84 lines
3.2 KiB
Plaintext
84 lines
3.2 KiB
Plaintext
@c Copyright (c) 1999, 2000, 2001, 2002, 2004
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@c Free Software Foundation, Inc.
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@c This is part of the CPP and GCC manuals.
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@c For copying conditions, see the file gcc.texi.
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@c ---------------------------------------------------------------------
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@c Environment variables affecting the preprocessor
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@c ---------------------------------------------------------------------
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@c If this file is included with the flag ``cppmanual'' set, it is
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@c formatted for inclusion in the CPP manual; otherwise the main GCC manual.
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@vtable @env
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@item CPATH
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@itemx C_INCLUDE_PATH
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@itemx CPLUS_INCLUDE_PATH
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@itemx OBJC_INCLUDE_PATH
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@c Commented out until ObjC++ is part of GCC:
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@c @itemx OBJCPLUS_INCLUDE_PATH
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Each variable's value is a list of directories separated by a special
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character, much like @env{PATH}, in which to look for header files.
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The special character, @code{PATH_SEPARATOR}, is target-dependent and
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determined at GCC build time. For Microsoft Windows-based targets it is a
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semicolon, and for almost all other targets it is a colon.
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@env{CPATH} specifies a list of directories to be searched as if
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specified with @option{-I}, but after any paths given with @option{-I}
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options on the command line. This environment variable is used
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regardless of which language is being preprocessed.
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The remaining environment variables apply only when preprocessing the
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particular language indicated. Each specifies a list of directories
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to be searched as if specified with @option{-isystem}, but after any
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paths given with @option{-isystem} options on the command line.
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In all these variables, an empty element instructs the compiler to
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search its current working directory. Empty elements can appear at the
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beginning or end of a path. For instance, if the value of
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@env{CPATH} is @code{:/special/include}, that has the same
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effect as @samp{@w{-I. -I/special/include}}.
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@c man end
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@ifset cppmanual
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See also @ref{Search Path}.
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@end ifset
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@c man begin ENVIRONMENT
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@item DEPENDENCIES_OUTPUT
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@cindex dependencies for make as output
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If this variable is set, its value specifies how to output
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dependencies for Make based on the non-system header files processed
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by the compiler. System header files are ignored in the dependency
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output.
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The value of @env{DEPENDENCIES_OUTPUT} can be just a file name, in
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which case the Make rules are written to that file, guessing the target
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name from the source file name. Or the value can have the form
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@samp{@var{file} @var{target}}, in which case the rules are written to
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file @var{file} using @var{target} as the target name.
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In other words, this environment variable is equivalent to combining
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the options @option{-MM} and @option{-MF}
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@ifset cppmanual
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(@pxref{Invocation}),
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@end ifset
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@ifclear cppmanual
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(@pxref{Preprocessor Options}),
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@end ifclear
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with an optional @option{-MT} switch too.
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@item SUNPRO_DEPENDENCIES
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@cindex dependencies for make as output
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This variable is the same as @env{DEPENDENCIES_OUTPUT} (see above),
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except that system header files are not ignored, so it implies
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@option{-M} rather than @option{-MM}. However, the dependence on the
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main input file is omitted.
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@ifset cppmanual
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@xref{Invocation}.
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@end ifset
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@ifclear cppmanual
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@xref{Preprocessor Options}.
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@end ifclear
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@end vtable
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