[clang-tools-extra] [clangd] Store documentation when indexing standard library (PR #133681)

[kadir çetinkaya via cfe-commits]

================
@@ -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());
----------------
kadircet wrote:

IIUC we're testing preamble vs stdlib index depending on which one finishes first here.

I think we can try with a vector implementation like:
```cpp
struct vector {
  // This shouldn't be indexed for code-completion, hence static-idx wouldn't have any docs for it.
  struct inner {};
};
```

afterwards we can add an empty file to clangd, to make sure we only index `vector` through stdlib-index and not preabmle.

afterwards we run a workspace symbol query for `vector::inner` and ensure it has docs. WDYT?

https://github.com/llvm/llvm-project/pull/133681