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diff --git a/gcc-4.8.1/gcc/fortran/invoke.texi b/gcc-4.8.1/gcc/fortran/invoke.texi deleted file mode 100644 index db958f9b3..000000000 --- a/gcc-4.8.1/gcc/fortran/invoke.texi +++ /dev/null @@ -1,1638 +0,0 @@ -@c Copyright (C) 2004-2013 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{} 2004-2013 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 1.3 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) -(see below). A copy of the license is included in the gfdl(7) man page. - -(a) The FSF's Front-Cover Text is: - - A GNU Manual - -(b) The FSF's Back-Cover Text is: - - You have freedom to copy and modify this GNU Manual, like GNU - software. Copies published by the Free Software Foundation raise - funds for GNU development. -@c man end -@c Set file name and title for the man page. -@setfilename gfortran -@settitle GNU Fortran compiler. -@c man begin SYNOPSIS -gfortran [@option{-c}|@option{-S}|@option{-E}] - [@option{-g}] [@option{-pg}] [@option{-O}@var{level}] - [@option{-W}@var{warn}@dots{}] [@option{-pedantic}] - [@option{-I}@var{dir}@dots{}] [@option{-L}@var{dir}@dots{}] - [@option{-D}@var{macro}[=@var{defn}]@dots{}] [@option{-U}@var{macro}] - [@option{-f}@var{option}@dots{}] - [@option{-m}@var{machine-option}@dots{}] - [@option{-o} @var{outfile}] @var{infile}@dots{} - -Only the most useful options are listed here; see below for the -remainder. -@c man end -@c man begin SEEALSO -gpl(7), gfdl(7), fsf-funding(7), -cpp(1), gcov(1), gcc(1), as(1), ld(1), gdb(1), adb(1), dbx(1), sdb(1) -and the Info entries for @file{gcc}, @file{cpp}, @file{gfortran}, @file{as}, -@file{ld}, @file{binutils} and @file{gdb}. -@c man end -@c man begin BUGS -For instructions on reporting bugs, see -@w{@value{BUGURL}}. -@c man end -@c man begin AUTHOR -See the Info entry for @command{gfortran} for contributors to GCC and -GNU Fortran. -@c man end -@end ignore - -@node Invoking GNU Fortran -@chapter GNU Fortran Command Options -@cindex GNU Fortran command options -@cindex command options -@cindex options, @command{gfortran} command - -@c man begin DESCRIPTION - -The @command{gfortran} command supports all the options supported by the -@command{gcc} command. Only options specific to GNU Fortran are documented -here. - -@xref{Invoking GCC,,GCC Command Options,gcc,Using the GNU Compiler -Collection (GCC)}, for information -on the non-Fortran-specific aspects of the @command{gcc} command (and, -therefore, the @command{gfortran} command). - -@cindex options, negative forms -All GCC and GNU Fortran options -are accepted both by @command{gfortran} and by @command{gcc} -(as well as any other drivers built at the same time, -such as @command{g++}), -since adding GNU Fortran to the GCC distribution -enables acceptance of GNU Fortran options -by all of the relevant drivers. - -In some cases, options have positive and negative forms; -the negative form of @option{-ffoo} would be @option{-fno-foo}. -This manual documents only one of these two forms, whichever -one is not the default. -@c man end - -@menu -* Option Summary:: Brief list of all @command{gfortran} options, - without explanations. -* Fortran Dialect Options:: Controlling the variant of Fortran language - compiled. -* Preprocessing Options:: Enable and customize preprocessing. -* Error and Warning Options:: How picky should the compiler be? -* Debugging Options:: Symbol tables, measurements, and debugging dumps. -* Directory Options:: Where to find module files -* Link Options :: Influencing the linking step -* Runtime Options:: Influencing runtime behavior -* Code Gen Options:: Specifying conventions for function calls, data layout - and register usage. -* Environment Variables:: Environment variables that affect @command{gfortran}. -@end menu - -@node Option Summary -@section Option summary - -@c man begin OPTIONS - -Here is a summary of all the options specific to GNU Fortran, grouped -by type. Explanations are in the following sections. - -@table @emph -@item Fortran Language Options -@xref{Fortran Dialect Options,,Options controlling Fortran dialect}. -@gccoptlist{-fall-intrinsics -fbackslash -fcray-pointer -fd-lines-as-code @gol --fd-lines-as-comments -fdefault-double-8 -fdefault-integer-8 @gol --fdefault-real-8 -fdollar-ok -ffixed-line-length-@var{n} @gol --ffixed-line-length-none -ffree-form -ffree-line-length-@var{n} @gol --ffree-line-length-none -fimplicit-none -finteger-4-integer-8 @gol --fmax-identifier-length -fmodule-private -fno-fixed-form -fno-range-check @gol --fopenmp -freal-4-real-10 -freal-4-real-16 -freal-4-real-8 @gol --freal-8-real-10 -freal-8-real-16 -freal-8-real-4 -std=@var{std} -} - -@item Preprocessing Options -@xref{Preprocessing Options,,Enable and customize preprocessing}. -@gccoptlist{-A-@var{question}@r{[}=@var{answer}@r{]} --A@var{question}=@var{answer} -C -CC -D@var{macro}@r{[}=@var{defn}@r{]} --H -P @gol --U@var{macro} -cpp -dD -dI -dM -dN -dU -fworking-directory --imultilib @var{dir} @gol --iprefix @var{file} -iquote -isysroot @var{dir} -isystem @var{dir} -nocpp --nostdinc @gol --undef -} - -@item Error and Warning Options -@xref{Error and Warning Options,,Options to request or suppress errors -and warnings}. -@gccoptlist{-Waliasing -Wall -Wampersand -Warray-bounds --Wc-binding-type -Wcharacter-truncation @gol --Wconversion -Wfunction-elimination -Wimplicit-interface @gol --Wimplicit-procedure -Wintrinsic-shadow -Wintrinsics-std @gol --Wline-truncation -Wno-align-commons -Wno-tabs -Wreal-q-constant @gol --Wsurprising -Wunderflow -Wunused-parameter -Wrealloc-lhs Wrealloc-lhs-all @gol --Wtarget-lifetime -fmax-errors=@var{n} -fsyntax-only -pedantic -pedantic-errors -} - -@item Debugging Options -@xref{Debugging Options,,Options for debugging your program or GNU Fortran}. -@gccoptlist{-fbacktrace -fdump-fortran-optimized -fdump-fortran-original @gol --fdump-parse-tree -ffpe-trap=@var{list} -} - -@item Directory Options -@xref{Directory Options,,Options for directory search}. -@gccoptlist{-I@var{dir} -J@var{dir} -fintrinsic-modules-path @var{dir}} - -@item Link Options -@xref{Link Options,,Options for influencing the linking step}. -@gccoptlist{-static-libgfortran} - -@item Runtime Options -@xref{Runtime Options,,Options for influencing runtime behavior}. -@gccoptlist{-fconvert=@var{conversion} -fmax-subrecord-length=@var{length} @gol --frecord-marker=@var{length} -fsign-zero -} - -@item Code Generation Options -@xref{Code Gen Options,,Options for code generation conventions}. -@gccoptlist{-faggressive-function-elimination -fblas-matmul-limit=@var{n} @gol --fbounds-check -fcheck-array-temporaries @gol --fcheck=@var{<all|array-temps|bounds|do|mem|pointer|recursion>} @gol --fcoarray=@var{<none|single|lib>} -fexternal-blas -ff2c --ffrontend-optimize @gol --finit-character=@var{n} -finit-integer=@var{n} -finit-local-zero @gol --finit-logical=@var{<true|false>} --finit-real=@var{<zero|inf|-inf|nan|snan>} @gol --fmax-array-constructor=@var{n} -fmax-stack-var-size=@var{n} --fno-align-commons @gol --fno-automatic -fno-protect-parens -fno-underscoring -fno-whole-file @gol --fsecond-underscore -fpack-derived -frealloc-lhs -frecursive @gol --frepack-arrays -fshort-enums -fstack-arrays -} -@end table - -@node Fortran Dialect Options -@section Options controlling Fortran dialect -@cindex dialect options -@cindex language, dialect options -@cindex options, dialect - -The following options control the details of the Fortran dialect -accepted by the compiler: - -@table @gcctabopt -@item -ffree-form -@itemx -ffixed-form -@opindex @code{ffree-form} -@opindex @code{fno-fixed-form} -@cindex options, Fortran dialect -@cindex file format, free -@cindex file format, fixed -Specify the layout used by the source file. The free form layout -was introduced in Fortran 90. Fixed form was traditionally used in -older Fortran programs. When neither option is specified, the source -form is determined by the file extension. - -@item -fall-intrinsics -@opindex @code{fall-intrinsics} -This option causes all intrinsic procedures (including the GNU-specific -extensions) to be accepted. This can be useful with @option{-std=f95} to -force standard-compliance but get access to the full range of intrinsics -available with @command{gfortran}. As a consequence, @option{-Wintrinsics-std} -will be ignored and no user-defined procedure with the same name as any -intrinsic will be called except when it is explicitly declared @code{EXTERNAL}. - -@item -fd-lines-as-code -@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} -in fixed form sources. If the @option{-fd-lines-as-code} option is -given they are treated as if the first column contained a blank. If the -@option{-fd-lines-as-comments} option is given, they are treated as -comment lines. - -@item -fdefault-double-8 -@opindex @code{fdefault-double-8} -Set the @code{DOUBLE PRECISION} type to an 8 byte wide type. If -@option{-fdefault-real-8} is given, @code{DOUBLE PRECISION} would -instead be promoted to 16 bytes if possible, and @option{-fdefault-double-8} -can be used to prevent this. The kind of real constants like @code{1.d0} will -not be changed by @option{-fdefault-real-8} though, so also -@option{-fdefault-double-8} does not affect it. - -@item -fdefault-integer-8 -@opindex @code{fdefault-integer-8} -Set the default integer and logical types to an 8 byte wide type. -Do nothing if this is already the default. This option also affects -the kind of integer constants like @code{42}. - -@item -fdefault-real-8 -@opindex @code{fdefault-real-8} -Set the default real type to an 8 byte wide type. -Do nothing if this is already the default. This option also affects -the kind of non-double real constants like @code{1.0}, and does promote -the default width of @code{DOUBLE PRECISION} to 16 bytes if possible, unless -@code{-fdefault-double-8} is given, too. - -@item -fdollar-ok -@opindex @code{fdollar-ok} -@cindex @code{$} -@cindex symbol names -@cindex character set -Allow @samp{$} as a valid non-first character in a symbol name. Symbols -that start with @samp{$} are rejected since it is unclear which rules to -apply to implicit typing as different vendors implement different rules. -Using @samp{$} in @code{IMPLICIT} statements is also rejected. - -@item -fbackslash -@opindex @code{backslash} -@cindex backslash -@cindex escape characters -Change the interpretation of backslashes in string literals from a single -backslash character to ``C-style'' escape characters. The following -combinations are expanded @code{\a}, @code{\b}, @code{\f}, @code{\n}, -@code{\r}, @code{\t}, @code{\v}, @code{\\}, and @code{\0} to the ASCII -characters alert, backspace, form feed, newline, carriage return, -horizontal tab, vertical tab, backslash, and NUL, respectively. -Additionally, @code{\x}@var{nn}, @code{\u}@var{nnnn} and -@code{\U}@var{nnnnnnnn} (where each @var{n} is a hexadecimal digit) are -translated into the Unicode characters corresponding to the specified code -points. All other combinations of a character preceded by \ are -unexpanded. - -@item -fmodule-private -@opindex @code{fmodule-private} -@cindex module entities -@cindex private -Set the default accessibility of module entities to @code{PRIVATE}. -Use-associated entities will not be accessible unless they are explicitly -declared as @code{PUBLIC}. - -@item -ffixed-line-length-@var{n} -@opindex @code{ffixed-line-length-}@var{n} -@cindex file format, fixed -Set column after which characters are ignored in typical fixed-form -lines in the source file, and through which spaces are assumed (as -if padded to that length) after the ends of short fixed-form lines. - -Popular values for @var{n} include 72 (the -standard and the default), 80 (card image), and 132 (corresponding -to ``extended-source'' options in some popular compilers). -@var{n} may also be @samp{none}, meaning that the entire line is meaningful -and that continued character constants never have implicit spaces appended -to them to fill out the line. -@option{-ffixed-line-length-0} means the same thing as -@option{-ffixed-line-length-none}. - -@item -ffree-line-length-@var{n} -@opindex @code{ffree-line-length-}@var{n} -@cindex file format, free -Set column after which characters are ignored in typical free-form -lines in the source file. The default value is 132. -@var{n} may be @samp{none}, meaning that the entire line is meaningful. -@option{-ffree-line-length-0} means the same thing as -@option{-ffree-line-length-none}. - -@item -fmax-identifier-length=@var{n} -@opindex @code{fmax-identifier-length=}@var{n} -Specify the maximum allowed identifier length. Typical values are -31 (Fortran 95) and 63 (Fortran 2003 and Fortran 2008). - -@item -fimplicit-none -@opindex @code{fimplicit-none} -Specify that no implicit typing is allowed, unless overridden by explicit -@code{IMPLICIT} statements. This is the equivalent of adding -@code{implicit none} to the start of every procedure. - -@item -finteger-4-integer-8 -@opindex @code{finteger-4-integer-8} -Promote all @code{INTEGER(KIND=4)} entities to an @code{INTEGER(KIND=8)} -entities. If @code{KIND=8} is unavailable, then an error will be issued. -This option should be used with care and may not be suitable for your codes. -Areas of possible concern include calls to external procedures, -alignment in @code{EQUIVALENCE} and/or @code{COMMON}, generic interfaces, -BOZ literal constant conversion, and I/O. Inspection of the intermediate -representation of the translated Fortran code, produced by -@option{-fdump-tree-original}, is suggested. - -@item -fcray-pointer -@opindex @code{fcray-pointer} -Enable the Cray pointer extension, which provides C-like pointer -functionality. - -@item -fopenmp -@opindex @code{fopenmp} -@cindex OpenMP -Enable the OpenMP extensions. This includes OpenMP @code{!$omp} directives -in free form -and @code{c$omp}, @code{*$omp} and @code{!$omp} directives in fixed form, -@code{!$} conditional compilation sentinels in free form -and @code{c$}, @code{*$} and @code{!$} sentinels in fixed form, -and when linking arranges for the OpenMP runtime library to be linked -in. The option @option{-fopenmp} implies @option{-frecursive}. - -@item -fno-range-check -@opindex @code{frange-check} -Disable range checking on results of simplification of constant -expressions during compilation. For example, GNU Fortran will give -an error at compile time when simplifying @code{a = 1. / 0}. -With this option, no error will be given and @code{a} will be assigned -the value @code{+Infinity}. If an expression evaluates to a value -outside of the relevant range of [@code{-HUGE()}:@code{HUGE()}], -then the expression will be replaced by @code{-Inf} or @code{+Inf} -as appropriate. -Similarly, @code{DATA i/Z'FFFFFFFF'/} will result in an integer overflow -on most systems, but with @option{-fno-range-check} the value will -``wrap around'' and @code{i} will be initialized to @math{-1} instead. - -@item -freal-4-real-8 -@itemx -freal-4-real-10 -@itemx -freal-8-real-4 -@itemx -freal-8-real-10 -@itemx -freal-8-real-16 -@opindex @code{freal-4-real-8} -@opindex @code{freal-4-real-10} -@opindex @code{freal-4-real-16} -@opindex @code{freal-8-real-4} -@opindex @code{freal-8-real-10} -@opindex @code{freal-8-real-16} -@cindex options, real kind type promotion -Promote all @code{REAL(KIND=M)} entities to @code{REAL(KIND=N)} entities. -If @code{REAL(KIND=N)} is unavailable, then an error will be issued. -All other real kind types are unaffected by this option. -These options should be used with care and may not be suitable for your -codes. Areas of possible concern include calls to external procedures, -alignment in @code{EQUIVALENCE} and/or @code{COMMON}, generic interfaces, -BOZ literal constant conversion, and I/O. Inspection of the intermediate -representation of the translated Fortran code, produced by -@option{-fdump-tree-original}, is suggested. - -@item -std=@var{std} -@opindex @code{std=}@var{std} option -Specify the standard to which the program is expected to conform, which -may be one of @samp{f95}, @samp{f2003}, @samp{f2008}, @samp{gnu}, or -@samp{legacy}. The default value for @var{std} is @samp{gnu}, which -specifies a superset of the Fortran 95 standard that includes all of the -extensions supported by GNU Fortran, although warnings will be given for -obsolete extensions not recommended for use in new code. The -@samp{legacy} value is equivalent but without the warnings for obsolete -extensions, and may be useful for old non-standard programs. The -@samp{f95}, @samp{f2003} and @samp{f2008} values specify strict -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. @samp{-std=f2008ts} -allows the Fortran 2008 standard including the additions of the -Technical Specification (TS) 29113 on Further Interoperability of Fortran -with C. - -@end table - -@node Preprocessing Options -@section Enable and customize preprocessing -@cindex preprocessor -@cindex options, preprocessor -@cindex CPP - -Preprocessor related options. See section -@ref{Preprocessing and conditional compilation} for more detailed -information on preprocessing in @command{gfortran}. - -@table @gcctabopt -@item -cpp -@itemx -nocpp -@opindex @code{cpp} -@opindex @code{fpp} -@cindex preprocessor, enable -@cindex preprocessor, disable -Enable preprocessing. The preprocessor is automatically invoked if -the file extension is @file{.fpp}, @file{.FPP}, @file{.F}, @file{.FOR}, -@file{.FTN}, @file{.F90}, @file{.F95}, @file{.F03} or @file{.F08}. Use -this option to manually enable preprocessing of any kind of Fortran file. - -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. 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} -@cindex preprocessor, debugging -@cindex debugging, preprocessor -Instead of the normal output, generate a list of @code{'#define'} -directives for all the macros defined during the execution of the -preprocessor, including predefined macros. This gives you a way -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 -E -dM foo.f90 -@end smallexample -will show all the predefined macros. - -@item -dD -@opindex @code{dD} -@cindex preprocessor, debugging -@cindex debugging, preprocessor -Like @option{-dM} except in two respects: it does not include the -predefined macros, and it outputs both the @code{#define} directives -and the result of preprocessing. Both kinds of output go to the -standard output file. - -@item -dN -@opindex @code{dN} -@cindex preprocessor, debugging -@cindex debugging, preprocessor -Like @option{-dD}, but emit only the macro names, not their expansions. - -@item -dU -@opindex @code{dU} -@cindex preprocessor, debugging -@cindex debugging, preprocessor -Like @option{dD} except that only macros that are expanded, or whose -definedness is tested in preprocessor directives, are output; the -output is delayed until the use or test of the macro; and @code{'#undef'} -directives are also output for macros tested but undefined at the time. - -@item -dI -@opindex @code{dI} -@cindex preprocessor, debugging -@cindex debugging, preprocessor -Output @code{'#include'} directives in addition to the result -of preprocessing. - -@item -fworking-directory -@opindex @code{fworking-directory} -@cindex preprocessor, working directory -Enable generation of linemarkers in the preprocessor output that will -let the compiler know the current working directory at the time of -preprocessing. When this option is enabled, the preprocessor will emit, -after the initial linemarker, a second linemarker with the current -working directory followed by two slashes. GCC will use this directory, -when it is present in the preprocessed input, as the directory emitted -as the current working directory in some debugging information formats. -This option is implicitly enabled if debugging information is enabled, -but this can be inhibited with the negated form -@option{-fno-working-directory}. If the @option{-P} flag is present -in the command line, this option has no effect, since no @code{#line} -directives are emitted whatsoever. - -@item -idirafter @var{dir} -@opindex @code{idirafter @var{dir}} -@cindex preprocessing, include path -Search @var{dir} for include files, but do it after all directories -specified with @option{-I} and the standard system directories have -been exhausted. @var{dir} is treated as a system include directory. -If dir begins with @code{=}, then the @code{=} will be replaced by -the sysroot prefix; see @option{--sysroot} and @option{-isysroot}. - -@item -imultilib @var{dir} -@opindex @code{imultilib @var{dir}} -@cindex preprocessing, include path -Use @var{dir} as a subdirectory of the directory containing target-specific -C++ headers. - -@item -iprefix @var{prefix} -@opindex @code{iprefix @var{prefix}} -@cindex preprocessing, include path -Specify @var{prefix} as the prefix for subsequent @option{-iwithprefix} -options. If the @var{prefix} represents a directory, you should include -the final @code{'/'}. - -@item -isysroot @var{dir} -@opindex @code{isysroot @var{dir}} -@cindex preprocessing, include path -This option is like the @option{--sysroot} option, but applies only to -header files. See the @option{--sysroot} option for more information. - -@item -iquote @var{dir} -@opindex @code{iquote @var{dir}} -@cindex preprocessing, include path -Search @var{dir} only for header files requested with @code{#include "file"}; -they are not searched for @code{#include <file>}, before all directories -specified by @option{-I} and before the standard system directories. If -@var{dir} begins with @code{=}, then the @code{=} will be replaced by the -sysroot prefix; see @option{--sysroot} and @option{-isysroot}. - -@item -isystem @var{dir} -@opindex @code{isystem @var{dir}} -@cindex preprocessing, include path -Search @var{dir} for header files, after all directories specified by -@option{-I} but before the standard system directories. Mark it as a -system directory, so that it gets the same special treatment as is -applied to the standard system directories. If @var{dir} begins with -@code{=}, then the @code{=} will be replaced by the sysroot prefix; -see @option{--sysroot} and @option{-isysroot}. - -@item -nostdinc -@opindex @code{nostdinc} -Do not search the standard system directories for header files. Only -the directories you have specified with @option{-I} options (and the -directory of the current file, if appropriate) are searched. - -@item -undef -@opindex @code{undef} -Do not predefine any system-specific or GCC-specific macros. -The standard predefined macros remain defined. - -@item -A@var{predicate}=@var{answer} -@opindex @code{A@var{predicate}=@var{answer}} -@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, assertion -Cancel an assertion with the predicate @var{predicate} and answer @var{answer}. - -@item -C -@opindex @code{C} -@cindex preprocessing, keep comments -Do not discard comments. All comments are passed through to the output -file, except for comments in processed directives, which are deleted -along with the directive. - -You should be prepared for side effects when using @option{-C}; it causes -the preprocessor to treat comments as tokens in their own right. For example, -comments appearing at the start of what would be a directive line have the -effect of turning that line into an ordinary source line, since the first -token on the line is no longer a @code{'#'}. - -Warning: this currently handles C-Style comments only. The preprocessor -does not yet recognize Fortran-style comments. - -@item -CC -@opindex @code{CC} -@cindex preprocessing, keep comments -Do not discard comments, including during macro expansion. This is like -@option{-C}, except that comments contained within macros are also passed -through to the output file where the macro is expanded. - -In addition to the side-effects of the @option{-C} option, the @option{-CC} -option causes all C++-style comments inside a macro to be converted to C-style -comments. This is to prevent later use of that macro from inadvertently -commenting out the remainder of the source line. The @option{-CC} option -is generally used to support lint comments. - -Warning: this currently handles C- and C++-Style comments only. The -preprocessor does not yet recognize Fortran-style comments. - -@item -D@var{name} -@opindex @code{D@var{name}} -@cindex preprocessing, define macros -Predefine name as a macro, with definition @code{1}. - -@item -D@var{name}=@var{definition} -@opindex @code{D@var{name}=@var{definition}} -@cindex preprocessing, define macros -The contents of @var{definition} are tokenized and processed as if they -appeared during translation phase three in a @code{'#define'} directive. -In particular, the definition will be truncated by embedded newline -characters. - -If you are invoking the preprocessor from a shell or shell-like program -you may need to use the shell's quoting syntax to protect characters such -as spaces that have a meaning in the shell syntax. - -If you wish to define a function-like macro on the command line, write -its argument list with surrounding parentheses before the equals sign -(if any). Parentheses are meaningful to most shells, so you will need -to quote the option. With sh and csh, @code{-D'name(args...)=definition'} -works. - -@option{-D} and @option{-U} options are processed in the order they are -given on the command line. All -imacros file and -include file options -are processed after all -D and -U options. - -@item -H -@opindex @code{H} -Print the name of each header file used, in addition to other normal -activities. Each name is indented to show how deep in the @code{'#include'} -stack it is. - -@item -P -@opindex @code{P} -@cindex preprocessing, no linemarkers -Inhibit generation of linemarkers in the output from the preprocessor. -This might be useful when running the preprocessor on something that -is not C code, and will be sent to a program which might be confused -by the linemarkers. - -@item -U@var{name} -@opindex @code{U@var{name}} -@cindex preprocessing, undefine macros -Cancel any previous definition of @var{name}, either built in or provided -with a @option{-D} option. -@end table - - -@node Error and Warning Options -@section Options to request or suppress errors and warnings -@cindex options, warnings -@cindex options, errors -@cindex warnings, suppressing -@cindex messages, error -@cindex messages, warning -@cindex suppressing warnings - -Errors are diagnostic messages that report that the GNU Fortran compiler -cannot compile the relevant piece of source code. The compiler will -continue to process the program in an attempt to report further errors -to aid in debugging, but will not produce any compiled output. - -Warnings are diagnostic messages that report constructions which -are not inherently erroneous but which are risky or suggest there is -likely to be a bug in the program. Unless @option{-Werror} is specified, -they do not prevent compilation of the program. - -You can request many specific warnings with options beginning @option{-W}, -for example @option{-Wimplicit} to request warnings on implicit -declarations. Each of these specific warning options also has a -negative form beginning @option{-Wno-} to turn off warnings; -for example, @option{-Wno-implicit}. This manual lists only one of the -two forms, whichever is not the default. - -These options control the amount and kinds of errors and warnings produced -by GNU Fortran: - -@table @gcctabopt -@item -fmax-errors=@var{n} -@opindex @code{fmax-errors=}@var{n} -@cindex errors, limiting -Limits the maximum number of error messages to @var{n}, at which point -GNU Fortran bails out rather than attempting to continue processing the -source code. If @var{n} is 0, there is no limit on the number of error -messages produced. - -@item -fsyntax-only -@opindex @code{fsyntax-only} -@cindex syntax checking -Check the code for syntax errors, but do not actually compile it. This -will generate module files for each module present in the code, but no -other output file. - -@item -pedantic -@opindex @code{pedantic} -Issue warnings for uses of extensions to Fortran 95. -@option{-pedantic} also applies to C-language constructs where they -occur in GNU Fortran source files, such as use of @samp{\e} in a -character constant within a directive like @code{#include}. - -Valid Fortran 95 programs should compile properly with or without -this option. -However, without this option, certain GNU extensions and traditional -Fortran features are supported as well. -With this option, many of them are rejected. - -Some users try to use @option{-pedantic} to check programs for conformance. -They soon find that it does not do quite what they want---it finds some -nonstandard practices, but not all. -However, improvements to GNU Fortran in this area are welcome. - -This should be used in conjunction with @option{-std=f95}, -@option{-std=f2003} or @option{-std=f2008}. - -@item -pedantic-errors -@opindex @code{pedantic-errors} -Like @option{-pedantic}, except that errors are produced rather than -warnings. - -@item -Wall -@opindex @code{Wall} -@cindex all warnings -@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{-Wconversion}, @option{-Wsurprising}, @option{-Wc-binding-type}, -@option{-Wintrinsics-std}, @option{-Wno-tabs}, @option{-Wintrinsic-shadow}, -@option{-Wline-truncation}, @option{-Wtarget-lifetime}, -@option{-Wreal-q-constant} and @option{-Wunused}. - -@item -Waliasing -@opindex @code{Waliasing} -@cindex aliasing -@cindex warnings, aliasing -Warn about possible aliasing of dummy arguments. Specifically, it warns -if the same actual argument is associated with a dummy argument with -@code{INTENT(IN)} and a dummy argument with @code{INTENT(OUT)} in a call -with an explicit interface. - -The following example will trigger the warning. -@smallexample - interface - subroutine bar(a,b) - integer, intent(in) :: a - integer, intent(out) :: b - end subroutine - end interface - integer :: a - - call bar(a,a) -@end smallexample - -@item -Wampersand -@opindex @code{Wampersand} -@cindex warnings, ampersand -@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 -given in a continued character constant, GNU Fortran assumes continuation -at the first non-comment, non-whitespace character after the ampersand -that initiated the continuation. - -@item -Warray-temporaries -@opindex @code{Warray-temporaries} -@cindex warnings, array temporaries -Warn about array temporaries generated by the compiler. The information -generated by this warning is sometimes useful in optimization, in order to -avoid such temporaries. - -@item -Wc-binding-type -@opindex @code{Wc-binding-type} -@cindex warning, C binding type -Warn if the a variable might not be C interoperable. In particular, warn if -the variable has been declared using an intrinsic type with default kind -instead of using a kind parameter defined for C interoperability in the -intrinsic @code{ISO_C_Binding} module. This option is implied by -@option{-Wall}. - -@item -Wcharacter-truncation -@opindex @code{Wcharacter-truncation} -@cindex warnings, character truncation -Warn when a character assignment will truncate the assigned string. - -@item -Wline-truncation -@opindex @code{Wline-truncation} -@cindex warnings, line truncation -Warn when a source code line will be truncated. This option is -implied by @option{-Wall}. - -@item -Wconversion -@opindex @code{Wconversion} -@cindex warnings, conversion -@cindex conversion -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 -Wextra -@opindex @code{Wextra} -@cindex extra warnings -@cindex warnings, extra -Enables some warning options for usages of language features which -may be problematic. This currently includes @option{-Wcompare-reals} -and @option{-Wunused-parameter}. - -@item -Wimplicit-interface -@opindex @code{Wimplicit-interface} -@cindex warnings, implicit interface -Warn if a procedure is called without an explicit interface. -Note this only checks that an explicit interface is present. It does not -check that the declared interfaces are consistent across program units. - -@item -Wimplicit-procedure -@opindex @code{Wimplicit-procedure} -@cindex warnings, implicit procedure -Warn if a procedure is called that has neither an explicit interface -nor has been declared as @code{EXTERNAL}. - -@item -Wintrinsics-std -@opindex @code{Wintrinsics-std} -@cindex warnings, non-standard intrinsics -@cindex warnings, intrinsics of other standards -Warn if @command{gfortran} finds a procedure named like an intrinsic not -available in the currently selected standard (with @option{-std}) and treats -it as @code{EXTERNAL} procedure because of this. @option{-fall-intrinsics} can -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 -Produce a warning when ``suspicious'' code constructs are encountered. -While technically legal these usually indicate that an error has been made. - -This currently produces a warning under the following circumstances: - -@itemize @bullet -@item -An INTEGER SELECT construct has a CASE that can never be matched as its -lower value is greater than its upper value. - -@item -A LOGICAL SELECT construct has three CASE statements. - -@item -A TRANSFER specifies a source that is shorter than the destination. - -@item -The type of a function result is declared more than once with the same type. If -@option{-pedantic} or standard-conforming mode is enabled, this is an error. - -@item -A @code{CHARACTER} variable is declared with negative length. -@end itemize - -@item -Wtabs -@opindex @code{Wtabs} -@cindex warnings, tabs -@cindex tabulators -By default, tabs are accepted as whitespace, but tabs are not members -of the Fortran Character Set. For continuation lines, a tab followed -by a digit between 1 and 9 is supported. @option{-Wno-tabs} will cause -a warning to be issued if a tab is encountered. Note, @option{-Wno-tabs} -is active for @option{-pedantic}, @option{-std=f95}, @option{-std=f2003}, -@option{-std=f2008} and @option{-Wall}. - -@item -Wunderflow -@opindex @code{Wunderflow} -@cindex warnings, underflow -@cindex underflow -Produce a warning when numerical constant expressions are -encountered, which yield an UNDERFLOW during compilation. - -@item -Wintrinsic-shadow -@opindex @code{Wintrinsic-shadow} -@cindex warnings, intrinsic -@cindex intrinsic -Warn if a user-defined procedure or module procedure has the same name as an -intrinsic; in this case, an explicit interface or @code{EXTERNAL} or -@code{INTRINSIC} declaration might be needed to get calls later resolved to -the desired intrinsic/procedure. This option is implied by @option{-Wall}. - -@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 (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 @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 @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 -Wrealloc-lhs -@opindex @code{Wrealloc-lhs} -@cindex Reallocate the LHS in assignments, notification -Warn when the compiler might insert code to for allocation or reallocation of -an allocatable array variable of intrinsic type in intrinsic assignments. In -hot loops, the Fortran 2003 reallocation feature may reduce the performance. -If the array is already allocated with the correct shape, consider using a -whole-array array-spec (e.g. @code{(:,:,:)}) for the variable on the left-hand -side to prevent the reallocation check. Note that in some cases the warning -is shown, even if the compiler will optimize reallocation checks away. For -instance, when the right-hand side contains the same variable multiplied by -a scalar. See also @option{-frealloc-lhs}. - -@item -Wrealloc-lhs-all -@opindex @code{Wrealloc-lhs-all} -Warn when the compiler inserts code to for allocation or reallocation of an -allocatable variable; this includes scalars and derived types. - -@item -Wcompare-reals -@opindex @code{Wcompare-reals} -Warn when comparing real or complex types for equality or inequality. -This option is implied by @option{-Wextra}. - -@item -Wtarget-lifetime -@opindex @code{Wtargt-lifetime} -Warn if the pointer in a pointer assignment might be longer than the its -target. This option is implied by @option{-Wall}. - -@item -Werror -@opindex @code{Werror} -@cindex warnings, to errors -Turns all warnings into errors. -@end table - -@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. - -Some of these have no effect when compiling programs written in Fortran. - -@node Debugging Options -@section Options for debugging your program or GNU Fortran -@cindex options, debugging -@cindex debugging information options - -GNU Fortran has various special options that are used for debugging -either your program or the GNU Fortran compiler. - -@table @gcctabopt -@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 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} -Specify a list of floating point exception traps to enable. On most -systems, if a floating point exception occurs and the trap for that -exception is enabled, a SIGFPE signal will be sent and the program -being aborted, producing a core file useful for debugging. @var{list} -is a (possibly empty) comma-separated list of the following -exceptions: @samp{invalid} (invalid floating point operation, such as -@code{SQRT(-1.0)}), @samp{zero} (division by zero), @samp{overflow} -(overflow in a floating point operation), @samp{underflow} (underflow -in a floating point operation), @samp{inexact} (loss of precision -during operation), and @samp{denormal} (operation performed on a -denormal value). The first five exceptions correspond to the five -IEEE 754 exceptions, whereas the last one (@samp{denormal}) is not -part of the IEEE 754 standard but is available on some common -architectures such as x86. - -The first three exceptions (@samp{invalid}, @samp{zero}, and -@samp{overflow}) often indicate serious errors, and unless the program -has provisions for dealing with these exceptions, enabling traps for -these three exceptions is probably a good idea. - -Many, if not most, floating point operations incur loss of precision -due to rounding, and hence the @code{ffpe-trap=inexact} is likely to -be uninteresting in practice. - -By default no exception traps are enabled. - -@item -fno-backtrace -@opindex @code{fno-backtrace} -@cindex backtrace -@cindex trace -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, -gcc,Using the GNU Compiler Collection (GCC)}, for more information on -debugging options. - -@node Directory Options -@section Options for directory search -@cindex directory, options -@cindex options, directory search -@cindex search path -@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. - -It also affects the search paths used by @command{cpp} when used to preprocess -Fortran source. - -@table @gcctabopt -@item -I@var{dir} -@opindex @code{I}@var{dir} -@cindex directory, search paths for inclusion -@cindex inclusion, directory search paths for -@cindex search paths, for included files -@cindex paths, search -@cindex module search path -These affect interpretation of the @code{INCLUDE} directive -(as well as of the @code{#include} directive of the @command{cpp} -preprocessor). - -Also note that the general behavior of @option{-I} and -@code{INCLUDE} is pretty much the same as of @option{-I} with -@code{#include} in the @command{cpp} preprocessor, with regard to -looking for @file{header.gcc} files and other such things. - -This path is also used to search for @file{.mod} files when previously -compiled modules are required by a @code{USE} statement. - -@xref{Directory Options,,Options for Directory Search, -gcc,Using the GNU Compiler Collection (GCC)}, for information on the -@option{-I} option. - -@item -J@var{dir} -@opindex @code{J}@var{dir} -@opindex @code{M}@var{dir} -@cindex paths, search -@cindex module search path -This option specifies where to put @file{.mod} files for compiled modules. -It is also added to the list of directories to searched by an @code{USE} -statement. - -The default is the current directory. - -@item -fintrinsic-modules-path @var{dir} -@opindex @code{fintrinsic-modules-path} @var{dir} -@cindex paths, search -@cindex module search path -This option specifies the location of pre-compiled intrinsic modules, if -they are not in the default location expected by the compiler. -@end table - -@node Link Options -@section Influencing the linking step -@cindex options, linking -@cindex linking, static - -These options come into play when the compiler links object files into an -executable output file. They are meaningless if the compiler is not doing -a link step. - -@table @gcctabopt -@item -static-libgfortran -@opindex @code{static-libgfortran} -On systems that provide @file{libgfortran} as a shared and a static -library, this option forces the use of the static version. If no -shared version of @file{libgfortran} was built when the compiler was -configured, this option has no effect. -@end table - - -@node Runtime Options -@section Influencing runtime behavior -@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} -Specify the representation of data for unformatted files. Valid -values for conversion are: @samp{native}, the default; @samp{swap}, -swap between big- and little-endian; @samp{big-endian}, use big-endian -representation for unformatted files; @samp{little-endian}, use little-endian -representation for unformatted files. - -@emph{This option has an effect only when used in the main program. -The @code{CONVERT} specifier and the GFORTRAN_CONVERT_UNIT environment -variable override the default specified by @option{-fconvert}.} - -@item -frecord-marker=@var{length} -@opindex @code{frecord-marker=}@var{length} -Specify the length of record markers for unformatted files. -Valid values for @var{length} are 4 and 8. Default is 4. -@emph{This is different from previous versions of @command{gfortran}}, -which specified a default record marker length of 8 on most -systems. If you want to read or write files compatible -with earlier versions of @command{gfortran}, use @option{-frecord-marker=8}. - -@item -fmax-subrecord-length=@var{length} -@opindex @code{fmax-subrecord-length=}@var{length} -Specify the maximum length for a subrecord. The maximum permitted -value for length is 2147483639, which is also the default. Only -really useful for use by the gfortran testsuite. - -@item -fsign-zero -@opindex @code{fsign-zero} -When enabled, floating point numbers of value zero with the sign bit set -are written as negative number in formatted output and treated as -negative in the @code{SIGN} intrinsic. @option{-fno-sign-zero} does not -print the negative sign of zero values (or values rounded to zero for I/O) -and regards zero as positive number in the @code{SIGN} intrinsic for -compatibility with Fortran 77. The default is @option{-fsign-zero}. -@end table - -@node Code Gen Options -@section Options for code generation conventions -@cindex code generation, conventions -@cindex options, code generation -@cindex options, run-time - -These machine-independent options control the interface conventions -used in code generation. - -Most of them have both positive and negative forms; the negative form -of @option{-ffoo} would be @option{-fno-foo}. In the table below, only -one of the forms is listed---the one which is not the default. You -can figure out the other form by either removing @option{no-} or adding -it. - -@table @gcctabopt -@item -fno-automatic -@opindex @code{fno-automatic} -@cindex @code{SAVE} statement -@cindex statement, @code{SAVE} -Treat each program unit (except those marked as RECURSIVE) as if the -@code{SAVE} statement were specified for every local variable and array -referenced in it. Does not affect common blocks. (Some Fortran compilers -provide this option under the name @option{-static} or @option{-save}.) -The default, which is @option{-fautomatic}, uses the stack for local -variables smaller than the value given by @option{-fmax-stack-var-size}. -Use the option @option{-frecursive} to use no static memory. - -@item -ff2c -@opindex ff2c -@cindex calling convention -@cindex @command{f2c} calling convention -@cindex @command{g77} calling convention -@cindex libf2c calling convention -Generate code designed to be compatible with code generated -by @command{g77} and @command{f2c}. - -The calling conventions used by @command{g77} (originally implemented -in @command{f2c}) require functions that return type -default @code{REAL} to actually return the C type @code{double}, and -functions that return type @code{COMPLEX} to return the values via an -extra argument in the calling sequence that points to where to -store the return value. Under the default GNU calling conventions, such -functions simply return their results as they would in GNU -C---default @code{REAL} functions return the C type @code{float}, and -@code{COMPLEX} functions return the GNU C type @code{complex}. -Additionally, this option implies the @option{-fsecond-underscore} -option, unless @option{-fno-second-underscore} is explicitly requested. - -This does not affect the generation of code that interfaces with -the @command{libgfortran} library. - -@emph{Caution:} It is not a good idea to mix Fortran code compiled with -@option{-ff2c} with code compiled with the default @option{-fno-f2c} -calling conventions as, calling @code{COMPLEX} or default @code{REAL} -functions between program parts which were compiled with different -calling conventions will break at execution time. - -@emph{Caution:} This will break code which passes intrinsic functions -of type default @code{REAL} or @code{COMPLEX} as actual arguments, as -the library implementations use the @option{-fno-f2c} calling conventions. - -@item -fno-underscoring -@opindex @code{fno-underscoring} -@cindex underscore -@cindex symbol names, underscores -@cindex transforming symbol names -@cindex symbol names, transforming -Do not transform names of entities specified in the Fortran -source file by appending underscores to them. - -With @option{-funderscoring} in effect, GNU Fortran appends one -underscore to external names with no underscores. This is done to ensure -compatibility with code produced by many UNIX Fortran compilers. - -@emph{Caution}: The default behavior of GNU Fortran is -incompatible with @command{f2c} and @command{g77}, please use the -@option{-ff2c} option if you want object files compiled with -GNU Fortran to be compatible with object code created with these -tools. - -Use of @option{-fno-underscoring} is not recommended unless you are -experimenting with issues such as integration of GNU Fortran into -existing system environments (vis-@`{a}-vis existing libraries, tools, -and so on). - -For example, with @option{-funderscoring}, and assuming other defaults like -@option{-fcase-lower} and that @code{j()} and @code{max_count()} are -external functions while @code{my_var} and @code{lvar} are local variables, -a statement like -@smallexample -I = J() + MAX_COUNT (MY_VAR, LVAR) -@end smallexample -@noindent -is implemented as something akin to: -@smallexample -i = j_() + max_count__(&my_var__, &lvar); -@end smallexample - -With @option{-fno-underscoring}, the same statement is implemented as: - -@smallexample -i = j() + max_count(&my_var, &lvar); -@end smallexample - -Use of @option{-fno-underscoring} allows direct specification of -user-defined names while debugging and when interfacing GNU Fortran -code with other languages. - -Note that just because the names match does @emph{not} mean that the -interface implemented by GNU Fortran for an external name matches the -interface implemented by some other language for that same name. -That is, getting code produced by GNU Fortran to link to code produced -by some other compiler using this or any other method can be only a -small part of the overall solution---getting the code generated by -both compilers to agree on issues other than naming can require -significant effort, and, unlike naming disagreements, linkers normally -cannot detect disagreements in these other areas. - -Also, note that with @option{-fno-underscoring}, the lack of appended -underscores introduces the very real possibility that a user-defined -external name will conflict with a name in a system library, which -could make finding unresolved-reference bugs quite difficult in some -cases---they might occur at program run time, and show up only as -buggy behavior at run time. - -In future versions of GNU Fortran we hope to improve naming and linking -issues so that debugging always involves using the names as they appear -in the source, even if the names as seen by the linker are mangled to -prevent accidental linking between procedures with incompatible -interfaces. - -@item -fno-whole-file -@opindex @code{fno-whole-file} -This flag causes the compiler to resolve and translate each procedure in -a file separately. - -By default, the whole file is parsed and placed in a single front-end tree. -During resolution, in addition to all the usual checks and fixups, references -to external procedures that are in the same file effect resolution of -that procedure, if not already done, and a check of the interfaces. The -dependences are resolved by changing the order in which the file is -translated into the backend tree. Thus, a procedure that is referenced -is translated before the reference and the duplication of backend tree -declarations eliminated. - -The @option{-fno-whole-file} option is deprecated and may lead to wrong code. - -@item -fsecond-underscore -@opindex @code{fsecond-underscore} -@cindex underscore -@cindex symbol names, underscores -@cindex transforming symbol names -@cindex symbol names, transforming -@cindex @command{f2c} calling convention -@cindex @command{g77} calling convention -@cindex libf2c calling convention -By default, GNU Fortran appends an underscore to external -names. If this option is used GNU Fortran appends two -underscores to names with underscores and one underscore to external names -with no underscores. GNU Fortran also appends two underscores to -internal names with underscores to avoid naming collisions with external -names. - -This option has no effect if @option{-fno-underscoring} is -in effect. It is implied by the @option{-ff2c} option. - -Otherwise, with this option, an external name such as @code{MAX_COUNT} -is implemented as a reference to the link-time external symbol -@code{max_count__}, instead of @code{max_count_}. This is required -for compatibility with @command{g77} and @command{f2c}, and is implied -by use of the @option{-ff2c} option. - -@item -fcoarray=@var{<keyword>} -@opindex @code{fcoarray} -@cindex coarrays - -@table @asis -@item @samp{none} -Disable coarray support; using coarray declarations and image-control -statements will produce a compile-time error. (Default) - -@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 - - -@item -fcheck=@var{<keyword>} -@opindex @code{fcheck} -@cindex array, bounds checking -@cindex bounds checking -@cindex pointer checking -@cindex memory checking -@cindex range checking -@cindex subscript checking -@cindex checking subscripts -@cindex run-time checking -@cindex checking array temporaries - -Enable the generation of run-time checks; the argument shall be -a comma-delimited list of the following keywords. - -@table @asis -@item @samp{all} -Enable all run-time test of @option{-fcheck}. - -@item @samp{array-temps} -Warns at run time when for passing an actual argument a temporary array -had to be generated. The information generated by this warning is -sometimes useful in optimization, in order to avoid such temporaries. - -Note: The warning is only printed once per location. - -@item @samp{bounds} -Enable generation of run-time checks for array subscripts -and against the declared minimum and maximum values. It also -checks array indices for assumed and deferred -shape arrays against the actual allocated bounds and ensures that all string -lengths are equal for character array constructors without an explicit -typespec. - -Some checks require that @option{-fcheck=bounds} is set for -the compilation of the main program. - -Note: In the future this may also include other forms of checking, e.g., -checking substring references. - -@item @samp{do} -Enable generation of run-time checks for invalid modification of loop -iteration variables. - -@item @samp{mem} -Enable generation of run-time checks for memory allocation. -Note: This option does not affect explicit allocations using the -@code{ALLOCATE} statement, which will be always checked. - -@item @samp{pointer} -Enable generation of run-time checks for pointers and allocatables. - -@item @samp{recursion} -Enable generation of run-time checks for recursively called subroutines and -functions which are not marked as recursive. See also @option{-frecursive}. -Note: This check does not work for OpenMP programs and is disabled if used -together with @option{-frecursive} and @option{-fopenmp}. -@end table - - -@item -fbounds-check -@opindex @code{fbounds-check} -@c Note: This option is also referred in gcc's manpage -Deprecated alias for @option{-fcheck=bounds}. - -@item -fcheck-array-temporaries -@opindex @code{fcheck-array-temporaries} -Deprecated alias for @option{-fcheck=array-temps}. - -@item -fmax-array-constructor=@var{n} -@opindex @code{fmax-array-constructor} -This option can be used to increase the upper limit permitted in -array constructors. The code below requires this option to expand -the array at compile time. - -@smallexample -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 -large object files.} - -The default value for @var{n} is 65535. - - -@item -fmax-stack-var-size=@var{n} -@opindex @code{fmax-stack-var-size} -This option specifies the size in bytes of the largest array that will be put -on the stack; if the size is exceeded static memory is used (except in -procedures marked as RECURSIVE). Use the option @option{-frecursive} to -allow for recursive procedures which do not have a RECURSIVE attribute or -for parallel programs. Use @option{-fno-automatic} to never use the stack. - -This option currently only affects local arrays declared with constant -bounds, and may not apply to all character variables. -Future versions of GNU Fortran may improve this behavior. - -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 is possible that you will have to extend your runtime -limits for stack memory on some operating systems. This flag is enabled -by default at optimization level @option{-Ofast}. - - -@item -fpack-derived -@opindex @code{fpack-derived} -@cindex structure packing -This option tells GNU Fortran to pack derived type members as closely as -possible. Code compiled with this option is likely to be incompatible -with code compiled without this option, and may execute slower. - -@item -frepack-arrays -@opindex @code{frepack-arrays} -@cindex repacking arrays -In some circumstances GNU Fortran may pass assumed shape array -sections via a descriptor describing a noncontiguous area of memory. -This option adds code to the function prologue to repack the data into -a contiguous block at runtime. - -This should result in faster accesses to the array. However it can introduce -significant overhead to the function call, especially when the passed data -is noncontiguous. - -@item -fshort-enums -@opindex @code{fshort-enums} -This option is provided for interoperability with C code that was -compiled with the @option{-fshort-enums} option. It will make -GNU Fortran choose the smallest @code{INTEGER} kind a given -enumerator set will fit in, and give all its enumerators this kind. - -@item -fexternal-blas -@opindex @code{fexternal-blas} -This option will make @command{gfortran} generate calls to BLAS functions -for some matrix operations like @code{MATMUL}, instead of using our own -algorithms, if the size of the matrices involved is larger than a given -limit (see @option{-fblas-matmul-limit}). This may be profitable if an -optimized vendor BLAS library is available. The BLAS library will have -to be specified at link time. - -@item -fblas-matmul-limit=@var{n} -@opindex @code{fblas-matmul-limit} -Only significant when @option{-fexternal-blas} is in effect. -Matrix multiplication of matrices with size larger than (or equal to) @var{n} -will be performed by calls to BLAS functions, while others will be -handled by @command{gfortran} internal algorithms. If the matrices -involved are not square, the size comparison is performed using the -geometric mean of the dimensions of the argument and result matrices. - -The default value for @var{n} is 30. - -@item -frecursive -@opindex @code{frecursive} -Allow indirect recursion by forcing all local arrays to be allocated -on the stack. This flag cannot be used together with -@option{-fmax-stack-var-size=} or @option{-fno-automatic}. - -@item -finit-local-zero -@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} -@opindex @code{finit-logical} -@opindex @code{finit-character} -The @option{-finit-local-zero} option instructs the compiler to -initialize local @code{INTEGER}, @code{REAL}, and @code{COMPLEX} -variables to zero, @code{LOGICAL} variables to false, and -@code{CHARACTER} variables to a string of null bytes. Finer-grained -initialization options are provided by the -@option{-finit-integer=@var{n}}, -@option{-finit-real=@var{<zero|inf|-inf|nan|snan>}} (which also initializes -the real and imaginary parts of local @code{COMPLEX} variables), -@option{-finit-logical=@var{<true|false>}}, and -@option{-finit-character=@var{n}} (where @var{n} is an ASCII character -value) options. These options do not initialize -@itemize @bullet -@item -allocatable arrays -@item -components of derived type variables -@item -variables that appear in an @code{EQUIVALENCE} statement. -@end itemize -(These limitations may be removed in future releases). - -Note that the @option{-finit-real=nan} option initializes @code{REAL} -and @code{COMPLEX} variables with a quiet NaN. For a signalling NaN -use @option{-finit-real=snan}; note, however, that compile-time -optimizations may convert them into quiet NaN and that trapping -needs to be enabled (e.g. via @option{-ffpe-trap}). - -Finally, note that enabling any of the @option{-finit-*} options will -silence warnings that would have been emitted by @option{-Wuninitialized} -for the affected local variables. - -@item -falign-commons -@opindex @code{falign-commons} -@cindex alignment of @code{COMMON} blocks -By default, @command{gfortran} enforces proper alignment of all variables in a -@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 @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 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 @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. 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. See -also @option{-Wrealloc-lhs}. - -@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, -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. - -@c man end - -@node Environment Variables -@section Environment variables affecting @command{gfortran} -@cindex environment variable - -@c man begin ENVIRONMENT - -The @command{gfortran} compiler currently does not make use of any environment -variables to control its operation above and beyond those -that affect the operation of @command{gcc}. - -@xref{Environment Variables,,Environment Variables Affecting GCC, -gcc,Using the GNU Compiler Collection (GCC)}, for information on environment -variables. - -@xref{Runtime}, for environment variables that affect the -run-time behavior of programs compiled with GNU Fortran. -@c man end |