GNU Fortran 95 Compiler
+@settitle The GNU Fortran Compiler
@c Create a separate index for command line options
@defcodeindex op
@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.
@end copying
@ifinfo
-@dircategory Programming
+@dircategory Software development
@direntry
-* gfortran: (gfortran). The GNU Fortran 95 Compiler.
+* gfortran: (gfortran). The GNU Fortran Compiler.
@end direntry
This file documents the use and the internals of
-the GNU Fortran 95 compiler, (@command{gfortran}).
+the GNU Fortran compiler, (@command{gfortran}).
Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
+51 Franklin Street, Fifth Floor
+Boston, MA 02110-1301 USA
@insertcopying
@end ifinfo
-Contributed by Steven Bosscher (@email{s.bosscher@@gcc.gnu.org}).
@setchapternewpage odd
@titlepage
-@title Using GNU Fortran 95
-@sp 2
-@center Steven Bosscher
+@title Using GNU Fortran
+@versionsubtitle
+@author The @t{gfortran} team
@page
@vskip 0pt plus 1filll
-For the @value{version-GCC} Version*
-@sp 1
-Published by the Free Software Foundation @*
-59 Temple Place - Suite 330@*
-Boston, MA 02111-1307, USA@*
+Published by the Free Software Foundation@*
+51 Franklin Street, Fifth Floor@*
+Boston, MA 02110-1301, USA@*
@c Last printed ??ber, 19??.@*
@c Printed copies are available for $? each.@*
@c ISBN ???
@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
-@node Top, Copying,, (DIR)
+@c ---------------------------------------------------------------------
+@c TexInfo table of contents.
+@c ---------------------------------------------------------------------
+
+@ifnottex
+@node Top
@top Introduction
@cindex Introduction
This manual documents the use of @command{gfortran},
-the GNU Fortran 95 compiler. You can find in this manual how to invoke
+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 @command{gfortran}.
+not accurately reflect the status of the most recent GNU Fortran compiler.
@end ifset
@comment
@comment better formatting.
@comment
@menu
+* Introduction::
+
+Part I: Invoking GNU Fortran
+* Invoking GNU Fortran:: Command options supported by @command{gfortran}.
+* Runtime:: Influencing runtime behavior with environment variables.
+
+Part II: Language Reference
+* Fortran 2003 and 2008 status:: Fortran 2003 and 2008 features supported by GNU Fortran.
+* Extensions:: Language extensions implemented by GNU Fortran.
+* Intrinsic Procedures:: Intrinsic procedures supported by GNU Fortran.
+* Intrinsic Modules:: Intrinsic modules 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::
How you can copy and share this manual.
* Funding:: How to help assure continued work for free software.
-* Getting Started:: What you should know about @command{gfortran}.
-* GFORTRAN and GCC:: You can compile Fortran, C, or other programs.
-* GFORTRAN and G77:: Why we chose to start from scratch.
-* Invoking GFORTRAN:: Command options supported by @command{gfortran}.
-* Project Status:: Status of @command{gfortran}, roadmap, proposed extensions.
-* Contributing:: How you can help.
-* Standards:: Standards supported by @command{gfortran}
-* Extensions:: Language extensions implemented by @command{gfortran}
-* Intrinsic Procedures:: Intrinsic procedures supported by @command{gfortran}
-* Index:: Index of this documentation.
+* Option Index:: Index of command line options
+* Keyword Index:: Index of concepts
@end menu
-
-
-
-@c ---------------------------------------------------------------------
-@c GNU General Public License
-@c ---------------------------------------------------------------------
-
-@include gpl.texi
-
-
+@end ifnottex
@c ---------------------------------------------------------------------
-@c GNU Free Documentation License
+@c Introduction
@c ---------------------------------------------------------------------
-@include fdl.texi
-
+@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.
-@c ---------------------------------------------------------------------
-@c Funding Free Software
-@c ---------------------------------------------------------------------
+@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
-@include funding.texi
+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.
+* Preprocessing and conditional compilation:: The Fortran preprocessor
+* 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 Getting Started
+@c About GNU Fortran
@c ---------------------------------------------------------------------
-@node Getting Started
-@chapter Getting Started
+@node About GNU Fortran
+@section About GNU Fortran
-Gfortran is the GNU Fortran 95 compiler front end,
-designed initially as a free replacement for,
-or alternative to, the unix @command{f95} command;
-@command{gfortran} is command you'll use to invoke the compiler.
-
-Gfortran is still in an early state of development.
-@command{gfortran} can generate code for most constructs and expressions,
+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.
-When @command{gfortran} is finished,
+When the GNU Fortran compiler is finished,
it will do everything you expect from any decent compiler:
@itemize @bullet
@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, Fortran 2003 or Fortran 2008.
This file contains @dfn{source code}.
@item
and @dfn{linked} to the user program.
@end itemize
-Gfortran consists of several components:
+The GNU Fortran compiler consists of several components:
@itemize @bullet
@item
The @command{gcc} command is the @dfn{driver} program for
all the languages in the GNU Compiler Collection (GCC);
With @command{gcc},
-you can compiler the source code of any language for
+you can compile the source code of any language for
which a front end is available in GCC.
@item
which also might be installed as the
system's @command{f95} command.
@command{gfortran} is just another driver program,
-but specifically for the Fortran 95 compiler only.
+but specifically for the Fortran compiler only.
The difference with @command{gcc} is that @command{gfortran}
will automatically link the correct libraries to your program.
@item
A collection of run-time libraries.
-These libraries contains the machine code needed to support
+These libraries contain the machine code needed to support
capabilities of the Fortran language that are not directly
provided by the machine code generated by the
@command{gfortran} compilation phase,
@item
The Fortran compiler itself, (@command{f951}).
-This is the gfortran parser and code generator,
+This is the GNU Fortran parser and code generator,
linked to and interfaced with the GCC backend library.
@command{f951} ``translates'' the source code to
assembler code. You would typically not use this
@end itemize
-
@c ---------------------------------------------------------------------
-@c GFORTRAN and GCC
+@c GNU Fortran and GCC
@c ---------------------------------------------------------------------
-@node GFORTRAN and GCC
-@chapter GFORTRAN and GCC
+@node GNU Fortran and GCC
+@section GNU Fortran and GCC
@cindex GNU Compiler Collection
+@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{.for}, @file{.ftn},
+@file{.f90}, @file{.f95}, @file{.f03} and @file{.f08} 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.
+
+Source files with @file{.f}, @file{.for}, @file{.fpp}, @file{.ftn}, @file{.F},
+@file{.FOR}, @file{.FPP}, and @file{.FTN} extensions are treated as fixed form.
+Source files with @file{.f90}, @file{.f95}, @file{.f03}, @file{.f08},
+@file{.F90}, @file{.F95}, @file{.F03} and @file{.F08} extensions are
+treated as free form. The capitalized versions of either form are run
+through preprocessing. Source files with the lower case @file{.fpp}
+extension are also run through preprocessing.
+
+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 Preprocessing and conditional compilation
+@c ---------------------------------------------------------------------
+
+@node Preprocessing and conditional compilation
+@section Preprocessing and conditional compilation
+@cindex CPP
+@cindex FPP
+@cindex Conditional compilation
+@cindex Preprocessing
+
+Many Fortran compilers including GNU Fortran allow passing the source code
+through a C preprocessor (CPP; sometimes also called the Fortran preprocessor,
+FPP) to allow for conditional compilation. In the case of GNU Fortran,
+this is the GNU C Preprocessor in the traditional mode. On systems with
+case-preserving file names, the preprocessor is automatically invoked if the
+file extension is @code{.F}, @code{.FOR}, @code{.FTN}, @code{.F90},
+@code{.F95}, @code{.F03} or @code{.F08}; otherwise use for fixed-format
+code the option @code{-x f77-cpp-input} and for free-format code @code{-x
+f95-cpp-input}. Invocation of the preprocessor can be suppressed using
+@code{-x f77} or @code{-x f95}.
+
+If the GNU Fortran invoked the preprocessor, @code{__GFORTRAN__}
+is defined and @code{__GNUC__}, @code{__GNUC_MINOR__} and
+@code{__GNUC_PATCHLEVEL__} can be used to determine the version of the
+compiler. See @ref{Top,,Overview,cpp,The C Preprocessor} for details.
+
+While CPP is the de-facto standard for preprocessing Fortran code,
+Part 3 of the Fortran 95 standard (ISO/IEC 1539-3:1998) defines
+Conditional Compilation, which is not widely used and not directly
+supported by the GNU Fortran compiler. You can use the program coco
+to preprocess such files (@uref{http://users.erols.com/dnagle/coco.html}).
+
+
+@c ---------------------------------------------------------------------
+@c GNU Fortran and G77
+@c ---------------------------------------------------------------------
-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 with 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 a pass to generate a representation of the semantics
-of the program in the source code in the GCC language
-independent intermediate language,
-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,
-pass the optimized AST and generate assembly
-for the program unit.
-
-Different phases in this translation process can be,
-and in fact @emph{are} merged in many compiler front ends.
-GNU Fortran 95 has a strict separation between the
-parser and code generator.
-
-The goal of the gfortran project is to build a new front end for GCC:
-A Fortran 95 front end.
-In a non-gfortran installation,
-@command{gcc} will not be able to compile Fortran 95 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 gfortran, @command{gcc} will recognize
-@file{.f/.f90/.f95} source files and accepts Fortran 95 specific
-command line options.
-
-
-
-@c ---------------------------------------------------------------------
-@c GFORTRAN and G77
-@c ---------------------------------------------------------------------
-
-@node GFORTRAN and G77
-@chapter GFORTRAN and G77
+@node GNU Fortran and G77
+@section GNU Fortran and G77
@cindex Fortran 77
-@cindex G77
-
-Why do we write a compiler front end from scratch?
-There's a fine Fortran 77 compiler in the
-GNU Compiler Collection that accepts some features
-of the Fortran 90 standard as extensions.
-Why not start from there and revamp it?
-
-One of the reasons is that Craig Burley, the author of G77,
-has decided to stop working on the G77 front end.
-On @uref{http://world.std.com/~burley/g77-why.html,
-Craig explains the reasons for his decision to stop working on G77}
-in one of the pages in his homepage.
-Among the reasons is a lack of interest in improvements to
-@command{g77}.
-Users appear to be quite satisfied with @command{g77} as it is.
-While @command{g77} is still being maintained (by Toon Moene),
-it is unlikely that sufficient people will be willing
-to completely rewrite the existing code.
-
-But there are other reasons to start from scratch.
-Many people, including Craig Burley,
-no longer agreed with certain design decisions in the G77 front end.
-Also, the interface of @command{g77} to the back end is written in
-a style which is confusing and not up to date on recommended practice.
-In fact, a full rewrite had already been planned for GCC 3.0.
-
-When Craig decided to stop,
-it just seemed to be a better idea to start a new project from scratch,
-because it was expected to be easier to maintain code we
-develop ourselves than to do a major overhaul of @command{g77} first,
-and then build a Fortran 95 compiler out of it.
+@cindex @command{g77}
+
+The GNU Fortran compiler is the successor to @command{g77}, the Fortran
+77 front end included in GCC prior to version 4. It is an entirely new
+program that has been designed to provide Fortran 95 support and
+extensibility for future Fortran language standards, as well as providing
+backwards compatibility for Fortran 77 and nearly all of the GNU language
+extensions supported by @command{g77}.
-@include invoke.texi
@c ---------------------------------------------------------------------
@c Project Status
@c ---------------------------------------------------------------------
@node Project Status
-@chapter Project Status
+@section Project Status
@quotation
-As soon as gfortran can parse all of the statements correctly,
+As soon as @command{gfortran} can parse all of the statements correctly,
it will be in the ``larva'' state.
When we generate code, the ``puppa'' state.
-When gfortran is done,
+When @command{gfortran} is done,
we'll see if it will be a beautiful butterfly,
or just a big bug....
The start of the GNU Fortran 95 project was announced on
the GCC homepage in March 18, 2000
(even though Andy had already been working on it for a while,
-or course).
+of course).
+
+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
+used on real-world programs. In particular, the supported extensions
+include OpenMP, Cray-style pointers, and several Fortran 2003 and Fortran
+2008 features such as enumeration, stream I/O, and some of the
+enhancements to allocatable array support from TR 15581. However, it is
+still under development and has a few remaining rough edges.
+
+At present, the GNU Fortran compiler passes the
+@uref{http://www.fortran-2000.com/ArnaudRecipes/fcvs21_f95.html,
+NIST Fortran 77 Test Suite}, and produces acceptable results on the
+@uref{http://www.netlib.org/lapack/faq.html#1.21, LAPACK Test Suite}.
+It also provides respectable performance on
+the @uref{http://www.polyhedron.com/pb05.html, Polyhedron Fortran
+compiler benchmarks} and the
+@uref{http://www.llnl.gov/asci_benchmarks/asci/limited/lfk/README.html,
+Livermore Fortran Kernels test}. It has been used to compile a number of
+large real-world programs, including
+@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}; 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
+G77 can be compiled with GNU Fortran, although there are a few minor known
+regressions.
+
+The primary work remaining to be done on GNU Fortran falls into three
+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.
+
+
+@c ---------------------------------------------------------------------
+@c Standards
+@c ---------------------------------------------------------------------
+
+@node Standards
+@section Standards
+@cindex Standards
+
+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.
+
+In the future, the GNU Fortran compiler will also support ISO/IEC
+1539-1:2004 (Fortran 2003) and future Fortran standards. Partial support
+of that standard is already provided; the current status of Fortran 2003
+support is reported in the @ref{Fortran 2003 status} section of the
+documentation.
+
+The next version of the Fortran standard after Fortran 2003 is currently
+being developped and the GNU Fortran compiler supports some of its new
+features. This support is based on the latest draft of the standard
+(available from @url{http://www.nag.co.uk/sc22wg5/}) and no guarantee of
+future compatibility is made, as the final standard might differ from the
+draft. For more information, see the @ref{Fortran 2008 status} section.
+
+
+@c =====================================================================
+@c PART I: INVOCATION REFERENCE
+@c =====================================================================
+
+@tex
+\part{I}{Invoking GNU Fortran}
+@end tex
+
+@c ---------------------------------------------------------------------
+@c Compiler Options
+@c ---------------------------------------------------------------------
+
+@include invoke.texi
+
+
+@c ---------------------------------------------------------------------
+@c Runtime
+@c ---------------------------------------------------------------------
-Gfortran is currently reaching the stage where is is able to compile real
-world programs. However it is still under development and has many rough
-edges.
+@node Runtime
+@chapter Runtime: Influencing runtime behavior with environment variables
+@cindex environment variable
+
+The behavior of the @command{gfortran} can be influenced by
+environment variables.
+
+Malformed environment variables are silently ignored.
@menu
-* Compiler Status::
-* Library Status::
-* Proposed Extensions::
+* GFORTRAN_STDIN_UNIT:: Unit number for standard input
+* GFORTRAN_STDOUT_UNIT:: Unit number for standard output
+* GFORTRAN_STDERR_UNIT:: Unit number for standard error
+* GFORTRAN_USE_STDERR:: Send library output to standard error
+* GFORTRAN_TMPDIR:: Directory for scratch files
+* GFORTRAN_UNBUFFERED_ALL:: Don't buffer I/O for all units.
+* GFORTRAN_UNBUFFERED_PRECONNECTED:: Don't buffer I/O for preconnected units.
+* GFORTRAN_SHOW_LOCUS:: Show location for runtime errors
+* GFORTRAN_OPTIONAL_PLUS:: Print leading + where permitted
+* GFORTRAN_DEFAULT_RECL:: Default record length for new files
+* GFORTRAN_LIST_SEPARATOR:: Separator for list output
+* GFORTRAN_CONVERT_UNIT:: Set endianness for unformatted I/O
+* GFORTRAN_ERROR_DUMPCORE:: Dump core on run-time errors
+* GFORTRAN_ERROR_BACKTRACE:: Show backtrace on run-time errors
@end menu
-@node Compiler Status
-@section Compiler Status
+@node GFORTRAN_STDIN_UNIT
+@section @env{GFORTRAN_STDIN_UNIT}---Unit number for standard input
-@table @emph
-@item Front end
-This is the part of gfortran which parses a source file, verifies that it
-is valid Fortran 95, performs compile time replacement of constants
-(PARAMETER variables) and reads and generate module files. This is
-almost complete. Every Fortran 95 source should be accepted, and most
-none-Fortran 95 source should be rejected. If you find a source file where
-this is not true, please tell us. You can use the -fsyntax-only switch to
-make gfortran quit after running the front end, effectively reducing it to
-a syntax checker.
-
-@item Middle end interface
-These are the parts of gfortran that take the parse tree generated by the
-front end and translate it to the GENERIC form required by the GCC back
-end. Work is ongoing in these parts of gfortran, but a large part has
-already been completed.
-@end table
+This environment variable can be used to select the unit number
+preconnected to standard input. This must be a positive integer.
+The default value is 5.
-@node Library Status
-@section Library Status
+@node GFORTRAN_STDOUT_UNIT
+@section @env{GFORTRAN_STDOUT_UNIT}---Unit number for standard output
-Some intrinsic functions map directly to library functions, and in most
-cases the name of the library function used depends on the type of the
-arguments. For some intrinsics we generate inline code, and for others,
-such as sin, cos and sqrt, we rely on the backend to use special
-instructions in the floating point unit of the CPU if available, or to
-fall back to a call to libm if these are not available.
+This environment variable can be used to select the unit number
+preconnected to standard output. This must be a positive integer.
+The default value is 6.
-Implementation of some non-elemental intrinsic functions (eg. DOT_PRODUCT,
-AVERAGE) is not yet optimal. This is hard because we have to make decisions
-whether to use inline code (good for small arrays as no function call
-overhead occurs) or generate function calls (good for large arrays as it
-allows use of hand-optimized assembly routines, SIMD instructions, etc.)
+@node GFORTRAN_STDERR_UNIT
+@section @env{GFORTRAN_STDERR_UNIT}---Unit number for standard error
-The IO library is still under development. The following features should be
-usable for real programs:
+This environment variable can be used to select the unit number
+preconnected to standard error. This must be a positive integer.
+The default value is 0.
-@itemize @minus
-@item List directed
-@item Unformatted sequential
-@end itemize
+@node GFORTRAN_USE_STDERR
+@section @env{GFORTRAN_USE_STDERR}---Send library output to standard error
-Usable with bugs:
+This environment variable controls where library output is sent.
+If the first letter is @samp{y}, @samp{Y} or @samp{1}, standard
+error is used. If the first letter is @samp{n}, @samp{N} or
+@samp{0}, standard output is used.
-@itemize @minus
-@item Formatted sequential ('T' edit descriptor, and others)
-@end itemize
+@node GFORTRAN_TMPDIR
+@section @env{GFORTRAN_TMPDIR}---Directory for scratch files
-Not recommended:
+This environment variable controls where scratch files are
+created. If this environment variable is missing,
+GNU Fortran searches for the environment variable @env{TMP}. If
+this is also missing, the default is @file{/tmp}.
-@itemize @minus
-@item Unformatted direct access
-@item Formatted direct access
-@end itemize
+@node GFORTRAN_UNBUFFERED_ALL
+@section @env{GFORTRAN_UNBUFFERED_ALL}---Don't buffer I/O on all units
-Many Fortran programs only use a small subset of the available IO
-capabilities, so your mileage may vary.
+This environment variable controls whether all I/O is unbuffered. If
+the first letter is @samp{y}, @samp{Y} or @samp{1}, all I/O is
+unbuffered. This will slow down small sequential reads and writes. If
+the first letter is @samp{n}, @samp{N} or @samp{0}, I/O is buffered.
+This is the default.
-@node Proposed Extensions
-@section Proposed Extensions
+@node GFORTRAN_UNBUFFERED_PRECONNECTED
+@section @env{GFORTRAN_UNBUFFERED_PRECONNECTED}---Don't buffer I/O on preconnected units
-Here's a list of proposed extensions for @command{gfortran}, 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 environment variable named @env{GFORTRAN_UNBUFFERED_PRECONNECTED} controls
+whether I/O on a preconnected unit (i.e.@: STDOUT or STDERR) is unbuffered. If
+the first letter is @samp{y}, @samp{Y} or @samp{1}, I/O is unbuffered. This
+will slow down small sequential reads and writes. If the first letter
+is @samp{n}, @samp{N} or @samp{0}, I/O is buffered. This is the default.
-@subsection Compiler extensions:
-@itemize @bullet
-@item
-Flag for defining the kind number for default logicals.
+@node GFORTRAN_SHOW_LOCUS
+@section @env{GFORTRAN_SHOW_LOCUS}---Show location for runtime errors
-@item
-User-specified alignment rules for structures.
-@item
-Flag to generate a @code{Makefile} info.
+If the first letter is @samp{y}, @samp{Y} or @samp{1}, filename and
+line numbers for runtime errors are printed. If the first letter is
+@samp{n}, @samp{N} or @samp{0}, don't print filename and line numbers
+for runtime errors. The default is to print the location.
-@item
-Automatically extend single precision constants to double.
+@node GFORTRAN_OPTIONAL_PLUS
+@section @env{GFORTRAN_OPTIONAL_PLUS}---Print leading + where permitted
-@item
-Cray pointers (this was high on the @command{g77} wishlist).
+If the first letter is @samp{y}, @samp{Y} or @samp{1},
+a plus sign is printed
+where permitted by the Fortran standard. If the first letter
+is @samp{n}, @samp{N} or @samp{0}, a plus sign is not printed
+in most cases. Default is not to print plus signs.
-@item
-Compile code that conserves memory by dynamically allocating common and
-module storage either on stack or heap.
+@node GFORTRAN_DEFAULT_RECL
+@section @env{GFORTRAN_DEFAULT_RECL}---Default record length for new files
-@item
-Flag to cause the compiler to distinguish between upper and lower case
-names. The Fortran 95 standard does not distinguish them.
+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).
-@item
-Compile switch for changing the interpretation of a backslash from a
-character to ``C''-style escape characters.
+@node GFORTRAN_LIST_SEPARATOR
+@section @env{GFORTRAN_LIST_SEPARATOR}---Separator for list output
-@item
-Compile flag to generate code for array conformance checking (suggest -CC).
+This environment variable specifies the separator when writing
+list-directed output. It may contain any number of spaces and
+at most one comma. If you specify this on the command line,
+be sure to quote spaces, as in
+@smallexample
+$ GFORTRAN_LIST_SEPARATOR=' , ' ./a.out
+@end smallexample
+when @command{a.out} is the compiled Fortran program that you want to run.
+Default is a single space.
-@item
-User control of symbol names (underscores, etc).
+@node GFORTRAN_CONVERT_UNIT
+@section @env{GFORTRAN_CONVERT_UNIT}---Set endianness for unformatted I/O
-@item
-Compile setting for maximum size of stack frame size before spilling
-parts to static or heap.
+By setting the @env{GFORTRAN_CONVERT_UNIT} variable, it is possible
+to change the representation of data for unformatted files.
+The syntax for the @env{GFORTRAN_CONVERT_UNIT} variable is:
+@smallexample
+GFORTRAN_CONVERT_UNIT: mode | mode ';' exception | exception ;
+mode: 'native' | 'swap' | 'big_endian' | 'little_endian' ;
+exception: mode ':' unit_list | unit_list ;
+unit_list: unit_spec | unit_list unit_spec ;
+unit_spec: INTEGER | INTEGER '-' INTEGER ;
+@end smallexample
+The variable consists of an optional default mode, followed by
+a list of optional exceptions, which are separated by semicolons
+from the preceding default and each other. Each exception consists
+of a format and a comma-separated list of units. Valid values for
+the modes are the same as for the @code{CONVERT} specifier:
+
+@itemize @w{}
+@item @code{NATIVE} Use the native format. This is the default.
+@item @code{SWAP} Swap between little- and big-endian.
+@item @code{LITTLE_ENDIAN} Use the little-endian format
+ for unformatted files.
+@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 @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
+in little_endian mode, except for units 10 to 20 and 25, which are in
+native format.
+@item @code{'10-20'} Units 10 to 20 are big-endian, the rest is native.
+@end itemize
-@item
-Flag to force local variables into static space.
+Setting the environment variables should be done on the command
+line or via the @command{export}
+command for @command{sh}-compatible shells and via @command{setenv}
+for @command{csh}-compatible shells.
-@item
-Flag to force local variables onto stack.
+Example for @command{sh}:
+@smallexample
+$ gfortran foo.f90
+$ GFORTRAN_CONVERT_UNIT='big_endian;native:10-20' ./a.out
+@end smallexample
-@item
-Flag to compile lines beginning with ``D''.
+Example code for @command{csh}:
+@smallexample
+% gfortran foo.f90
+% setenv GFORTRAN_CONVERT_UNIT 'big_endian;native:10-20'
+% ./a.out
+@end smallexample
-@item
-Flag to ignore lines beginning with ``D''.
+Using anything but the native representation for unformatted data
+carries a significant speed overhead. If speed in this area matters
+to you, it is best if you use this only for data that needs to be
+portable.
+
+@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 @option{-fconvert} compile options.
+
+@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
+users who do not have the source code of their program available.
+
+@node GFORTRAN_ERROR_DUMPCORE
+@section @env{GFORTRAN_ERROR_DUMPCORE}---Dump core on run-time errors
+
+If the @env{GFORTRAN_ERROR_DUMPCORE} variable is set to
+@samp{y}, @samp{Y} or @samp{1} (only the first letter is relevant)
+then library run-time errors cause core dumps. To disable the core
+dumps, set the variable to @samp{n}, @samp{N}, @samp{0}. Default
+is not to core dump unless the @option{-fdump-core} compile option
+was used.
+
+@node GFORTRAN_ERROR_BACKTRACE
+@section @env{GFORTRAN_ERROR_BACKTRACE}---Show backtrace on run-time errors
+
+If the @env{GFORTRAN_ERROR_BACKTRACE} variable is set to
+@samp{y}, @samp{Y} or @samp{1} (only the first letter is relevant)
+then a backtrace is printed when a run-time error occurs.
+To disable the backtracing, set the variable to
+@samp{n}, @samp{N}, @samp{0}. Default is not to print a backtrace
+unless the @option{-fbacktrace} compile option
+was used.
+
+@c =====================================================================
+@c PART II: LANGUAGE REFERENCE
+@c =====================================================================
+
+@tex
+\part{II}{Language Reference}
+@end tex
-@item
-Flag for maximum errors before ending compile.
+@c ---------------------------------------------------------------------
+@c Fortran 2003 and 2008 Status
+@c ---------------------------------------------------------------------
-@item
-Generate code to check for null pointer dereferences -- prints locus of
-dereference instead of segfaulting. There was some discussion about this
-option in the g95 development mailing list.
+@node Fortran 2003 and 2008 status
+@chapter Fortran 2003 and 2008 Status
-@item
-Allow setting default unit number.
+@menu
+* Fortran 2003 status::
+* Fortran 2008 status::
+@end menu
-@item
-Option to initialize of otherwise uninitialized integer and floating
-point variables.
+@node Fortran 2003 status
+@section Fortran 2003 status
-@item
-Support for OpenMP directives. This also requires support from the runtime
-library and the rest of the compiler.
+Although GNU Fortran focuses on implementing the Fortran 95
+standard for the time being, a few Fortran 2003 features are currently
+available.
-@item
-Support for Fortran 200x. This includes several new features including
-floating point exceptions, extended use of allocatable arrays, C
-interoperability, Parameterizer data types and function pointers.
-@end itemize
+@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{(/.../)}.
-@subsection Environment Options
-@itemize @bullet
@item
-Pluggable library modules for random numbers, linear algebra.
-LA should use BLAS calling conventions.
+@cindex @code{FLUSH} statement
+@cindex statement, @code{FLUSH}
+@code{FLUSH} statement.
@item
-Environment variables controlling actions on arithmetic exceptions like
-overflow, underflow, precision loss -- Generate NaN, abort, default.
-action.
+@cindex @code{IOMSG=} specifier
+@code{IOMSG=} specifier for I/O statements.
@item
-Set precision for fp units that support it (i387).
+@cindex @code{ENUM} statement
+@cindex @code{ENUMERATOR} statement
+@cindex statement, @code{ENUM}
+@cindex statement, @code{ENUMERATOR}
+@opindex @code{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.
@item
-Variables for setting fp rounding mode.
+@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
-Variable to fill uninitialized variables with a user-defined bit
-pattern.
+@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
-Environment variable controlling filename that is opened for that unit
-number.
+Namelist input/output for internal files.
@item
-Environment variable to clear/trash memory being freed.
+@cindex @code{PROTECTED} statement
+@cindex statement, @code{PROTECTED}
+The @code{PROTECTED} statement and attribute.
@item
-Environment variable to control tracing of allocations and frees.
+@cindex @code{VALUE} statement
+@cindex statement, @code{VALUE}
+The @code{VALUE} statement and attribute.
@item
-Environment variable to display allocated memory at normal program end.
+@cindex @code{VOLATILE} statement
+@cindex statement, @code{VOLATILE}
+The @code{VOLATILE} statement and attribute.
@item
-Environment variable for filename for * IO-unit.
+@cindex @code{IMPORT} statement
+@cindex statement, @code{IMPORT}
+The @code{IMPORT} statement, allowing to import
+host-associated derived types.
@item
-Environment variable for temporary file directory.
+@cindex @code{USE, INTRINSIC} statement
+@cindex statement, @code{USE, INTRINSIC}
+@cindex @code{ISO_FORTRAN_ENV} statement
+@cindex statement, @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}.
@item
-Environment variable forcing standard output to be line buffered (unix).
+Renaming of operators in the @code{USE} statement.
@item
-Variable for swapping endianness during unformatted read.
+@cindex ISO C Bindings
+Interoperability with C (ISO C Bindings)
@item
-Variable for swapping Endianness during unformatted write.
+BOZ as argument of INT, REAL, DBLE and CMPLX.
+
@end itemize
+
+@node Fortran 2008 status
+@section Fortran 2008 status
+
+The next version of the Fortran standard after Fortran 2003 is currently
+being worked on by the Working Group 5 of Sub-Committee 22 of the Joint
+Technical Committee 1 of the International Organization for
+Standardization (ISO) and the International Electrotechnical Commission
+(IEC). This group is known at @uref{http://www.nag.co.uk/sc22wg5/, WG5}.
+The next revision of the Fortran standard is informally referred to as
+Fortran 2008, reflecting its planned release year. The GNU Fortran
+compiler has support for some of the new features in Fortran 2008. This
+support is based on the latest draft, available from
+@url{http://www.nag.co.uk/sc22wg5/}. However, as the final standard may
+differ from the drafts, no guarantee of backward compatibility can be
+made and you should only use it for experimental purposes.
+
@c ---------------------------------------------------------------------
@c Extensions
@c ---------------------------------------------------------------------
@node Extensions
@chapter Extensions
-@cindex Extension
+@cindex extensions
+
+The two sections below detail the extensions to standard Fortran that are
+implemented in GNU Fortran, as well as some of the popular or
+historically important extensions that are not (or not yet) implemented.
+For the latter case, we explain the alternatives available to GNU Fortran
+users, including replacement by standard-conforming code or GNU
+extensions.
+
+@menu
+* Extensions implemented in GNU Fortran::
+* Extensions not implemented in GNU Fortran::
+@end menu
-@command{gfortran} implements a number of extensions over standard
+
+@node Extensions implemented in GNU Fortran
+@section Extensions implemented in GNU Fortran
+@cindex extensions, implemented
+
+GNU Fortran implements a number of extensions over standard
Fortran. This chapter contains information on their syntax and
-meaning. There are currently two categories of @command{gfortran}
+meaning. There are currently two categories of GNU Fortran
extensions, those that provide functionality beyond that provided
-by any standard, and those that are supported by @command{gfortran}
+by any standard, and those that are supported by GNU Fortran
purely for backward compatibility with legacy compilers. By default,
@option{-std=gnu} allows the compiler to accept both types of
extensions, but to warn about the use of the latter. Specifying
-either @option{-std=f95} or @option{-std=f2003} disables both types
-of extensions, and @option{-std=legacy} allows both without warning.
+either @option{-std=f95}, @option{-std=f2003} or @option{-std=f2008}
+disables both types of extensions, and @option{-std=legacy} allows both
+without warning.
@menu
* 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 convert LOGICAL and INTEGER values::
+* Hollerith constants support::
+* Cray pointers::
+* CONVERT specifier::
+* OpenMP::
+* Argument list functions::
@end menu
@node Old-style kind specifications
-@section Old-style kind specifications
-@cindex Kind specifications
+@subsection Old-style kind specifications
+@cindex kind, old-style
-@command{gfortran} 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
+@noindent
+where @code{TYPESPEC} is a basic type (@code{INTEGER}, @code{REAL},
+etc.), and where @code{size} is a byte count corresponding to the
+storage size of a valid kind for that type. (For @code{COMPLEX}
+variables, @code{size} is the total size of the real and imaginary
+parts.) 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
+@noindent
+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
-@cindex Initialization
+@subsection Old-style variable initialization
-@command{gfortran} allows old-style initialization of variables of the
+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 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
+@subsection Extensions to namelist
@cindex Namelist
-@command{gfortran} fully supports the fortran95 standard for namelist io
+GNU Fortran fully supports the Fortran 95 standard for namelist I/O
including array qualifiers, substrings and fully qualified derived types.
The output from a namelist write is compatible with namelist read. The
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
=?
CH=abcd, /
@end smallexample
-To aid this dialog, when input is from stdin, errors produce send their
-messages to stderr and execution continues, even if IOSTAT is set.
+To aid this dialog, when input is from stdin, errors send their
+messages to stderr and execution continues, even if @code{IOSTAT} is set.
-@node X format descriptor
-@section X format descriptor
-@cindex X format descriptor
+@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/)
+ NAMELIST /mynml/ x
+ PRINT mynml
+END PROGRAM test_print
+@end smallexample
-To support legacy codes, @command{gfortran} 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.
+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 without count field
+@subsection @code{X} format descriptor without count field
+
+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
+@subsection Commas in @code{FORMAT} specifications
-To support legacy codes, @command{gfortran} allows the comma separator
+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
10 FORMAT ('FOO='I1' BAR='I2)
@end smallexample
-@node I/O item lists
-@section I/O item lists
-@cindex I/O item lists
-To support legacy codes, @command{gfortran} 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.
+@node Missing period in FORMAT specifications
+@subsection Missing period in @code{FORMAT} specifications
+
+To support legacy codes, GNU Fortran allows missing periods in format
+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
+ READ(*,10) value
+10 FORMAT ('F4')
+@end smallexample
-@node Hexadecimal constants
-@section Hexadecimal constants
-@cindex Hexadecimal constants
+@node I/O item lists
+@subsection I/O item lists
+@cindex I/O item lists
-As a GNU extension, @command{gfortran} allows hexadecimal constants to
-be specified using the X prefix, in addition to the standard Z prefix.
+To support legacy codes, GNU Fortran allows the input item list
+of the @code{READ} statement, and the output item lists of the
+@code{WRITE} and @code{PRINT} statements, to start with a comma.
+
+@node BOZ literal constants
+@subsection BOZ literal constants
+@cindex BOZ literal constants
+
+Besides decimal constants, Fortran also supports binary (@code{b}),
+octal (@code{o}) and hexadecimal (@code{z}) integer constants. The
+syntax is: @samp{prefix quote digits quote}, were the prefix is
+either @code{b}, @code{o} or @code{z}, quote is either @code{'} or
+@code{"} and the digits are for binary @code{0} or @code{1}, for
+octal between @code{0} and @code{7}, and for hexadecimal between
+@code{0} and @code{F}. (Example: @code{b'01011101'}.)
+
+Up to Fortran 95, BOZ literals were only allowed to initialize
+integer variables in DATA statements. Since Fortran 2003 BOZ literals
+are also allowed as argument of @code{REAL}, @code{DBLE}, @code{INT}
+and @code{CMPLX}; the result is the same as if the integer BOZ
+literal had been converted by @code{TRANSFER} to, respectively,
+@code{real}, @code{double precision}, @code{integer} or @code{complex}.
+As GNU Fortran extension the intrinsic procedures @code{FLOAT},
+@code{DFLOAT}, @code{COMPLEX} and @code{DCMPLX} are treated alike.
+
+As an extension, GNU Fortran allows hexadecimal BOZ literal constants to
+be specified using the @code{X} prefix, in addition to the standard
+@code{Z} prefix. The BOZ literal can also be specified by adding a
+suffix to the string, for example, @code{Z'ABC'} and @code{'ABC'Z} are
+equivalent.
+
+Furthermore, GNU Fortran allows using BOZ literal constants outside
+DATA statements and the four intrinsic functions allowed by Fortran 2003.
+In DATA statements, in direct assignments, where the right-hand side
+only contains a BOZ literal constant, and for old-style initializers of
+the form @code{integer i /o'0173'/}, the constant is transferred
+as if @code{TRANSFER} had been used; for @code{COMPLEX} numbers, only
+the real part is initialized unless @code{CMPLX} is used. In all other
+cases, the BOZ literal constant is converted to an @code{INTEGER} value with
+the largest decimal representation. This value is then converted
+numerically to the type and kind of the variable in question.
+(For instance @code{real :: r = b'0000001' + 1} initializes @code{r}
+with @code{2.0}.) As different compilers implement the extension
+differently, one should be careful when doing bitwise initialization
+of non-integer variables.
+
+Note that initializing an @code{INTEGER} variable with a statement such
+as @code{DATA i/Z'FFFFFFFF'/} will give an integer overflow error 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
+@subsection Real array indices
+@cindex array, indices of type real
-As a GNU extension, @command{gfortran} 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
+@subsection Unary operators
+@cindex operators, unary
-As a GNU extension, @command{gfortran} 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 convert LOGICAL and INTEGER values
+@subsection Implicitly convert @code{LOGICAL} and @code{INTEGER} values
+@cindex conversion, to integer
+@cindex conversion, to logical
+
+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
+ LOGICAL :: l
+ l = 1
+@end smallexample
+@smallexample
+ INTEGER :: i
+ i = .TRUE.
+@end smallexample
+
+However, there is no implicit conversion of @code{INTEGER} values in
+@code{if}-statements, nor of @code{LOGICAL} or @code{INTEGER} values
+in I/O operations.
+
+@node Hollerith constants support
+@subsection Hollerith constants support
+@cindex Hollerith constants
+
+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.
+
+Examples of valid uses of Hollerith constants:
+@smallexample
+ 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 ! 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
+@subsection Cray pointers
+@cindex pointer, Cray
+
+Cray pointers are part of a non-standard extension that provides a
+C-like pointer in Fortran. This is accomplished through a pair of
+variables: an integer "pointer" that holds a memory address, and a
+"pointee" that is used to dereference the pointer.
+
+Pointer/pointee pairs are declared in statements of the form:
+@smallexample
+ pointer ( <pointer> , <pointee> )
+@end smallexample
+or,
+@smallexample
+ pointer ( <pointer1> , <pointee1> ), ( <pointer2> , <pointee2> ), ...
+@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 @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
+before, during, or after the pointer statement. The pointer may be
+declared as an integer prior to the pointer statement. However, some
+machines have default integer sizes that are different than the size
+of a pointer, and so the following code is not portable:
+@smallexample
+ integer ipt
+ pointer (ipt, iarr)
+@end smallexample
+If a pointer is declared with a kind that is too small, the compiler
+will issue a warning; the resulting binary will probably not work
+correctly, because the memory addresses stored in the pointers may be
+truncated. It is safer to omit the first line of the above example;
+if explicit declaration of ipt's type is omitted, then the compiler
+will ensure that ipt is an integer variable large enough to hold a
+pointer.
+
+Pointer arithmetic is valid with Cray pointers, but it is not the same
+as C pointer arithmetic. Cray pointers are just ordinary integers, so
+the user is responsible for determining how many bytes to add to a
+pointer in order to increment it. Consider the following example:
+@smallexample
+ real target(10)
+ real pointee(10)
+ pointer (ipt, pointee)
+ ipt = loc (target)
+ ipt = ipt + 1
+@end smallexample
+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 @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))
+ real arpte
+ ipt = loc(ar) ! Makes arpte is an alias for ar
+ arpte(1) = 1.0 ! Sets ar(1) to 1.0
+@end smallexample
+The pointer can also be set by a call to the @code{MALLOC} intrinsic
+(see @ref{MALLOC}).
+
+Cray pointees often are used to alias an existing variable. For
+example:
+@smallexample
+ integer target(10)
+ integer iarr(10)
+ pointer (ipt, iarr)
+ ipt = loc(target)
+@end smallexample
+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 also point to a function or a subroutine. For
+example, the following excerpt is valid:
+@smallexample
+ implicit none
+ external sub
+ pointer (subptr,subpte)
+ external subpte
+ subptr = loc(sub)
+ call subpte()
+ [...]
+ subroutine sub
+ [...]
+ end subroutine sub
+@end smallexample
+
+A pointer may be modified during the course of a program, and this
+will change the location to which the pointee refers. However, when
+pointees are passed as arguments, they are treated as ordinary
+variables in the invoked function. Subsequent changes to the pointer
+will not change the base address of the array that was passed.
+
+@node CONVERT specifier
+@subsection @code{CONVERT} specifier
+@cindex @code{CONVERT} specifier
+
+GNU Fortran allows the conversion of unformatted data between little-
+and big-endian representation to facilitate moving of data
+between different systems. The conversion can be indicated with
+the @code{CONVERT} specifier on the @code{OPEN} statement.
+@xref{GFORTRAN_CONVERT_UNIT}, for an alternative way of specifying
+the data format via an environment variable.
+
+Valid values for @code{CONVERT} are:
+@itemize @w{}
+@item @code{CONVERT='NATIVE'} Use the native format. This is the default.
+@item @code{CONVERT='SWAP'} Swap between little- and big-endian.
+@item @code{CONVERT='LITTLE_ENDIAN'} Use the little-endian representation
+ for unformatted files.
+@item @code{CONVERT='BIG_ENDIAN'} Use the big-endian representation for
+ unformatted files.
+@end itemize
+
+Using the option could look like this:
+@smallexample
+ open(file='big.dat',form='unformatted',access='sequential', &
+ convert='big_endian')
+@end smallexample
+
+The value of the conversion can be queried by using
+@code{INQUIRE(CONVERT=ch)}. The values returned are
+@code{'BIG_ENDIAN'} and @code{'LITTLE_ENDIAN'}.
+
+@code{CONVERT} works between big- and little-endian for
+@code{INTEGER} values of all supported kinds and for @code{REAL}
+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)} 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
+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
+to you, it is best if you use this only for data that needs to be
+portable.
+
+@node OpenMP
+@subsection OpenMP
+@cindex OpenMP
+
+OpenMP (Open Multi-Processing) is an application programming
+interface (API) that supports multi-platform shared memory
+multiprocessing programming in C/C++ and Fortran on many
+architectures, including Unix and Microsoft Windows platforms.
+It consists of a set of compiler directives, library routines,
+and environment variables that influence run-time behavior.
+
+GNU Fortran strives to be compatible to the
+@uref{http://www.openmp.org/drupal/mp-documents/spec25.pdf,
+OpenMP Application Program Interface v2.5}.
+
+To enable the processing of the OpenMP directive @code{!$omp} in
+free-form source code; the @code{c$omp}, @code{*$omp} and @code{!$omp}
+directives in fixed form; the @code{!$} conditional compilation sentinels
+in free form; and the @code{c$}, @code{*$} and @code{!$} sentinels
+in fixed form, @command{gfortran} needs to be invoked with the
+@option{-fopenmp}. This also arranges for automatic linking of the
+GNU OpenMP runtime library @ref{Top,,libgomp,libgomp,GNU OpenMP
+runtime library}.
+
+The OpenMP Fortran runtime library routines are provided both in a
+form of a Fortran 90 module named @code{omp_lib} and in a form of
+a Fortran @code{include} file named @file{omp_lib.h}.
+
+An example of a parallelized loop taken from Appendix A.1 of
+the OpenMP Application Program Interface v2.5:
+@smallexample
+SUBROUTINE A1(N, A, B)
+ INTEGER I, N
+ REAL B(N), A(N)
+!$OMP PARALLEL DO !I is private by default
+ DO I=2,N
+ B(I) = (A(I) + A(I-1)) / 2.0
+ ENDDO
+!$OMP END PARALLEL DO
+END SUBROUTINE A1
+@end smallexample
+
+Please note:
+@itemize
+@item
+@option{-fopenmp} implies @option{-frecursive}, i.e., all local arrays
+will be allocated on the stack. When porting existing code to OpenMP,
+this may lead to surprising results, especially to segmentation faults
+if the stacksize is limited.
+
+@item
+On glibc-based systems, OpenMP enabled applications can not be statically
+linked due to limitations of the underlying pthreads-implementation. It
+might be possible to get a working solution if
+@command{-Wl,--whole-archive -lpthread -Wl,--no-whole-archive} is added
+to the command line. However, this is not supported by @command{gcc} and
+thus not recommended.
+@end itemize
+
+@node Argument list functions
+@subsection Argument list functions @code{%VAL}, @code{%REF} and @code{%LOC}
+@cindex argument list functions
+@cindex @code{%VAL}
+@cindex @code{%REF}
+@cindex @code{%LOC}
+
+GNU Fortran supports argument list functions @code{%VAL}, @code{%REF}
+and @code{%LOC} statements, for backward compatibility with g77.
+It is recommended that these should be used only for code that is
+accessing facilities outside of GNU Fortran, such as operating system
+or windowing facilities. It is best to constrain such uses to isolated
+portions of a program--portions that deal specifically and exclusively
+with low-level, system-dependent facilities. Such portions might well
+provide a portable interface for use by the program as a whole, but are
+themselves not portable, and should be thoroughly tested each time they
+are rebuilt using a new compiler or version of a compiler.
+
+@code{%VAL} passes a scalar argument by value, @code{%REF} passes it by
+reference and @code{%LOC} passes its memory location. Since gfortran
+already passes scalar arguments by reference, @code{%REF} is in effect
+a do-nothing. @code{%LOC} has the same effect as a fortran pointer.
+
+An example of passing an argument by value to a C subroutine foo.:
+@smallexample
+C
+C prototype void foo_ (float x);
+C
+ external foo
+ real*4 x
+ x = 3.14159
+ call foo (%VAL (x))
+ end
+@end smallexample
+
+For details refer to the g77 manual
+@uref{http://gcc.gnu.org/onlinedocs/gcc-3.4.6/g77/index.html#Top}.
+
+Also, the gfortran testsuite c_by_val.f and its partner c_by_val.c are
+worth a look.
+
+
+
+@node Extensions not implemented in GNU Fortran
+@section Extensions not implemented in GNU Fortran
+@cindex extensions, not implemented
+
+The long history of the Fortran language, its wide use and broad
+userbase, the large number of different compiler vendors and the lack of
+some features crucial to users in the first standards have lead to the
+existence of an important number of extensions to the language. While
+some of the most useful or popular extensions are supported by the GNU
+Fortran compiler, not all existing extensions are supported. This section
+aims at listing these extensions and offering advice on how best make
+code that uses them running with the GNU Fortran compiler.
+
+@c More can be found here:
+@c -- http://gcc.gnu.org/onlinedocs/gcc-3.4.6/g77/Missing-Features.html
+@c -- the list of fortran and libgfortran bugs closed as WONTFIX:
+@c http://tinyurl.com/2u4h5y
+
+@menu
+* STRUCTURE and RECORD::
+@c * UNION and MAP::
+* ENCODE and DECODE statements::
+@c * Expressions in FORMAT statements::
+@c * Q edit descriptor::
+@c * AUTOMATIC statement::
+@c * TYPE and ACCEPT I/O Statements::
+@c * .XOR. operator::
+@c * CARRIAGECONTROL, DEFAULTFILE, DISPOSE and RECORDTYPE I/O specifiers::
+@c * Omitted arguments in procedure call:
+@end menu
+
+
+@node STRUCTURE and RECORD
+@subsection @code{STRUCTURE} and @code{RECORD}
+@cindex @code{STRUCTURE}
+@cindex @code{RECORD}
+
+Structures are user-defined aggregate data types; this functionality was
+standardized in Fortran 90 with an different syntax, under the name of
+``derived types''. Here is an example of code using the non portable
+structure syntax:
+
+@example
+! Declaring a structure named ``item'' and containing three fields:
+! an integer ID, an description string and a floating-point price.
+STRUCTURE /item/
+ INTEGER id
+ CHARACTER(LEN=200) description
+ REAL price
+END STRUCTURE
+
+! Define two variables, an single record of type ``item''
+! named ``pear'', and an array of items named ``store_catalog''
+RECORD /item/ pear, store_catalog(100)
+
+! We can directly access the fields of both variables
+pear.id = 92316
+pear.description = "juicy D'Anjou pear"
+pear.price = 0.15
+store_catalog(7).id = 7831
+store_catalog(7).description = "milk bottle"
+store_catalog(7).price = 1.2
+
+! We can also manipulates the whole structure
+store_catalog(12) = pear
+print *, store_catalog(12)
+@end example
+
+@noindent
+This code can easily be rewritten in the Fortran 90 syntax as following:
+
+@example
+! ``STRUCTURE /name/ ... END STRUCTURE'' becomes
+! ``TYPE name ... END TYPE''
+TYPE item
+ INTEGER id
+ CHARACTER(LEN=200) description
+ REAL price
+END TYPE
+
+! ``RECORD /name/ variable'' becomes ``TYPE(name) variable''
+TYPE(item) pear, store_catalog(100)
+
+! Instead of using a dot (.) to access fields of a record, the
+! standard syntax uses a percent sign (%)
+pear%id = 92316
+pear%description = "juicy D'Anjou pear"
+pear%price = 0.15
+store_catalog(7)%id = 7831
+store_catalog(7)%description = "milk bottle"
+store_catalog(7)%price = 1.2
+
+! Assignments of a whole variable don't change
+store_catalog(12) = pear
+print *, store_catalog(12)
+@end example
+
+
+@c @node UNION and MAP
+@c @subsection @code{UNION} and @code{MAP}
+@c @cindex @code{UNION}
+@c @cindex @code{MAP}
+@c
+@c For help writing this one, see
+@c http://www.eng.umd.edu/~nsw/ench250/fortran1.htm#UNION and
+@c http://www.tacc.utexas.edu/services/userguides/pgi/pgiws_ug/pgi32u06.htm
+
+
+@node ENCODE and DECODE statements
+@subsection @code{ENCODE} and @code{DECODE} statements
+@cindex @code{ENCODE}
+@cindex @code{DECODE}
+
+GNU Fortran doesn't support the @code{ENCODE} and @code{DECODE}
+statements. These statements are best replaced by @code{READ} and
+@code{WRITE} statements involving internal files (@code{CHARACTER}
+variables and arrays), which have been part of the Fortran standard since
+Fortran 77. For example, replace a code fragment like
+
+@smallexample
+ INTEGER*1 LINE(80)
+ REAL A, B, C
+c ... Code that sets LINE
+ DECODE (80, 9000, LINE) A, B, C
+ 9000 FORMAT (1X, 3(F10.5))
+@end smallexample
+
+@noindent
+with the following:
+
+@smallexample
+ CHARACTER(LEN=80) LINE
+ REAL A, B, C
+c ... Code that sets LINE
+ READ (UNIT=LINE, FMT=9000) A, B, C
+ 9000 FORMAT (1X, 3(F10.5))
+@end smallexample
+
+Similarly, replace a code fragment like
+
+@smallexample
+ INTEGER*1 LINE(80)
+ REAL A, B, C
+c ... Code that sets A, B and C
+ ENCODE (80, 9000, LINE) A, B, C
+ 9000 FORMAT (1X, 'OUTPUT IS ', 3(F10.5))
+@end smallexample
+
+@noindent
+with the following:
+
+@smallexample
+ INTEGER*1 LINE(80)
+ REAL A, B, C
+c ... Code that sets A, B and C
+ WRITE (UNIT=LINE, FMT=9000) A, B, C
+ 9000 FORMAT (1X, 'OUTPUT IS ', 3(F10.5))
+@end smallexample
+
+
+@c ---------------------------------------------------------------------
+@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
We're always in need of more people helping out with ideas
and comments, writing documentation and contributing code.
-If you want to contribute to GNU Fortran 95,
+If you want to contribute to GNU Fortran,
have a look at the long lists of projects you can take on.
Some of these projects are small,
some of them are large;
some are completely orthogonal to the rest of what is
-happening on @command{gfortran},
+happening on GNU Fortran,
but others are ``mainstream'' projects in need of enthusiastic hackers.
All of these projects are important!
We'll eventually get around to the things here,
@menu
* Contributors::
* Projects::
+* Proposed Extensions::
@end menu
@node Contributors
-@section Contributors to GNU Fortran 95
+@section Contributors to GNU Fortran
@cindex Contributors
@cindex Credits
@cindex Authors
Most of the interface with GCC was written by @emph{Paul Brook}.
The following individuals have contributed code and/or
-ideas and significant help to the gfortran project
-(in no particular order):
+ideas and significant help to the GNU Fortran project
+(in alphabetical order):
@itemize @minus
-@item Andy Vaught
-@item Katherine Holcomb
-@item Tobias Schlüter
+@item Janne Blomqvist
@item Steven Bosscher
-@item Toon Moene
-@item Tim Prince
+@item Paul Brook
+@item Tobias Burnus
+@item Fran@,{c}ois-Xavier Coudert
+@item Bud Davis
+@item Jerry DeLisle
+@item Erik Edelmann
+@item Bernhard Fischer
+@item Daniel Franke
+@item Richard Guenther
+@item Richard Henderson
+@item Katherine Holcomb
+@item Jakub Jelinek
@item Niels Kristian Bech Jensen
@item Steven Johnson
-@item Paul Brook
+@item Steven G. Kargl
+@item Thomas Koenig
+@item Asher Langton
+@item H. J. Lu
+@item Toon Moene
+@item Brooks Moses
+@item Andrew Pinski
+@item Tim Prince
+@item Christopher D. Rickett
+@item Richard Sandiford
+@item Tobias Schl@"uter
+@item Roger Sayle
+@item Paul Thomas
+@item Andy Vaught
@item Feng Wang
-@item Bud Davis
+@item Janus Weil
@end itemize
The following people have contributed bug reports,
smaller or larger patches,
and much needed feedback and encouragement for the
-@command{gfortran} project:
+GNU Fortran project:
@itemize @minus
-@item Erik Schnetter
@item Bill Clodius
+@item Dominique d'Humi@`eres
@item Kate Hedstrom
+@item Erik Schnetter
@end itemize
Many other individuals have helped debug,
-test and improve @command{gfortran} over the past two years,
+test and improve the GNU Fortran compiler over the past few years,
and we welcome you to do the same!
If you already have done so,
and you would like to see your name listed in the
@table @emph
@item Help build the test suite
-Solicit more code for donation to the test suite.
-We can keep code private on request.
+Solicit more code for donation to the test suite: the more extensive the
+testsuite, the smaller the risk of breaking things in the future! We can
+keep code private on request.
@item Bug hunting/squishing
-Find bugs and write more test cases!
-Test cases are especially very welcome,
-because it allows us to concentrate on fixing bugs
-instead of isolating them.
-
-@item Smaller projects (``bug'' fixes):
- @itemize @minus
- @item Allow init exprs to be numbers raised to integer powers.
- @item Implement correct rounding.
- @item Implement F restrictions on Fortran 95 syntax.
- @item See about making Emacs-parsable error messages.
- @end itemize
+Find bugs and write more test cases! Test cases are especially very
+welcome, because it allows us to concentrate on fixing bugs instead of
+isolating them. Going through the bugzilla database at
+@url{http://gcc.gnu.org/bugzilla/} to reduce testcases posted there and
+add more information (for example, for which version does the testcase
+work, for which versions does it fail?) is also very helpful.
+
@end table
-If you wish to work on the runtime libraries,
-please contact a project maintainer.
-@c TODO: email!
+
+@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.
+@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.
+
+@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
@c ---------------------------------------------------------------------
-@c Standards
+@c GNU General Public License
@c ---------------------------------------------------------------------
-@node Standards
-@chapter Standards
-@cindex Standards
+@include gpl_v3.texi
+
+
+
+@c ---------------------------------------------------------------------
+@c GNU Free Documentation License
+@c ---------------------------------------------------------------------
+
+@include fdl.texi
+
+
-The GNU Fortran 95 Compiler aims to be a conforming implementation of
-ISO/IEC 1539:1997 (Fortran 95).
+@c ---------------------------------------------------------------------
+@c Funding Free Software
+@c ---------------------------------------------------------------------
-In the future it may also support other variants and extensions to the Fortran
-language. This includes ANSI Fortran 77, Fortran 90, Fortran 2000 (not yet
-finalized), and OpenMP.
+@include funding.texi
-@node Index
-@unnumbered Index
+@c ---------------------------------------------------------------------
+@c Indices
+@c ---------------------------------------------------------------------
+@node Option Index
+@unnumbered Option Index
+@command{gfortran}'s command line options are indexed here without any
+initial @samp{-} or @samp{--}. Where an option has both positive and
+negative forms (such as -foption and -fno-option), relevant entries in
+the manual are indexed under the most appropriate form; it may sometimes
+be useful to look up both forms.
+@printindex op
+
+@node Keyword Index
+@unnumbered Keyword Index
@printindex cp
@bye
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