Fix isDerivedFrom matcher.

Without this patch, the isDerivedFrom matcher asserts in the
"assert(ClassDecl != NULL);" in the new test, as a
DependentTemplateSpecilizationType is not a sub-type of
TemplateSpecializationType and also does not offer getAsCXXRecordDecl().

I am not sure why this did not cause problems before. It is now (after
the changed implementation of isDerivedFrom) easier to write a matcher
that actually gets into this branch of the code.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@164127 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/ASTMatchers/ASTMatchFinder.cpp b/lib/ASTMatchers/ASTMatchFinder.cpp
index cba2e50..80ea16a 100644
--- a/lib/ASTMatchers/ASTMatchFinder.cpp
+++ b/lib/ASTMatchers/ASTMatchFinder.cpp
@@ -487,6 +487,7 @@
 
     // Type::getAs<...>() drills through typedefs.
     if (TypeNode->getAs<DependentNameType>() != NULL ||
+        TypeNode->getAs<DependentTemplateSpecializationType>() != NULL ||
         TypeNode->getAs<TemplateTypeParmType>() != NULL)
       // Dependent names and template TypeNode parameters will be matched when
       // the template is instantiated.
diff --git a/unittests/ASTMatchers/ASTMatchersTest.cpp b/unittests/ASTMatchers/ASTMatchersTest.cpp
index b8ffaa4..6556444 100644
--- a/unittests/ASTMatchers/ASTMatchersTest.cpp
+++ b/unittests/ASTMatchers/ASTMatchersTest.cpp
@@ -294,6 +294,16 @@
       recordDecl(isDerivedFrom(recordDecl(hasName("X")).bind("test")))));
 }
 
+TEST(DeclarationMatcher, ClassDerivedFromDependentTemplateSpecialization) {
+  EXPECT_TRUE(matches(
+     "template <typename T> struct A {"
+     "  template <typename T2> struct F {};"
+     "};"
+     "template <typename T> struct B : A<T>::template F<T> {};"
+     "B<int> b;",
+     recordDecl(hasName("B"), isDerivedFrom(recordDecl()))));
+}
+
 TEST(ClassTemplate, DoesNotMatchClass) {
   DeclarationMatcher ClassX = classTemplateDecl(hasName("X"));
   EXPECT_TRUE(notMatches("class X;", ClassX));