[clangd] Highlighting dependent types in more contexts

Fixes https://github.com/clangd/clangd/issues/214.

Reviewers: ilya-biryukov

Reviewed By: ilya-biryukov

Subscribers: MaskRay, jkorous, arphaman, kadircet, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70746

2 files changed, 37 insertions, 1 deletions

diff --git a/clang-tools-extra/clangd/SemanticHighlighting.cpp b/clang-tools-extra/clangd/SemanticHighlighting.cpp
index 049afb741b2..2b65625ae2d 100644
--- a/clang-tools-extra/clangd/SemanticHighlighting.cpp
+++ b/clang-tools-extra/clangd/SemanticHighlighting.cpp
@@ -258,6 +258,25 @@ public:
     return true;
   }
 
+  bool VisitDependentTemplateSpecializationTypeLoc(
+      DependentTemplateSpecializationTypeLoc L) {
+    H.addToken(L.getTemplateNameLoc(), HighlightingKind::DependentType);
+    return true;
+  }
+
+  // findExplicitReferences will walk nested-name-specifiers and
+  // find anything that can be resolved to a Decl. However, non-leaf
+  // components of nested-name-specifiers which are dependent names
+  // (kind "Identifier") cannot be resolved to a decl, so we visit
+  // them here.
+  bool TraverseNestedNameSpecifierLoc(NestedNameSpecifierLoc Q) {
+    if (NestedNameSpecifier *NNS = Q.getNestedNameSpecifier()) {
+      if (NNS->getKind() == NestedNameSpecifier::Identifier)
+        H.addToken(Q.getLocalBeginLoc(), HighlightingKind::DependentType);
+    }
+    return RecursiveASTVisitor::TraverseNestedNameSpecifierLoc(Q);
+  }
+
 private:
   HighlightingsBuilder &H;
 };
diff --git a/clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp b/clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp
index 2df0f1c9a57..b353c0bdb4e 100644
--- a/clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp
+++ b/clang-tools-extra/clangd/unittests/SemanticHighlightingTests.cpp
@@ -630,7 +630,24 @@ $InactiveCode[[]]      #else
       R"cpp(
       template <typename... $TemplateParameter[[Elements]]>
       struct $Class[[TupleSize]] {
-        static const int $StaticField[[size]] = sizeof...($TemplateParameter[[Elements]]);
+        static const int $StaticField[[size]] =
+sizeof...($TemplateParameter[[Elements]]);
+      };
+    )cpp",
+      // More dependent types
+      R"cpp(
+      template <typename $TemplateParameter[[T]]>
+      struct $Class[[Waldo]] {
+        using $Typedef[[Location1]] = typename $TemplateParameter[[T]]
+            ::$DependentType[[Resolver]]::$DependentType[[Location]];
+        using $Typedef[[Location2]] = typename $TemplateParameter[[T]]
+            ::template $DependentType[[Resolver]]<$TemplateParameter[[T]]>
+            ::$DependentType[[Location]];
+        using $Typedef[[Location3]] = typename $TemplateParameter[[T]]
+            ::$DependentType[[Resolver]]
+            ::template $DependentType[[Location]]<$TemplateParameter[[T]]>;
+        static const int $StaticField[[Value]] = $TemplateParameter[[T]]
+            ::$DependentType[[Resolver]]::$DependentName[[Value]];
       };
     )cpp"};
   for (const auto &TestCase : TestCases) {