1 files changed, 19 insertions, 0 deletions
diff --git a/gcc/testsuite/g++.dg/lookup/builtin2.C b/gcc/testsuite/g++.dg/lookup/builtin2.C
new file mode 100644
index 000000000..be0a6f65d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/lookup/builtin2.C
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+
+/* PR c++/21087 */
+
+/* We used to overload the template function with the built-in
+   declaration, instead of replacing it as we should, and then barf at
+   the using decl because of a test that none of the overload set
+   members were anticipated built-ins.  */
+
+extern "C" signed int toupper(signed int __c) throw();
+namespace std
+{
+  template< typename a > a toupper(a,int){}
+  using ::toupper;
+}
+
+int f () {
+  std::toupper((signed int)'a');
+}