-@c Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010
+@c Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
@c Free Software Foundation, Inc.
@c This is part of the GNU Fortran manual.
@c For copying conditions, see the file gfortran.texi.
@ignore
@c man begin COPYRIGHT
-Copyright @copyright{} 2004, 2005, 2006, 2007, 2008, 2009
+Copyright @copyright{} 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.2 or
+under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being ``Funding Free Software'', the Front-Cover
Texts being (a) (see below), and with the Back-Cover Texts being (b)
@item Error and Warning Options
@xref{Error and Warning Options,,Options to request or suppress errors
and warnings}.
-@gccoptlist{-fmax-errors=@var{n} @gol
--fsyntax-only -pedantic -pedantic-errors @gol
--Wall -Waliasing -Wampersand -Warray-bounds -Wcharacter-truncation @gol
--Wconversion -Wimplicit-interface -Wimplicit-procedure -Wline-truncation @gol
--Wintrinsics-std -Wsurprising -Wno-tabs -Wunderflow -Wunused-parameter @gol
--Wintrinsics-shadow -Wno-align-commons}
+@gccoptlist{-fmax-errors=@var{n}
+-fsyntax-only -pedantic -pedantic-errors -Wall @gol
+-Waliasing -Wampersand -Warray-bounds -Wcharacter-truncation @gol
+-Wconversion -Wimplicit-interface -Wimplicit-procedure -Wline-truncation @gol
+-Wintrinsics-std -Wreal-q-constant -Wsurprising -Wno-tabs -Wunderflow @gol
+-Wunused-parameter -Wintrinsic-shadow -Wno-align-commons @gol
+-Wfunction-elimination}
@item Debugging Options
@xref{Debugging Options,,Options for debugging your program or GNU Fortran}.
-@gccoptlist{-fdump-parse-tree -ffpe-trap=@var{list} @gol
--fdump-core -fbacktrace}
+@gccoptlist{-fdump-fortran-original -fdump-fortran-optimized @gol
+-ffpe-trap=@var{list} -fbacktrace -fdump-parse-tree}
@item Directory Options
@xref{Directory Options,,Options for directory search}.
-@gccoptlist{-I@var{dir} -J@var{dir} -M@var{dir} @gol
--fintrinsic-modules-path @var{dir}}
+@gccoptlist{-I@var{dir} -J@var{dir} -fintrinsic-modules-path @var{dir}}
@item Link Options
@xref{Link Options,,Options for influencing the linking step}.
-fwhole-file -fsecond-underscore @gol
-fbounds-check -fcheck-array-temporaries -fmax-array-constructor =@var{n} @gol
-fcheck=@var{<all|array-temps|bounds|do|mem|pointer|recursion>} @gol
--fcoarray=@var{<none|single>} -fmax-stack-var-size=@var{n} @gol
+-fcoarray=@var{<none|single|lib>} -fmax-stack-var-size=@var{n} @gol
+-fstack-arrays @gol
-fpack-derived -frepack-arrays -fshort-enums -fexternal-blas @gol
-fblas-matmul-limit=@var{n} -frecursive -finit-local-zero @gol
-finit-integer=@var{n} -finit-real=@var{<zero|inf|-inf|nan|snan>} @gol
-finit-logical=@var{<true|false>} -finit-character=@var{n} @gol
--fno-align-commons -fno-protect-parens}
+-fno-align-commons -fno-protect-parens -frealloc-lhs @gol
+-faggressive-function-elimination -ffrontend-optimize}
@end table
@menu
@table @gcctabopt
@item -ffree-form
-@item -ffixed-form
+@itemx -ffixed-form
@opindex @code{ffree-form}
@opindex @code{fno-fixed-form}
@cindex options, fortran dialect
intrinsic will be called except when it is explicitly declared @code{EXTERNAL}.
@item -fd-lines-as-code
-@item -fd-lines-as-comments
+@itemx -fd-lines-as-comments
@opindex @code{fd-lines-as-code}
@opindex @code{fd-lines-as-comments}
Enable special treatment for lines beginning with @code{d} or @code{D}
@item -fdollar-ok
@opindex @code{fdollar-ok}
-@cindex $
+@cindex @code{$}
@cindex symbol names
@cindex character set
Allow @samp{$} as a valid non-first character in a symbol name. Symbols
conformance to the Fortran 95, Fortran 2003 and Fortran 2008 standards,
respectively; errors are given for all extensions beyond the relevant
language standard, and warnings are given for the Fortran 77 features
-that are permitted but obsolescent in later standards.
+that are permitted but obsolescent in later standards. @samp{-std=f2008tr}
+allows the Fortran 2008 standard including the additions of the
+technical report (TR) 29113.
@end table
@table @gcctabopt
@item -cpp
-@item -nocpp
+@itemx -nocpp
@opindex @code{cpp}
@opindex @code{fpp}
@cindex preprocessor, enable
To disable preprocessing of files with any of the above listed extensions,
use the negative form: @option{-nocpp}.
-The preprocessor is run in traditional mode, be aware that any
-restrictions of the file-format, e.g. fixed-form line width,
-apply for preprocessed output as well.
+The preprocessor is run in traditional mode. Any restrictions of the
+file-format, especially the limits on line length, apply for
+preprocessed output as well, so it might be advisable to use the
+@option{-ffree-line-length-none} or @option{-ffixed-line-length-none}
+options.
@item -dM
@opindex @code{dM}
of finding out what is predefined in your version of the preprocessor.
Assuming you have no file @file{foo.f90}, the command
@smallexample
- touch foo.f90; gfortran -cpp -dM foo.f90
+ touch foo.f90; gfortran -cpp -E -dM foo.f90
@end smallexample
will show all the predefined macros.
@item -A@var{predicate}=@var{answer}
@opindex @code{A@var{predicate}=@var{answer}}
-@cindex preprocessing, assertation
+@cindex preprocessing, assertion
Make an assertion with the predicate @var{predicate} and answer @var{answer}.
This form is preferred to the older form -A predicate(answer), which is still
supported, because it does not use shell special characters.
@item -A-@var{predicate}=@var{answer}
@opindex @code{A-@var{predicate}=@var{answer}}
-@cindex preprocessing, assertation
+@cindex preprocessing, assertion
Cancel an assertion with the predicate @var{predicate} and answer @var{answer}.
@item -C
@cindex warnings, all
Enables commonly used warning options pertaining to usage that
we recommend avoiding and that we believe are easy to avoid.
-This currently includes @option{-Waliasing},
-@option{-Wampersand}, @option{-Wsurprising}, @option{-Wintrinsics-std},
-@option{-Wno-tabs}, @option{-Wintrinsic-shadow} and @option{-Wline-truncation}.
+This currently includes @option{-Waliasing}, @option{-Wampersand},
+@option{-Wconversion}, @option{-Wsurprising}, @option{-Wintrinsics-std},
+@option{-Wno-tabs}, @option{-Wintrinsic-shadow}, @option{-Wline-truncation},
+@option{-Wreal-q-constant} and @option{-Wunused}.
@item -Waliasing
@opindex @code{Waliasing}
@item -Wampersand
@opindex @code{Wampersand}
@cindex warnings, ampersand
-@cindex &
+@cindex @code{&}
Warn about missing ampersand in continued character constants. The warning is
given with @option{-Wampersand}, @option{-pedantic}, @option{-std=f95},
@option{-std=f2003} and @option{-std=f2008}. Note: With no ampersand
@opindex @code{Wconversion}
@cindex warnings, conversion
@cindex conversion
-Warn about implicit conversions between different types.
+Warn about implicit conversions that are likely to change the value of
+the expression after conversion. Implied by @option{-Wall}.
+
+@item -Wconversion-extra
+@opindex @code{Wconversion-extra}
+@cindex warnings, conversion
+@cindex conversion
+Warn about implicit conversions between different types and kinds.
@item -Wimplicit-interface
@opindex @code{Wimplicit-interface}
be used to never trigger this behavior and always link to the intrinsic
regardless of the selected standard.
+@item -Wreal-q-constant
+@opindex @code{Wreal-q-constant}
+@cindex warnings, @code{q} exponent-letter
+Produce a warning if a real-literal-constant contains a @code{q}
+exponent-letter.
+
@item -Wsurprising
@opindex @code{Wsurprising}
@cindex warnings, suspicious code
@code{INTRINSIC} declaration might be needed to get calls later resolved to
the desired intrinsic/procedure.
+@item -Wunused-dummy-argument
+@opindex @code{Wunused-dummy-argument}
+@cindex warnings, unused dummy argument
+@cindex unused dummy argument
+@cindex dummy argument, unused
+Warn about unused dummy arguments. This option is implied by @option{-Wall}.
+
@item -Wunused-parameter
@opindex @code{Wunused-parameter}
@cindex warnings, unused parameter
@cindex unused parameter
Contrary to @command{gcc}'s meaning of @option{-Wunused-parameter},
@command{gfortran}'s implementation of this option does not warn
-about unused dummy arguments, but about unused @code{PARAMETER} values.
-@option{-Wunused-parameter} is not included in @option{-Wall} but is
-implied by @option{-Wall -Wextra}.
+about unused dummy arguments (see @option{-Wunused-dummy-argument}),
+but about unused @code{PARAMETER} values. @option{-Wunused-parameter}
+is not included in @option{-Wall} but is implied by @option{-Wall -Wextra}.
@item -Walign-commons
@opindex @code{Walign-commons}
-@cindex warnings, alignment of COMMON blocks
-@cindex alignment of COMMON blocks
+@cindex warnings, alignment of @code{COMMON} blocks
+@cindex alignment of @code{COMMON} blocks
By default, @command{gfortran} warns about any occasion of variables being
-padded for proper alignment inside a COMMON block. This warning can be turned
+padded for proper alignment inside a @code{COMMON} block. This warning can be turned
off via @option{-Wno-align-commons}. See also @option{-falign-commons}.
+@item -Wfunction-elimination
+@opindex @code{Wfunction-elimination}
+@cindex function elimination
+@cindex warnings, function elimination
+Warn if any calls to functions are eliminated by the optimizations
+enabled by the @option{-ffrontend-optimize} option.
+
+
@item -Werror
@opindex @code{Werror}
@cindex warnings, to errors
Turns all warnings into errors.
@end table
-@xref{Error and Warning Options,,Options to Request or Suppress Errors and
+@xref{Warning Options,,Options to Request or Suppress Errors and
Warnings, gcc,Using the GNU Compiler Collection (GCC)}, for information on
more options offered by the GBE shared by @command{gfortran}, @command{gcc}
and other GNU compilers.
either your program or the GNU Fortran compiler.
@table @gcctabopt
-@item -fdump-parse-tree
+@item -fdump-fortran-original
+@opindex @code{fdump-fortran-original}
+Output the internal parse tree after translating the source program
+into internal representation. Only really useful for debugging the
+GNU Fortran compiler itself.
+
+@item -fdump-optimized-tree
+@opindex @code{fdump-fortran-optimized}
+Output the parse tree after front-end optimization. Only really
+useful for debugging the GNU Fortran compiler itself.
+
@opindex @code{fdump-parse-tree}
-Output the internal parse tree before starting code generation. Only
-really useful for debugging the GNU Fortran compiler itself.
+Output the internal parse tree after translating the source program
+into internal representation. Only really useful for debugging the
+GNU Fortran compiler itself. This option is deprecated; use
+@code{-fdump-fortran-original} instead.
@item -ffpe-trap=@var{list}
@opindex @code{ffpe-trap=}@var{list}
@code{ffpe-trap=precision} is used. For this reason, the use of
@code{ffpe-trap=precision} is not recommended.
-@item -fbacktrace
-@opindex @code{fbacktrace}
+@item -fno-backtrace
+@opindex @code{fno-backtrace}
@cindex backtrace
@cindex trace
-Specify that, when a runtime error is encountered or a deadly signal is
-emitted (segmentation fault, illegal instruction, bus error or
-floating-point exception), the Fortran runtime
-library should output a backtrace of the error. This option
-only has influence for compilation of the Fortran main program.
-
-@item -fdump-core
-@cindex core, dump
-@opindex @code{fdump-core}
-Request that a core-dump file is written to disk when a runtime error
-is encountered on systems that support core dumps. This option is
-only effective for the compilation of the Fortran main program.
+When a serious runtime error is encountered or a deadly signal is
+emitted (segmentation fault, illegal instruction, bus error,
+floating-point exception, and the other POSIX signals that have the
+action @samp{core}), the Fortran runtime library tries to output a
+backtrace of the error. @code{-fno-backtrace} disables the backtrace
+generation. This option only has influence for compilation of the
+Fortran main program.
+
@end table
@xref{Debugging Options,,Options for Debugging Your Program or GCC,
@cindex directory, options
@cindex options, directory search
@cindex search path
-@cindex INCLUDE directive
-@cindex directive, INCLUDE
+@cindex @code{INCLUDE} directive
+@cindex directive, @code{INCLUDE}
These options affect how GNU Fortran searches
for files specified by the @code{INCLUDE} directive and where it searches
for previously compiled modules.
@option{-I} option.
@item -J@var{dir}
-@item -M@var{dir}
@opindex @code{J}@var{dir}
@opindex @code{M}@var{dir}
@cindex paths, search
The default is the current directory.
-@option{-M} is deprecated to avoid conflicts with existing GCC options.
-
@item -fintrinsic-modules-path @var{dir}
@opindex @code{fintrinsic-modules-path} @var{dir}
@cindex paths, search
@cindex options, runtime
These options affect the runtime behavior of programs compiled with GNU Fortran.
+
@table @gcctabopt
@item -fconvert=@var{conversion}
@opindex @code{fconvert=}@var{conversion}
@item @samp{single}
Single-image mode, i.e. @code{num_images()} is always one.
+
+@item @samp{lib}
+Library-based coarray parallelization; a suitable GNU Fortran coarray
+library needs to be linked.
@end table
the array at compile time.
@smallexample
-@code{program test}
-@code{implicit none}
-@code{integer j}
-@code{integer, parameter :: n = 100000}
-@code{integer, parameter :: i(n) = (/ (2*j, j = 1, n) /)}
-@code{print '(10(I0,1X))', i}
-@code{end program test}
+program test
+implicit none
+integer j
+integer, parameter :: n = 100000
+integer, parameter :: i(n) = (/ (2*j, j = 1, n) /)
+print '(10(I0,1X))', i
+end program test
@end smallexample
@emph{Caution: This option can lead to long compile times and excessively
The default value for @var{n} is 32768.
+@item -fstack-arrays
+@opindex @code{fstack-arrays}
+Adding this option will make the fortran compiler put all local arrays,
+even those of unknown size onto stack memory. If your program uses very
+large local arrays it's possible that you'll have to extend your runtime
+limits for stack memory on some operating systems.
+
@item -fpack-derived
@opindex @code{fpack-derived}
@cindex structure packing
@option{-fmax-stack-var-size=} or @option{-fno-automatic}.
@item -finit-local-zero
-@item -finit-integer=@var{n}
-@item -finit-real=@var{<zero|inf|-inf|nan|snan>}
-@item -finit-logical=@var{<true|false>}
-@item -finit-character=@var{n}
+@itemx -finit-integer=@var{n}
+@itemx -finit-real=@var{<zero|inf|-inf|nan|snan>}
+@itemx -finit-logical=@var{<true|false>}
+@itemx -finit-character=@var{n}
@opindex @code{finit-local-zero}
@opindex @code{finit-integer}
@opindex @code{finit-real}
@item -falign-commons
@opindex @code{falign-commons}
-@cindex alignment of COMMON blocks
+@cindex alignment of @code{COMMON} blocks
By default, @command{gfortran} enforces proper alignment of all variables in a
-COMMON block by padding them as needed. On certain platforms this is mandatory,
-on others it increases performance. If a COMMON block is not declared with
+@code{COMMON} block by padding them as needed. On certain platforms this is mandatory,
+on others it increases performance. If a @code{COMMON} block is not declared with
consistent data types everywhere, this padding can cause trouble, and
-@option{-fno-align-commons } can be used to disable automatic alignment. The
-same form of this option should be used for all files that share a COMMON block.
-To avoid potential alignment issues in COMMON blocks, it is recommended to order
-objects from largests to smallest.
+@option{-fno-align-commons} can be used to disable automatic alignment. The
+same form of this option should be used for all files that share a @code{COMMON} block.
+To avoid potential alignment issues in @code{COMMON} blocks, it is recommended to order
+objects from largest to smallest.
@item -fno-protect-parens
@opindex @code{fno-protect-parens}
-@cindex re-association of parenthesed expressions
+@cindex re-association of parenthesized expressions
By default the parentheses in expression are honored for all optimization
levels such that the compiler does not do any re-association. Using
-@option{-fno-protect-parens} allows the compiler to reorder REAL and
-COMPLEX expressions to produce faster code. Note that for the re-association
+@option{-fno-protect-parens} allows the compiler to reorder @code{REAL} and
+@code{COMPLEX} expressions to produce faster code. Note that for the re-association
optimization @option{-fno-signed-zeros} and @option{-fno-trapping-math}
-need to be in effect.
+need to be in effect. The parentheses protection is enabled by default, unless
+@option{-Ofast} is given.
+
+@item -frealloc-lhs
+@opindex @code{frealloc-lhs}
+@cindex Reallocate the LHS in assignments
+An allocatable left-hand side of an intrinsic assignment is automatically
+(re)allocated if it is either unallocated or has a different shape. The
+option is enabled by default except when @option{-std=f95} is given.
+
+@item -faggressive-function-elimination
+@opindex @code{faggressive-function-elimination}
+@cindex Elimination of functions with identical argument lists
+Functions with identical argument lists are eliminated within
+statements, regardless of whether these functions are marked
+@code{PURE} or not. For example, in
+@smallexample
+ a = f(b,c) + f(b,c)
+@end smallexample
+there will only be a single call to @code{f}. This option only works
+if @option{-ffrontend-optimize} is in effect.
+
+@item -ffrontend-optimize
+@opindex @code{frontend-optimize}
+@cindex Front-end optimization
+This option performs front-end optimization, based on manipulating
+parts the Fortran parse tree. Enabled by default by any @option{-O}
+option. Optimizations enabled by this option include elimination of
+identical function calls within expressions, removing unnecessary
+calls to @code{TRIM} in comparisons and assignments and replacing
+@code{TRIM(a)} with @code{a(1:LEN_TRIM(a))}.
+It can be deselected by specifying @option{-fno-frontend-optimize}.
@end table
@xref{Code Gen Options,,Options for Code Generation Conventions,
offered by the GBE
shared by @command{gfortran}, @command{gcc}, and other GNU compilers.
-
@c man end
@node Environment Variables
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