cpplib.h (struct cpp_options): Add canonical_system_headers.

    * include/cpplib.h (struct cpp_options): Add canonical_system_headers.
    * files.c (find_file_in_dir): Call maybe_shorter_path() only if
    canonical_system_headers is set.
    * init.c (cpp_create_reader): Initialize canonical_system_headers.
    * configure.ac: Add new --enable-canonical-system-headers.
    * configure: Regenerate.
    * config.in: Regenerate.

    * doc/cppopts.texi: Document -f[no-]canonical-system-headers.
    * doc/install.texi: Document --enable-canonical-system-headers.

    * c.opt: Add f[no-]canonical-system-headers.
    * c-opts.c (c_common_handle_option): Handle
    OPT_fcanonical_system_headers.

From-SVN: r193569

6 files changed, 31 insertions, 0 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 0f149c4..e430af9 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2012-11-16  Simon Baldwin  <simonb@google.com>
+
+	* doc/cppopts.texi: Document -f[no-]canonical-system-headers.
+	* doc/install.texi: Document --enable-canonical-system-headers.
+
 2012-11-16  Vladimir Makarov  <vmakarov@redhat.com>
 
 	PR rtl-optimization/55330
diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index 85e113c..2938662 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,9 @@
+2012-11-16  Simon Baldwin  <simonb@google.com>
+
+	* c.opt: Add f[no-]canonical-system-headers.
+	* c-opts.c (c_common_handle_option): Handle
+	OPT_fcanonical_system_headers.
+
 2012-11-09  Ed Smith-Rowland  <3dw4rd@verizon.net>
 
 	PR c++/54413
diff --git a/gcc/c-family/c-opts.c b/gcc/c-family/c-opts.c
index d86a165..488c085 100644
--- a/gcc/c-family/c-opts.c
+++ b/gcc/c-family/c-opts.c
@@ -456,6 +456,10 @@ c_common_handle_option (size_t scode, const char *arg, int value,
       handle_OPT_d (arg);
       break;
 
+    case OPT_fcanonical_system_headers:
+      cpp_opts->canonical_system_headers = value;
+      break;
+
     case OPT_fcond_mismatch:
       if (!c_dialect_cxx ())
 	{
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 1b5c51a..f5f0867 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -840,6 +840,10 @@ Recognize built-in functions
 fbuiltin-
 C ObjC C++ ObjC++ Joined
 
+fcanonical-system-headers
+C ObjC C++ ObjC++
+Where shorter, use canonicalized paths to systems headers.
+
 fcheck-new
 C++ ObjC++ Var(flag_check_new)
 Check the return value of new
diff --git a/gcc/doc/cppopts.texi b/gcc/doc/cppopts.texi
index a2eb79d..37e0b7b5 100644
--- a/gcc/doc/cppopts.texi
+++ b/gcc/doc/cppopts.texi
@@ -564,6 +564,10 @@ Accept universal character names in identifiers.  This option is
 experimental; in a future version of GCC, it will be enabled by
 default for C99 and C++.
 
+@item -fno-canonical-system-headers
+@opindex fno-canonical-system-headers
+When preprocessing, do not shorten system header paths with canonicalization.
+
 @item -fpreprocessed
 @opindex fpreprocessed
 Indicate to the preprocessor that the input file has already been
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index 7396158..b78d127 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -1719,6 +1719,14 @@ link time when @option{-fuse-linker-plugin} is enabled.
 This linker should have plugin support such as gold starting with
 version 2.20 or GNU ld starting with version 2.21.
 See @option{-fuse-linker-plugin} for details.
+
+@item --enable-canonical-system-headers
+@itemx --disable-canonical-system-headers
+Enable system header path canonicalization for @file{libcpp}.  This can
+produce shorter header file paths in diagnostics and dependency output
+files, but these changed header paths may conflict with some compilation
+environments.  Enabled by default, and may be disabled using
+@option{--disable-canonical-system-headers}.
 @end table
 
 @subheading Cross-Compiler-Specific Options