re PR preprocessor/22231 (-MG ignores missing headers even with -c)

gcc
	PR preprocessor/22231:
	* c-opts.c (sanitize_cpp_opts): Disallow -MG if compilation is
	proceeding.
gcc/testsuite
	PR preprocessor/22231:
	* gcc.dg/pr22231.c: New file.

From-SVN: r135128

gcc/ChangeLog

+2008-05-09  Tom Tromey  <tromey@redhat.com>
+
+	PR preprocessor/22231:
+	* c-opts.c (sanitize_cpp_opts): Disallow -MG if compilation is
+	proceeding.
+
 2008-05-09  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR tree-optimization/36129

gcc/c-opts.c

@@ -1427,6 +1427,8 @@ sanitize_cpp_opts (void)
       flag_dump_includes = 0;
       flag_no_line_commands = 1;
     }
+  else if (cpp_opts->deps.missing_files)
+    error ("-MG may only be used with -M or -MM");
 
   cpp_opts->unsigned_char = !flag_signed_char;
   cpp_opts->stdc_0_in_system_headers = STDC_0_IN_SYSTEM_HEADERS;

gcc/testsuite/ChangeLog

+2008-05-09  Tom Tromey  <tromey@redhat.com>
+
+	PR preprocessor/22231:
+	* gcc.dg/pr22231.c: New file.
+
 2008-05-09  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/36187

gcc/testsuite/gcc.dg/pr22231.c

+/* Test case for PR 22231.  -c and -MG are invalid together.  */
+
+/* { dg-do compile } */
+/* { dg-options "-MG -MD -c" } */
+/* { dg-error "may only be used with -M" "" 0 */
+
+int anything;