re PR c/13029 (static consts and -Wunused-variable)

	PR c/13029
	* toplev.c (check_global_declarations): Do not warn about unused
	static consts.

	PR c/13029
	* gcc.dg/unused-4.c: Update.

Co-Authored-By: Kean Johnston <jkj@sco.com>

From-SVN: r73554

gcc/ChangeLog

+2003-11-13  Mark Mitchell  <mark@codesourcery.com>
+            Kean Johnston <jkj@sco.com>
+
+	PR c/13029
+	* toplev.c (check_global_declarations): Do not warn about unused
+	static consts.
+
 2003-11-13  Pavel Pisa  <pisa@cmp.felk.cvut.cz>
 	    Kazu Hirata  <kazu@cs.umass.edu>
 

gcc/testsuite/ChangeLog

+2003-11-13  Mark Mitchell  <mark@codesourcery.com>
+            Kean Johnston <jkj@sco.com>
+
+	PR c/13029
+	* gcc.dg/unused-4.c: Update.
+
 2003-11-13  Eric Botcazou  <ebotcazou@libertysurf.fr>
 
 	* g++.dg/opt/const3.C: New test.

gcc/testsuite/gcc.dg/unused-4.c

 /* { dg-do compile } */
 /* { dg-options "-Wunused -O3" } */
 
-static const int i = 0;		/* { dg-warning "defined but not used" } */
+static const int i = 0;
 static void f() { }		/* { dg-warning "defined but not used" } */
 static inline void g() { }

gcc/toplev.c

@@ -1720,7 +1720,11 @@ check_global_declarations (tree *vec, int len)
 
       /* Warn about static fns or vars defined but not used.  */
       if (((warn_unused_function && TREE_CODE (decl) == FUNCTION_DECL)
-	   || (warn_unused_variable && TREE_CODE (decl) == VAR_DECL))
+	   /* We don't warn about "static const" variables because the
+	      "rcs_id" idiom uses that construction.  */
+	   || (warn_unused_variable
+	       && TREE_CODE (decl) == VAR_DECL && ! TREE_READONLY (decl)))
+	  && ! DECL_IN_SYSTEM_HEADER (decl)
 	  && ! TREE_USED (decl)
 	  /* The TREE_USED bit for file-scope decls is kept in the identifier,
 	     to handle multiple external decls in different scopes.  */