[clangd] Fix a regression in rL366996.

Summary: That patch made the tweak always annotate the whole file by accident.

Reviewers: jvikstrom

Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, kadircet, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D65443

llvm-svn: 367313

clang-tools-extra/clangd/refactor/tweaks/AnnotateHighlightings.cpp

@@ -33,18 +33,16 @@ class AnnotateHighlightings : public Tweak {
 REGISTER_TWEAK(AnnotateHighlightings)
 
 Expected<Tweak::Effect> AnnotateHighlightings::apply(const Selection &Inputs) {
-  // TUDecl is always the root ancestor.
-  const Decl *CommonDecl =
-      Inputs.ASTSelection.root().ASTNode.get<TranslationUnitDecl>();
+  const Decl *CommonDecl = nullptr;
   for (auto N = Inputs.ASTSelection.commonAncestor(); N && !CommonDecl;
        N = N->Parent)
     CommonDecl = N->ASTNode.get<Decl>();
 
   std::vector<HighlightingToken> HighlightingTokens;
-  if (llvm::isa<TranslationUnitDecl>(CommonDecl)) {
-    // We only annotate tokens in the main file, if CommonDecl is a TUDecl,
-    // we use the default traversal scope (which is the top level decls of the
-    // main file).
+  if (!CommonDecl) {
+    // Now we hit the TUDecl case where commonAncestor() returns null
+    // intendedly. We only annotate tokens in the main file, so use the default
+    // traversal scope (which is the top level decls of the main file).
     HighlightingTokens = getSemanticHighlightings(Inputs.AST);
   } else {
     // Store the existing scopes.

clang-tools-extra/clangd/unittests/TweakTests.cpp

@@ -571,6 +571,17 @@ void f2();]]
   R"cpp(
 void /* entity.name.function.cpp */f1();
 void /* entity.name.function.cpp */f2();
+)cpp");
+
+   checkTransform(ID,
+  R"cpp(
+void f1();
+void f2() {^};
+)cpp",
+
+  R"cpp(
+void f1();
+void /* entity.name.function.cpp */f2() {};
 )cpp");
 }