From a50ce325b1ddd2bcbbfc1082ac93f3861d0a3a3d Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Sun, 7 Mar 2010 23:26:22 +0000
Subject: [PATCH] Robustify callers that rebuild typename type nodes again NULL
 return types. Fixes PR6463.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@97924 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaDeclCXX.cpp                   |  3 +++
 lib/Sema/SemaTemplate.cpp                  |  3 +++
 test/SemaTemplate/typename-specifier-4.cpp | 17 +++++++++++++++++
 3 files changed, 23 insertions(+)

diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index b959202b88..e32d14e1c8 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -1083,6 +1083,9 @@ Sema::ActOnMemInitializer(DeclPtrTy ConstructorD,
           // specialization, we take it as a type name.
           BaseType = CheckTypenameType((NestedNameSpecifier *)SS.getScopeRep(),
                                        *MemberOrBase, SS.getRange());
+          if (BaseType.isNull())
+            return true;
+
           R.clear();
         }
       }
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index 03219580f9..445b68b167 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -4992,6 +4992,9 @@ CurrentInstantiationRebuilder::TransformTypenameType(TypeLocBuilder &TLB,
     Result = getDerived().RebuildTypenameType(NNS, T->getIdentifier(),
                                               SourceRange(TL.getNameLoc()));
 
+  if (Result.isNull())
+    return QualType();
+
   TypenameTypeLoc NewTL = TLB.push<TypenameTypeLoc>(Result);
   NewTL.setNameLoc(TL.getNameLoc());
   return Result;
diff --git a/test/SemaTemplate/typename-specifier-4.cpp b/test/SemaTemplate/typename-specifier-4.cpp
index 0a6fef74c3..280a1b4c39 100644
--- a/test/SemaTemplate/typename-specifier-4.cpp
+++ b/test/SemaTemplate/typename-specifier-4.cpp
@@ -99,3 +99,20 @@ namespace PR6268 {
     return Inner<U>();
   }
 }
+
+namespace PR6463 {
+  struct B { typedef int type; }; // expected-note 2{{member found by ambiguous name lookup}}
+  struct C { typedef int type; }; // expected-note 2{{member found by ambiguous name lookup}}
+
+  template<typename T>
+  struct A : B, C { 
+    type& a(); // expected-error{{found in multiple base classes}}
+    int x; 
+  };
+
+  // FIXME: Improve source location info here.
+  template<typename T>
+  typename A<T>::type& A<T>::a() { // expected-error{{found in multiple base classes}}
+    return x;  // expected-error{{undeclared identifier}}
+  }
+}
-- 
2.40.0