Index: clang-tools-extra/trunk/clangd/Selection.cpp
===================================================================
--- clang-tools-extra/trunk/clangd/Selection.cpp
+++ clang-tools-extra/trunk/clangd/Selection.cpp
@@ -51,7 +51,7 @@
   //  - those that can't be stored in DynTypedNode.
   // We're missing some interesting things like Attr due to the latter.
   bool TraverseDecl(Decl *X) {
-    if (isa<TranslationUnitDecl>(X))
+    if (X && isa<TranslationUnitDecl>(X))
       return Base::TraverseDecl(X); // Already pushed by constructor.
     return traverseNode(X, [&] { return Base::TraverseDecl(X); });
   }
Index: clang-tools-extra/trunk/unittests/clangd/SelectionTests.cpp
===================================================================
--- clang-tools-extra/trunk/unittests/clangd/SelectionTests.cpp
+++ clang-tools-extra/trunk/unittests/clangd/SelectionTests.cpp
@@ -176,6 +176,16 @@
 
       // Node types that have caused problems in the past.
       {"template <typename T> void foo() { [[^T]] t; }", "TypeLoc"},
+
+      // No crash
+      {
+          R"cpp(
+            template <class T> struct Foo {};
+            template <[[template<class> class /*cursor here*/^U]]>
+             struct Foo<U<int>*> {};
+          )cpp",
+          "TemplateTemplateParmDecl"
+      },
   };
   for (const Case &C : Cases) {
     Annotations Test(C.Code);