Fix crashing rdar://9122854 & http://llvm.org/PR9461.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@129967 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Sema/TreeTransform.h

@@ -7216,8 +7216,10 @@ TreeTransform<Derived>::TransformUnresolvedMemberExpr(UnresolvedMemberExpr *Old)
       // This can happen because of dependent hiding.
       if (isa<UsingShadowDecl>(*I))
         continue;
-      else
+      else {
+        R.clear();
         return ExprError();
+      }
     }
 
     // Expand using declarations.

test/SemaCXX/PR9461.cpp

@@ -0,0 +1,32 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s 
+
+// Don't crash.
+
+template<typename,typename=int,typename=int>struct basic_string;
+
+typedef basic_string<char> string;
+
+
+
+template<typename aT,typename,typename oc>
+struct basic_string
+{
+int us;
+basic_string(const aT*,const oc&a=int());
+
+int _S_construct();
+
+int _S_construct(int);
+
+_S_construct(); // expected-error {{requires}}
+};
+
+template<typename _CharT,typename _Traits,typename _Alloc>
+basic_string<_CharT,_Traits,_Alloc>::basic_string(const _CharT*,const _Alloc&)
+:us(_S_construct)
+{string a;}
+
+struct runtime_error{runtime_error(string);};
+
+struct system_error:runtime_error{ // expected-note {{to match}} expected-note {{specified here}}
+system_error():time_error("" // expected-error 4 {{expected}} expected-error {{initializer}} expected-note {{to match}}