re PR c/18314 (Abnormal behavior in optimization)

	PR 18314
	* c-decl.c (diagnose_mismatched_decls): Also discard a
	built-in if we encounter an old-style definition with the
	same name.
testsuite:
	* gcc.dg/builtins-30.c: New testcase.

From-SVN: r76441

gcc/ChangeLog

+2004-01-23  Zack Weinberg  <zack@codesourcery.com>
+
+	PR 18314
+	* c-decl.c (diagnose_mismatched_decls): Also discard a
+	built-in if we encounter an old-style definition with the
+	same name.
+
 2004-01-23  Jakub Jelinek  <jakub@redhat.com>
 
 	* config.gcc (powerpc*-*): Clear $with_cpu or $with_tune if it was

gcc/c-decl.c

@@ -1029,11 +1029,15 @@ diagnose_mismatched_decls (tree newdecl, tree olddecl,
      extern-inline definition supersedes the extern-inline definition.  */
   else if (TREE_CODE (newdecl) == FUNCTION_DECL)
     {
-      if (DECL_BUILT_IN (olddecl) && !TREE_PUBLIC (newdecl))
+      /* If you declare a built-in function name as static, or
+	 define the built-in with an old-style definition (so we
+	 can't validate the argument list) the built-in definition is
+	 overridden, but optionally warn this was a bad choice of name.  */
+      if (DECL_BUILT_IN (olddecl)
+	  && (!TREE_PUBLIC (newdecl)
+	      || (DECL_INITIAL (newdecl)
+		  && !TYPE_ARG_TYPES (TREE_TYPE (newdecl)))))
 	{
-	  /* If you declare a built-in function name as static, the
-	     built-in definition is overridden,
-	     but optionally warn this was a bad choice of name.  */
 	  if (warn_shadow)
 	    warning ("%Jshadowing built-in function '%D'", newdecl, newdecl);
 	  /* Discard the old built-in function.  */

gcc/testsuite/ChangeLog

+2004-01-23  Zack Weinberg  <zack@codesourcery.com>
+
+	PR 18314
+	* gcc.dg/builtins-30.c: New testcase.
+
 2004-01-23  Andreas Tobler  <a.tobler@schweiz.ch>
 
 	* g++.dg/compat/compat.exp: Add LD_LIBRARY_PATH_32/64 for Solaris.

gcc/testsuite/gcc.dg/builtins-30.c

+/* { dg-do compile } */
+/* { dg-options "-Wall -Wshadow" } */
+
+extern double strtod (const char *, char **);
+#define UNUSED __attribute__ ((unused))
+
+/* A built-in function may be overridden by an old-style definition
+   specifying too few arguments... */
+double nan ()
+{
+  return strtod ("nan", 0);  /* { dg-warning "shadowing built-in" } */
+}
+
+/* the right number, but the wrong type, arguments... */
+float nanf (foo)
+     int foo UNUSED;
+{
+  return strtod ("nan", 0);  /* { dg-warning "shadowing built-in" } */
+}
+
+/* or too many arguments.  */
+long double nanl (foo, bar)
+     const char *foo UNUSED;
+     int bar UNUSED;
+{
+  return strtod ("nan", 0);  /* { dg-warning "shadowing built-in" } */
+}