From 3f318c863b1bb1a66c4683f79cbcdcc018b1462d Mon Sep 17 00:00:00 2001
From: Alex Lorenz <arphaman@gmail.com>
Date: Tue, 16 May 2017 17:33:17 +0000
Subject: [PATCH] [index] Avoid another crash that happens when looking up a
 dependent name in a record that has a base without a definition

rdar://32224197


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@303192 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/AST/CXXInheritance.cpp                 |  2 ++
 test/Index/Core/index-dependent-source.cpp | 10 ++++++++++
 2 files changed, 12 insertions(+)

diff --git a/lib/AST/CXXInheritance.cpp b/lib/AST/CXXInheritance.cpp
index 4499ec7036..746602d47b 100644
--- a/lib/AST/CXXInheritance.cpp
+++ b/lib/AST/CXXInheritance.cpp
@@ -278,6 +278,8 @@ bool CXXBasePaths::lookupInBases(ASTContext &Context,
                   dyn_cast_or_null<ClassTemplateDecl>(TN.getAsTemplateDecl()))
             BaseRecord = TD->getTemplatedDecl();
         }
+        if (BaseRecord && !BaseRecord->hasDefinition())
+          BaseRecord = nullptr;
       } else {
         BaseRecord = cast<CXXRecordDecl>(
             BaseSpec.getType()->castAs<RecordType>()->getDecl());
diff --git a/test/Index/Core/index-dependent-source.cpp b/test/Index/Core/index-dependent-source.cpp
index 25410799a8..8c097b935a 100644
--- a/test/Index/Core/index-dependent-source.cpp
+++ b/test/Index/Core/index-dependent-source.cpp
@@ -131,3 +131,13 @@ void undefinedTemplateLookup(UndefinedTemplateClass<T> &x) {
   x.lookup;
   typename UndefinedTemplateClass<T>::Type y;
 }
+
+template<typename T>
+struct UserOfUndefinedTemplateClass: UndefinedTemplateClass<T> { };
+
+template<typename T>
+void undefinedTemplateLookup2(UserOfUndefinedTemplateClass<T> &x) {
+// Shouldn't crash!
+  x.lookup;
+  typename UserOfUndefinedTemplateClass<T>::Type y;
+}
-- 
2.40.0