[PATCH] D88469: [clangd] Heuristic resolution for dependent type and template names

[Nathan Ridge via Phabricator via cfe-commits]

nridge created this revision.
Herald added subscribers: cfe-commits, usaxena95, kadircet, arphaman.
Herald added a project: clang.
nridge requested review of this revision.
Herald added subscribers: MaskRay, ilya-biryukov.

Fixes https://github.com/clangd/clangd/issues/543


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D88469

Files:
  clang-tools-extra/clangd/FindTarget.cpp
  clang-tools-extra/clangd/unittests/FindTargetTests.cpp


Index: clang-tools-extra/clangd/unittests/FindTargetTests.cpp
===================================================================
--- clang-tools-extra/clangd/unittests/FindTargetTests.cpp
+++ clang-tools-extra/clangd/unittests/FindTargetTests.cpp
@@ -731,6 +731,33 @@
                "template <typename T> T convert() const");
 }
 
+TEST_F(TargetDeclTest, DependentTypes) {
+  Flags = {"-fno-delayed-template-parsing"};
+
+  // Heuristic resolution of dependent type name
+  Code = R"cpp(
+        template <typename>
+        struct A { struct B {}; };
+
+        template <typename T>
+        void foo(typename A<T>::[[B]]);
+      )cpp";
+  EXPECT_DECLS("DependentNameTypeLoc", "struct B");
+
+  // Heuristic resolution of dependent template name
+  Code = R"cpp(
+        template <typename>
+        struct A { 
+          template <typename> struct B {};
+        };
+
+        template <typename T>
+        void foo(typename A<T>::template [[B]]<int>);
+      )cpp";
+  EXPECT_DECLS("DependentTemplateSpecializationTypeLoc",
+               "template <typename> struct B");
+}
+
 TEST_F(TargetDeclTest, ObjC) {
   Flags = {"-xobjective-c"};
   Code = R"cpp(
Index: clang-tools-extra/clangd/FindTarget.cpp
===================================================================
--- clang-tools-extra/clangd/FindTarget.cpp
+++ clang-tools-extra/clangd/FindTarget.cpp
@@ -125,6 +125,7 @@
   return !D->isCXXInstanceMember();
 };
 const auto ValueFilter = [](const NamedDecl *D) { return isa<ValueDecl>(D); };
+const auto TypeFilter = [](const NamedDecl *D) { return !isa<ValueDecl>(D); };
 
 // Given the type T of a dependent expression that appears of the LHS of a
 // "->", heuristically find a corresponding pointee type in whose scope we
@@ -291,10 +292,8 @@
 //    and both are lossy. We must know upfront what the caller ultimately wants.
 //
 // FIXME: improve common dependent scope using name lookup in primary templates.
-// We currently handle DependentScopeDeclRefExpr and
-// CXXDependentScopeMemberExpr, but some other constructs remain to be handled:
-//  - DependentTemplateSpecializationType,
-//  - DependentNameType
+// We currently handle several dependent constructs, but some others remain to
+// be handled:
 //  - UnresolvedUsingTypenameDecl
 struct TargetFinder {
   using RelSet = DeclRelationSet;
@@ -536,6 +535,23 @@
         if (auto *TD = DTST->getTemplateName().getAsTemplateDecl())
           Outer.add(TD->getTemplatedDecl(), Flags | Rel::TemplatePattern);
       }
+      void VisitDependentNameType(const DependentNameType *DNT) {
+        for (const NamedDecl *ND : getMembersReferencedViaDependentName(
+                 DNT->getQualifier()->getAsType(),
+                 [DNT](ASTContext &) { return DNT->getIdentifier(); },
+                 TypeFilter)) {
+          Outer.add(ND, Flags);
+        }
+      }
+      void VisitDependentTemplateSpecializationType(
+          const DependentTemplateSpecializationType *DTST) {
+        for (const NamedDecl *ND : getMembersReferencedViaDependentName(
+                 DTST->getQualifier()->getAsType(),
+                 [DTST](ASTContext &) { return DTST->getIdentifier(); },
+                 TypeFilter)) {
+          Outer.add(ND, Flags);
+        }
+      }
       void VisitTypedefType(const TypedefType *TT) {
         Outer.add(TT->getDecl(), Flags);
       }


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