re PR debug/66869 (-Wunused-function no longer warns for static declarations without definition)

	PR debug/66869
	* c-decl.c (c_write_global_declarations_1): Warn with
	warn_unused_function if static prototype without definition
	is not C_DECL_USED.

	* gcc.dg/pr66869.c: New test.

From-SVN: r232899

gcc/c/ChangeLog

+2016-01-27  Jakub Jelinek  <jakub@redhat.com>
+
+	PR debug/66869
+	* c-decl.c (c_write_global_declarations_1): Warn with
+	warn_unused_function if static prototype without definition
+	is not C_DECL_USED.
+
 2016-01-27  Marek Polacek  <polacek@redhat.com>
 
 	PR c/68062

gcc/c/c-decl.c

@@ -10741,11 +10741,22 @@ c_write_global_declarations_1 (tree globals)
       if (TREE_CODE (decl) == FUNCTION_DECL
 	  && DECL_INITIAL (decl) == 0
 	  && DECL_EXTERNAL (decl)
-	  && !TREE_PUBLIC (decl)
-	  && C_DECL_USED (decl))
+	  && !TREE_PUBLIC (decl))
 	{
-	  pedwarn (input_location, 0, "%q+F used but never defined", decl);
-	  TREE_NO_WARNING (decl) = 1;
+	  if (C_DECL_USED (decl))
+	    {
+	      pedwarn (input_location, 0, "%q+F used but never defined", decl);
+	      TREE_NO_WARNING (decl) = 1;
+	    }
+	  /* For -Wunused-function warn about unused static prototypes.  */
+	  else if (warn_unused_function
+		   && ! DECL_ARTIFICIAL (decl)
+		   && ! TREE_NO_WARNING (decl))
+	    {
+	      warning (OPT_Wunused_function,
+		       "%q+F declared %<static%> but never defined", decl);
+	      TREE_NO_WARNING (decl) = 1;
+	    }
 	}
 
       wrapup_global_declaration_1 (decl);

gcc/testsuite/ChangeLog

+2016-01-27  Jakub Jelinek  <jakub@redhat.com>
+
+	PR debug/66869
+	* gcc.dg/pr66869.c: New test.
+
 2016-01-25  Jeff Law  <law@redhat.com>
 
 	PR tree-optimization/68398

gcc/testsuite/gcc.dg/pr66869.c

+/* PR debug/66869 */
+/* { dg-do compile } */
+/* { dg-options "-Wunused-function" } */
+
+static void test (void); /* { dg-warning "'test' declared 'static' but never defined" } */
+int i;