cppinit.c (cpp_handle_option): Suppress warnings with an implicit "-w" for "-M" and "-MM".

	* cppinit.c (cpp_handle_option):  Suppress warnings with an
	implicit "-w" for "-M" and "-MM".
doc:
	* cppopts.texi: Update.
testsuite:
	* gcc.dg/cpp/cmdlne-M.c: New test.

From-SVN: r55185

gcc/ChangeLog

+2002-07-02  Neil Booth  <neil@daikokuya.co.uk>
+
+	* cppinit.c (cpp_handle_option):  Suppress warnings with an
+	implicit "-w" for "-M" and "-MM".
+	* doc/cppopts.texi: Update.
+
 2002-07-01  Roger Sayle  <roger@eyesopen.com>
 
 	* config/sh/sh.c (sh_media_init_builtins): Change use of poisoned

gcc/doc/cppopts.texi

@@ -178,7 +178,8 @@ rules you should explicitly specify the dependency output file with
 @env{DEPENDENCIES_OUTPUT} (@pxref{Environment Variables}).  Debug output
 will still be sent to the regular output stream as normal.
 
-Passing @option{-M} to the driver implies @option{-E}.
+Passing @option{-M} to the driver implies @option{-E}, and suppresses
+warnings with an implicit @option{-w}.
 
 @item -MM
 @opindex MM

gcc/testsuite/gcc.dg/cpp/cmdlne-M.c

+/* Copyright (C) 2002 Free Software Foundation, Inc.  */
+
+/* { dg-do preprocess } */
+/* { dg-options "-M" } */
+
+/* Test that dependency output suppresses warnings by implying -w.  */
+
+#warning bogus /* { dg-bogus "warning" "warning not suppressed" } */