[WIP] [clangd] Extend heuristic resolution to support nested templates

[nridge]

Summary

https://github.com/clangd/clangd/issues/451

[nridge]

(This is not ready for review, I just posted it in case it helps inform discussion in D92290.)

clang-tools-extra/clangd/ClangdServer.cpp

void onPreambleAST(PathRef Path, llvm::StringRef Version, ASTContext &Ctx,
                      std::shared_ptr<clang::Preprocessor> PP,
                      const CanonicalIncludes &CanonIncludes) override {
     if (FIndex)
       FIndex->updatePreamble(Path, Version, Ctx, std::move(PP), CanonIncludes);
   }
 
   void onMainAST(PathRef Path, ParsedAST &AST, PublishFn Publish) override {
     WithContextValue ASTCtx(ParsedAST::CurrentASTContext, &AST.getASTContext());
+    WithContextValue SemaCtx(ParsedAST::CurrentSema, &AST.getSema());
 
     if (FIndex)
       FIndex->updateMain(Path, AST);
 
     std::vector<Diag> Diagnostics = AST.getDiagnostics();
     std::vector<HighlightingToken> Highlightings;
     if (TheiaSemanticHighlighting)
       Highlightings = getSemanticHighlightings(AST);

clang-tools-extra/clangd/FindTarget.cpp

 #include "clang/AST/Type.h"
 #include "clang/AST/TypeLoc.h"
 #include "clang/AST/TypeLocVisitor.h"
 #include "clang/AST/TypeVisitor.h"
 #include "clang/Basic/LangOptions.h"
 #include "clang/Basic/OperatorKinds.h"
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Basic/Specifiers.h"
+#include "clang/Sema/Template.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/raw_ostream.h"
 #include <iterator>
 #include <utility>
 #include <vector>
std::string S = std::string(N.getNodeKind().asStringRef());
     llvm::raw_string_ostream OS(S);
     OS << ": ";
     N.print(OS, PrintingPolicy(LangOptions()));
   }
   std::replace(S.begin(), S.end(), '\n', ' ');
   return S;
 }
 
+// FIXME: Use ASTContext::getCanonicalTemplateArgument()
+TemplateArgument canonicalizeTemplateArg(const TemplateArgument &Arg) {
+  switch (Arg.getKind()) {
+  case TemplateArgument::Type: {
+    return TemplateArgument(Arg.getAsType().getCanonicalType());
+  }
+  default:
+    return Arg;
+  }
+}
+
+// A structure that resolveTypeToRecordDecl() can optionally populate
+// in the case where it discards template arguments.
+// The discarded template arguments are saved, along with other info
+// the caller may need to substitute the arguments back into declarations
+// it derives from the result of the operation (such as, into members of
+// the RecordDecl).
+struct SubstInfo {
+  // The template arguments that were discarded.
+  SmallVector<TemplateArgument, 4> TemplateArgs;
+};
+
 // Helper function for getMembersReferencedViaDependentName()
 // which takes a possibly-dependent type `T` and heuristically
 // resolves it to a CXXRecordDecl in which we can try name lookup.
-CXXRecordDecl *resolveTypeToRecordDecl(const Type *T) {
+CXXRecordDecl *resolveTypeToRecordDecl(const Type *T,
+                                       SubstInfo *OutSubstInfo = nullptr) {
   assert(T);
 
   if (const auto *RT = T->getAs<RecordType>())
     return dyn_cast<CXXRecordDecl>(RT->getDecl());
 
   if (const auto *ICNT = T->getAs<InjectedClassNameType>())
     T = ICNT->getInjectedSpecializationType().getTypePtrOrNull();
   if (!T)
     return nullptr;
 
   const auto *TST = T->getAs<TemplateSpecializationType>();
   if (!TST)
     return nullptr;
 
-  const ClassTemplateDecl *TD = dyn_cast_or_null<ClassTemplateDecl>(
+  ClassTemplateDecl *TD = dyn_cast_or_null<ClassTemplateDecl>(
       TST->getTemplateName().getAsTemplateDecl());
   if (!TD)
     return nullptr;
 
+  if (OutSubstInfo) {
+    for (const TemplateArgument &Arg : TST->template_arguments()) {
+      OutSubstInfo->TemplateArgs.push_back(canonicalizeTemplateArg(Arg));
+    }
+  }
   return TD->getTemplatedDecl();
 }
 
+const NamedDecl *getTemplatePattern(const NamedDecl *D) {
+  if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(D)) {
+    if (const auto *Result = CRD->getTemplateInstantiationPattern())
+      return Result;
+    // getTemplateInstantiationPattern returns null if the Specialization is
+    // incomplete (e.g. the type didn't need to be complete), fall back to the
+    // primary template.
+    if (CRD->getTemplateSpecializationKind() == TSK_Undeclared)
+      if (const auto *Spec = dyn_cast<ClassTemplateSpecializationDecl>(CRD))
+        return Spec->getSpecializedTemplate()->getTemplatedDecl();
+  } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
+    return FD->getTemplateInstantiationPattern();
+  } else if (auto *VD = dyn_cast<VarDecl>(D)) {
+    // Hmm: getTIP returns its arg if it's not an instantiation?!
+    VarDecl *T = VD->getTemplateInstantiationPattern();
+    return (T == D) ? nullptr : T;
+  } else if (const auto *ED = dyn_cast<EnumDecl>(D)) {
+    return ED->getInstantiatedFromMemberEnum();
+  } else if (isa<FieldDecl>(D) || isa<TypedefNameDecl>(D)) {
+    if (const auto *Parent = llvm::dyn_cast<NamedDecl>(D->getDeclContext()))
+      if (const DeclContext *ParentPat =
+              dyn_cast_or_null<DeclContext>(getTemplatePattern(Parent)))
+        for (const NamedDecl *BaseND : ParentPat->lookup(D->getDeclName()))
+          if (!BaseND->isImplicit() && BaseND->getKind() == D->getKind())
+            return BaseND;
+  } else if (const auto *ECD = dyn_cast<EnumConstantDecl>(D)) {
+    if (const auto *ED = dyn_cast<EnumDecl>(ECD->getDeclContext())) {
+      if (const EnumDecl *Pattern = ED->getInstantiatedFromMemberEnum()) {
+        for (const NamedDecl *BaseECD : Pattern->lookup(ECD->getDeclName()))
+          return BaseECD;
+      }
+    }
+  }
+  return nullptr;
+}
+
 // Given a tag-decl type and a member name, heuristically resolve the
 // name to one or more declarations.
 // The current heuristic is simply to look up the name in the primary
 // template. This is a heuristic because the template could potentially
 // have specializations that declare different members.
 // Multiple declarations could be returned if the name is overloaded
 // (e.g. an overloaded method in the primary template).
 // This heuristic will give the desired answer in many cases, e.g.
 // for a call to vector<T>::size().
 // The name to look up is provided in the form of a factory that takes
 // an ASTContext, because an ASTContext may be needed to obtain the
 // name (e.g. if it's an operator name), but the caller may not have
 // access to an ASTContext.
 std::vector<const NamedDecl *> getMembersReferencedViaDependentName(
     const Type *T, DeclarationName Name,
     llvm::function_ref<bool(const NamedDecl *ND)> Filter) {
   if (!T)
     return {};
   if (auto *ET = T->getAs<EnumType>()) {
     auto Result = ET->getDecl()->lookup(Name);
     return {Result.begin(), Result.end()};
   }
-  if (auto *RD = resolveTypeToRecordDecl(T)) {
-    if (!RD->hasDefinition())
+  SubstInfo SubstInfo;
+  if (auto *RD = resolveTypeToRecordDecl(T, &SubstInfo)) {
+    if (!RD->hasDefinition()) {
+      // FIXME: Explain why we try the template pattern here.
+      RD = const_cast<CXXRecordDecl *>(
+          cast<CXXRecordDecl>(getTemplatePattern(RD)));
+      if (!RD->hasDefinition()) {
         return {};
+      }
+    }
     RD = RD->getDefinition();
+
+    // If resolveTypeToRecordDecl() discarded template arguments,
+    // substitute them back into the decl here. This makes the
+    // results of lookupDependentName() more useful; for example,
+    // if the incoming type was `vector<vector<U>>`, and we are looking
+    // up the name `front()`, the return type of the lookup result
+    // will be `vector<U>` rather than just a template-parameter, making
+    // it possible to do another lookup in the return type.
+    if (!SubstInfo.TemplateArgs.empty()) {
+      auto *Sema = Context::current().getExisting(ParsedAST::CurrentSema);
+      Sema::InstantiatingTemplate Inst(*Sema, RD->getLocation(), RD);
+      void *InsertPos = nullptr;
+      ClassTemplateDecl *CT = RD->getDescribedClassTemplate();
+      assert(CT);
+      ClassTemplateSpecializationDecl *SubstRD =
+          CT->findSpecialization(SubstInfo.TemplateArgs, InsertPos);
+      if (!SubstRD) {
+        SubstRD = ClassTemplateSpecializationDecl::Create(
+            Sema->getASTContext(), CT->getTemplatedDecl()->getTagKind(),
+            CT->getDeclContext(), CT->getTemplatedDecl()->getBeginLoc(),
+            CT->getLocation(), CT, SubstInfo.TemplateArgs, nullptr);
+        Sema->InstantiateClassTemplateSpecialization(RD->getLocation(), SubstRD,
+                                                     TSK_ImplicitInstantiation);
+      }
+      RD = SubstRD;
+    }
+
     return RD->lookupDependentName(Name, Filter);
   }
   return {};
 }
 
 const auto NonStaticFilter = [](const NamedDecl *D) {
   return D->isCXXInstanceMember();
 };
return resolveDeclsToType(getMembersReferencedViaDependentName(
         NNS->getAsIdentifier(), TypeFilter));
   }
   default:
     break;
   }
   return nullptr;
 }
 
-const NamedDecl *getTemplatePattern(const NamedDecl *D) {
-  if (const CXXRecordDecl *CRD = dyn_cast<CXXRecordDecl>(D)) {
-    if (const auto *Result = CRD->getTemplateInstantiationPattern())
-      return Result;
-    // getTemplateInstantiationPattern returns null if the Specialization is
-    // incomplete (e.g. the type didn't need to be complete), fall back to the
-    // primary template.
-    if (CRD->getTemplateSpecializationKind() == TSK_Undeclared)
-      if (const auto *Spec = dyn_cast<ClassTemplateSpecializationDecl>(CRD))
-        return Spec->getSpecializedTemplate()->getTemplatedDecl();
-  } else if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
-    return FD->getTemplateInstantiationPattern();
-  } else if (auto *VD = dyn_cast<VarDecl>(D)) {
-    // Hmm: getTIP returns its arg if it's not an instantiation?!
-    VarDecl *T = VD->getTemplateInstantiationPattern();
-    return (T == D) ? nullptr : T;
-  } else if (const auto *ED = dyn_cast<EnumDecl>(D)) {
-    return ED->getInstantiatedFromMemberEnum();
-  } else if (isa<FieldDecl>(D) || isa<TypedefNameDecl>(D)) {
-    if (const auto *Parent = llvm::dyn_cast<NamedDecl>(D->getDeclContext()))
-      if (const DeclContext *ParentPat =
-              dyn_cast_or_null<DeclContext>(getTemplatePattern(Parent)))
-        for (const NamedDecl *BaseND : ParentPat->lookup(D->getDeclName()))
-          if (!BaseND->isImplicit() && BaseND->getKind() == D->getKind())
-            return BaseND;
-  } else if (const auto *ECD = dyn_cast<EnumConstantDecl>(D)) {
-    if (const auto *ED = dyn_cast<EnumDecl>(ECD->getDeclContext())) {
-      if (const EnumDecl *Pattern = ED->getInstantiatedFromMemberEnum()) {
-        for (const NamedDecl *BaseECD : Pattern->lookup(ECD->getDeclName()))
-          return BaseECD;
-      }
-    }
-  }
-  return nullptr;
-}
-
 // TargetFinder locates the entities that an AST node refers to.
 //
 // Typically this is (possibly) one declaration and (possibly) one type, but
 // may be more:
 //  - for ambiguous nodes like OverloadExpr
 //  - if we want to include e.g. both typedefs and the underlying type
 //
 // This is organized as a set of mutually recursive helpers for particular node

clang-tools-extra/clangd/ParsedAST.h

public:
   ~ParsedAST();
 
   /// Note that the returned ast will not contain decls from the preamble that
   /// were not deserialized during parsing. Clients should expect only decls
   /// from the main file to be in the AST.
   ASTContext &getASTContext();
   const ASTContext &getASTContext() const;
 
+  Sema &getSema();
+
   Preprocessor &getPreprocessor();
   std::shared_ptr<Preprocessor> getPreprocessorPtr();
   const Preprocessor &getPreprocessor() const;
 
   SourceManager &getSourceManager() {
     return getASTContext().getSourceManager();
   }
   const SourceManager &getSourceManager() const {
public:
 
   /// Returns the version of the ParseInputs this AST was built from.
   llvm::StringRef version() const { return Version; }
 
   /// Returns the version of the ParseInputs used to build Preamble part of this
   /// AST. Might be None if no Preamble is used.
   llvm::Optional<llvm::StringRef> preambleVersion() const;
 
-  /// This context variable makes available the ASTContext of the AST being
-  /// operated on currently.
+  /// This context variable makes available the ASTContext and Sema of the AST
+  /// being operated on currently.
   static Key<ASTContext *> CurrentASTContext;
+  static Key<Sema *> CurrentSema;
 
 private:
   ParsedAST(llvm::StringRef Version,
             std::shared_ptr<const PreambleData> Preamble,
             std::unique_ptr<CompilerInstance> Clang,
             std::unique_ptr<FrontendAction> Action, syntax::TokenBuffer Tokens,
             MainFileMacros Macros, std::vector<Decl *> LocalTopLevelDecls,
             std::vector<Diag> Diags, IncludeStructure Includes,

clang-tools-extra/clangd/ParsedAST.cpp

private:
   const SourceManager &SM;
   Preprocessor &PP;
   std::vector<syntax::Token> MainFileTokens;
 };
 
 } // namespace
 
 Key<ASTContext *> ParsedAST::CurrentASTContext;
+Key<Sema *> ParsedAST::CurrentSema;
 
 llvm::Optional<ParsedAST>
 ParsedAST::build(llvm::StringRef Filename, const ParseInputs &Inputs,
                  std::unique_ptr<clang::CompilerInvocation> CI,
                  llvm::ArrayRef<Diag> CompilerInvocationDiags,
                  std::shared_ptr<const PreambleData> Preamble) {
   trace::Span Tracer("BuildAST");
   SPAN_ATTACH(Tracer, "File", Filename);

 }
 
 ASTContext &ParsedAST::getASTContext() { return Clang->getASTContext(); }
 
 const ASTContext &ParsedAST::getASTContext() const {
   return Clang->getASTContext();
 }
 
+Sema &ParsedAST::getSema() { return Clang->getSema(); }
+
 Preprocessor &ParsedAST::getPreprocessor() { return Clang->getPreprocessor(); }
 
 std::shared_ptr<Preprocessor> ParsedAST::getPreprocessorPtr() {
   return Clang->getPreprocessorPtr();
 }
 
 const Preprocessor &ParsedAST::getPreprocessor() const {
   return Clang->getPreprocessor();

clang-tools-extra/clangd/TUScheduler.cpp

auto Task = [=, Action = std::move(Action)]() mutable {
     // Make sure we put the AST back into the LRU cache.
     auto _ = llvm::make_scope_exit(
         [&AST, this]() { IdleASTs.put(this, std::move(*AST)); });
     // Run the user-provided action.
     if (!*AST)
       return Action(error(llvm::errc::invalid_argument, "invalid AST"));
     vlog("ASTWorker running {0} on version {2} of {1}", Name, FileName,
          FileInputs.Version);
-    WithContextValue Ctx(ParsedAST::CurrentASTContext,
+    WithContextValue ASTCtx(ParsedAST::CurrentASTContext,
                             &(*AST)->getASTContext());
+    WithContextValue SemaCtx(ParsedAST::CurrentSema, &(*AST)->getSema());
     Action(InputsAndAST{FileInputs, **AST});
   };
   startTask(Name, std::move(Task), /*UpdateType=*/None, Invalidation);
 }
 
 void PreambleThread::build(Request Req) {
   assert(Req.CI && "Got preamble request with null compiler invocation");
   const ParseInputs &Inputs = Req.Inputs;

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

Code = R"cpp(
         void waldo() {}
       };
       template <typename T>
       struct Derived : Base<T> {
         using Base<T>::[[waldo]];
       };
     )cpp";
   EXPECT_DECLS("UnresolvedUsingValueDecl", {"using Base<T>::waldo", Rel::Alias},
-               {"void waldo()"});
+               {"void waldo()", Rel::TemplatePattern},
+               {"void waldo()", Rel::TemplateInstantiation});
 }
 
 TEST_F(TargetDeclTest, ConstructorInitList) {
   Code = R"cpp(
     struct X {
       int a;
       X() : [[a]](42) {}
     };
Code = R"cpp(
         };
         template <typename T>
         void test() {
           Foo::k(T()).template [[convert]]<T>();
         }
       )cpp";
   EXPECT_DECLS("CXXDependentScopeMemberExpr",
                "template <typename T> T convert() const");
+
+  Code = R"cpp(
+        template <typename T>
+        struct vector {
+          T front();
+        };
+        template <typename T>
+        void foo(vector<vector<T>> c) {
+          c.front().[[front]]();
+        }
+      )cpp";
+  EXPECT_DECLS("CXXDependentScopeMemberExpr",
+               {"T front()", Rel::TemplatePattern},
+               {"type-parameter-0-0 front()", Rel::TemplateInstantiation});
 }
 
 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");
+  EXPECT_DECLS("DependentNameTypeLoc", {"struct B", Rel::TemplatePattern},
+               {"struct B", Rel::TemplateInstantiation});
 
   // Heuristic resolution of dependent type name which doesn't get a TypeLoc
   Code = R"cpp(
         template <typename>
         struct A { struct B { struct C {}; }; };
 
         template <typename T>
         void foo(typename A<T>::[[B]]::C);
       )cpp";
-  EXPECT_DECLS("NestedNameSpecifierLoc", "struct B");
+  EXPECT_DECLS("NestedNameSpecifierLoc", {"struct B", Rel::TemplatePattern},
+               {"struct B", Rel::TemplateInstantiation});
 
   // Heuristic resolution of dependent type name whose qualifier is also
   // dependent
   Code = R"cpp(
         template <typename>
         struct A { struct B { struct C {}; }; };
 
         template <typename T>
for (unsigned I = 0; I < Refs.size(); ++I)
       DumpedReferences += std::string(llvm::formatv("{0}: {1}\n", I, Refs[I]));
 
     return AllRefs{std::move(AnnotatedCode), std::move(DumpedReferences)};
   }
 };
 
 TEST_F(FindExplicitReferencesTest, All) {
   std::pair</*Code*/ llvm::StringRef, /*References*/ llvm::StringRef> Cases[] =
-      {
-          // Simple expressions.
-          {R"cpp(
+      {// Simple expressions.
         int global;
         int func();
         void foo(int param) {
           $0^global = $1^param + $2^func();
         }
         )cpp",
-           "0: targets = {global}\n"
-           "1: targets = {param}\n"
-           "2: targets = {func}\n"},
-          {R"cpp(
         struct X { int a; };
         void foo(X x) {
           $0^x.$1^a = 10;
         }
         )cpp",
-           "0: targets = {x}\n"
-           "1: targets = {X::a}\n"},
-          {R"cpp(
         // error-ok: testing with broken code
         int bar();
         int foo() {
           return $0^bar() + $1^bar(42);
         }
         )cpp",
-           "0: targets = {bar}\n"
-           "1: targets = {bar}\n"},
-          // Namespaces and aliases.
-          {R"cpp(
           namespace ns {}
           namespace alias = ns;
           void foo() {
             using namespace $0^ns;
             using namespace $1^alias;
           }
         )cpp",
-           "0: targets = {ns}\n"
-           "1: targets = {alias}\n"},
-          // Using declarations.
-          {R"cpp(
           namespace ns { int global; }
           void foo() {
             using $0^ns::$1^global;
           }
         )cpp",
-           "0: targets = {ns}\n"
-           "1: targets = {ns::global}, qualifier = 'ns::'\n"},
-          // Simple types.
-          {R"cpp(
          struct Struct { int a; };
          using Typedef = int;
          void foo() {
            $0^Struct $1^x;
            $2^Typedef $3^y;
            static_cast<$4^Struct*>(0);
          }
        )cpp",
-           "0: targets = {Struct}\n"
-           "1: targets = {x}, decl\n"
-           "2: targets = {Typedef}\n"
-           "3: targets = {y}, decl\n"
-           "4: targets = {Struct}\n"},
-          // Name qualifiers.
-          {R"cpp(
          namespace a { namespace b { struct S { typedef int type; }; } }
          void foo() {
            $0^a::$1^b::$2^S $3^x;
            using namespace $4^a::$5^b;
            $6^S::$7^type $8^y;
          }
         )cpp",
-           "0: targets = {a}\n"
-           "1: targets = {a::b}, qualifier = 'a::'\n"
-           "2: targets = {a::b::S}, qualifier = 'a::b::'\n"
-           "3: targets = {x}, decl\n"
-           "4: targets = {a}\n"
-           "5: targets = {a::b}, qualifier = 'a::'\n"
-           "6: targets = {a::b::S}\n"
-           "7: targets = {a::b::S::type}, qualifier = 'struct S::'\n"
-           "8: targets = {y}, decl\n"},
-          {R"cpp(
          void foo() {
            $0^ten: // PRINT "HELLO WORLD!"
            goto $1^ten;
          }
        )cpp",
         "0: targets = {ten}, decl\n"
         "1: targets = {ten}\n"},
        // Simple templates.
        {R"cpp(
           template <class T> struct vector { using value_type = T; };
           template <> struct vector<bool> { using value_type = bool; };
           void foo() {
             $0^vector<int> $1^vi;
             $2^vector<bool> $3^vb;
           }
         )cpp",
-           "0: targets = {vector<int>}\n"
-           "1: targets = {vi}, decl\n"
-           "2: targets = {vector<bool>}\n"
-           "3: targets = {vb}, decl\n"},
-          // Template type aliases.
-          {R"cpp(
             template <class T> struct vector { using value_type = T; };
             template <> struct vector<bool> { using value_type = bool; };
             template <class T> using valias = vector<T>;
             void foo() {
               $0^valias<int> $1^vi;
               $2^valias<bool> $3^vb;
             }
           )cpp",
-           "0: targets = {valias}\n"
-           "1: targets = {vi}, decl\n"
-           "2: targets = {valias}\n"
-           "3: targets = {vb}, decl\n"},
-          // Injected class name.
-          {R"cpp(
             namespace foo {
               template <typename $0^T>
               class $1^Bar {
                 ~$2^Bar();
                 void $3^f($4^Bar);
               };
             }
           )cpp",
-           "0: targets = {foo::Bar::T}, decl\n"
-           "1: targets = {foo::Bar}, decl\n"
-           "2: targets = {foo::Bar}\n"
-           "3: targets = {foo::Bar::f}, decl\n"
-           "4: targets = {foo::Bar}\n"},
-          // MemberExpr should know their using declaration.
-          {R"cpp(
             struct X { void func(int); };
             struct Y : X {
               using X::func;
             };
             void foo(Y y) {
               $0^y.$1^func(1);
             }
         )cpp",
-           "0: targets = {y}\n"
-           "1: targets = {Y::func}\n"},
-          // DeclRefExpr should know their using declaration.
-          {R"cpp(
             namespace ns { void bar(int); }
             using ns::bar;
 
             void foo() {
               $0^bar(10);
             }
         )cpp",
-           "0: targets = {bar}\n"},
-          // References from a macro.
-          {R"cpp(
             #define FOO a
             #define BAR b
 
             void foo(int a, int b) {
               $0^FOO+$1^BAR;
             }
         )cpp",
-           "0: targets = {a}\n"
-           "1: targets = {b}\n"},
-          // No references from implicit nodes.
-          {R"cpp(
             struct vector {
               int *begin();
               int *end();
             };
 
             void foo() {
               for (int $0^x : $1^vector()) {
                 $2^x = 10;
               }
             }
         )cpp",
-           "0: targets = {x}, decl\n"
-           "1: targets = {vector}\n"
-           "2: targets = {x}\n"},
 // Handle UnresolvedLookupExpr.
 // FIXME
 // This case fails when expensive checks are enabled.
 // Seems like the order of ns1::func and ns2::func isn't defined.
 #ifndef EXPENSIVE_CHECKS
-          {R"cpp(
             namespace ns1 { void func(char*); }
             namespace ns2 { void func(int*); }
             using namespace ns1;
             using namespace ns2;
 
             template <class T>
             void foo(T t) {
               $0^func($1^t);
             }
         )cpp",
-           "0: targets = {ns1::func, ns2::func}\n"
-           "1: targets = {t}\n"},
 #endif
-          // Handle UnresolvedMemberExpr.
-          {R"cpp(
             struct X {
               void func(char*);
               void func(int*);
             };
 
             template <class T>
             void foo(X x, T t) {
               $0^x.$1^func($2^t);
             }
         )cpp",
-           "0: targets = {x}\n"
-           "1: targets = {X::func, X::func}\n"
-           "2: targets = {t}\n"},
-          // Handle DependentScopeDeclRefExpr.
-          {R"cpp(
             template <class T>
             struct S {
               static int value;
             };
 
             template <class T>
             void foo() {
               $0^S<$1^T>::$2^value;
             }
        )cpp",
-           "0: targets = {S}\n"
-           "1: targets = {T}\n"
-           "2: targets = {S::value}, qualifier = 'S<T>::'\n"},
-          // Handle CXXDependentScopeMemberExpr.
-          {R"cpp(
+        "2: targets = {S<type-parameter-0-0>::value}, qualifier = 'S<T>::'\n"},
             template <class T>
             struct S {
               int value;
             };
 
             template <class T>
             void foo(S<T> t) {
               $0^t.$1^value;
             }
        )cpp",
-           "0: targets = {t}\n"
-           "1: targets = {S::value}\n"},
-          // Type template parameters.
-          {R"cpp(
+        "1: targets = {S<type-parameter-0-0>::value}\n"},
             template <class T>
             void foo() {
               static_cast<$0^T>(0);
               $1^T();
               $2^T $3^t;
             }
         )cpp",
-           "0: targets = {T}\n"
-           "1: targets = {T}\n"
-           "2: targets = {T}\n"
-           "3: targets = {t}, decl\n"},
-          // Non-type template parameters.
-          {R"cpp(
             template <int I>
             void foo() {
               int $0^x = $1^I;
             }
         )cpp",
-           "0: targets = {x}, decl\n"
-           "1: targets = {I}\n"},
-          // Template template parameters.
-          {R"cpp(
             template <class T> struct vector {};
 
             template <template<class> class TT, template<class> class ...TP>
             void foo() {
               $0^TT<int> $1^x;
               $2^foo<$3^TT>();
               $4^foo<$5^vector>();
               $6^foo<$7^TP...>();
             }
         )cpp",
-           "0: targets = {TT}\n"
-           "1: targets = {x}, decl\n"
-           "2: targets = {foo}\n"
-           "3: targets = {TT}\n"
-           "4: targets = {foo}\n"
-           "5: targets = {vector}\n"
-           "6: targets = {foo}\n"
-           "7: targets = {TP}\n"},
-          // Non-type template parameters with declarations.
-          {R"cpp(
             int func();
             template <int(*)()> struct wrapper {};
 
             template <int(*FuncParam)()>
             void foo() {
               $0^wrapper<$1^func> $2^w;
               $3^FuncParam();
             }
         )cpp",
-           "0: targets = {wrapper<&func>}\n"
-           "1: targets = {func}\n"
-           "2: targets = {w}, decl\n"
-           "3: targets = {FuncParam}\n"},
-          // declaration references.
-          {R"cpp(
              namespace ns {}
              class S {};
              void foo() {
                class $0^Foo { $1^Foo(); ~$2^Foo(); int $3^field; };
                int $4^Var;
                enum $5^E { $6^ABC };
                typedef int $7^INT;
                using $8^INT2 = int;
                namespace $9^NS = $10^ns;
              }
            )cpp",
-           "0: targets = {Foo}, decl\n"
-           "1: targets = {foo()::Foo::Foo}, decl\n"
-           "2: targets = {Foo}\n"
-           "3: targets = {foo()::Foo::field}, decl\n"
-           "4: targets = {Var}, decl\n"
-           "5: targets = {E}, decl\n"
-           "6: targets = {foo()::ABC}, decl\n"
-           "7: targets = {INT}, decl\n"
-           "8: targets = {INT2}, decl\n"
-           "9: targets = {NS}, decl\n"
-           "10: targets = {ns}\n"},
-          // User-defined conversion operator.
-          {R"cpp(
             void foo() {
                class $0^Bar {};
                class $1^Foo {
                public:
                  // FIXME: This should have only one reference to Bar.
                  $2^operator $3^$4^Bar();
                };
 
                $5^Foo $6^f;
                $7^f.$8^operator $9^Bar();
             }
         )cpp",
-           "0: targets = {Bar}, decl\n"
-           "1: targets = {Foo}, decl\n"
-           "2: targets = {foo()::Foo::operator Bar}, decl\n"
-           "3: targets = {Bar}\n"
-           "4: targets = {Bar}\n"
-           "5: targets = {Foo}\n"
-           "6: targets = {f}, decl\n"
-           "7: targets = {f}\n"
-           "8: targets = {foo()::Foo::operator Bar}\n"
-           "9: targets = {Bar}\n"},
-          // Destructor.
-          {R"cpp(
              void foo() {
                class $0^Foo {
                public:
                  ~$1^Foo() {}
 
                  void $2^destructMe() {
                    this->~$3^Foo();
                  }
                };
 
                $4^Foo $5^f;
                $6^f.~ /*...*/ $7^Foo();
              }
            )cpp",
-           "0: targets = {Foo}, decl\n"
-           // FIXME: It's better to target destructor's FunctionDecl instead of
-           // the type itself (similar to constructor).
-           "1: targets = {Foo}\n"
-           "2: targets = {foo()::Foo::destructMe}, decl\n"
-           "3: targets = {Foo}\n"
-           "4: targets = {Foo}\n"
-           "5: targets = {f}, decl\n"
-           "6: targets = {f}\n"
-           "7: targets = {Foo}\n"},
-          // cxx constructor initializer.
-          {R"cpp(
              class Base {};
              void foo() {
                // member initializer
                class $0^X {
                  int $1^abc;
                  $2^X(): $3^abc() {}
                };
                // base initializer
                class $4^Derived : public $5^Base {
                  $6^Base $7^B;
                  $8^Derived() : $9^Base() {}
                };
                // delegating initializer
                class $10^Foo {
                  $11^Foo(int);
                  $12^Foo(): $13^Foo(111) {}
                };
              }
            )cpp",
-           "0: targets = {X}, decl\n"
-           "1: targets = {foo()::X::abc}, decl\n"
-           "2: targets = {foo()::X::X}, decl\n"
-           "3: targets = {foo()::X::abc}\n"
-           "4: targets = {Derived}, decl\n"
-           "5: targets = {Base}\n"
-           "6: targets = {Base}\n"
-           "7: targets = {foo()::Derived::B}, decl\n"
-           "8: targets = {foo()::Derived::Derived}, decl\n"
-           "9: targets = {Base}\n"
-           "10: targets = {Foo}, decl\n"
-           "11: targets = {foo()::Foo::Foo}, decl\n"
-           "12: targets = {foo()::Foo::Foo}, decl\n"
-           "13: targets = {Foo}\n"},
-          // Anonymous entities should not be reported.
-          {
-              R"cpp(
              void foo() {
               class {} $0^x;
               int (*$1^fptr)(int $2^a, int) = nullptr;
              }
            )cpp",
-              "0: targets = {x}, decl\n"
-              "1: targets = {fptr}, decl\n"
-              "2: targets = {a}, decl\n"},
-          // Namespace aliases should be handled properly.
-          {
-              R"cpp(
                 namespace ns { struct Type {}; }
                 namespace alias = ns;
                 namespace rec_alias = alias;
 
                 void foo() {
                   $0^ns::$1^Type $2^a;
                   $3^alias::$4^Type $5^b;
                   $6^rec_alias::$7^Type $8^c;
                 }
            )cpp",
-              "0: targets = {ns}\n"
-              "1: targets = {ns::Type}, qualifier = 'ns::'\n"
-              "2: targets = {a}, decl\n"
-              "3: targets = {alias}\n"
-              "4: targets = {ns::Type}, qualifier = 'alias::'\n"
-              "5: targets = {b}, decl\n"
-              "6: targets = {rec_alias}\n"
-              "7: targets = {ns::Type}, qualifier = 'rec_alias::'\n"
-              "8: targets = {c}, decl\n"},
-          // Handle SizeOfPackExpr.
-          {
-              R"cpp(
                 template <typename... E>
                 void foo() {
                   constexpr int $0^size = sizeof...($1^E);
                 };
             )cpp",
-              "0: targets = {size}, decl\n"
-              "1: targets = {E}\n"},
-          // Class template argument deduction
-          {
-              R"cpp(
                 template <typename T>
                 struct Test {
                 Test(T);
               };
               void foo() {
                 $0^Test $1^a(5);
               }
             )cpp",
-              "0: targets = {Test}\n"
-              "1: targets = {a}, decl\n"},
-          // Templates
-          {R"cpp(
             namespace foo {
               template <typename $0^T>
               class $1^Bar {};
             }
           )cpp",
-           "0: targets = {foo::Bar::T}, decl\n"
-           "1: targets = {foo::Bar}, decl\n"},
-          // Templates
-          {R"cpp(
             namespace foo {
               template <typename $0^T>
               void $1^func();
             }
           )cpp",
-           "0: targets = {T}, decl\n"
-           "1: targets = {foo::func}, decl\n"},
-          // Templates
-          {R"cpp(
             namespace foo {
               template <typename $0^T>
               $1^T $2^x;
             }
           )cpp",
-           "0: targets = {foo::T}, decl\n"
-           "1: targets = {foo::T}\n"
-           "2: targets = {foo::x}, decl\n"},
-          // Templates
-          {R"cpp(
             template<typename T> class vector {};
             namespace foo {
               template <typename $0^T>
               using $1^V = $2^vector<$3^T>;
             }
           )cpp",
-           "0: targets = {foo::T}, decl\n"
-           "1: targets = {foo::V}, decl\n"
-           "2: targets = {vector}\n"
-           "3: targets = {foo::T}\n"},
-          // Concept
-          {
-              R"cpp(
               template <typename T>
               concept Drawable = requires (T t) { t.draw(); };
 
               namespace foo {
                 template <typename $0^T> requires $1^Drawable<$2^T>
                 void $3^bar($4^T $5^t) {
                   $6^t.$7^draw();
                 }
               }
           )cpp",
-              "0: targets = {T}, decl\n"
-              "1: targets = {Drawable}\n"
-              "2: targets = {T}\n"
-              "3: targets = {foo::bar}, decl\n"
-              "4: targets = {T}\n"
-              "5: targets = {t}, decl\n"
-              "6: targets = {t}\n"
-              "7: targets = {}\n"},
-          // Objective-C: properties
-          {
-              R"cpp(
             @interface I {}
             @property(retain) I* x;
             @property(retain) I* y;
             @end
             I *f;
             void foo() {
               $0^f.$1^x.$2^y = 0;
             }
           )cpp",
-              "0: targets = {f}\n"
-              "1: targets = {I::x}\n"
-              "2: targets = {I::y}\n"},
-          // Objective-C: implicit properties
-          {
-              R"cpp(
             @interface I {}
             -(I*)x;
             -(void)setY:(I*)y;
             @end
             I *f;
             void foo() {
               $0^f.$1^x.$2^y = 0;
             }
           )cpp",
-              "0: targets = {f}\n"
-              "1: targets = {I::x}\n"
-              "2: targets = {I::setY:}\n"},
-          // Designated initializers.
-          {R"cpp(
             void foo() {
               struct $0^Foo {
                 int $1^Bar;
               };
               $2^Foo $3^f { .$4^Bar = 42 };
             }
         )cpp",
-           "0: targets = {Foo}, decl\n"
-           "1: targets = {foo()::Foo::Bar}, decl\n"
-           "2: targets = {Foo}\n"
-           "3: targets = {f}, decl\n"
-           "4: targets = {foo()::Foo::Bar}\n"},
-          {R"cpp(
             void foo() {
               struct $0^Baz {
                 int $1^Field;
               };
               struct $2^Bar {
                 $3^Baz $4^Foo;
               };
               $5^Bar $6^bar { .$7^Foo.$8^Field = 42 };

clang-tools-extra/clangd/unittests/TestTU.h

struct TestTU {
   // disk and later read back.
   // FIXME: Change the way reading/writing modules work to allow us to keep them
   // in memory across multiple clang invocations, at least in tests, to
   // eliminate the need for real file system here.
   // Please avoid using this for things other than implicit modules. The plan is
   // to eliminate this option some day.
   bool OverlayRealFileSystemForModules = false;
 
-  // This is used to add the ASTContext of the AST produced by build() to the
-  // clangd Context.
+  // This is used to add the ASTContext and Sema of the AST produced by build()
+  // to the clangd Context.
   mutable std::unique_ptr<WithContextValue> ASTCtx;
+  mutable std::unique_ptr<WithContextValue> SemaCtx;
 
   // By default, build() will report Error diagnostics as GTest errors.
   // Suppress this behavior by adding an 'error-ok' comment to the code.
   ParsedAST build() const;
   std::shared_ptr<const PreambleData>
   preamble(PreambleParsedCallback PreambleCallback = nullptr) const;
   ParseInputs inputs(MockFS &FS) const;
   SymbolSlab headerSymbols() const;

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

for (const auto &D : AST->getDiagnostics())
             << "TestTU failed to build (suppress with /*error-ok*/): \n"
             << D << "\n\nFor code:\n"
             << Code;
         break; // Just report first error for simplicity.
       }
   }
   ASTCtx = std::make_unique<WithContextValue>(ParsedAST::CurrentASTContext,
                                               &AST->getASTContext());
+  SemaCtx = std::make_unique<WithContextValue>(ParsedAST::CurrentSema,
+                                               &AST->getSema());
   return std::move(*AST);
 }
 
 SymbolSlab TestTU::headerSymbols() const {
   auto AST = build();
   return std::get<0>(indexHeaderSymbols(/*Version=*/"null", AST.getASTContext(),
                                         AST.getPreprocessorPtr(),
                                         AST.getCanonicalIncludes()));

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

)cpp",
         using Base<T>::w^aldo;
       };
     )cpp",
   };
 
   for (const auto *Case : Tests) {
     SCOPED_TRACE(Case);
     auto T = Annotations(Case);
-    auto AST = TestTU::withCode(T.code()).build();
+    TestTU TU = TestTU::withCode(T.code());
+    auto AST = TU.build();
     EXPECT_THAT(locateSymbolAt(AST, T.point()),
                 UnorderedPointwise(DeclRange(), T.ranges()));
   }
 }
 
 TEST(LocateSymbol, RelPathsInCompileCommand) {
   // The source is in "/clangd-test/src".
   // We build in "/clangd-test/build".