* cppinit.c (remove_dup_dirs): Inform if a system include

        directory is being reordered.
	* doc/invoke.texi (Directory Options): GCC warns if you hide a
	system include.
	* doc/cpp.texi (Search Paths): Likewise.
	* doc/gcc.texi (Interoperation): Remove information about
	-I/usr/include.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@43769 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 15 insertions, 0 deletions

diff --git a/gcc/cppinit.c b/gcc/cppinit.c
index 3c446b27989..5ac676a5c0b 100644
--- a/gcc/cppinit.c
+++ b/gcc/cppinit.c
@@ -297,6 +297,21 @@ remove_dup_dirs (pfile, head)
       for (other = head; other != cur; other = other->next)
         if (INO_T_EQ (cur->ino, other->ino) && cur->dev == other->dev)
 	  {
+	    if (cur->sysp)
+	      {
+		cpp_warning (pfile,
+			     "changing search order for system directory \"%s\"",
+			     cur->name);
+		if (strcmp (cur->name, other->name))
+		  cpp_warning (pfile, other->sysp
+			       ? "  as it is the same as system directory \"%s\""
+			       : "  as it is the same as non-system directory \"%s\"",
+			       other->name);
+		else
+		  cpp_warning (pfile, other->sysp
+			       ? "  as it has already been specified as a system directory"
+			       : "  as it has already been specified as a non-system directory");
+	      }
 	    cur = remove_dup_dir (pfile, prev);
 	    break;
 	  }