@@ -180,7 +180,6 @@ Part I: Invoking GNU Fortran
* Runtime:: Influencing runtime behavior with environment variables.
Part II: Language Reference
-* Fortran standards status:: Fortran 2003, 2008 and 2018 features supported by GNU Fortran.
* Compiler Characteristics:: User-visible implementation details.
* Extensions:: Language extensions implemented by GNU Fortran.
* Mixed-Language Programming:: Interoperability with C
@@ -524,7 +523,10 @@ Fortran 2008 and Fortran 2018.
@cindex Standards
@menu
-* Varying Length Character Strings::
+* Fortran 95 status::
+* Fortran 2003 status::
+* Fortran 2008 status::
+* Fortran 2018 status::
@end menu
The GNU Fortran compiler implements
@@ -547,8 +549,8 @@ There also is support for the OpenACC specification (targeting
version 2.6, @uref{http://www.openacc.org/}). See
@uref{https://gcc.gnu.org/wiki/OpenACC} for more information.
-@node Varying Length Character Strings
-@subsection Varying Length Character Strings
+@node Fortran 95 status
+@subsection Fortran 95 status
@cindex Varying length character strings
@cindex Varying length strings
@cindex strings, varying length
@@ -565,257 +567,8 @@ the features of @code{ISO_VARYING_STRING} and should be considered as
replacement. (Namely, allocatable or pointers of the type
@code{character(len=:)}.)
-
-@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 ---------------------------------------------------------------------
-
-@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
-* TMPDIR:: Directory for scratch files
-* 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_UNBUFFERED_ALL:: Do not buffer I/O for all units
-* GFORTRAN_UNBUFFERED_PRECONNECTED:: Do not buffer I/O for preconnected units.
-* GFORTRAN_SHOW_LOCUS:: Show location for runtime errors
-* GFORTRAN_OPTIONAL_PLUS:: Print leading + where permitted
-* GFORTRAN_LIST_SEPARATOR:: Separator for list output
-* GFORTRAN_CONVERT_UNIT:: Set endianness for unformatted I/O
-* GFORTRAN_ERROR_BACKTRACE:: Show backtrace on run-time errors
-* GFORTRAN_FORMATTED_BUFFER_SIZE:: Buffer size for formatted files
-* GFORTRAN_UNFORMATTED_BUFFER_SIZE:: Buffer size for unformatted files
-@end menu
-
-@node TMPDIR
-@section @env{TMPDIR}---Directory for scratch files
-
-When opening a file with @code{STATUS='SCRATCH'}, GNU Fortran tries to
-create the file in one of the potential directories by testing each
-directory in the order below.
-
-@enumerate
-@item
-The environment variable @env{TMPDIR}, if it exists.
-
-@item
-On the MinGW target, the directory returned by the @code{GetTempPath}
-function. Alternatively, on the Cygwin target, the @env{TMP} and
-@env{TEMP} environment variables, if they exist, in that order.
-
-@item
-The @code{P_tmpdir} macro if it is defined, otherwise the directory
-@file{/tmp}.
-@end enumerate
-
-@node GFORTRAN_STDIN_UNIT
-@section @env{GFORTRAN_STDIN_UNIT}---Unit number for standard input
-
-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 GFORTRAN_STDOUT_UNIT
-@section @env{GFORTRAN_STDOUT_UNIT}---Unit number for standard output
-
-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.
-
-@node GFORTRAN_STDERR_UNIT
-@section @env{GFORTRAN_STDERR_UNIT}---Unit number for standard error
-
-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.
-
-@node GFORTRAN_UNBUFFERED_ALL
-@section @env{GFORTRAN_UNBUFFERED_ALL}---Do not buffer I/O on all units
-
-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 GFORTRAN_UNBUFFERED_PRECONNECTED
-@section @env{GFORTRAN_UNBUFFERED_PRECONNECTED}---Do not buffer I/O on preconnected units
-
-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.
-
-@node GFORTRAN_SHOW_LOCUS
-@section @env{GFORTRAN_SHOW_LOCUS}---Show location for runtime errors
-
-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}, do not print filename and line numbers
-for runtime errors. The default is to print the location.
-
-@node GFORTRAN_OPTIONAL_PLUS
-@section @env{GFORTRAN_OPTIONAL_PLUS}---Print leading + where permitted
-
-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.
-
-@node GFORTRAN_LIST_SEPARATOR
-@section @env{GFORTRAN_LIST_SEPARATOR}---Separator for list output
-
-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.
-
-@node GFORTRAN_CONVERT_UNIT
-@section @env{GFORTRAN_CONVERT_UNIT}---Set endianness for unformatted I/O
-
-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
-
-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.
-
-Example for @command{sh}:
-@smallexample
-$ gfortran foo.f90
-$ GFORTRAN_CONVERT_UNIT='big_endian;native:10-20' ./a.out
-@end smallexample
-
-Example code for @command{csh}:
-@smallexample
-% gfortran foo.f90
-% setenv GFORTRAN_CONVERT_UNIT 'big_endian;native:10-20'
-% ./a.out
-@end smallexample
-
-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_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 serious run-time error occurs. To disable
-the backtracing, set the variable to @samp{n}, @samp{N}, @samp{0}.
-Default is to print a backtrace unless the @option{-fno-backtrace}
-compile option was used.
-
-@node GFORTRAN_FORMATTED_BUFFER_SIZE
-@section @env{GFORTRAN_FORMATTED_BUFFER_SIZE}---Set buffer size for formatted I/O
-
-The @env{GFORTRAN_FORMATTED_BUFFER_SIZE} environment variable
-specifies buffer size in bytes to be used for formatted output.
-The default value is 8192.
-
-@node GFORTRAN_UNFORMATTED_BUFFER_SIZE
-@section @env{GFORTRAN_UNFORMATTED_BUFFER_SIZE}---Set buffer size for unformatted I/O
-
-The @env{GFORTRAN_UNFORMATTED_BUFFER_SIZE} environment variable
-specifies buffer size in bytes to be used for unformatted output.
-The default value is 131072.
-
-@c =====================================================================
-@c PART II: LANGUAGE REFERENCE
-@c =====================================================================
-
-@tex
-\part{II}{Language Reference}
-@end tex
-
-@c ---------------------------------------------------------------------
-@c Fortran standards status
-@c ---------------------------------------------------------------------
-
-@node Fortran standards status
-@chapter Fortran standards status
-
-@menu
-* Fortran 2003 status::
-* Fortran 2008 status::
-* Fortran 2018 status::
-@end menu
-
@node Fortran 2003 status
-@section Fortran 2003 status
+@subsection Fortran 2003 status
GNU Fortran supports several Fortran 2003 features; an incomplete
list can be found below. See also the
@@ -992,7 +745,7 @@ Renaming of operators in the @code{USE} statement.
@node Fortran 2008 status
-@section Fortran 2008 status
+@subsection Fortran 2008 status
The latest version of the Fortran standard is ISO/IEC 1539-1:2010, informally
known as Fortran 2008. The official version is available from International
@@ -1112,7 +865,7 @@ arrays are supported for named constants (@code{PARAMETER}).
@node Fortran 2018 status
-@section Status of Fortran 2018 support
+@subsection Status of Fortran 2018 support
@itemize
@item ERROR STOP in a PURE procedure
@@ -1131,7 +884,7 @@ specifier now conforms to Fortran 2018.
@end itemize
-@subsection TS 29113 Status (Further Interoperability with C)
+@subsubsection TS 29113 Status (Further Interoperability with C)
GNU Fortran supports some of the new features of the Technical
Specification (TS) 29113 on Further Interoperability of Fortran with C.
@@ -1162,7 +915,7 @@ done in the library. The include file ISO_Fortran_binding.h is can be found in
-@subsection TS 18508 Status (Additional Parallel Features)
+@subsubsection TS 18508 Status (Additional Parallel Features)
GNU Fortran supports the following new features of the Technical
Specification 18508 on Additional Parallel Features in Fortran:
@@ -1183,6 +936,245 @@ polymorphic components.
@end itemize
+
+
+@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 ---------------------------------------------------------------------
+
+@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
+* TMPDIR:: Directory for scratch files
+* 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_UNBUFFERED_ALL:: Do not buffer I/O for all units
+* GFORTRAN_UNBUFFERED_PRECONNECTED:: Do not buffer I/O for preconnected units.
+* GFORTRAN_SHOW_LOCUS:: Show location for runtime errors
+* GFORTRAN_OPTIONAL_PLUS:: Print leading + where permitted
+* GFORTRAN_LIST_SEPARATOR:: Separator for list output
+* GFORTRAN_CONVERT_UNIT:: Set endianness for unformatted I/O
+* GFORTRAN_ERROR_BACKTRACE:: Show backtrace on run-time errors
+* GFORTRAN_FORMATTED_BUFFER_SIZE:: Buffer size for formatted files
+* GFORTRAN_UNFORMATTED_BUFFER_SIZE:: Buffer size for unformatted files
+@end menu
+
+@node TMPDIR
+@section @env{TMPDIR}---Directory for scratch files
+
+When opening a file with @code{STATUS='SCRATCH'}, GNU Fortran tries to
+create the file in one of the potential directories by testing each
+directory in the order below.
+
+@enumerate
+@item
+The environment variable @env{TMPDIR}, if it exists.
+
+@item
+On the MinGW target, the directory returned by the @code{GetTempPath}
+function. Alternatively, on the Cygwin target, the @env{TMP} and
+@env{TEMP} environment variables, if they exist, in that order.
+
+@item
+The @code{P_tmpdir} macro if it is defined, otherwise the directory
+@file{/tmp}.
+@end enumerate
+
+@node GFORTRAN_STDIN_UNIT
+@section @env{GFORTRAN_STDIN_UNIT}---Unit number for standard input
+
+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 GFORTRAN_STDOUT_UNIT
+@section @env{GFORTRAN_STDOUT_UNIT}---Unit number for standard output
+
+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.
+
+@node GFORTRAN_STDERR_UNIT
+@section @env{GFORTRAN_STDERR_UNIT}---Unit number for standard error
+
+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.
+
+@node GFORTRAN_UNBUFFERED_ALL
+@section @env{GFORTRAN_UNBUFFERED_ALL}---Do not buffer I/O on all units
+
+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 GFORTRAN_UNBUFFERED_PRECONNECTED
+@section @env{GFORTRAN_UNBUFFERED_PRECONNECTED}---Do not buffer I/O on preconnected units
+
+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.
+
+@node GFORTRAN_SHOW_LOCUS
+@section @env{GFORTRAN_SHOW_LOCUS}---Show location for runtime errors
+
+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}, do not print filename and line numbers
+for runtime errors. The default is to print the location.
+
+@node GFORTRAN_OPTIONAL_PLUS
+@section @env{GFORTRAN_OPTIONAL_PLUS}---Print leading + where permitted
+
+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.
+
+@node GFORTRAN_LIST_SEPARATOR
+@section @env{GFORTRAN_LIST_SEPARATOR}---Separator for list output
+
+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.
+
+@node GFORTRAN_CONVERT_UNIT
+@section @env{GFORTRAN_CONVERT_UNIT}---Set endianness for unformatted I/O
+
+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
+
+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.
+
+Example for @command{sh}:
+@smallexample
+$ gfortran foo.f90
+$ GFORTRAN_CONVERT_UNIT='big_endian;native:10-20' ./a.out
+@end smallexample
+
+Example code for @command{csh}:
+@smallexample
+% gfortran foo.f90
+% setenv GFORTRAN_CONVERT_UNIT 'big_endian;native:10-20'
+% ./a.out
+@end smallexample
+
+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_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 serious run-time error occurs. To disable
+the backtracing, set the variable to @samp{n}, @samp{N}, @samp{0}.
+Default is to print a backtrace unless the @option{-fno-backtrace}
+compile option was used.
+
+@node GFORTRAN_FORMATTED_BUFFER_SIZE
+@section @env{GFORTRAN_FORMATTED_BUFFER_SIZE}---Set buffer size for formatted I/O
+
+The @env{GFORTRAN_FORMATTED_BUFFER_SIZE} environment variable
+specifies buffer size in bytes to be used for formatted output.
+The default value is 8192.
+
+@node GFORTRAN_UNFORMATTED_BUFFER_SIZE
+@section @env{GFORTRAN_UNFORMATTED_BUFFER_SIZE}---Set buffer size for unformatted I/O
+
+The @env{GFORTRAN_UNFORMATTED_BUFFER_SIZE} environment variable
+specifies buffer size in bytes to be used for unformatted output.
+The default value is 131072.
+
+@c =====================================================================
+@c PART II: LANGUAGE REFERENCE
+@c =====================================================================
+
+@tex
+\part{II}{Language Reference}
+@end tex
+
+
+
@c ---------------------------------------------------------------------
@c Compiler Characteristics
@c ---------------------------------------------------------------------