2007-10-02  Jakub Jelinek  <jakub@redhat.com>

	* decl.c (duplicate_decls): When redeclaring a builtin function,
	keep the merged decl builtin whenever types match, even if new
	decl defines a function.

	* gcc.dg/builtins-65.c: New test.
	* g++.dg/ext/builtin10.C: New test.

Index: gcc/cp/decl.c
===================================================================
--- gcc/cp/decl.c.orig	2010-04-01 11:48:46.000000000 -0700
+++ gcc/cp/decl.c	2010-06-25 10:10:54.749131719 -0700
@@ -2021,23 +2021,21 @@
 	  DECL_ARGUMENTS (olddecl) = DECL_ARGUMENTS (newdecl);
 	  DECL_RESULT (olddecl) = DECL_RESULT (newdecl);
 	}
+      /* If redeclaring a builtin function, it stays built in.  */
+      if (types_match && DECL_BUILT_IN (olddecl))
+	{
+	  DECL_BUILT_IN_CLASS (newdecl) = DECL_BUILT_IN_CLASS (olddecl);
+	  DECL_FUNCTION_CODE (newdecl) = DECL_FUNCTION_CODE (olddecl);
+	  /* If we're keeping the built-in definition, keep the rtl,
+	     regardless of declaration matches.  */
+	  COPY_DECL_RTL (olddecl, newdecl);
+	}
       if (new_defines_function)
 	/* If defining a function declared with other language
 	   linkage, use the previously declared language linkage.  */
 	SET_DECL_LANGUAGE (newdecl, DECL_LANGUAGE (olddecl));
       else if (types_match)
 	{
-	  /* If redeclaring a builtin function, and not a definition,
-	     it stays built in.  */
-	  if (DECL_BUILT_IN (olddecl))
-	    {
-	      DECL_BUILT_IN_CLASS (newdecl) = DECL_BUILT_IN_CLASS (olddecl);
-	      DECL_FUNCTION_CODE (newdecl) = DECL_FUNCTION_CODE (olddecl);
-	      /* If we're keeping the built-in definition, keep the rtl,
-		 regardless of declaration matches.  */
-	      COPY_DECL_RTL (olddecl, newdecl);
-	    }
-
 	  DECL_RESULT (newdecl) = DECL_RESULT (olddecl);
 	  /* Don't clear out the arguments if we're just redeclaring a
 	     function.  */
Index: gcc/testsuite/gcc.dg/builtins-65.c
===================================================================
--- gcc/testsuite/gcc.dg/builtins-65.c.orig	2009-06-26 02:02:04.000000000 -0700
+++ gcc/testsuite/gcc.dg/builtins-65.c	2010-06-25 10:10:54.784464429 -0700
@@ -1,3 +1,28 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+typedef __SIZE_TYPE__ size_t;
+extern void __chk_fail (void);
+extern int snprintf (char *, size_t, const char *, ...);
+extern inline __attribute__((gnu_inline, always_inline)) int snprintf (char *a, size_t b, const char *fmt, ...)
+{
+  if (__builtin_object_size (a, 0) != -1UL && __builtin_object_size (a, 0) < b)
+    __chk_fail ();
+  return __builtin_snprintf (a, b, fmt, __builtin_va_arg_pack ());
+}
+extern int snprintf (char *, size_t, const char *, ...) __asm ("mysnprintf");
+
+char buf[10];
+
+int
+main (void)
+{
+  snprintf (buf, 10, "%d%d\n", 10, 10);
+  return 0;
+}
+
+/* { dg-final { scan-assembler "mysnprintf" } } */
+/* { dg-final { scan-assembler-not "__chk_fail" } } */
 /* { dg-do link } */
 /* { dg-options "-O2 -ffast-math" } */
 /* { dg-require-effective-target c99_runtime } */
Index: gcc/testsuite/g++.dg/ext/builtin10.C
===================================================================
--- gcc/testsuite/g++.dg/ext/builtin10.C.orig	2009-02-02 03:27:50.000000000 -0800
+++ gcc/testsuite/g++.dg/ext/builtin10.C	2010-06-25 10:10:54.816467202 -0700
@@ -1,3 +1,30 @@
+// { dg-do compile }
+// { dg-options "-O2" }
+
+typedef __SIZE_TYPE__ size_t;
+extern "C" {
+extern void __chk_fail (void);
+extern int snprintf (char *, size_t, const char *, ...);
+extern inline __attribute__((gnu_inline, always_inline)) int snprintf (char *a, size_t b, const char *fmt, ...)
+{
+  if (__builtin_object_size (a, 0) != -1UL && __builtin_object_size (a, 0) < b)
+    __chk_fail ();
+  return __builtin_snprintf (a, b, fmt, __builtin_va_arg_pack ());
+}
+extern int snprintf (char *, size_t, const char *, ...) __asm ("mysnprintf");
+}
+
+char buf[10];
+
+int
+main (void)
+{
+  snprintf (buf, 10, "%d%d\n", 10, 10);
+  return 0;
+}
+
+// { dg-final { scan-assembler "mysnprintf" } }
+// { dg-final { scan-assembler-not "__chk_fail" } }
 // { dg-do compile { target correct_iso_cpp_string_wchar_protos } }
 // { dg-options "-O2 -fdump-tree-optimized" }