3 files changed, 27 insertions, 1 deletions
diff --git a/clang/include/clang/ASTMatchers/ASTMatchersInternal.h b/clang/include/clang/ASTMatchers/ASTMatchersInternal.h
index 94435fd274e..68b18164c23 100644
--- a/clang/include/clang/ASTMatchers/ASTMatchersInternal.h
+++ b/clang/include/clang/ASTMatchers/ASTMatchersInternal.h
@@ -103,6 +103,16 @@ public:
     return NodeMap;
   }
 
+  /// \brief Returns \c true if this \c BoundNodesMap can be compared, i.e. all
+  /// stored nodes have memoization data.
+  bool isComparable() const {
+    for (const auto &IDAndNode : NodeMap) {
+      if (!IDAndNode.second.getMemoizationData())
+        return false;
+    }
+    return true;
+  }
+
 private:
   IDToNodeMap NodeMap;
 };
@@ -153,6 +163,16 @@ public:
     return Bindings < Other.Bindings;
   }
 
+  /// \brief Returns \c true if this \c BoundNodesTreeBuilder can be compared,
+  /// i.e. all stored node maps have memoization data.
+  bool isComparable() const {
+    for (const BoundNodesMap &NodesMap : Bindings) {
+      if (!NodesMap.isComparable())
+        return false;
+    }
+    return true;
+  }
+
 private:
   SmallVector<BoundNodesMap, 16> Bindings;
 };
diff --git a/clang/lib/ASTMatchers/ASTMatchFinder.cpp b/clang/lib/ASTMatchers/ASTMatchFinder.cpp
index 23708e2ff0c..b8ac68aad72 100644
--- a/clang/lib/ASTMatchers/ASTMatchFinder.cpp
+++ b/clang/lib/ASTMatchers/ASTMatchFinder.cpp
@@ -372,7 +372,7 @@ public:
                                   BoundNodesTreeBuilder *Builder, int MaxDepth,
                                   TraversalKind Traversal, BindKind Bind) {
     // For AST-nodes that don't have an identity, we can't memoize.
-    if (!Node.getMemoizationData())
+    if (!Node.getMemoizationData() || !Builder->isComparable())
       return matchesRecursively(Node, Matcher, Builder, MaxDepth, Traversal,
                                 Bind);
 
diff --git a/clang/unittests/ASTMatchers/ASTMatchersTest.cpp b/clang/unittests/ASTMatchers/ASTMatchersTest.cpp
index d4f867114e9..e769e887bd1 100644
--- a/clang/unittests/ASTMatchers/ASTMatchersTest.cpp
+++ b/clang/unittests/ASTMatchers/ASTMatchersTest.cpp
@@ -643,6 +643,12 @@ TEST(DeclarationMatcher, HasDescendant) {
       "};", ZDescendantClassXDescendantClassY));
 }
 
+TEST(DeclarationMatcher, HasDescendantMemoization) {
+  DeclarationMatcher CannotMemoize =
+      decl(hasDescendant(typeLoc().bind("x")), has(decl()));
+  EXPECT_TRUE(matches("void f() { int i; }", CannotMemoize));
+}
+
 // Implements a run method that returns whether BoundNodes contains a
 // Decl bound to Id that can be dynamically cast to T.
 // Optionally checks that the check succeeded a specific number of times.