CbC/CbC_gcc: gcc/doc/gfortran.1 comparison

comparison gcc/doc/gfortran.1 @ 0:a06113de4d67

first commit

author	kent <kent@cr.ie.u-ryukyu.ac.jp>
date	Fri, 17 Jul 2009 14:47:48 +0900
parents
children	58ad6c70ea60

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+:a06113de4d67
+.\" Automatically generated by Pod::Man 2.16 (Pod::Simple 3.07)
+.\"
+.\" Standard preamble:
+.\" ========================================================================
+.de Sh \" Subsection heading
+.br
+.if t .Sp
+.ne 5
+.PP
+\fB\\$1\fR
+.PP
+..
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+.\}
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+.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
+.ds ae a\h'-(\w'a'u*4/10)'e
+.ds Ae A\h'-(\w'A'u*4/10)'E
+.    \" corrections for vroff
+.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
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+.    \" for low resolution devices (crt and lpr)
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+\{\
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+.    ds ae ae
+.    ds Ae AE
+.\}
+.rm #[ #] #H #V #F C
+.\" ========================================================================
+.\"
+.IX Title "GFORTRAN 1"
+.TH GFORTRAN 1 "2009-04-21" "gcc-4.4.0" "GNU"
+.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
+.\" way too many mistakes in technical documents.
+.if n .ad l
+.nh
+.SH "NAME"
+gfortran \- GNU Fortran compiler
+.SH "SYNOPSIS"
+.IX Header "SYNOPSIS"
+gfortran [\fB\-c\fR|\fB\-S\fR|\fB\-E\fR]
+[\fB\-g\fR] [\fB\-pg\fR] [\fB\-O\fR\fIlevel\fR]
+[\fB\-W\fR\fIwarn\fR...] [\fB\-pedantic\fR]
+[\fB\-I\fR\fIdir\fR...] [\fB\-L\fR\fIdir\fR...]
+[\fB\-D\fR\fImacro\fR[=\fIdefn\fR]...] [\fB\-U\fR\fImacro\fR]
+[\fB\-f\fR\fIoption\fR...]
+[\fB\-m\fR\fImachine-option\fR...]
+[\fB\-o\fR \fIoutfile\fR] \fIinfile\fR...
+.PP
+Only the most useful options are listed here; see below for the
+remainder.
+.SH "DESCRIPTION"
+.IX Header "DESCRIPTION"
+The \fBgfortran\fR command supports all the options supported by the
+\&\fBgcc\fR command.  Only options specific to \s-1GNU\s0 Fortran are documented here.
+.PP
+All \s-1GCC\s0 and \s-1GNU\s0 Fortran options
+are accepted both by \fBgfortran\fR and by \fBgcc\fR
+(as well as any other drivers built at the same time,
+such as \fBg++\fR),
+since adding \s-1GNU\s0 Fortran to the \s-1GCC\s0 distribution
+enables acceptance of \s-1GNU\s0 Fortran options
+by all of the relevant drivers.
+.PP
+In some cases, options have positive and negative forms;
+the negative form of \fB\-ffoo\fR would be \fB\-fno\-foo\fR.
+This manual documents only one of these two forms, whichever
+one is not the default.
+.SH "OPTIONS"
+.IX Header "OPTIONS"
+Here is a summary of all the options specific to \s-1GNU\s0 Fortran, grouped
+by type.  Explanations are in the following sections.
+.IP "\fIFortran Language Options\fR" 4
+.IX Item "Fortran Language Options"
+\&\fB\-fall\-intrinsics  \-ffree\-form  \-fno\-fixed\-form
+\&\-fdollar\-ok  \-fimplicit\-none  \-fmax\-identifier\-length
+\&\-std=\fR\fIstd\fR \fB\-fd\-lines\-as\-code  \-fd\-lines\-as\-comments
+\&\-ffixed\-line\-length\-\fR\fIn\fR  \fB\-ffixed\-line\-length\-none
+\&\-ffree\-line\-length\-\fR\fIn\fR  \fB\-ffree\-line\-length\-none
+\&\-fdefault\-double\-8  \-fdefault\-integer\-8  \-fdefault\-real\-8
+\&\-fcray\-pointer  \-fopenmp  \-fno\-range\-check \-fbackslash \-fmodule\-private\fR
+.IP "\fIPreprocessing Options\fR" 4
+.IX Item "Preprocessing Options"
+\&\fB\-cpp \-dD \-dI \-dM \-dN \-dU \-fworking\-directory
+\&\-imultilib\fR \fIdir\fR \fB\-iprefix\fR \fIfile\fR \fB\-isysroot\fR \fIdir\fR
+\&\fB\-iquote \-isystem\fR \fIdir\fR \fB\-nocpp \-nostdinc \-undef
+\&\-A\fR\fIquestion\fR\fB=\fR\fIanswer\fR \fB\-A\-\fR\fIquestion\fR[\fB=\fR\fIanswer\fR]
+\&\fB\-C \-CC \-D\fR\fImacro\fR[\fB=\fR\fIdefn\fR] \fB\-U\fR\fImacro\fR \fB\-H \-P\fR
+.IP "\fIError and Warning Options\fR" 4
+.IX Item "Error and Warning Options"
+\&\fB\-fmax\-errors=\fR\fIn\fR
+\&\fB\-fsyntax\-only  \-pedantic  \-pedantic\-errors
+\&\-Wall  \-Waliasing  \-Wampersand  \-Warray\-bounds \-Wcharacter\-truncation
+\&\-Wconversion \-Wimplicit\-interface  \-Wline\-truncation  \-Wintrinsics\-std
+\&\-Wsurprising \-Wno\-tabs  \-Wunderflow \-Wunused\-parameter \-Wintrinsics\-shadow
+\&\-Wno\-align\-commons\fR
+.IP "\fIDebugging Options\fR" 4
+.IX Item "Debugging Options"
+\&\fB\-fdump\-parse\-tree  \-ffpe\-trap=\fR\fIlist\fR
+\&\fB\-fdump\-core \-fbacktrace\fR
+.IP "\fIDirectory Options\fR" 4
+.IX Item "Directory Options"
+\&\fB\-I\fR\fIdir\fR  \fB\-J\fR\fIdir\fR  \fB\-M\fR\fIdir\fR
+\&\fB\-fintrinsic\-modules\-path\fR \fIdir\fR
+.IP "\fILink Options\fR" 4
+.IX Item "Link Options"
+\&\fB\-static\-libgfortran\fR
+.IP "\fIRuntime Options\fR" 4
+.IX Item "Runtime Options"
+\&\fB\-fconvert=\fR\fIconversion\fR  \fB\-fno\-range\-check
+\&\-frecord\-marker=\fR\fIlength\fR   \fB\-fmax\-subrecord\-length=\fR\fIlength\fR
+\&\fB\-fsign\-zero\fR
+.IP "\fICode Generation Options\fR" 4
+.IX Item "Code Generation Options"
+\&\fB\-fno\-automatic  \-ff2c  \-fno\-underscoring
+\&\-fsecond\-underscore
+\&\-fbounds\-check \-fcheck\-array\-temporaries  \-fmax\-array\-constructor =\fR\fIn\fR
+\&\fB\-fmax\-stack\-var\-size=\fR\fIn\fR
+\&\fB\-fpack\-derived  \-frepack\-arrays  \-fshort\-enums  \-fexternal\-blas
+\&\-fblas\-matmul\-limit=\fR\fIn\fR \fB\-frecursive \-finit\-local\-zero
+\&\-finit\-integer=\fR\fIn\fR \fB\-finit\-real=\fR\fI<zero|inf|\-inf|nan>\fR
+\&\fB\-finit\-logical=\fR\fI<true|false>\fR \fB\-finit\-character=\fR\fIn\fR \fB\-fno\-align\-commons\fR
+.Sh "Options controlling Fortran dialect"
+.IX Subsection "Options controlling Fortran dialect"
+The following options control the details of the Fortran dialect
+accepted by the compiler:
+.IP "\fB\-ffree\-form\fR" 4
+.IX Item "-ffree-form"
+.PD 0
+.IP "\fB\-ffixed\-form\fR" 4
+.IX Item "-ffixed-form"
+.PD
+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.
+.IP "\fB\-fall\-intrinsics\fR" 4
+.IX Item "-fall-intrinsics"
+This option causes all intrinsic procedures (including the GNU-specific
+extensions) to be accepted.  This can be useful with \fB\-std=f95\fR to
+force standard-compliance but get access to the full range of intrinsics
+available with \fBgfortran\fR.  As a consequence, \fB\-Wintrinsics\-std\fR
+will be ignored and no user-defined procedure with the same name as any
+intrinsic will be called except when it is explicitly declared \f(CW\*(C`EXTERNAL\*(C'\fR.
+.IP "\fB\-fd\-lines\-as\-code\fR" 4
+.IX Item "-fd-lines-as-code"
+.PD 0
+.IP "\fB\-fd\-lines\-as\-comments\fR" 4
+.IX Item "-fd-lines-as-comments"
+.PD
+Enable special treatment for lines beginning with \f(CW\*(C`d\*(C'\fR or \f(CW\*(C`D\*(C'\fR
+in fixed form sources.  If the \fB\-fd\-lines\-as\-code\fR option is
+given they are treated as if the first column contained a blank.  If the
+\&\fB\-fd\-lines\-as\-comments\fR option is given, they are treated as
+comment lines.
+.IP "\fB\-fdefault\-double\-8\fR" 4
+.IX Item "-fdefault-double-8"
+Set the \f(CW\*(C`DOUBLE PRECISION\*(C'\fR type to an 8 byte wide type.  If
+\&\fB\-fdefault\-real\-8\fR is given, \f(CW\*(C`DOUBLE PRECISION\*(C'\fR would
+instead be promoted to 16 bytes if possible, and \fB\-fdefault\-double\-8\fR
+can be used to prevent this.  The kind of real constants like \f(CW\*(C`1.d0\*(C'\fR will
+not be changed by \fB\-fdefault\-real\-8\fR though, so also
+\&\fB\-fdefault\-double\-8\fR does not affect it.
+.IP "\fB\-fdefault\-integer\-8\fR" 4
+.IX Item "-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 \f(CW42\fR.
+.IP "\fB\-fdefault\-real\-8\fR" 4
+.IX Item "-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 \f(CW1.0\fR, and does promote
+the default width of \f(CW\*(C`DOUBLE PRECISION\*(C'\fR to 16 bytes if possible, unless
+\&\f(CW\*(C`\-fdefault\-double\-8\*(C'\fR is given, too.
+.IP "\fB\-fdollar\-ok\fR" 4
+.IX Item "-fdollar-ok"
+Allow \fB$\fR as a valid character in a symbol name.
+.IP "\fB\-fbackslash\fR" 4
+.IX Item "-fbackslash"
+Change the interpretation of backslashes in string literals from a single
+backslash character to \*(L"C\-style\*(R" escape characters. The following
+combinations are expanded \f(CW\*(C`\ea\*(C'\fR, \f(CW\*(C`\eb\*(C'\fR, \f(CW\*(C`\ef\*(C'\fR, \f(CW\*(C`\en\*(C'\fR,
+\&\f(CW\*(C`\er\*(C'\fR, \f(CW\*(C`\et\*(C'\fR, \f(CW\*(C`\ev\*(C'\fR, \f(CW\*(C`\e\e\*(C'\fR, and \f(CW\*(C`\e0\*(C'\fR to the \s-1ASCII\s0
+characters alert, backspace, form feed, newline, carriage return,
+horizontal tab, vertical tab, backslash, and \s-1NUL\s0, respectively.
+Additionally, \f(CW\*(C`\ex\*(C'\fR\fInn\fR, \f(CW\*(C`\eu\*(C'\fR\fInnnn\fR and
+\&\f(CW\*(C`\eU\*(C'\fR\fInnnnnnnn\fR (where each \fIn\fR is a hexadecimal digit) are
+translated into the Unicode characters corresponding to the specified code
+points. All other combinations of a character preceded by \e are
+unexpanded.
+.IP "\fB\-fmodule\-private\fR" 4
+.IX Item "-fmodule-private"
+Set the default accessibility of module entities to \f(CW\*(C`PRIVATE\*(C'\fR.
+Use-associated entities will not be accessible unless they are explicitly
+declared as \f(CW\*(C`PUBLIC\*(C'\fR.
+.IP "\fB\-ffixed\-line\-length\-\fR\fIn\fR" 4
+.IX Item "-ffixed-line-length-n"
+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.
+.Sp
+Popular values for \fIn\fR include 72 (the
+standard and the default), 80 (card image), and 132 (corresponding
+to \*(L"extended-source\*(R" options in some popular compilers).
+\&\fIn\fR may also be \fBnone\fR, meaning that the entire line is meaningful
+and that continued character constants never have implicit spaces appended
+to them to fill out the line.
+\&\fB\-ffixed\-line\-length\-0\fR means the same thing as
+\&\fB\-ffixed\-line\-length\-none\fR.
+.IP "\fB\-ffree\-line\-length\-\fR\fIn\fR" 4
+.IX Item "-ffree-line-length-n"
+Set column after which characters are ignored in typical free-form
+lines in the source file. The default value is 132.
+\&\fIn\fR may be \fBnone\fR, meaning that the entire line is meaningful.
+\&\fB\-ffree\-line\-length\-0\fR means the same thing as
+\&\fB\-ffree\-line\-length\-none\fR.
+.IP "\fB\-fmax\-identifier\-length=\fR\fIn\fR" 4
+.IX Item "-fmax-identifier-length=n"
+Specify the maximum allowed identifier length. Typical values are
+31 (Fortran 95) and 63 (Fortran 2003 and Fortran 2008).
+.IP "\fB\-fimplicit\-none\fR" 4
+.IX Item "-fimplicit-none"
+Specify that no implicit typing is allowed, unless overridden by explicit
+\&\f(CW\*(C`IMPLICIT\*(C'\fR statements.  This is the equivalent of adding
+\&\f(CW\*(C`implicit none\*(C'\fR to the start of every procedure.
+.IP "\fB\-fcray\-pointer\fR" 4
+.IX Item "-fcray-pointer"
+Enable the Cray pointer extension, which provides C\-like pointer
+functionality.
+.IP "\fB\-fopenmp\fR" 4
+.IX Item "-fopenmp"
+Enable the OpenMP extensions.  This includes OpenMP \f(CW\*(C`!$omp\*(C'\fR directives
+in free form
+and \f(CW\*(C`c$omp\*(C'\fR, \f(CW*$omp\fR and \f(CW\*(C`!$omp\*(C'\fR directives in fixed form,
+\&\f(CW\*(C`!$\*(C'\fR conditional compilation sentinels in free form
+and \f(CW\*(C`c$\*(C'\fR, \f(CW\*(C`*$\*(C'\fR and \f(CW\*(C`!$\*(C'\fR sentinels in fixed form,
+and when linking arranges for the OpenMP runtime library to be linked
+in.  The option \fB\-fopenmp\fR implies \fB\-frecursive\fR.
+.IP "\fB\-fno\-range\-check\fR" 4
+.IX Item "-fno-range-check"
+Disable range checking on results of simplification of constant
+expressions during compilation.  For example, \s-1GNU\s0 Fortran will give
+an error at compile time when simplifying \f(CW\*(C`a = 1. / 0\*(C'\fR.
+With this option, no error will be given and \f(CW\*(C`a\*(C'\fR will be assigned
+the value \f(CW\*(C`+Infinity\*(C'\fR.  If an expression evaluates to a value
+outside of the relevant range of [\f(CW\*(C`\-HUGE()\*(C'\fR:\f(CW\*(C`HUGE()\*(C'\fR],
+then the expression will be replaced by \f(CW\*(C`\-Inf\*(C'\fR or \f(CW\*(C`+Inf\*(C'\fR
+as appropriate.
+Similarly, \f(CW\*(C`DATA i/Z\*(AqFFFFFFFF\*(Aq/\*(C'\fR will result in an integer overflow
+on most systems, but with \fB\-fno\-range\-check\fR the value will
+\&\*(L"wrap around\*(R" and \f(CW\*(C`i\*(C'\fR will be initialized to \-1 instead.
+.IP "\fB\-std=\fR\fIstd\fR" 4
+.IX Item "-std=std"
+Specify the standard to which the program is expected to conform, which
+may be one of \fBf95\fR, \fBf2003\fR, \fBf2008\fR, \fBgnu\fR, or
+\&\fBlegacy\fR.  The default value for \fIstd\fR is \fBgnu\fR, which
+specifies a superset of the Fortran 95 standard that includes all of the
+extensions supported by \s-1GNU\s0 Fortran, although warnings will be given for
+obsolete extensions not recommended for use in new code.  The
+\&\fBlegacy\fR value is equivalent but without the warnings for obsolete
+extensions, and may be useful for old non-standard programs.  The
+\&\fBf95\fR, \fBf2003\fR and \fBf2008\fR 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.
+.Sh "Enable and customize preprocessing"
+.IX Subsection "Enable and customize preprocessing"
+Preprocessor related options. See section
+\&\fBPreprocessing and conditional compilation\fR for more detailed
+information on preprocessing in \fBgfortran\fR.
+.IP "\fB\-cpp\fR" 4
+.IX Item "-cpp"
+.PD 0
+.IP "\fB\-nocpp\fR" 4
+.IX Item "-nocpp"
+.PD
+Enable preprocessing. The preprocessor is automatically invoked if
+the file extension is \fI.fpp\fR, \fI.FPP\fR,  \fI.F\fR, \fI.FOR\fR,
+\&\fI.FTN\fR, \fI.F90\fR, \fI.F95\fR, \fI.F03\fR or \fI.F08\fR. Use
+this option to manually enable preprocessing of any kind of Fortran file.
+.Sp
+To disable preprocessing of files with any of the above listed extensions,
+use the negative form: \fB\-nocpp\fR.
+.Sp
+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.
+.IP "\fB\-dM\fR" 4
+.IX Item "-dM"
+Instead of the normal output, generate a list of \f(CW\*(Aq#define\*(Aq\fR
+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 \fIfoo.f90\fR, the command
+.Sp
+.Vb 1
+\&          touch foo.f90; gfortran \-cpp \-dM foo.f90
+.Ve
+.Sp
+will show all the predefined macros.
+.IP "\fB\-dD\fR" 4
+.IX Item "-dD"
+Like \fB\-dM\fR except in two respects: it does not include the
+predefined macros, and it outputs both the \f(CW\*(C`#define\*(C'\fR directives
+and the result of preprocessing. Both kinds of output go to the
+standard output file.
+.IP "\fB\-dN\fR" 4
+.IX Item "-dN"
+Like \fB\-dD\fR, but emit only the macro names, not their expansions.
+.IP "\fB\-dU\fR" 4
+.IX Item "-dU"
+Like \fBdD\fR 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 \f(CW\*(Aq#undef\*(Aq\fR
+directives are also output for macros tested but undefined at the time.
+.IP "\fB\-dI\fR" 4
+.IX Item "-dI"
+Output \f(CW\*(Aq#include\*(Aq\fR directives in addition to the result
+of preprocessing.
+.IP "\fB\-fworking\-directory\fR" 4
+.IX Item "-fworking-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. \s-1GCC\s0 will use this directory,
+when it's 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
+\&\fB\-fno\-working\-directory\fR. If the \fB\-P\fR flag is present
+in the command line, this option has no effect, since no \f(CW\*(C`#line\*(C'\fR
+directives are emitted whatsoever.
+.IP "\fB\-idirafter\fR \fIdir\fR" 4
+.IX Item "-idirafter dir"
+Search \fIdir\fR for include files, but do it after all directories
+specified with \fB\-I\fR and the standard system directories have
+been exhausted. \fIdir\fR is treated as a system include directory.
+If dir begins with \f(CW\*(C`=\*(C'\fR, then the \f(CW\*(C`=\*(C'\fR will be replaced by
+the sysroot prefix; see \fB\-\-sysroot\fR and \fB\-isysroot\fR.
+.IP "\fB\-imultilib\fR \fIdir\fR" 4
+.IX Item "-imultilib dir"
+Use \fIdir\fR as a subdirectory of the directory containing target-specific
+\&\*(C+ headers.
+.IP "\fB\-iprefix\fR \fIprefix\fR" 4
+.IX Item "-iprefix prefix"
+Specify \fIprefix\fR as the prefix for subsequent \fB\-iwithprefix\fR
+options. If the \fIprefix\fR represents a directory, you should include
+the final \f(CW\*(Aq/\*(Aq\fR.
+.IP "\fB\-isysroot\fR \fIdir\fR" 4
+.IX Item "-isysroot dir"
+This option is like the \fB\-\-sysroot\fR option, but applies only to
+header files. See the \fB\-\-sysroot\fR option for more information.
+.IP "\fB\-iquote\fR \fIdir\fR" 4
+.IX Item "-iquote dir"
+Search \fIdir\fR only for header files requested with \f(CW\*(C`#include "file"\*(C'\fR;
+they are not searched for \f(CW\*(C`#include <file>\*(C'\fR, before all directories
+specified by \fB\-I\fR and before the standard system directories. If
+\&\fIdir\fR begins with \f(CW\*(C`=\*(C'\fR, then the \f(CW\*(C`=\*(C'\fR will be replaced by the
+sysroot prefix; see \fB\-\-sysroot\fR and \fB\-isysroot\fR.
+.IP "\fB\-isystem\fR \fIdir\fR" 4
+.IX Item "-isystem dir"
+Search \fIdir\fR for header files, after all directories specified by
+\&\fB\-I\fR 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 \fIdir\fR begins with
+\&\f(CW\*(C`=\*(C'\fR, then the \f(CW\*(C`=\*(C'\fR will be replaced by the sysroot prefix;
+see \fB\-\-sysroot\fR and \fB\-isysroot\fR.
+.IP "\fB\-nostdinc\fR" 4
+.IX Item "-nostdinc"
+Do not search the standard system directories for header files. Only
+the directories you have specified with \fB\-I\fR options (and the
+directory of the current file, if appropriate) are searched.
+.IP "\fB\-undef\fR" 4
+.IX Item "-undef"
+Do not predefine any system-specific or GCC-specific macros.
+The standard predefined macros remain defined.
+.IP "\fB\-A\fR\fIpredicate\fR\fB=\fR\fIanswer\fR" 4
+.IX Item "-Apredicate=answer"
+Make an assertion with the predicate \fIpredicate\fR and answer \fIanswer\fR.
+This form is preferred to the older form \-A predicate(answer), which is still
+supported, because it does not use shell special characters.
+.IP "\fB\-A\-\fR\fIpredicate\fR\fB=\fR\fIanswer\fR" 4
+.IX Item "-A-predicate=answer"
+Cancel an assertion with the predicate \fIpredicate\fR and answer \fIanswer\fR.
+.IP "\fB\-C\fR" 4
+.IX Item "-C"
+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.
+.Sp
+You should be prepared for side effects when using \fB\-C\fR; 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 \f(CW\*(Aq#\*(Aq\fR.
+.Sp
+Warning: this currently handles C\-Style comments only. The preprocessor
+does not yet recognize Fortran-style comments.
+.IP "\fB\-CC\fR" 4
+.IX Item "-CC"
+Do not discard comments, including during macro expansion. This is like
+\&\fB\-C\fR, except that comments contained within macros are also passed
+through to the output file where the macro is expanded.
+.Sp
+In addition to the side-effects of the \fB\-C\fR option, the \fB\-CC\fR
+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 \fB\-CC\fR option
+is generally used to support lint comments.
+.Sp
+Warning: this currently handles C\- and \*(C+\-Style comments only. The
+preprocessor does not yet recognize Fortran-style comments.
+.IP "\fB\-D\fR\fIname\fR" 4
+.IX Item "-Dname"
+Predefine name as a macro, with definition \f(CW1\fR.
+.IP "\fB\-D\fR\fIname\fR\fB=\fR\fIdefinition\fR" 4
+.IX Item "-Dname=definition"
+The contents of \fIdefinition\fR are tokenized and processed as if they
+appeared during translation phase three in a \f(CW\*(Aq#define\*(Aq\fR directive.
+In particular, the definition will be truncated by embedded newline
+characters.
+.Sp
+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.
+.Sp
+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, \f(CW\*(C`\-D\*(Aqname(args...)=definition\*(Aq\*(C'\fR
+works.
+.Sp
+\&\fB\-D\fR and \fB\-U\fR 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.
+.IP "\fB\-H\fR" 4
+.IX Item "-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 \f(CW\*(Aq#include\*(Aq\fR
+stack it is.
+.IP "\fB\-P\fR" 4
+.IX Item "-P"
+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.
+.IP "\fB\-U\fR\fIname\fR" 4
+.IX Item "-Uname"
+Cancel any previous definition of \fIname\fR, either built in or provided
+with a \fB\-D\fR option.
+.Sh "Options to request or suppress errors and warnings"
+.IX Subsection "Options to request or suppress errors and warnings"
+Errors are diagnostic messages that report that the \s-1GNU\s0 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.
+.PP
+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 \fB\-Werror\fR is specified,
+they do not prevent compilation of the program.
+.PP
+You can request many specific warnings with options beginning \fB\-W\fR,
+for example \fB\-Wimplicit\fR to request warnings on implicit
+declarations.  Each of these specific warning options also has a
+negative form beginning \fB\-Wno\-\fR to turn off warnings;
+for example, \fB\-Wno\-implicit\fR.  This manual lists only one of the
+two forms, whichever is not the default.
+.PP
+These options control the amount and kinds of errors and warnings produced
+by \s-1GNU\s0 Fortran:
+.IP "\fB\-fmax\-errors=\fR\fIn\fR" 4
+.IX Item "-fmax-errors=n"
+Limits the maximum number of error messages to \fIn\fR, at which point
+\&\s-1GNU\s0 Fortran bails out rather than attempting to continue processing the
+source code.  If \fIn\fR is 0, there is no limit on the number of error
+messages produced.
+.IP "\fB\-fsyntax\-only\fR" 4
+.IX Item "-fsyntax-only"
+Check the code for syntax errors, but don't actually compile it.  This
+will generate module files for each module present in the code, but no
+other output file.
+.IP "\fB\-pedantic\fR" 4
+.IX Item "-pedantic"
+Issue warnings for uses of extensions to Fortran 95.
+\&\fB\-pedantic\fR also applies to C\-language constructs where they
+occur in \s-1GNU\s0 Fortran source files, such as use of \fB\ee\fR in a
+character constant within a directive like \f(CW\*(C`#include\*(C'\fR.
+.Sp
+Valid Fortran 95 programs should compile properly with or without
+this option.
+However, without this option, certain \s-1GNU\s0 extensions and traditional
+Fortran features are supported as well.
+With this option, many of them are rejected.
+.Sp
+Some users try to use \fB\-pedantic\fR 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 \s-1GNU\s0 Fortran in this area are welcome.
+.Sp
+This should be used in conjunction with \fB\-std=f95\fR,
+\&\fB\-std=f2003\fR or \fB\-std=f2008\fR.
+.IP "\fB\-pedantic\-errors\fR" 4
+.IX Item "-pedantic-errors"
+Like \fB\-pedantic\fR, except that errors are produced rather than
+warnings.
+.IP "\fB\-Wall\fR" 4
+.IX Item "-Wall"
+Enables commonly used warning options pertaining to usage that
+we recommend avoiding and that we believe are easy to avoid.
+This currently includes \fB\-Waliasing\fR,
+\&\fB\-Wampersand\fR, \fB\-Wsurprising\fR, \fB\-Wintrinsics\-std\fR,
+\&\fB\-Wno\-tabs\fR, \fB\-Wintrinsic\-shadow\fR and \fB\-Wline\-truncation\fR.
+.IP "\fB\-Waliasing\fR" 4
+.IX Item "-Waliasing"
+Warn about possible aliasing of dummy arguments. Specifically, it warns
+if the same actual argument is associated with a dummy argument with
+\&\f(CW\*(C`INTENT(IN)\*(C'\fR and a dummy argument with \f(CW\*(C`INTENT(OUT)\*(C'\fR in a call
+with an explicit interface.
+.Sp
+The following example will trigger the warning.
+.Sp
+.Vb 7
+\&          interface
+\&            subroutine bar(a,b)
+\&              integer, intent(in) :: a
+\&              integer, intent(out) :: b
+\&            end subroutine
+\&          end interface
+\&          integer :: a
+\&
+\&          call bar(a,a)
+.Ve
+.IP "\fB\-Wampersand\fR" 4
+.IX Item "-Wampersand"
+Warn about missing ampersand in continued character constants. The warning is
+given with \fB\-Wampersand\fR, \fB\-pedantic\fR, \fB\-std=f95\fR,
+\&\fB\-std=f2003\fR and \fB\-std=f2008\fR. Note: With no ampersand
+given in a continued character constant, \s-1GNU\s0 Fortran assumes continuation
+at the first non-comment, non-whitespace character after the ampersand
+that initiated the continuation.
+.IP "\fB\-Warray\-temporaries\fR" 4
+.IX Item "-Warray-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.
+.IP "\fB\-Wcharacter\-truncation\fR" 4
+.IX Item "-Wcharacter-truncation"
+Warn when a character assignment will truncate the assigned string.
+.IP "\fB\-Wline\-truncation\fR" 4
+.IX Item "-Wline-truncation"
+Warn when a source code line will be truncated.
+.IP "\fB\-Wconversion\fR" 4
+.IX Item "-Wconversion"
+Warn about implicit conversions between different types.
+.IP "\fB\-Wimplicit\-interface\fR" 4
+.IX Item "-Wimplicit-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.
+.IP "\fB\-Wintrinsics\-std\fR" 4
+.IX Item "-Wintrinsics-std"
+Warn if \fBgfortran\fR finds a procedure named like an intrinsic not
+available in the currently selected standard (with \fB\-std\fR) and treats
+it as \f(CW\*(C`EXTERNAL\*(C'\fR procedure because of this.  \fB\-fall\-intrinsics\fR can
+be used to never trigger this behaviour and always link to the intrinsic
+regardless of the selected standard.
+.IP "\fB\-Wsurprising\fR" 4
+.IX Item "-Wsurprising"
+Produce a warning when \*(L"suspicious\*(R" code constructs are encountered.
+While technically legal these usually indicate that an error has been made.
+.Sp
+This currently produces a warning under the following circumstances:
+.RS 4
+.IP "\(bu" 4
+An \s-1INTEGER\s0 \s-1SELECT\s0 construct has a \s-1CASE\s0 that can never be matched as its
+lower value is greater than its upper value.
+.IP "\(bu" 4
+A \s-1LOGICAL\s0 \s-1SELECT\s0 construct has three \s-1CASE\s0 statements.
+.IP "\(bu" 4
+A \s-1TRANSFER\s0 specifies a source that is shorter than the destination.
+.IP "\(bu" 4
+The type of a function result is declared more than once with the same type.  If
+\&\fB\-pedantic\fR or standard-conforming mode is enabled, this is an error.
+.RE
+.RS 4
+.RE
+.IP "\fB\-Wtabs\fR" 4
+.IX Item "-Wtabs"
+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.  \fB\-Wno\-tabs\fR will cause
+a warning to be issued if a tab is encountered. Note, \fB\-Wno\-tabs\fR
+is active for \fB\-pedantic\fR, \fB\-std=f95\fR, \fB\-std=f2003\fR,
+\&\fB\-std=f2008\fR and \fB\-Wall\fR.
+.IP "\fB\-Wunderflow\fR" 4
+.IX Item "-Wunderflow"
+Produce a warning when numerical constant expressions are
+encountered, which yield an \s-1UNDERFLOW\s0 during compilation.
+.IP "\fB\-Wintrinsic\-shadow\fR" 4
+.IX Item "-Wintrinsic-shadow"
+Warn if a user-defined procedure or module procedure has the same name as an
+intrinsic; in this case, an explicit interface or \f(CW\*(C`EXTERNAL\*(C'\fR or
+\&\f(CW\*(C`INTRINSIC\*(C'\fR declaration might be needed to get calls later resolved to
+the desired intrinsic/procedure.
+.IP "\fB\-Wunused\-parameter\fR" 4
+.IX Item "-Wunused-parameter"
+Contrary to \fBgcc\fR's meaning of \fB\-Wunused\-parameter\fR,
+\&\fBgfortran\fR's implementation of this option does not warn
+about unused dummy arguments, but about unused \f(CW\*(C`PARAMETER\*(C'\fR values.
+\&\fB\-Wunused\-parameter\fR is not included in \fB\-Wall\fR but is
+implied by \fB\-Wall \-Wextra\fR.
+.IP "\fB\-Walign\-commons\fR" 4
+.IX Item "-Walign-commons"
+By default, \fBgfortran\fR warns about any occasion of variables being
+padded for proper alignment inside a \s-1COMMON\s0 block. This warning can be turned
+off via \fB\-Wno\-align\-commons\fR. See also \fB\-falign\-commons\fR.
+.IP "\fB\-Werror\fR" 4
+.IX Item "-Werror"
+Turns all warnings into errors.
+.PP
+Some of these have no effect when compiling programs written in Fortran.
+.Sh "Options for debugging your program or \s-1GNU\s0 Fortran"
+.IX Subsection "Options for debugging your program or GNU Fortran"
+\&\s-1GNU\s0 Fortran has various special options that are used for debugging
+either your program or the \s-1GNU\s0 Fortran compiler.
+.IP "\fB\-fdump\-parse\-tree\fR" 4
+.IX Item "-fdump-parse-tree"
+Output the internal parse tree before starting code generation.  Only
+really useful for debugging the \s-1GNU\s0 Fortran compiler itself.
+.IP "\fB\-ffpe\-trap=\fR\fIlist\fR" 4
+.IX Item "-ffpe-trap=list"
+Specify a list of \s-1IEEE\s0 exceptions when a Floating Point Exception
+(\s-1FPE\s0) should be raised.  On most systems, this will result in a \s-1SIGFPE\s0
+signal being sent and the program being interrupted, producing a core
+file useful for debugging.  \fIlist\fR is a (possibly empty) comma-separated
+list of the following \s-1IEEE\s0 exceptions: \fBinvalid\fR (invalid floating
+point operation, such as \f(CW\*(C`SQRT(\-1.0)\*(C'\fR), \fBzero\fR (division by
+zero), \fBoverflow\fR (overflow in a floating point operation),
+\&\fBunderflow\fR (underflow in a floating point operation),
+\&\fBprecision\fR (loss of precision during operation) and \fBdenormal\fR
+(operation produced a denormal value).
+.Sp
+Some of the routines in the Fortran runtime library, like
+\&\fB\s-1CPU_TIME\s0\fR, are likely to trigger floating point exceptions when
+\&\f(CW\*(C`ffpe\-trap=precision\*(C'\fR is used. For this reason, the use of
+\&\f(CW\*(C`ffpe\-trap=precision\*(C'\fR is not recommended.
+.IP "\fB\-fbacktrace\fR" 4
+.IX Item "-fbacktrace"
+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.
+.IP "\fB\-fdump\-core\fR" 4
+.IX Item "-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.
+.Sh "Options for directory search"
+.IX Subsection "Options for directory search"
+These options affect how \s-1GNU\s0 Fortran searches
+for files specified by the \f(CW\*(C`INCLUDE\*(C'\fR directive and where it searches
+for previously compiled modules.
+.PP
+It also affects the search paths used by \fBcpp\fR when used to preprocess
+Fortran source.
+.IP "\fB\-I\fR\fIdir\fR" 4
+.IX Item "-Idir"
+These affect interpretation of the \f(CW\*(C`INCLUDE\*(C'\fR directive
+(as well as of the \f(CW\*(C`#include\*(C'\fR directive of the \fBcpp\fR
+preprocessor).
+.Sp
+Also note that the general behavior of \fB\-I\fR and
+\&\f(CW\*(C`INCLUDE\*(C'\fR is pretty much the same as of \fB\-I\fR with
+\&\f(CW\*(C`#include\*(C'\fR in the \fBcpp\fR preprocessor, with regard to
+looking for \fIheader.gcc\fR files and other such things.
+.Sp
+This path is also used to search for \fI.mod\fR files when previously
+compiled modules are required by a \f(CW\*(C`USE\*(C'\fR statement.
+.IP "\fB\-J\fR\fIdir\fR" 4
+.IX Item "-Jdir"
+.PD 0
+.IP "\fB\-M\fR\fIdir\fR" 4
+.IX Item "-Mdir"
+.PD
+This option specifies where to put \fI.mod\fR files for compiled modules.
+It is also added to the list of directories to searched by an \f(CW\*(C`USE\*(C'\fR
+statement.
+.Sp
+The default is the current directory.
+.Sp
+\&\fB\-M\fR is deprecated to avoid conflicts with existing \s-1GCC\s0 options.
+.IP "\fB\-fintrinsic\-modules\-path\fR \fIdir\fR" 4
+.IX Item "-fintrinsic-modules-path dir"
+This option specifies the location of pre-compiled intrinsic modules, if
+they are not in the default location expected by the compiler.
+.Sh "Influencing the linking step"
+.IX Subsection "Influencing the linking step"
+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.
+.IP "\fB\-static\-libgfortran\fR" 4
+.IX Item "-static-libgfortran"
+On systems that provide \fIlibgfortran\fR as a shared and a static
+library, this option forces the use of the static version. If no
+shared version of \fIlibgfortran\fR was built when the compiler was
+configured, this option has no effect.
+.Sh "Influencing runtime behavior"
+.IX Subsection "Influencing runtime behavior"
+These options affect the runtime behavior of programs compiled with \s-1GNU\s0 Fortran.
+.IP "\fB\-fconvert=\fR\fIconversion\fR" 4
+.IX Item "-fconvert=conversion"
+Specify the representation of data for unformatted files.  Valid
+values for conversion are: \fBnative\fR, the default; \fBswap\fR,
+swap between big\- and little-endian; \fBbig-endian\fR, use big-endian
+representation for unformatted files; \fBlittle-endian\fR, use little-endian
+representation for unformatted files.
+.Sp
+\&\fIThis option has an effect only when used in the main program.
+The \f(CI\*(C`CONVERT\*(C'\fI specifier and the \s-1GFORTRAN_CONVERT_UNIT\s0 environment
+variable override the default specified by \f(BI\-fconvert\fI.\fR
+.IP "\fB\-fno\-range\-check\fR" 4
+.IX Item "-fno-range-check"
+Disable range checking of input values during integer \f(CW\*(C`READ\*(C'\fR operations.
+For example, \s-1GNU\s0 Fortran will give an error if an input value is
+outside of the relevant range of [\f(CW\*(C`\-HUGE()\*(C'\fR:\f(CW\*(C`HUGE()\*(C'\fR]. In other words,
+with \f(CW\*(C`INTEGER (kind=4) :: i\*(C'\fR , attempting to read \-2147483648 will
+give an error unless \fB\-fno\-range\-check\fR is given.
+.IP "\fB\-frecord\-marker=\fR\fIlength\fR" 4
+.IX Item "-frecord-marker=length"
+Specify the length of record markers for unformatted files.
+Valid values for \fIlength\fR are 4 and 8.  Default is 4.
+\&\fIThis is different from previous versions of\fR \fBgfortran\fR,
+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 \fBgfortran\fR, use \fB\-frecord\-marker=8\fR.
+.IP "\fB\-fmax\-subrecord\-length=\fR\fIlength\fR" 4
+.IX Item "-fmax-subrecord-length=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.
+.IP "\fB\-fsign\-zero\fR" 4
+.IX Item "-fsign-zero"
+When writing zero values, show the negative sign if the sign bit is set.
+\&\f(CW\*(C`fno\-sign\-zero\*(C'\fR does not print the negative sign of zero values for
+compatibility with F77.  Default behavior is to show the negative sign.
+.Sh "Options for code generation conventions"
+.IX Subsection "Options for code generation conventions"
+These machine-independent options control the interface conventions
+used in code generation.
+.PP
+Most of them have both positive and negative forms; the negative form
+of \fB\-ffoo\fR would be \fB\-fno\-foo\fR.  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 \fBno\-\fR or adding
+it.
+.IP "\fB\-fno\-automatic\fR" 4
+.IX Item "-fno-automatic"
+Treat each program unit (except those marked as \s-1RECURSIVE\s0) as if the
+\&\f(CW\*(C`SAVE\*(C'\fR 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 \fB\-static\fR or \fB\-save\fR.)
+The default, which is \fB\-fautomatic\fR, uses the stack for local
+variables smaller than the value given by \fB\-fmax\-stack\-var\-size\fR.
+Use the option \fB\-frecursive\fR to use no static memory.
+.IP "\fB\-ff2c\fR" 4
+.IX Item "-ff2c"
+Generate code designed to be compatible with code generated
+by \fBg77\fR and \fBf2c\fR.
+.Sp
+The calling conventions used by \fBg77\fR (originally implemented
+in \fBf2c\fR) require functions that return type
+default \f(CW\*(C`REAL\*(C'\fR to actually return the C type \f(CW\*(C`double\*(C'\fR, and
+functions that return type \f(CW\*(C`COMPLEX\*(C'\fR to return the values via an
+extra argument in the calling sequence that points to where to
+store the return value.  Under the default \s-1GNU\s0 calling conventions, such
+functions simply return their results as they would in \s-1GNU\s0
+C\-\-\-default \f(CW\*(C`REAL\*(C'\fR functions return the C type \f(CW\*(C`float\*(C'\fR, and
+\&\f(CW\*(C`COMPLEX\*(C'\fR functions return the \s-1GNU\s0 C type \f(CW\*(C`complex\*(C'\fR.
+Additionally, this option implies the \fB\-fsecond\-underscore\fR
+option, unless \fB\-fno\-second\-underscore\fR is explicitly requested.
+.Sp
+This does not affect the generation of code that interfaces with
+the \fBlibgfortran\fR library.
+.Sp
+\&\fICaution:\fR It is not a good idea to mix Fortran code compiled with
+\&\fB\-ff2c\fR with code compiled with the default \fB\-fno\-f2c\fR
+calling conventions as, calling \f(CW\*(C`COMPLEX\*(C'\fR or default \f(CW\*(C`REAL\*(C'\fR
+functions between program parts which were compiled with different
+calling conventions will break at execution time.
+.Sp
+\&\fICaution:\fR This will break code which passes intrinsic functions
+of type default \f(CW\*(C`REAL\*(C'\fR or \f(CW\*(C`COMPLEX\*(C'\fR as actual arguments, as
+the library implementations use the \fB\-fno\-f2c\fR calling conventions.
+.IP "\fB\-fno\-underscoring\fR" 4
+.IX Item "-fno-underscoring"
+Do not transform names of entities specified in the Fortran
+source file by appending underscores to them.
+.Sp
+With \fB\-funderscoring\fR in effect, \s-1GNU\s0 Fortran appends one
+underscore to external names with no underscores.  This is done to ensure
+compatibility with code produced by many \s-1UNIX\s0 Fortran compilers.
+.Sp
+\&\fICaution\fR: The default behavior of \s-1GNU\s0 Fortran is
+incompatible with \fBf2c\fR and \fBg77\fR, please use the
+\&\fB\-ff2c\fR option if you want object files compiled with
+\&\s-1GNU\s0 Fortran to be compatible with object code created with these
+tools.
+.Sp
+Use of \fB\-fno\-underscoring\fR is not recommended unless you are
+experimenting with issues such as integration of \s-1GNU\s0 Fortran into
+existing system environments (vis\-@`{a}\-vis existing libraries, tools,
+and so on).
+.Sp
+For example, with \fB\-funderscoring\fR, and assuming other defaults like
+\&\fB\-fcase\-lower\fR and that \f(CW\*(C`j()\*(C'\fR and \f(CW\*(C`max_count()\*(C'\fR are
+external functions while \f(CW\*(C`my_var\*(C'\fR and \f(CW\*(C`lvar\*(C'\fR are local variables,
+a statement like
+.Sp
+.Vb 1
+\&        I = J() + MAX_COUNT (MY_VAR, LVAR)
+.Ve
+.Sp
+is implemented as something akin to:
+.Sp
+.Vb 1
+\&        i = j_() + max_count_\|_(&my_var_\|_, &lvar);
+.Ve
+.Sp
+With \fB\-fno\-underscoring\fR, the same statement is implemented as:
+.Sp
+.Vb 1
+\&        i = j() + max_count(&my_var, &lvar);
+.Ve
+.Sp
+Use of \fB\-fno\-underscoring\fR allows direct specification of
+user-defined names while debugging and when interfacing \s-1GNU\s0 Fortran
+code with other languages.
+.Sp
+Note that just because the names match does \fInot\fR mean that the
+interface implemented by \s-1GNU\s0 Fortran for an external name matches the
+interface implemented by some other language for that same name.
+That is, getting code produced by \s-1GNU\s0 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.
+.Sp
+Also, note that with \fB\-fno\-underscoring\fR, 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.
+.Sp
+In future versions of \s-1GNU\s0 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.
+.IP "\fB\-fsecond\-underscore\fR" 4
+.IX Item "-fsecond-underscore"
+By default, \s-1GNU\s0 Fortran appends an underscore to external
+names.  If this option is used \s-1GNU\s0 Fortran appends two
+underscores to names with underscores and one underscore to external names
+with no underscores.  \s-1GNU\s0 Fortran also appends two underscores to
+internal names with underscores to avoid naming collisions with external
+names.
+.Sp
+This option has no effect if \fB\-fno\-underscoring\fR is
+in effect.  It is implied by the \fB\-ff2c\fR option.
+.Sp
+Otherwise, with this option, an external name such as \f(CW\*(C`MAX_COUNT\*(C'\fR
+is implemented as a reference to the link-time external symbol
+\&\f(CW\*(C`max_count_\|_\*(C'\fR, instead of \f(CW\*(C`max_count_\*(C'\fR.  This is required
+for compatibility with \fBg77\fR and \fBf2c\fR, and is implied
+by use of the \fB\-ff2c\fR option.
+.IP "\fB\-fbounds\-check\fR" 4
+.IX Item "-fbounds-check"
+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.
+.Sp
+Some checks require that \fB\-fbounds\-check\fR is set for
+the compilation of the main program.
+.Sp
+Note: In the future this may also include other forms of checking, e.g.,
+checking substring references.
+.IP "\fBfcheck-array-temporaries\fR" 4
+.IX Item "fcheck-array-temporaries"
+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.
+.Sp
+Note: The warning is only printed once per location.
+.IP "\fB\-fmax\-array\-constructor=\fR\fIn\fR" 4
+.IX Item "-fmax-array-constructor=n"
+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.
+.Sp
+.Vb 7
+\&        C<program test>
+\&        C<implicit none>
+\&        C<integer j>
+\&        C<integer, parameter :: n = 100000>
+\&        C<integer, parameter :: i(n) = (/ (2*j, j = 1, n) /)>
+\&        C<print \*(Aq(10(I0,1X))\*(Aq, i>
+\&        C<end program test>
+.Ve
+.Sp
+\&\fICaution:  This option can lead to long compile times and excessively
+large object files.\fR
+.Sp
+The default value for \fIn\fR is 65535.
+.IP "\fB\-fmax\-stack\-var\-size=\fR\fIn\fR" 4
+.IX Item "-fmax-stack-var-size=n"
+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 \s-1RECURSIVE\s0). Use the option \fB\-frecursive\fR to
+allow for recursive procedures which do not have a \s-1RECURSIVE\s0 attribute or
+for parallel programs. Use \fB\-fno\-automatic\fR to never use the stack.
+.Sp
+This option currently only affects local arrays declared with constant
+bounds, and may not apply to all character variables.
+Future versions of \s-1GNU\s0 Fortran may improve this behavior.
+.Sp
+The default value for \fIn\fR is 32768.
+.IP "\fB\-fpack\-derived\fR" 4
+.IX Item "-fpack-derived"
+This option tells \s-1GNU\s0 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.
+.IP "\fB\-frepack\-arrays\fR" 4
+.IX Item "-frepack-arrays"
+In some circumstances \s-1GNU\s0 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.
+.Sp
+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.
+.IP "\fB\-fshort\-enums\fR" 4
+.IX Item "-fshort-enums"
+This option is provided for interoperability with C code that was
+compiled with the \fB\-fshort\-enums\fR option.  It will make
+\&\s-1GNU\s0 Fortran choose the smallest \f(CW\*(C`INTEGER\*(C'\fR kind a given
+enumerator set will fit in, and give all its enumerators this kind.
+.IP "\fB\-fexternal\-blas\fR" 4
+.IX Item "-fexternal-blas"
+This option will make \fBgfortran\fR generate calls to \s-1BLAS\s0 functions
+for some matrix operations like \f(CW\*(C`MATMUL\*(C'\fR, instead of using our own
+algorithms, if the size of the matrices involved is larger than a given
+limit (see \fB\-fblas\-matmul\-limit\fR).  This may be profitable if an
+optimized vendor \s-1BLAS\s0 library is available.  The \s-1BLAS\s0 library will have
+to be specified at link time.
+.IP "\fB\-fblas\-matmul\-limit=\fR\fIn\fR" 4
+.IX Item "-fblas-matmul-limit=n"
+Only significant when \fB\-fexternal\-blas\fR is in effect.
+Matrix multiplication of matrices with size larger than (or equal to) \fIn\fR
+will be performed by calls to \s-1BLAS\s0 functions, while others will be
+handled by \fBgfortran\fR 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.
+.Sp
+The default value for \fIn\fR is 30.
+.IP "\fB\-frecursive\fR" 4
+.IX Item "-frecursive"
+Allow indirect recursion by forcing all local arrays to be allocated
+on the stack. This flag cannot be used together with
+\&\fB\-fmax\-stack\-var\-size=\fR or \fB\-fno\-automatic\fR.
+.IP "\fB\-finit\-local\-zero\fR" 4
+.IX Item "-finit-local-zero"
+.PD 0
+.IP "\fB\-finit\-integer=\fR\fIn\fR" 4
+.IX Item "-finit-integer=n"
+.IP "\fB\-finit\-real=\fR\fI<zero|inf|\-inf|nan>\fR\fB \fR" 4
+.IX Item "-finit-real=<zero|inf|-inf|nan> "
+.IP "\fB\-finit\-logical=\fR\fI<true|false>\fR" 4
+.IX Item "-finit-logical=<true|false>"
+.IP "\fB\-finit\-character=\fR\fIn\fR" 4
+.IX Item "-finit-character=n"
+.PD
+The \fB\-finit\-local\-zero\fR option instructs the compiler to
+initialize local \f(CW\*(C`INTEGER\*(C'\fR, \f(CW\*(C`REAL\*(C'\fR, and \f(CW\*(C`COMPLEX\*(C'\fR
+variables to zero, \f(CW\*(C`LOGICAL\*(C'\fR variables to false, and
+\&\f(CW\*(C`CHARACTER\*(C'\fR variables to a string of null bytes.  Finer-grained
+initialization options are provided by the
+\&\fB\-finit\-integer=\fR\fIn\fR,
+\&\fB\-finit\-real=\fR\fI<zero|inf|\-inf|nan>\fR (which also initializes
+the real and imaginary parts of local \f(CW\*(C`COMPLEX\*(C'\fR variables),
+\&\fB\-finit\-logical=\fR\fI<true|false>\fR, and
+\&\fB\-finit\-character=\fR\fIn\fR (where \fIn\fR is an \s-1ASCII\s0 character
+value) options.  These options do not initialize components of derived
+type variables, nor do they initialize variables that appear in an
+\&\f(CW\*(C`EQUIVALENCE\*(C'\fR statement.  (This limitation may be removed in
+future releases).
+.Sp
+Note that the \fB\-finit\-real=nan\fR option initializes \f(CW\*(C`REAL\*(C'\fR
+and \f(CW\*(C`COMPLEX\*(C'\fR variables with a quiet NaN.
+.IP "\fB\-falign\-commons\fR" 4
+.IX Item "-falign-commons"
+By default, \fBgfortran\fR enforces proper alignment of all variables in a
+\&\s-1COMMON\s0 block by padding them as needed. On certain platforms this is mandatory,
+on others it increases performance. If a \s-1COMMON\s0 block is not declared with
+consistent data types everywhere, this padding can cause trouble, and
+\&\fB\-fno\-align\-commons\fR  can be used to disable automatic alignment. The
+same form of this option should be used for all files that share a \s-1COMMON\s0 block.
+To avoid potential alignment issues in \s-1COMMON\s0 blocks, it is recommended to order
+objects from largests to smallest.
+.SH "ENVIRONMENT"
+.IX Header "ENVIRONMENT"
+The \fBgfortran\fR compiler currently does not make use of any environment
+variables to control its operation above and beyond those
+that affect the operation of \fBgcc\fR.
+.SH "BUGS"
+.IX Header "BUGS"
+For instructions on reporting bugs, see
+<\fBhttp://gcc.gnu.org/bugs.html\fR>.
+.SH "SEE ALSO"
+.IX Header "SEE ALSO"
+\&\fIgpl\fR\|(7), \fIgfdl\fR\|(7), \fIfsf\-funding\fR\|(7),
+\&\fIcpp\fR\|(1), \fIgcov\fR\|(1), \fIgcc\fR\|(1), \fIas\fR\|(1), \fIld\fR\|(1), \fIgdb\fR\|(1), \fIadb\fR\|(1), \fIdbx\fR\|(1), \fIsdb\fR\|(1)
+and the Info entries for \fIgcc\fR, \fIcpp\fR, \fIgfortran\fR, \fIas\fR,
+\&\fIld\fR, \fIbinutils\fR and \fIgdb\fR.
+.SH "AUTHOR"
+.IX Header "AUTHOR"
+See the Info entry for \fBgfortran\fR for contributors to \s-1GCC\s0 and
+\&\s-1GNU\s0 Fortran.
+.SH "COPYRIGHT"
+.IX Header "COPYRIGHT"
+Copyright (c) 2004, 2005, 2006, 2007, 2008
+Free Software Foundation, Inc.
+.PP
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the \s-1GNU\s0 Free Documentation License, Version 1.2 or
+any later version published by the Free Software Foundation; with the
+Invariant Sections being \*(L"Funding Free Software\*(R", 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 \fIgfdl\fR\|(7) man page.
+.PP
+(a) The \s-1FSF\s0's Front-Cover Text is:
+.PP
+.Vb 1
+\&     A GNU Manual
+.Ve
+.PP
+(b) The \s-1FSF\s0's Back-Cover Text is:
+.PP
+.Vb 3
+\&     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.
+.Ve

Mercurial > hg > CbC > CbC_gcc

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