[clang][Index] Enable indexing of Template Type Parameters behind a flag

Summary:
clangd uses indexing api to provide references and it was not possible
to perform symbol information for template parameters. This patch enables
visiting of TemplateTypeParmTypeLocs.

Reviewers: ilya-biryukov, akyrtzi

Subscribers: javed.absar, kristof.beyls, ioeric, arphaman, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D58293

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@354560 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/Index/IndexingAction.h

@@ -46,6 +46,7 @@ struct IndexingOptions {
   bool IndexMacrosInPreprocessor = false;
   // Has no effect if IndexFunctionLocals are false.
   bool IndexParametersInDeclarations = false;
+  bool IndexTemplateParameters = false;
 };
 
 /// Creates a frontend action that indexes all symbols (macros and AST decls).

lib/Index/IndexDecl.cpp

@@ -672,6 +672,8 @@ public:
         shouldIndexTemplateParameterDefaultValue(Parent)) {
       const TemplateParameterList *Params = D->getTemplateParameters();
       for (const NamedDecl *TP : *Params) {
+        if (IndexCtx.shouldIndexTemplateParameters())
+          IndexCtx.handleDecl(TP);
         if (const auto *TTP = dyn_cast<TemplateTypeParmDecl>(TP)) {
           if (TTP->hasDefaultArgument())
             IndexCtx.indexTypeSourceInfo(TTP->getDefaultArgumentInfo(), Parent);

lib/Index/IndexSymbol.cpp

@@ -55,9 +55,6 @@ bool index::isFunctionLocalSymbol(const Decl *D) {
   if (isa<ParmVarDecl>(D))
     return true;
 
-  if (isa<TemplateTemplateParmDecl>(D))
-    return true;
-
   if (isa<ObjCTypeParamDecl>(D))
     return true;
 

lib/Index/IndexTypeSourceInfo.cpp

@@ -45,6 +45,13 @@ public:
       return false;                                                            \
   } while (0)
 
+  bool VisitTemplateTypeParmTypeLoc(TemplateTypeParmTypeLoc TTPL) {
+    SourceLocation Loc = TTPL.getNameLoc();
+    TemplateTypeParmDecl *TTPD = TTPL.getDecl();
+    return IndexCtx.handleReference(TTPD, Loc, Parent, ParentDC,
+                                    SymbolRoleSet());
+  }
+
   bool VisitTypedefTypeLoc(TypedefTypeLoc TL) {
     SourceLocation Loc = TL.getNameLoc();
     TypedefNameDecl *ND = TL.getTypedefNameDecl();

lib/Index/IndexingContext.cpp

@@ -44,6 +44,10 @@ bool IndexingContext::shouldIndexParametersInDeclarations() const {
   return IndexOpts.IndexParametersInDeclarations;
 }
 
+bool IndexingContext::shouldIndexTemplateParameters() const {
+  return IndexOpts.IndexTemplateParameters;
+}
+
 bool IndexingContext::handleDecl(const Decl *D,
                                  SymbolRoleSet Roles,
                                  ArrayRef<SymbolRelation> Relations) {
@@ -76,8 +80,11 @@ bool IndexingContext::handleReference(const NamedDecl *D, SourceLocation Loc,
   if (!shouldIndexFunctionLocalSymbols() && isFunctionLocalSymbol(D))
     return true;
 
-  if (isa<NonTypeTemplateParmDecl>(D) || isa<TemplateTypeParmDecl>(D))
+  if (!shouldIndexTemplateParameters() &&
+      (isa<NonTypeTemplateParmDecl>(D) || isa<TemplateTypeParmDecl>(D) ||
+       isa<TemplateTemplateParmDecl>(D))) {
     return true;
+  }
 
   return handleDeclOccurrence(D, Loc, /*IsRef=*/true, Parent, Roles, Relations,
                               RefE, RefD, DC);

lib/Index/IndexingContext.h

@@ -63,6 +63,8 @@ public:
 
   bool shouldIndexParametersInDeclarations() const;
 
+  bool shouldIndexTemplateParameters() const;
+
   static bool isTemplateImplicitInstantiation(const Decl *D);
 
   bool handleDecl(const Decl *D, SymbolRoleSet Roles = SymbolRoleSet(),

unittests/Index/IndexTests.cpp

@@ -216,6 +216,30 @@ TEST(IndexTest, IndexTemplateInstantiationPartial) {
                              DeclAt(Position(5, 12)))));
 }
 
+TEST(IndexTest, IndexTypeParmDecls) {
+  std::string Code = R"cpp(
+    template <typename T, int I, template<typename> class C, typename NoRef>
+    struct Foo {
+      T t = I;
+      C<int> x;
+    };
+  )cpp";
+  auto Index = std::make_shared<Indexer>();
+  IndexingOptions Opts;
+  tooling::runToolOnCode(new IndexAction(Index, Opts), Code);
+  EXPECT_THAT(Index->Symbols, AllOf(Not(Contains(QName("Foo::T"))),
+                                    Not(Contains(QName("Foo::I"))),
+                                    Not(Contains(QName("Foo::C"))),
+                                    Not(Contains(QName("Foo::NoRef")))));
+
+  Opts.IndexTemplateParameters = true;
+  Index->Symbols.clear();
+  tooling::runToolOnCode(new IndexAction(Index, Opts), Code);
+  EXPECT_THAT(Index->Symbols,
+              AllOf(Contains(QName("Foo::T")), Contains(QName("Foo::I")),
+                    Contains(QName("Foo::C")), Contains(QName("Foo::NoRef"))));
+}
+
 } // namespace
 } // namespace index
 } // namespace clang