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1 @c Copyright (c) 1999, 2000, 2001, 2002, 2004
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2 @c Free Software Foundation, Inc.
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3 @c This is part of the CPP and GCC manuals.
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4 @c For copying conditions, see the file gcc.texi.
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5
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6 @c ---------------------------------------------------------------------
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7 @c Environment variables affecting the preprocessor
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8 @c ---------------------------------------------------------------------
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9
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10 @c If this file is included with the flag ``cppmanual'' set, it is
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11 @c formatted for inclusion in the CPP manual; otherwise the main GCC manual.
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12
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13 @vtable @env
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14 @item CPATH
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15 @itemx C_INCLUDE_PATH
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16 @itemx CPLUS_INCLUDE_PATH
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17 @itemx OBJC_INCLUDE_PATH
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18 @c Commented out until ObjC++ is part of GCC:
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19 @c @itemx OBJCPLUS_INCLUDE_PATH
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20 Each variable's value is a list of directories separated by a special
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21 character, much like @env{PATH}, in which to look for header files.
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22 The special character, @code{PATH_SEPARATOR}, is target-dependent and
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23 determined at GCC build time. For Microsoft Windows-based targets it is a
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24 semicolon, and for almost all other targets it is a colon.
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25
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26 @env{CPATH} specifies a list of directories to be searched as if
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27 specified with @option{-I}, but after any paths given with @option{-I}
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28 options on the command line. This environment variable is used
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29 regardless of which language is being preprocessed.
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30
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31 The remaining environment variables apply only when preprocessing the
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32 particular language indicated. Each specifies a list of directories
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33 to be searched as if specified with @option{-isystem}, but after any
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34 paths given with @option{-isystem} options on the command line.
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35
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36 In all these variables, an empty element instructs the compiler to
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37 search its current working directory. Empty elements can appear at the
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38 beginning or end of a path. For instance, if the value of
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39 @env{CPATH} is @code{:/special/include}, that has the same
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40 effect as @samp{@w{-I. -I/special/include}}.
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41
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42 @c man end
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43 @ifset cppmanual
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44 See also @ref{Search Path}.
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45 @end ifset
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46 @c man begin ENVIRONMENT
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47
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48 @item DEPENDENCIES_OUTPUT
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49 @cindex dependencies for make as output
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50 If this variable is set, its value specifies how to output
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51 dependencies for Make based on the non-system header files processed
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52 by the compiler. System header files are ignored in the dependency
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53 output.
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54
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55 The value of @env{DEPENDENCIES_OUTPUT} can be just a file name, in
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56 which case the Make rules are written to that file, guessing the target
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57 name from the source file name. Or the value can have the form
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58 @samp{@var{file} @var{target}}, in which case the rules are written to
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59 file @var{file} using @var{target} as the target name.
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60
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61 In other words, this environment variable is equivalent to combining
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62 the options @option{-MM} and @option{-MF}
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63 @ifset cppmanual
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64 (@pxref{Invocation}),
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65 @end ifset
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66 @ifclear cppmanual
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67 (@pxref{Preprocessor Options}),
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68 @end ifclear
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69 with an optional @option{-MT} switch too.
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70
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71 @item SUNPRO_DEPENDENCIES
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72 @cindex dependencies for make as output
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73 This variable is the same as @env{DEPENDENCIES_OUTPUT} (see above),
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74 except that system header files are not ignored, so it implies
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75 @option{-M} rather than @option{-MM}. However, the dependence on the
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76 main input file is omitted.
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77 @ifset cppmanual
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78 @xref{Invocation}.
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79 @end ifset
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80 @ifclear cppmanual
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81 @xref{Preprocessor Options}.
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82 @end ifclear
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83 @end vtable
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