PR c++/77563 - missing ambiguous conversion error.

	* call.c (convert_like_real): Use LOOKUP_IMPLICIT.

From-SVN: r246417

gcc/cp/ChangeLog

+2017-03-23  Jason Merrill  <jason@redhat.com>
+
+	PR c++/77563 - missing ambiguous conversion error.
+	* call.c (convert_like_real): Use LOOKUP_IMPLICIT.
+
 2017-03-23  Marek Polacek  <polacek@redhat.com>
 
 	* cp-tree.h: Remove a C_RID_YYCODE reference.

gcc/cp/call.c

@@ -6764,7 +6764,7 @@ convert_like_real (conversion *convs, tree expr, tree fn, int argnum,
       if (complain & tf_error)
 	{
 	  /* Call build_user_type_conversion again for the error.  */
-	  build_user_type_conversion (totype, convs->u.expr, LOOKUP_NORMAL,
+	  build_user_type_conversion (totype, convs->u.expr, LOOKUP_IMPLICIT,
 				      complain);
 	  if (fn)
 	    inform (DECL_SOURCE_LOCATION (fn),

gcc/testsuite/g++.dg/overload/ambig3.C

+// PR c++/77563
+
+struct A {
+  A(int) {}
+  A(unsigned) {}  // Comment to make it work
+
+  explicit A(long) {}  // Comment to make it work
+};
+
+void f(A) { }
+
+int main() {
+  f(2);
+  f(3l);			// { dg-error "ambiguous" }
+}