[clangd] Extend findTarget()'s dependent name heuristic to handle enumerators

Fixes https://github.com/clangd/clangd/issues/296

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

Tags: #clang

Differential Revision: https://reviews.llvm.org/D76103

clang-tools-extra/clangd/FindTarget.cpp

@@ -37,6 +37,7 @@
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/raw_ostream.h"
+#include <iterator>
 #include <utility>
 #include <vector>
 
@@ -76,6 +77,11 @@ std::vector<const NamedDecl *> getMembersReferencedViaDependentName(
     bool IsNonstaticMember) {
   if (!T)
     return {};
+  if (auto *ET = T->getAs<EnumType>()) {
+    auto Result =
+        ET->getDecl()->lookup(NameFactory(ET->getDecl()->getASTContext()));
+    return {Result.begin(), Result.end()};
+  }
   if (auto *ICNT = T->getAs<InjectedClassNameType>()) {
     T = ICNT->getInjectedSpecializationType().getTypePtrOrNull();
   }

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

@@ -529,6 +529,14 @@ TEST(LocateSymbol, All) {
         void test(unique_ptr<S<T>>& V) {
           V->fo^o();
         }
+      )cpp",
+
+      R"cpp(// Heuristic resolution of dependent enumerator
+        template <typename T>
+        struct Foo {
+          enum class E { [[A]], B };
+          E e = E::A^;
+        };
       )cpp"};
   for (const char *Test : Tests) {
     Annotations T(Test);