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1.\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.14
2.\"
3.\" Standard preamble:
4.\" ========================================================================
5.de Sh \" Subsection heading
6.br
7.if t .Sp
8.ne 5

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214\&\fB\-fno\-threadsafe\-statics \-fuse\-cxa\-atexit \-fno\-weak \-nostdinc++
215\&\-fno\-default\-inline \-fvisibility\-inlines\-hidden
216\&\-Wabi \-Wctor\-dtor\-privacy
217\&\-Wnon\-virtual\-dtor \-Wreorder
218\&\-Weffc++ \-Wno\-deprecated \-Wstrict\-null\-sentinel
219\&\-Wno\-non\-template\-friend \-Wold\-style\-cast
220\&\-Woverloaded\-virtual \-Wno\-pmf\-conversions
221\&\-Wsign\-promo\fR
1.\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.14
2.\"
3.\" Standard preamble:
4.\" ========================================================================
5.de Sh \" Subsection heading
6.br
7.if t .Sp
8.ne 5

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214\&\fB\-fno\-threadsafe\-statics \-fuse\-cxa\-atexit \-fno\-weak \-nostdinc++
215\&\-fno\-default\-inline \-fvisibility\-inlines\-hidden
216\&\-Wabi \-Wctor\-dtor\-privacy
217\&\-Wnon\-virtual\-dtor \-Wreorder
218\&\-Weffc++ \-Wno\-deprecated \-Wstrict\-null\-sentinel
219\&\-Wno\-non\-template\-friend \-Wold\-style\-cast
220\&\-Woverloaded\-virtual \-Wno\-pmf\-conversions
221\&\-Wsign\-promo\fR
222.IP "\fIObjective-C and Objective\-\*(C+ Language Options\fR" 4
223.IX Item "Objective-C and Objective- Language Options"
224\&\fB\-fconstant\-string\-class=\fR\fIclass-name\fR
225\&\fB\-fgnu\-runtime \-fnext\-runtime
226\&\-fno\-nil\-receivers
227\&\-fobjc\-call\-cxx\-cdtors
228\&\-fobjc\-direct\-dispatch
229\&\-fobjc\-exceptions
230\&\-fobjc\-gc
231\&\-freplace\-objc\-classes
232\&\-fzero\-link
233\&\-gen\-decls
234\&\-Wassign\-intercept
235\&\-Wno\-protocol \-Wselector
236\&\-Wstrict\-selector\-match
237\&\-Wundeclared\-selector\fR
238.IP "\fILanguage Independent Options\fR" 4
239.IX Item "Language Independent Options"
240\&\fB\-fmessage\-length=\fR\fIn\fR
241\&\fB\-fdiagnostics\-show\-location=\fR[\fBonce\fR|\fBevery-line\fR]
242\&\fB\-fdiagnostics\-show\-option\fR
243.IP "\fIWarning Options\fR" 4
244.IX Item "Warning Options"
245\&\fB\-fsyntax\-only \-pedantic \-pedantic\-errors

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810.IX Item "file.c"
811C source code which must be preprocessed.
812.IP "\fIfile\fR\fB.i\fR" 4
813.IX Item "file.i"
814C source code which should not be preprocessed.
815.IP "\fIfile\fR\fB.ii\fR" 4
816.IX Item "file.ii"
817\&\*(C+ source code which should not be preprocessed.
222.IP "\fILanguage Independent Options\fR" 4
223.IX Item "Language Independent Options"
224\&\fB\-fmessage\-length=\fR\fIn\fR
225\&\fB\-fdiagnostics\-show\-location=\fR[\fBonce\fR|\fBevery-line\fR]
226\&\fB\-fdiagnostics\-show\-option\fR
227.IP "\fIWarning Options\fR" 4
228.IX Item "Warning Options"
229\&\fB\-fsyntax\-only \-pedantic \-pedantic\-errors

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794.IX Item "file.c"
795C source code which must be preprocessed.
796.IP "\fIfile\fR\fB.i\fR" 4
797.IX Item "file.i"
798C source code which should not be preprocessed.
799.IP "\fIfile\fR\fB.ii\fR" 4
800.IX Item "file.ii"
801\&\*(C+ source code which should not be preprocessed.
818.IP "\fIfile\fR\fB.m\fR" 4
819.IX Item "file.m"
820Objective-C source code. Note that you must link with the \fIlibobjc\fR
821library to make an Objective-C program work.
822.IP "\fIfile\fR\fB.mi\fR" 4
823.IX Item "file.mi"
824Objective-C source code which should not be preprocessed.
825.IP "\fIfile\fR\fB.mm\fR" 4
826.IX Item "file.mm"
827.PD 0
828.IP "\fIfile\fR\fB.M\fR" 4
829.IX Item "file.M"
830.PD
831Objective\-\*(C+ source code. Note that you must link with the \fIlibobjc\fR
832library to make an Objective\-\*(C+ program work. Note that \fB.M\fR refers
833to a literal capital M.
834.IP "\fIfile\fR\fB.mii\fR" 4
835.IX Item "file.mii"
836Objective\-\*(C+ source code which should not be preprocessed.
837.IP "\fIfile\fR\fB.h\fR" 4
838.IX Item "file.h"
802.IP "\fIfile\fR\fB.h\fR" 4
803.IX Item "file.h"
839C, \*(C+, Objective-C or Objective\-\*(C+ header file to be turned into a
840precompiled header.
804C, or \*(C+ header file to be turned into a precompiled header.
841.IP "\fIfile\fR\fB.cc\fR" 4
842.IX Item "file.cc"
843.PD 0
844.IP "\fIfile\fR\fB.cp\fR" 4
845.IX Item "file.cp"
846.IP "\fIfile\fR\fB.cxx\fR" 4
847.IX Item "file.cxx"
848.IP "\fIfile\fR\fB.cpp\fR" 4
849.IX Item "file.cpp"
850.IP "\fIfile\fR\fB.CPP\fR" 4
851.IX Item "file.CPP"
852.IP "\fIfile\fR\fB.c++\fR" 4
853.IX Item "file.c++"
854.IP "\fIfile\fR\fB.C\fR" 4
855.IX Item "file.C"
856.PD
857\&\*(C+ source code which must be preprocessed. Note that in \fB.cxx\fR,
858the last two letters must both be literally \fBx\fR. Likewise,
859\&\fB.C\fR refers to a literal capital C.
805.IP "\fIfile\fR\fB.cc\fR" 4
806.IX Item "file.cc"
807.PD 0
808.IP "\fIfile\fR\fB.cp\fR" 4
809.IX Item "file.cp"
810.IP "\fIfile\fR\fB.cxx\fR" 4
811.IX Item "file.cxx"
812.IP "\fIfile\fR\fB.cpp\fR" 4
813.IX Item "file.cpp"
814.IP "\fIfile\fR\fB.CPP\fR" 4
815.IX Item "file.CPP"
816.IP "\fIfile\fR\fB.c++\fR" 4
817.IX Item "file.c++"
818.IP "\fIfile\fR\fB.C\fR" 4
819.IX Item "file.C"
820.PD
821\&\*(C+ source code which must be preprocessed. Note that in \fB.cxx\fR,
822the last two letters must both be literally \fBx\fR. Likewise,
823\&\fB.C\fR refers to a literal capital C.
860.IP "\fIfile\fR\fB.mm\fR" 4
861.IX Item "file.mm"
862.PD 0
863.IP "\fIfile\fR\fB.M\fR" 4
864.IX Item "file.M"
865.PD
866Objective\-\*(C+ source code which must be preprocessed.
867.IP "\fIfile\fR\fB.mii\fR" 4
868.IX Item "file.mii"
869Objective\-\*(C+ source code which should not be preprocessed.
870.IP "\fIfile\fR\fB.hh\fR" 4
871.IX Item "file.hh"
872.PD 0
873.IP "\fIfile\fR\fB.H\fR" 4
874.IX Item "file.H"
875.PD
876\&\*(C+ header file to be turned into a precompiled header.
877.IP "\fIfile\fR\fB.f\fR" 4

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936Specify explicitly the \fIlanguage\fR for the following input files
937(rather than letting the compiler choose a default based on the file
938name suffix). This option applies to all following input files until
939the next \fB\-x\fR option. Possible values for \fIlanguage\fR are:
940.Sp
941.Vb 9
942\& c c-header c-cpp-output
943\& c++ c++-header c++-cpp-output
824.IP "\fIfile\fR\fB.hh\fR" 4
825.IX Item "file.hh"
826.PD 0
827.IP "\fIfile\fR\fB.H\fR" 4
828.IX Item "file.H"
829.PD
830\&\*(C+ header file to be turned into a precompiled header.
831.IP "\fIfile\fR\fB.f\fR" 4

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890Specify explicitly the \fIlanguage\fR for the following input files
891(rather than letting the compiler choose a default based on the file
892name suffix). This option applies to all following input files until
893the next \fB\-x\fR option. Possible values for \fIlanguage\fR are:
894.Sp
895.Vb 9
896\& c c-header c-cpp-output
897\& c++ c++-header c++-cpp-output
944\& objective-c objective-c-header objective-c-cpp-output
945\& objective-c++ objective-c++-header objective-c++-cpp-output
946\& assembler assembler-with-cpp
947\& ada
948\& f95 f95-cpp-input
949\& java
950\& treelang
951.Ve
952.IP "\fB\-x none\fR" 4
953.IX Item "-x none"

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1090.PP
1091When you compile \*(C+ programs, you may specify many of the same
1092command-line options that you use for compiling programs in any
1093language; or command-line options meaningful for C and related
1094languages; or options that are meaningful only for \*(C+ programs.
1095.Sh "Options Controlling C Dialect"
1096.IX Subsection "Options Controlling C Dialect"
1097The following options control the dialect of C (or languages derived
898\& assembler assembler-with-cpp
899\& ada
900\& f95 f95-cpp-input
901\& java
902\& treelang
903.Ve
904.IP "\fB\-x none\fR" 4
905.IX Item "-x none"

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1042.PP
1043When you compile \*(C+ programs, you may specify many of the same
1044command-line options that you use for compiling programs in any
1045language; or command-line options meaningful for C and related
1046languages; or options that are meaningful only for \*(C+ programs.
1047.Sh "Options Controlling C Dialect"
1048.IX Subsection "Options Controlling C Dialect"
1049The following options control the dialect of C (or languages derived
1098from C, such as \*(C+, Objective-C and Objective\-\*(C+) that the compiler
1099accepts:
1050from C, such as \*(C+) that the compiler accepts:
1100.IP "\fB\-ansi\fR" 4
1101.IX Item "-ansi"
1102In C mode, support all \s-1ISO\s0 C90 programs. In \*(C+ mode,
1103remove \s-1GNU\s0 extensions that conflict with \s-1ISO\s0 \*(C+.
1104.Sp
1105This turns off certain features of \s-1GCC\s0 that are incompatible with \s-1ISO\s0
1106C90 (when compiling C code), or of standard \*(C+ (when compiling \*(C+ code),
1107such as the \f(CW\*(C`asm\*(C'\fR and \f(CW\*(C`typeof\*(C'\fR keywords, and

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1835\& {
1836\& A a,b;
1837\& a = b;
1838\& }
1839.Ve
1840.Sp
1841In this example, G++ will synthesize a default \fBA& operator =
1842(const A&);\fR, while cfront will use the user-defined \fBoperator =\fR.
1051.IP "\fB\-ansi\fR" 4
1052.IX Item "-ansi"
1053In C mode, support all \s-1ISO\s0 C90 programs. In \*(C+ mode,
1054remove \s-1GNU\s0 extensions that conflict with \s-1ISO\s0 \*(C+.
1055.Sp
1056This turns off certain features of \s-1GCC\s0 that are incompatible with \s-1ISO\s0
1057C90 (when compiling C code), or of standard \*(C+ (when compiling \*(C+ code),
1058such as the \f(CW\*(C`asm\*(C'\fR and \f(CW\*(C`typeof\*(C'\fR keywords, and

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1786\& {
1787\& A a,b;
1788\& a = b;
1789\& }
1790.Ve
1791.Sp
1792In this example, G++ will synthesize a default \fBA& operator =
1793(const A&);\fR, while cfront will use the user-defined \fBoperator =\fR.
1843.Sh "Options Controlling Objective-C and Objective\-\*(C+ Dialects"
1844.IX Subsection "Options Controlling Objective-C and Objective- Dialects"
1845(\s-1NOTE:\s0 This manual does not describe the Objective-C and Objective\-\*(C+
1846languages themselves. See
1847.PP
1848This section describes the command-line options that are only meaningful
1849for Objective-C and Objective\-\*(C+ programs, but you can also use most of
1850the language-independent \s-1GNU\s0 compiler options.
1851For example, you might compile a file \f(CW\*(C`some_class.m\*(C'\fR like this:
1852.PP
1853.Vb 1
1854\& gcc -g -fgnu-runtime -O -c some_class.m
1855.Ve
1856.PP
1857In this example, \fB\-fgnu\-runtime\fR is an option meant only for
1858Objective-C and Objective\-\*(C+ programs; you can use the other options with
1859any language supported by \s-1GCC\s0.
1860.PP
1861Note that since Objective-C is an extension of the C language, Objective-C
1862compilations may also use options specific to the C front-end (e.g.,
1863\&\fB\-Wtraditional\fR). Similarly, Objective\-\*(C+ compilations may use
1864\&\*(C+\-specific options (e.g., \fB\-Wabi\fR).
1865.PP
1866Here is a list of options that are \fIonly\fR for compiling Objective-C
1867and Objective\-\*(C+ programs:
1868.IP "\fB\-fconstant\-string\-class=\fR\fIclass-name\fR" 4
1869.IX Item "-fconstant-string-class=class-name"
1870Use \fIclass-name\fR as the name of the class to instantiate for each
1871literal string specified with the syntax \f(CW\*(C`@"..."\*(C'\fR. The default
1872class name is \f(CW\*(C`NXConstantString\*(C'\fR if the \s-1GNU\s0 runtime is being used, and
1873\&\f(CW\*(C`NSConstantString\*(C'\fR if the NeXT runtime is being used (see below). The
1874\&\fB\-fconstant\-cfstrings\fR option, if also present, will override the
1875\&\fB\-fconstant\-string\-class\fR setting and cause \f(CW\*(C`@"..."\*(C'\fR literals
1876to be laid out as constant CoreFoundation strings.
1877.IP "\fB\-fgnu\-runtime\fR" 4
1878.IX Item "-fgnu-runtime"
1879Generate object code compatible with the standard \s-1GNU\s0 Objective-C
1880runtime. This is the default for most types of systems.
1881.IP "\fB\-fnext\-runtime\fR" 4
1882.IX Item "-fnext-runtime"
1883Generate output compatible with the NeXT runtime. This is the default
1884for NeXT-based systems, including Darwin and Mac \s-1OS\s0 X. The macro
1885\&\f(CW\*(C`_\|_NEXT_RUNTIME_\|_\*(C'\fR is predefined if (and only if) this option is
1886used.
1887.IP "\fB\-fno\-nil\-receivers\fR" 4
1888.IX Item "-fno-nil-receivers"
1889Assume that all Objective-C message dispatches (e.g.,
1890\&\f(CW\*(C`[receiver message:arg]\*(C'\fR) in this translation unit ensure that the receiver
1891is not \f(CW\*(C`nil\*(C'\fR. This allows for more efficient entry points in the runtime
1892to be used. Currently, this option is only available in conjunction with
1893the NeXT runtime on Mac \s-1OS\s0 X 10.3 and later.
1894.IP "\fB\-fobjc\-call\-cxx\-cdtors\fR" 4
1895.IX Item "-fobjc-call-cxx-cdtors"
1896For each Objective-C class, check if any of its instance variables is a
1897\&\*(C+ object with a non-trivial default constructor. If so, synthesize a
1898special \f(CW\*(C`\- (id) .cxx_construct\*(C'\fR instance method that will run
1899non-trivial default constructors on any such instance variables, in order,
1900and then return \f(CW\*(C`self\*(C'\fR. Similarly, check if any instance variable
1901is a \*(C+ object with a non-trivial destructor, and if so, synthesize a
1902special \f(CW\*(C`\- (void) .cxx_destruct\*(C'\fR method that will run
1903all such default destructors, in reverse order.
1904.Sp
1905The \f(CW\*(C`\- (id) .cxx_construct\*(C'\fR and/or \f(CW\*(C`\- (void) .cxx_destruct\*(C'\fR methods
1906thusly generated will only operate on instance variables declared in the
1907current Objective-C class, and not those inherited from superclasses. It
1908is the responsibility of the Objective-C runtime to invoke all such methods
1909in an object's inheritance hierarchy. The \f(CW\*(C`\- (id) .cxx_construct\*(C'\fR methods
1910will be invoked by the runtime immediately after a new object
1911instance is allocated; the \f(CW\*(C`\- (void) .cxx_destruct\*(C'\fR methods will
1912be invoked immediately before the runtime deallocates an object instance.
1913.Sp
1914As of this writing, only the NeXT runtime on Mac \s-1OS\s0 X 10.4 and later has
1915support for invoking the \f(CW\*(C`\- (id) .cxx_construct\*(C'\fR and
1916\&\f(CW\*(C`\- (void) .cxx_destruct\*(C'\fR methods.
1917.IP "\fB\-fobjc\-direct\-dispatch\fR" 4
1918.IX Item "-fobjc-direct-dispatch"
1919Allow fast jumps to the message dispatcher. On Darwin this is
1920accomplished via the comm page.
1921.IP "\fB\-fobjc\-exceptions\fR" 4
1922.IX Item "-fobjc-exceptions"
1923Enable syntactic support for structured exception handling in Objective\-C,
1924similar to what is offered by \*(C+ and Java. This option is
1925unavailable in conjunction with the NeXT runtime on Mac \s-1OS\s0 X 10.2 and
1926earlier.
1927.Sp
1928.Vb 23
1929\& @try {
1930\& ...
1931\& @throw expr;
1932\& ...
1933\& }
1934\& @catch (AnObjCClass *exc) {
1935\& ...
1936\& @throw expr;
1937\& ...
1938\& @throw;
1939\& ...
1940\& }
1941\& @catch (AnotherClass *exc) {
1942\& ...
1943\& }
1944\& @catch (id allOthers) {
1945\& ...
1946\& }
1947\& @finally {
1948\& ...
1949\& @throw expr;
1950\& ...
1951\& }
1952.Ve
1953.Sp
1954The \f(CW@throw\fR statement may appear anywhere in an Objective-C or
1955Objective\-\*(C+ program; when used inside of a \f(CW@catch\fR block, the
1956\&\f(CW@throw\fR may appear without an argument (as shown above), in which case
1957the object caught by the \f(CW@catch\fR will be rethrown.
1958.Sp
1959Note that only (pointers to) Objective-C objects may be thrown and
1960caught using this scheme. When an object is thrown, it will be caught
1961by the nearest \f(CW@catch\fR clause capable of handling objects of that type,
1962analogously to how \f(CW\*(C`catch\*(C'\fR blocks work in \*(C+ and Java. A
1963\&\f(CW\*(C`@catch(id ...)\*(C'\fR clause (as shown above) may also be provided to catch
1964any and all Objective-C exceptions not caught by previous \f(CW@catch\fR
1965clauses (if any).
1966.Sp
1967The \f(CW@finally\fR clause, if present, will be executed upon exit from the
1968immediately preceding \f(CW\*(C`@try ... @catch\*(C'\fR section. This will happen
1969regardless of whether any exceptions are thrown, caught or rethrown
1970inside the \f(CW\*(C`@try ... @catch\*(C'\fR section, analogously to the behavior
1971of the \f(CW\*(C`finally\*(C'\fR clause in Java.
1972.Sp
1973There are several caveats to using the new exception mechanism:
1974.RS 4
1975.IP "*" 4
1976Although currently designed to be binary compatible with \f(CW\*(C`NS_HANDLER\*(C'\fR\-style
1977idioms provided by the \f(CW\*(C`NSException\*(C'\fR class, the new
1978exceptions can only be used on Mac \s-1OS\s0 X 10.3 (Panther) and later
1979systems, due to additional functionality needed in the (NeXT) Objective-C
1980runtime.
1981.IP "*" 4
1982As mentioned above, the new exceptions do not support handling
1983types other than Objective-C objects. Furthermore, when used from
1984Objective\-\*(C+, the Objective-C exception model does not interoperate with \*(C+
1985exceptions at this time. This means you cannot \f(CW@throw\fR an exception
1986from Objective-C and \f(CW\*(C`catch\*(C'\fR it in \*(C+, or vice versa
1987(i.e., \f(CW\*(C`throw ... @catch\*(C'\fR).
1988.RE
1989.RS 4
1990.Sp
1991The \fB\-fobjc\-exceptions\fR switch also enables the use of synchronization
1992blocks for thread-safe execution:
1993.Sp
1994.Vb 3
1995\& @synchronized (ObjCClass *guard) {
1996\& ...
1997\& }
1998.Ve
1999.Sp
2000Upon entering the \f(CW@synchronized\fR block, a thread of execution shall
2001first check whether a lock has been placed on the corresponding \f(CW\*(C`guard\*(C'\fR
2002object by another thread. If it has, the current thread shall wait until
2003the other thread relinquishes its lock. Once \f(CW\*(C`guard\*(C'\fR becomes available,
2004the current thread will place its own lock on it, execute the code contained in
2005the \f(CW@synchronized\fR block, and finally relinquish the lock (thereby
2006making \f(CW\*(C`guard\*(C'\fR available to other threads).
2007.Sp
2008Unlike Java, Objective-C does not allow for entire methods to be marked
2009\&\f(CW@synchronized\fR. Note that throwing exceptions out of
2010\&\f(CW@synchronized\fR blocks is allowed, and will cause the guarding object
2011to be unlocked properly.
2012.RE
2013.IP "\fB\-fobjc\-gc\fR" 4
2014.IX Item "-fobjc-gc"
2015Enable garbage collection (\s-1GC\s0) in Objective-C and Objective\-\*(C+ programs.
2016.IP "\fB\-freplace\-objc\-classes\fR" 4
2017.IX Item "-freplace-objc-classes"
2018Emit a special marker instructing \fB\f(BIld\fB\|(1)\fR not to statically link in
2019the resulting object file, and allow \fB\f(BIdyld\fB\|(1)\fR to load it in at
2020run time instead. This is used in conjunction with the Fix-and-Continue
2021debugging mode, where the object file in question may be recompiled and
2022dynamically reloaded in the course of program execution, without the need
2023to restart the program itself. Currently, Fix-and-Continue functionality
2024is only available in conjunction with the NeXT runtime on Mac \s-1OS\s0 X 10.3
2025and later.
2026.IP "\fB\-fzero\-link\fR" 4
2027.IX Item "-fzero-link"
2028When compiling for the NeXT runtime, the compiler ordinarily replaces calls
2029to \f(CW\*(C`objc_getClass("...")\*(C'\fR (when the name of the class is known at
2030compile time) with static class references that get initialized at load time,
2031which improves run-time performance. Specifying the \fB\-fzero\-link\fR flag
2032suppresses this behavior and causes calls to \f(CW\*(C`objc_getClass("...")\*(C'\fR
2033to be retained. This is useful in Zero-Link debugging mode, since it allows
2034for individual class implementations to be modified during program execution.
2035.IP "\fB\-gen\-decls\fR" 4
2036.IX Item "-gen-decls"
2037Dump interface declarations for all classes seen in the source file to a
2038file named \fI\fIsourcename\fI.decl\fR.
2039.IP "\fB\-Wassign\-intercept\fR" 4
2040.IX Item "-Wassign-intercept"
2041Warn whenever an Objective-C assignment is being intercepted by the
2042garbage collector.
2043.IP "\fB\-Wno\-protocol\fR" 4
2044.IX Item "-Wno-protocol"
2045If a class is declared to implement a protocol, a warning is issued for
2046every method in the protocol that is not implemented by the class. The
2047default behavior is to issue a warning for every method not explicitly
2048implemented in the class, even if a method implementation is inherited
2049from the superclass. If you use the \fB\-Wno\-protocol\fR option, then
2050methods inherited from the superclass are considered to be implemented,
2051and no warning is issued for them.
2052.IP "\fB\-Wselector\fR" 4
2053.IX Item "-Wselector"
2054Warn if multiple methods of different types for the same selector are
2055found during compilation. The check is performed on the list of methods
2056in the final stage of compilation. Additionally, a check is performed
2057for each selector appearing in a \f(CW\*(C`@selector(...)\*(C'\fR
2058expression, and a corresponding method for that selector has been found
2059during compilation. Because these checks scan the method table only at
2060the end of compilation, these warnings are not produced if the final
2061stage of compilation is not reached, for example because an error is
2062found during compilation, or because the \fB\-fsyntax\-only\fR option is
2063being used.
2064.IP "\fB\-Wstrict\-selector\-match\fR" 4
2065.IX Item "-Wstrict-selector-match"
2066Warn if multiple methods with differing argument and/or return types are
2067found for a given selector when attempting to send a message using this
2068selector to a receiver of type \f(CW\*(C`id\*(C'\fR or \f(CW\*(C`Class\*(C'\fR. When this flag
2069is off (which is the default behavior), the compiler will omit such warnings
2070if any differences found are confined to types which share the same size
2071and alignment.
2072.IP "\fB\-Wundeclared\-selector\fR" 4
2073.IX Item "-Wundeclared-selector"
2074Warn if a \f(CW\*(C`@selector(...)\*(C'\fR expression referring to an
2075undeclared selector is found. A selector is considered undeclared if no
2076method with that name has been declared before the
2077\&\f(CW\*(C`@selector(...)\*(C'\fR expression, either explicitly in an
2078\&\f(CW@interface\fR or \f(CW@protocol\fR declaration, or implicitly in
2079an \f(CW@implementation\fR section. This option always performs its
2080checks as soon as a \f(CW\*(C`@selector(...)\*(C'\fR expression is found,
2081while \fB\-Wselector\fR only performs its checks in the final stage of
2082compilation. This also enforces the coding style convention
2083that methods and selectors must be declared before being used.
2084.IP "\fB\-print\-objc\-runtime\-info\fR" 4
2085.IX Item "-print-objc-runtime-info"
2086Generate C header describing the largest structure that is passed by
2087value, if any.
2088.Sh "Options to Control Diagnostic Messages Formatting"
2089.IX Subsection "Options to Control Diagnostic Messages Formatting"
2090Traditionally, diagnostic messages have been formatted irrespective of
2091the output device's aspect (e.g. its width, ...). The options described
2092below can be used to control the diagnostic messages formatting
2093algorithm, e.g. how many characters per line, how often source location
2094information should be reported. Right now, only the \*(C+ front end can
2095honor these options. However it is expected, in the near future, that

--- 35 unchanged lines hidden (view full) ---

2131for example \fB\-Wimplicit\fR to request warnings on implicit
2132declarations. Each of these specific warning options also has a
2133negative form beginning \fB\-Wno\-\fR to turn off warnings;
2134for example, \fB\-Wno\-implicit\fR. This manual lists only one of the
2135two forms, whichever is not the default.
2136.PP
2137The following options control the amount and kinds of warnings produced
2138by \s-1GCC\s0; for further, language-specific options also refer to
1794.Sh "Options to Control Diagnostic Messages Formatting"
1795.IX Subsection "Options to Control Diagnostic Messages Formatting"
1796Traditionally, diagnostic messages have been formatted irrespective of
1797the output device's aspect (e.g. its width, ...). The options described
1798below can be used to control the diagnostic messages formatting
1799algorithm, e.g. how many characters per line, how often source location
1800information should be reported. Right now, only the \*(C+ front end can
1801honor these options. However it is expected, in the near future, that

--- 35 unchanged lines hidden (view full) ---

1837for example \fB\-Wimplicit\fR to request warnings on implicit
1838declarations. Each of these specific warning options also has a
1839negative form beginning \fB\-Wno\-\fR to turn off warnings;
1840for example, \fB\-Wno\-implicit\fR. This manual lists only one of the
1841two forms, whichever is not the default.
1842.PP
1843The following options control the amount and kinds of warnings produced
1844by \s-1GCC\s0; for further, language-specific options also refer to
2139\&\fB\*(C+ Dialect Options\fR and \fBObjective-C and Objective\-\*(C+ Dialect
2140Options\fR.
1845\&\fB\*(C+ Dialect Options\fR.
2141.IP "\fB\-fsyntax\-only\fR" 4
2142.IX Item "-fsyntax-only"
2143Check the code for syntax errors, but don't do anything beyond that.
2144.IP "\fB\-pedantic\fR" 4
2145.IX Item "-pedantic"
2146Issue all the warnings demanded by strict \s-1ISO\s0 C and \s-1ISO\s0 \*(C+;
2147reject all programs that use forbidden extensions, and some other
2148programs that do not follow \s-1ISO\s0 C and \s-1ISO\s0 \*(C+. For \s-1ISO\s0 C, follows the

--- 133 unchanged lines hidden (view full) ---

2282\&\-Wformat\-nonliteral \-Wformat\-security \-Wformat\-y2k\fR.
2283.IP "\fB\-Wnonnull\fR" 4
2284.IX Item "-Wnonnull"
2285Warn about passing a null pointer for arguments marked as
2286requiring a non-null value by the \f(CW\*(C`nonnull\*(C'\fR function attribute.
2287.Sp
2288\&\fB\-Wnonnull\fR is included in \fB\-Wall\fR and \fB\-Wformat\fR. It
2289can be disabled with the \fB\-Wno\-nonnull\fR option.
1846.IP "\fB\-fsyntax\-only\fR" 4
1847.IX Item "-fsyntax-only"
1848Check the code for syntax errors, but don't do anything beyond that.
1849.IP "\fB\-pedantic\fR" 4
1850.IX Item "-pedantic"
1851Issue all the warnings demanded by strict \s-1ISO\s0 C and \s-1ISO\s0 \*(C+;
1852reject all programs that use forbidden extensions, and some other
1853programs that do not follow \s-1ISO\s0 C and \s-1ISO\s0 \*(C+. For \s-1ISO\s0 C, follows the

--- 133 unchanged lines hidden (view full) ---

1987\&\-Wformat\-nonliteral \-Wformat\-security \-Wformat\-y2k\fR.
1988.IP "\fB\-Wnonnull\fR" 4
1989.IX Item "-Wnonnull"
1990Warn about passing a null pointer for arguments marked as
1991requiring a non-null value by the \f(CW\*(C`nonnull\*(C'\fR function attribute.
1992.Sp
1993\&\fB\-Wnonnull\fR is included in \fB\-Wall\fR and \fB\-Wformat\fR. It
1994can be disabled with the \fB\-Wno\-nonnull\fR option.
2290.IP "\fB\-Winit\-self\fR (C, \*(C+, Objective-C and Objective\-\*(C+ only)" 4
2291.IX Item "-Winit-self (C, , Objective-C and Objective- only)"
1995.IP "\fB\-Winit\-self\fR (C, \*(C+ only)" 4
1996.IX Item "-Winit-self (C, only)"
2292Warn about uninitialized variables which are initialized with themselves.
2293Note this option can only be used with the \fB\-Wuninitialized\fR option,
2294which in turn only works with \fB\-O1\fR and above.
2295.Sp
2296For example, \s-1GCC\s0 will warn about \f(CW\*(C`i\*(C'\fR being uninitialized in the
2297following snippet only when \fB\-Winit\-self\fR has been specified:
2298.Sp
2299.Vb 5

--- 34 unchanged lines hidden (view full) ---

2334bracketed, but that for \fBb\fR is fully bracketed.
2335.Sp
2336.Vb 2
2337\& int a[2][2] = { 0, 1, 2, 3 };
2338\& int b[2][2] = { { 0, 1 }, { 2, 3 } };
2339.Ve
2340.Sp
2341This warning is enabled by \fB\-Wall\fR.
1997Warn about uninitialized variables which are initialized with themselves.
1998Note this option can only be used with the \fB\-Wuninitialized\fR option,
1999which in turn only works with \fB\-O1\fR and above.
2000.Sp
2001For example, \s-1GCC\s0 will warn about \f(CW\*(C`i\*(C'\fR being uninitialized in the
2002following snippet only when \fB\-Winit\-self\fR has been specified:
2003.Sp
2004.Vb 5

--- 34 unchanged lines hidden (view full) ---

2039bracketed, but that for \fBb\fR is fully bracketed.
2040.Sp
2041.Vb 2
2042\& int a[2][2] = { 0, 1, 2, 3 };
2043\& int b[2][2] = { { 0, 1 }, { 2, 3 } };
2044.Ve
2045.Sp
2046This warning is enabled by \fB\-Wall\fR.
2342.IP "\fB\-Wmissing\-include\-dirs\fR (C, \*(C+, Objective-C and Objective\-\*(C+ only)" 4
2343.IX Item "-Wmissing-include-dirs (C, , Objective-C and Objective- only)"
2047.IP "\fB\-Wmissing\-include\-dirs\fR (C and \*(C+ only)" 4
2048.IX Item "-Wmissing-include-dirs (C, only)"
2344Warn if a user-supplied include directory does not exist.
2345.IP "\fB\-Wparentheses\fR" 4
2346.IX Item "-Wparentheses"
2347Warn if parentheses are omitted in certain contexts, such
2348as when there is an assignment in a context where a truth value
2349is expected, or when operators are nested whose precedence people
2350often get confused about. Only the warning for an assignment used as
2351a truth value is supported when compiling \*(C+; the other warnings are

--- 318 unchanged lines hidden (view full) ---

2670.RS 4
2671.RE
2672.IP "\fB\-Wall\fR" 4
2673.IX Item "-Wall"
2674All of the above \fB\-W\fR options combined. This enables all the
2675warnings about constructions that some users consider questionable, and
2676that are easy to avoid (or modify to prevent the warning), even in
2677conjunction with macros. This also enables some language-specific
2049Warn if a user-supplied include directory does not exist.
2050.IP "\fB\-Wparentheses\fR" 4
2051.IX Item "-Wparentheses"
2052Warn if parentheses are omitted in certain contexts, such
2053as when there is an assignment in a context where a truth value
2054is expected, or when operators are nested whose precedence people
2055often get confused about. Only the warning for an assignment used as
2056a truth value is supported when compiling \*(C+; the other warnings are

--- 318 unchanged lines hidden (view full) ---

2375.RS 4
2376.RE
2377.IP "\fB\-Wall\fR" 4
2378.IX Item "-Wall"
2379All of the above \fB\-W\fR options combined. This enables all the
2380warnings about constructions that some users consider questionable, and
2381that are easy to avoid (or modify to prevent the warning), even in
2382conjunction with macros. This also enables some language-specific
2678warnings described in \fB\*(C+ Dialect Options\fR and
2679\&\fBObjective-C and Objective\-\*(C+ Dialect Options\fR.
2383warnings described in \fB\*(C+ Dialect Options\fR.
2680.PP
2681The following \fB\-W...\fR options are not implied by \fB\-Wall\fR.
2682Some of them warn about constructions that users generally do not
2683consider questionable, but which occasionally you might wish to check
2684for; others warn about constructions that are necessary or hard to avoid
2685in some cases, and there is no simple way to modify the code to suppress
2686the warning.
2687.IP "\fB\-Wextra\fR" 4

--- 531 unchanged lines hidden (view full) ---

3219not generally indicate that there is anything wrong with your code; it
3220merely indicates that \s-1GCC\s0's optimizers were unable to handle the code
3221effectively. Often, the problem is that your code is too big or too
3222complex; \s-1GCC\s0 will refuse to optimize programs when the optimization
3223itself is likely to take inordinate amounts of time.
3224.IP "\fB\-Wpointer\-sign\fR" 4
3225.IX Item "-Wpointer-sign"
3226Warn for pointer argument passing or assignment with different signedness.
2384.PP
2385The following \fB\-W...\fR options are not implied by \fB\-Wall\fR.
2386Some of them warn about constructions that users generally do not
2387consider questionable, but which occasionally you might wish to check
2388for; others warn about constructions that are necessary or hard to avoid
2389in some cases, and there is no simple way to modify the code to suppress
2390the warning.
2391.IP "\fB\-Wextra\fR" 4

--- 531 unchanged lines hidden (view full) ---

2923not generally indicate that there is anything wrong with your code; it
2924merely indicates that \s-1GCC\s0's optimizers were unable to handle the code
2925effectively. Often, the problem is that your code is too big or too
2926complex; \s-1GCC\s0 will refuse to optimize programs when the optimization
2927itself is likely to take inordinate amounts of time.
2928.IP "\fB\-Wpointer\-sign\fR" 4
2929.IX Item "-Wpointer-sign"
2930Warn for pointer argument passing or assignment with different signedness.
3227This option is only supported for C and Objective\-C. It is implied by
3228\&\fB\-Wall\fR and by \fB\-pedantic\fR, which can be disabled with
2931This option is only supported for C. It is implied by \&\fB\-Wall\fR
2932and by \fB\-pedantic\fR, which can be disabled with
3229\&\fB\-Wno\-pointer\-sign\fR.
3230.IP "\fB\-Werror\fR" 4
3231.IX Item "-Werror"
3232Make all warnings into errors.
3233.IP "\fB\-Werror=\fR" 4
3234.IX Item "-Werror="
3235Make the specified warning into an errors. The specifier for a
3236warning is appended, for example \fB\-Werror=switch\fR turns the

--- 3052 unchanged lines hidden (view full) ---

6289safe to edit the filename if the \s-1PCH\s0 file is available in a different
6290location. The filename may be absolute or it may be relative to \s-1GCC\s0's
6291current directory.
6292.IP "\fB\-x c\fR" 4
6293.IX Item "-x c"
6294.PD 0
6295.IP "\fB\-x c++\fR" 4
6296.IX Item "-x c++"
2933\&\fB\-Wno\-pointer\-sign\fR.
2934.IP "\fB\-Werror\fR" 4
2935.IX Item "-Werror"
2936Make all warnings into errors.
2937.IP "\fB\-Werror=\fR" 4
2938.IX Item "-Werror="
2939Make the specified warning into an errors. The specifier for a
2940warning is appended, for example \fB\-Werror=switch\fR turns the

--- 3052 unchanged lines hidden (view full) ---

5993safe to edit the filename if the \s-1PCH\s0 file is available in a different
5994location. The filename may be absolute or it may be relative to \s-1GCC\s0's
5995current directory.
5996.IP "\fB\-x c\fR" 4
5997.IX Item "-x c"
5998.PD 0
5999.IP "\fB\-x c++\fR" 4
6000.IX Item "-x c++"
6297.IP "\fB\-x objective-c\fR" 4
6298.IX Item "-x objective-c"
6299.IP "\fB\-x assembler-with-cpp\fR" 4
6300.IX Item "-x assembler-with-cpp"
6301.PD
6001.IP "\fB\-x assembler-with-cpp\fR" 4
6002.IX Item "-x assembler-with-cpp"
6003.PD
6302Specify the source language: C, \*(C+, Objective\-C, or assembly. This has
6004Specify the source language: C, \*(C+, or assembly. This has
6303nothing to do with standards conformance or extensions; it merely
6304selects which base syntax to expect. If you give none of these options,
6305cpp will deduce the language from the extension of the source file:
6306\&\fB.c\fR, \fB.cc\fR, \fB.m\fR, or \fB.S\fR. Some other common
6307extensions for \*(C+ and assembly are also recognized. If cpp does not
6308recognize the extension, it will treat the file as C; this is the most
6309generic mode.
6310.Sp

--- 412 unchanged lines hidden (view full) ---

6723Normally the files found this way are library files\-\-\-archive files
6724whose members are object files. The linker handles an archive file by
6725scanning through it for members which define symbols that have so far
6726been referenced but not defined. But if the file that is found is an
6727ordinary object file, it is linked in the usual fashion. The only
6728difference between using an \fB\-l\fR option and specifying a file name
6729is that \fB\-l\fR surrounds \fIlibrary\fR with \fBlib\fR and \fB.a\fR
6730and searches several directories.
6005nothing to do with standards conformance or extensions; it merely
6006selects which base syntax to expect. If you give none of these options,
6007cpp will deduce the language from the extension of the source file:
6008\&\fB.c\fR, \fB.cc\fR, \fB.m\fR, or \fB.S\fR. Some other common
6009extensions for \*(C+ and assembly are also recognized. If cpp does not
6010recognize the extension, it will treat the file as C; this is the most
6011generic mode.
6012.Sp

--- 412 unchanged lines hidden (view full) ---

6425Normally the files found this way are library files\-\-\-archive files
6426whose members are object files. The linker handles an archive file by
6427scanning through it for members which define symbols that have so far
6428been referenced but not defined. But if the file that is found is an
6429ordinary object file, it is linked in the usual fashion. The only
6430difference between using an \fB\-l\fR option and specifying a file name
6431is that \fB\-l\fR surrounds \fIlibrary\fR with \fBlib\fR and \fB.a\fR
6432and searches several directories.
6731.IP "\fB\-lobjc\fR" 4
6732.IX Item "-lobjc"
6733You need this special case of the \fB\-l\fR option in order to
6734link an Objective-C or Objective\-\*(C+ program.
6735.IP "\fB\-nostartfiles\fR" 4
6736.IX Item "-nostartfiles"
6737Do not use the standard system startup files when linking.
6738The standard system libraries are used normally, unless \fB\-nostdlib\fR
6739or \fB\-nodefaultlibs\fR is used.
6740.IP "\fB\-nodefaultlibs\fR" 4
6741.IX Item "-nodefaultlibs"
6742Do not use the standard system libraries when linking.

--- 6287 unchanged lines hidden (view full) ---

13030preprocessor.
13031.IP "\fB\s-1CPATH\s0\fR" 4
13032.IX Item "CPATH"
13033.PD 0
13034.IP "\fBC_INCLUDE_PATH\fR" 4
13035.IX Item "C_INCLUDE_PATH"
13036.IP "\fB\s-1CPLUS_INCLUDE_PATH\s0\fR" 4
13037.IX Item "CPLUS_INCLUDE_PATH"
6433.IP "\fB\-nostartfiles\fR" 4
6434.IX Item "-nostartfiles"
6435Do not use the standard system startup files when linking.
6436The standard system libraries are used normally, unless \fB\-nostdlib\fR
6437or \fB\-nodefaultlibs\fR is used.
6438.IP "\fB\-nodefaultlibs\fR" 4
6439.IX Item "-nodefaultlibs"
6440Do not use the standard system libraries when linking.

--- 6287 unchanged lines hidden (view full) ---

12728preprocessor.
12729.IP "\fB\s-1CPATH\s0\fR" 4
12730.IX Item "CPATH"
12731.PD 0
12732.IP "\fBC_INCLUDE_PATH\fR" 4
12733.IX Item "C_INCLUDE_PATH"
12734.IP "\fB\s-1CPLUS_INCLUDE_PATH\s0\fR" 4
12735.IX Item "CPLUS_INCLUDE_PATH"
13038.IP "\fB\s-1OBJC_INCLUDE_PATH\s0\fR" 4
13039.IX Item "OBJC_INCLUDE_PATH"
13040.PD
13041Each variable's value is a list of directories separated by a special
13042character, much like \fB\s-1PATH\s0\fR, in which to look for header files.
13043The special character, \f(CW\*(C`PATH_SEPARATOR\*(C'\fR, is target-dependent and
13044determined at \s-1GCC\s0 build time. For Microsoft Windows-based targets it is a
13045semicolon, and for almost all other targets it is a colon.
13046.Sp
13047\&\fB\s-1CPATH\s0\fR specifies a list of directories to be searched as if

--- 86 unchanged lines hidden --- 		12736.PD
12737Each variable's value is a list of directories separated by a special
12738character, much like \fB\s-1PATH\s0\fR, in which to look for header files.
12739The special character, \f(CW\*(C`PATH_SEPARATOR\*(C'\fR, is target-dependent and
12740determined at \s-1GCC\s0 build time. For Microsoft Windows-based targets it is a
12741semicolon, and for almost all other targets it is a colon.
12742.Sp
12743\&\fB\s-1CPATH\s0\fR specifies a list of directories to be searched as if

--- 86 unchanged lines hidden ---