[clangd] Store documentation when indexing standard library

Fixes clangd/clangd#2344

Author: HighCommander4

clang-tools-extra/clangd/index/Background.cpp

@@ -306,6 +306,7 @@ llvm::Error BackgroundIndex::index(tooling::CompileCommand Cmd) {
     return true;
   };
   IndexOpts.CollectMainFileRefs = true;
+  IndexOpts.StoreAllDocumentation = false;
 
   IndexFileIn Index;
   auto Action = createStaticIndexingAction(

clang-tools-extra/clangd/index/IndexAction.cpp

@@ -223,7 +223,6 @@ std::unique_ptr<FrontendAction> createStaticIndexingAction(
   Opts.CollectIncludePath = true;
   if (Opts.Origin == SymbolOrigin::Unknown)
     Opts.Origin = SymbolOrigin::Static;
-  Opts.StoreAllDocumentation = false;
   if (RefsCallback != nullptr) {
     Opts.RefFilter = RefKind::All;
     Opts.RefsInHeaders = true;

clang-tools-extra/clangd/indexer/IndexerMain.cpp

@@ -55,6 +55,7 @@ class IndexActionFactory : public tooling::FrontendActionFactory {
   std::unique_ptr<FrontendAction> create() override {
     SymbolCollector::Options Opts;
     Opts.CountReferences = true;
+    Opts.StoreAllDocumentation = false;
     Opts.FileFilter = [&](const SourceManager &SM, FileID FID) {
       const auto F = SM.getFileEntryRefForID(FID);
       if (!F)

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

@@ -158,6 +158,43 @@ TEST(StdLibTests, EndToEnd) {
       UnorderedElementsAre(StdlibSymbol("list"), StdlibSymbol("vector")));
 }
 
+TEST(StdLibTests, StdLibDocComments) {
+  Config Cfg;
+  Cfg.Index.StandardLibrary = true;
+  WithContextValue Enabled(Config::Key, std::move(Cfg));
+
+  MockFS FS;
+  FS.Files["stdlib/vector"] = R"cpp(
+    namespace std {
+      template <typename T>
+      class vector {
+      public:
+        /**doc comment*/
+        unsigned int size() const;
+      };
+    }
+  )cpp";
+  MockCompilationDatabase CDB;
+  CDB.ExtraClangFlags.push_back("-isystem" + testPath("stdlib"));
+  ClangdServer::Options Opts = ClangdServer::optsForTest();
+  Opts.BuildDynamicSymbolIndex = true; // also used for stdlib index
+  ClangdServer Server(CDB, FS, Opts);
+
+  Annotations A(R"cpp(
+    #include <vector>
+    void foo() {
+      std::vector<int> v;
+      v.si^ze();
+    }
+  )cpp");
+
+  Server.addDocument(testPath("foo.cc"), A.code());
+  ASSERT_TRUE(Server.blockUntilIdleForTest());
+  auto HI = cantFail(runHover(Server, testPath("foo.cc"), A.point()));
+  EXPECT_TRUE(HI.has_value());
+  EXPECT_EQ(HI->Documentation, "doc comment");
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang

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

@@ -68,6 +68,13 @@ template <typename T> CaptureProxy<T> capture(std::optional<T> &Target) {
 }
 } // namespace
 
+llvm::Expected<std::optional<HoverInfo>> runHover(ClangdServer &Server,
+                                                  PathRef File, Position Pos) {
+  std::optional<llvm::Expected<std::optional<HoverInfo>>> HI;
+  Server.findHover(File, Pos, capture(HI));
+  return std::move(*HI);
+}
+
 llvm::Expected<CodeCompleteResult>
 runCodeComplete(ClangdServer &Server, PathRef File, Position Pos,
                 clangd::CodeCompleteOptions Opts) {

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

@@ -29,6 +29,9 @@ void runAddDocument(ClangdServer &Server, PathRef File, StringRef Contents,
                     WantDiagnostics WantDiags = WantDiagnostics::Auto,
                     bool ForceRebuild = false);
 
+llvm::Expected<std::optional<HoverInfo>> runHover(ClangdServer &Server,
+                                                  PathRef File, Position Pos);
+
 llvm::Expected<CodeCompleteResult>
 runCodeComplete(ClangdServer &Server, PathRef File, Position Pos,
                 clangd::CodeCompleteOptions Opts);