Patch to warn for format warning options with no effect

["Joseph S. Myers" <jsm28 at cam dot ac dot uk>]

This patch makes GCC warn if options such as
-Wmissing-format-attribute and -Wformat-nonliteral get used without
-Wformat (in which case they do nothing useful).

Bootstrapped with no regressions on i686-pc-linux-gnu.  OK to commit?

2000-12-07  Joseph S. Myers  <jsm28@cam.ac.uk>

	* c-common.c (c_common_lang_init): New function.  Warn if format
	warning options which only have effects when used with -Wformat
	are used without -Wformat.
	* c-common.h (c_common_lang_init): Declare.
	* c-lang.c (lang_init): Call c_common_lang_init.

2000-12-07  Joseph S. Myers  <jsm28@cam.ac.uk>

	* lex.c (lang_init): Call c_common_lang_init.

--- c-common.c.orig	Wed Dec  6 22:19:27 2000
+++ c-common.c	Wed Dec  6 22:44:47 2000
@@ -6452,3 +6452,26 @@ boolean_increment (code, arg)
   TREE_SIDE_EFFECTS (val) = 1;
   return val;
 }
+
+
+/* Do the parts of lang_init common to C and C++.  */
+void
+c_common_lang_init ()
+{
+  /* If still "unspecified", make it match -fbounded-pointers.  */
+  if (flag_bounds_check < 0)
+    flag_bounds_check = flag_bounded_pointers;
+
+  /* Special format checking options don't work without -Wformat; warn if
+     they are used.  */
+  if (warn_format_y2k && !warn_format)
+    warning ("-Wformat-y2k ignored without -Wformat");
+  if (warn_format_extra_args && !warn_format)
+    warning ("-Wformat-extra-args ignored without -Wformat");
+  if (warn_format_nonliteral && !warn_format)
+    warning ("-Wformat-nonliteral ignored without -Wformat");
+  if (warn_format_security && !warn_format)
+    warning ("-Wformat-security ignored without -Wformat");
+  if (warn_missing_format_attribute && !warn_format)
+    warning ("-Wmissing-format-attribute ignored without -Wformat");
+}
--- c-common.h.orig	Wed Dec  6 22:19:28 2000
+++ c-common.h	Wed Dec  6 22:39:28 2000
@@ -502,6 +502,8 @@ extern void c_common_nodes_and_builtins

 extern tree build_va_arg			PARAMS ((tree, tree));

+extern void c_common_lang_init			PARAMS ((void));
+
 /* Nonzero if the type T promotes to itself.
    ANSI C states explicitly the list of types that promote;
    in particular, short promotes to int even if they have the same width.  */
--- c-lang.c.orig	Wed Nov 29 00:33:05 2000
+++ c-lang.c	Wed Dec  6 22:41:22 2000
@@ -61,9 +61,7 @@ lang_init_options ()
 void
 lang_init ()
 {
-  /* If still "unspecified", make it match -fbounded-pointers.  */
-  if (flag_bounds_check < 0)
-    flag_bounds_check = flag_bounded_pointers;
+  c_common_lang_init ();

   /* If still unspecified, make it match pedantic && -std=c99.  */
   if (mesg_implicit_function_declaration < 0)
--- cp/lex.c.orig	Wed Nov 29 00:33:15 2000
+++ cp/lex.c	Wed Dec  6 22:41:39 2000
@@ -262,9 +262,7 @@ lang_init_options ()
 void
 lang_init ()
 {
-  /* If still "unspecified", make it match -fbounded-pointers.  */
-  if (flag_bounds_check < 0)
-    flag_bounds_check = flag_bounded_pointers;
+  c_common_lang_init ();

   if (flag_gnu_xref) GNU_xref_begin (input_filename);
   init_repo (input_filename);

-- 
Joseph S. Myers
jsm28@cam.ac.uk