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+++ b/gcc/doc/cppdiropts.texi	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,154 @@
+@c Copyright (C) 1999-2017 Free Software Foundation, Inc.
+@c This is part of the CPP and GCC manuals.
+@c For copying conditions, see the file gcc.texi.
+
+@c ---------------------------------------------------------------------
+@c Options affecting include directory search in the preprocessor
+@c ---------------------------------------------------------------------
+
+@c If this file is included with the flag ``cppmanual'' set, it is
+@c formatted for inclusion in the CPP manual; otherwise the main GCC manual.
+
+@item -I @var{dir}
+@itemx -iquote @var{dir}
+@itemx -isystem @var{dir}
+@itemx -idirafter @var{dir}
+@opindex I
+@opindex iquote
+@opindex isystem
+@opindex idirafter
+Add the directory @var{dir} to the list of directories to be searched
+for header files during preprocessing.
+@ifset cppmanual
+@xref{Search Path}.
+@end ifset
+If @var{dir} begins with @samp{=} or @code{$SYSROOT}, then the @samp{=}
+or @code{$SYSROOT} is replaced by the sysroot prefix; see
+@option{--sysroot} and @option{-isysroot}.
+
+Directories specified with @option{-iquote} apply only to the quote 
+form of the directive, @code{@w{#include "@var{file}"}}.
+Directories specified with @option{-I}, @option{-isystem}, 
+or @option{-idirafter} apply to lookup for both the
+@code{@w{#include "@var{file}"}} and
+@code{@w{#include <@var{file}>}} directives.
+
+You can specify any number or combination of these options on the 
+command line to search for header files in several directories.  
+The lookup order is as follows:
+
+@enumerate
+@item
+For the quote form of the include directive, the directory of the current
+file is searched first.
+
+@item
+For the quote form of the include directive, the directories specified
+by @option{-iquote} options are searched in left-to-right order,
+as they appear on the command line.
+
+@item
+Directories specified with @option{-I} options are scanned in
+left-to-right order.
+
+@item
+Directories specified with @option{-isystem} options are scanned in
+left-to-right order.
+
+@item
+Standard system directories are scanned.
+
+@item
+Directories specified with @option{-idirafter} options are scanned in
+left-to-right order.
+@end enumerate
+
+You can use @option{-I} to override a system header
+file, substituting your own version, since these directories are
+searched before the standard system header file directories.  
+However, you should
+not use this option to add directories that contain vendor-supplied
+system header files; use @option{-isystem} for that.
+
+The @option{-isystem} and @option{-idirafter} options also mark the directory
+as a system directory, so that it gets the same special treatment that
+is applied to the standard system directories.
+@ifset cppmanual
+@xref{System Headers}.
+@end ifset
+
+If a standard system include directory, or a directory specified with
+@option{-isystem}, is also specified with @option{-I}, the @option{-I}
+option is ignored.  The directory is still searched but as a
+system directory at its normal position in the system include chain.
+This is to ensure that GCC's procedure to fix buggy system headers and
+the ordering for the @code{#include_next} directive are not inadvertently
+changed.
+If you really need to change the search order for system directories,
+use the @option{-nostdinc} and/or @option{-isystem} options.
+@ifset cppmanual
+@xref{System Headers}.
+@end ifset
+
+@item -I-
+@opindex I-
+Split the include path.
+This option has been deprecated.  Please use @option{-iquote} instead for
+@option{-I} directories before the @option{-I-} and remove the @option{-I-}
+option.
+
+Any directories specified with @option{-I}
+options before @option{-I-} are searched only for headers requested with
+@code{@w{#include "@var{file}"}}; they are not searched for
+@code{@w{#include <@var{file}>}}.  If additional directories are
+specified with @option{-I} options after the @option{-I-}, those
+directories are searched for all @samp{#include} directives.
+
+In addition, @option{-I-} inhibits the use of the directory of the current
+file directory as the first search directory for @code{@w{#include
+"@var{file}"}}.  There is no way to override this effect of @option{-I-}.
+@ifset cppmanual
+@xref{Search Path}.
+@end ifset
+
+@item -iprefix @var{prefix}
+@opindex iprefix
+Specify @var{prefix} as the prefix for subsequent @option{-iwithprefix}
+options.  If the prefix represents a directory, you should include the
+final @samp{/}.
+
+@item -iwithprefix @var{dir}
+@itemx -iwithprefixbefore @var{dir}
+@opindex iwithprefix
+@opindex iwithprefixbefore
+Append @var{dir} to the prefix specified previously with
+@option{-iprefix}, and add the resulting directory to the include search
+path.  @option{-iwithprefixbefore} puts it in the same place @option{-I}
+would; @option{-iwithprefix} puts it where @option{-idirafter} would.
+
+@item -isysroot @var{dir}
+@opindex isysroot
+This option is like the @option{--sysroot} option, but applies only to
+header files (except for Darwin targets, where it applies to both header
+files and libraries).  See the @option{--sysroot} option for more
+information.
+
+@item -imultilib @var{dir}
+@opindex imultilib
+Use @var{dir} as a subdirectory of the directory containing
+target-specific C++ headers.
+
+@item -nostdinc
+@opindex nostdinc
+Do not search the standard system directories for header files.
+Only the directories explicitly specified with @option{-I},
+@option{-iquote}, @option{-isystem}, and/or @option{-idirafter}
+options (and the directory of the current file, if appropriate) 
+are searched.
+
+@item -nostdinc++
+@opindex nostdinc++
+Do not search for header files in the C++-specific standard directories,
+but do still search the other standard directories.  (This option is
+used when building the C++ library.)
+