1 @c Copyright (c) 1999, 2000, 2001, 2002
2 @c Free Software Foundation, Inc.
3 @c This is part of the CPP and GCC manuals.
4 @c For copying conditions, see the file gcc.texi.
6 @c ---------------------------------------------------------------------
7 @c Environment variables affecting the preprocessor
8 @c ---------------------------------------------------------------------
10 @c If this file is included with the flag ``cppmanual'' set, it is
11 @c formatted for inclusion in the CPP manual; otherwise the main GCC manual.
16 @itemx CPLUS_INCLUDE_PATH
17 @itemx OBJC_INCLUDE_PATH
18 @c Commented out until ObjC++ is part of GCC:
19 @c @itemx OBJCPLUS_INCLUDE_PATH
20 Each variable's value is a list of directories separated by a special
21 character, much like @env{PATH}, in which to look for header files.
22 The special character, @code{PATH_SEPARATOR}, is target-dependent and
23 determined at GCC build time. For Windows-based targets it is a
24 semicolon, and for almost all other targets it is a colon.
26 @env{CPATH} specifies a list of directories to be searched as if
27 specified with @option{-I}, but after any paths given with @option{-I}
28 options on the command line. The environment variable is used
29 regardless of which language is being preprocessed.
31 The remaining environment variables apply only when preprocessing the
32 particular language indicated. Each specifies a list of directories
33 to be searched as if specified with @option{-isystem}, but after any
34 paths given with @option{-isystem} options on the command line.
37 See also @ref{Search Path}.
40 @item DEPENDENCIES_OUTPUT
41 @anchor{DEPENDENCIES_OUTPUT}
42 @cindex dependencies for make as output
43 If this variable is set, its value specifies how to output
44 dependencies for Make based on the non-system header files processed
45 by the compiler. System header files are ignored in the dependency
48 The value of @env{DEPENDENCIES_OUTPUT} can be just a file name, in
49 which case the Make rules are written to that file, guessing the target
50 name from the source file name. Or the value can have the form
51 @samp{@var{file} @var{target}}, in which case the rules are written to
52 file @var{file} using @var{target} as the target name.
54 In other words, this environment variable is equivalent to combining
55 the options @option{-MM} and @option{-MF}
60 (@pxref{Preprocessor Options}),
62 with an optional @option{-MT} switch too.
64 @item SUNPRO_DEPENDENCIES
65 @cindex dependencies for make as output
66 This variable is the same as the environment variable
67 @env{DEPENDENCIES_OUTPUT} (@pxref{DEPENDENCIES_OUTPUT}), except that
68 system header files are not ignored, so it implies @option{-M} rather
74 @xref{Preprocessor Options}.