[clangd] Add a flag to clangdServer rename function to control whether we want format the replacements.

[hokein]

Summary

This would allow clangd embedders to use the ClangdServer::rename for other
purposes (highlighting all the occurrences of the symbol in prepare
stage).

[ilya-biryukov]

LGTM with a small NIT.

Was also thinking about adding a test for this, but the amount of work required to do so seems to outweigh the usefulness. Therefore seems ok to land without the test too.
But up to you.

clang-tools-extra/clangd/ClangdServer.h

247

Could you add a short comment mentioning the highlight use-case? (the review description seems to be a good fit)

[hokein]

Address review comment.

clang-tools-extra/clangd/ClangdLSPServer.cpp

void ClangdLSPServer::onRename(const RenameParams &Params,
                                Callback<WorkspaceEdit> Reply) {
   Path File = Params.textDocument.uri.file();
   llvm::Optional<std::string> Code = DraftMgr.getDraft(File);
   if (!Code)
     return Reply(llvm::make_error<LSPError>(
         "onRename called for non-added file", ErrorCode::InvalidParams));
 
   Server->rename(
-      File, Params.position, Params.newName,
+      File, Params.position, Params.newName, /*WantFormat=*/true,
       Bind(
           [File, Code, Params](decltype(Reply) Reply,
                                llvm::Expected<std::vector<TextEdit>> Edits) {
             if (!Edits)
               return Reply(Edits.takeError());
 
             WorkspaceEdit WE;
             WE.changes = {{Params.textDocument.uri.uri(), *Edits}};

clang-tools-extra/clangd/ClangdServer.h

public:
   /// Run formatting after \p TriggerText was typed at \p Pos in \p File with
   /// content \p Code.
   llvm::Expected<std::vector<TextEdit>> formatOnType(StringRef Code,
                                                      PathRef File, Position Pos,
                                                      StringRef TriggerText);
 
   /// Rename all occurrences of the symbol at the \p Pos in \p File to
   /// \p NewName.
+  /// If WantFormat is false, the final TextEdit will be not formatted,
+  /// embedders could use this method to get all occurrences of the symbol (e.g.
+  /// highlighting them in prepare stage).
   void rename(PathRef File, Position Pos, llvm::StringRef NewName,
-              Callback<std::vector<TextEdit>> CB);
+              bool WantFormat, Callback<std::vector<TextEdit>> CB);
 
   struct TweakRef {
     std::string ID;    /// ID to pass for applyTweak.
     std::string Title; /// A single-line message to show in the UI.
     Tweak::Intent Intent;
   };
   /// Enumerate the code tweaks available to the user at a specified point.
   void enumerateTweaks(PathRef File, Range Sel,

clang-tools-extra/clangd/ClangdServer.cpp

ClangdServer::formatOnType(llvm::StringRef Code, PathRef File, Position Pos,
   std::vector<TextEdit> Result;
   for (const tooling::Replacement &R :
        formatIncremental(Code, *CursorPos, TriggerText, *Style))
     Result.push_back(replacementToEdit(Code, R));
   return Result;
 }
 
 void ClangdServer::rename(PathRef File, Position Pos, llvm::StringRef NewName,
-                          Callback<std::vector<TextEdit>> CB) {
-  auto Action = [Pos, this](Path File, std::string NewName,
+                          bool WantFormat, Callback<std::vector<TextEdit>> CB) {
+  auto Action = [Pos, WantFormat, this](Path File, std::string NewName,
                                         Callback<std::vector<TextEdit>> CB,
                                         llvm::Expected<InputsAndAST> InpAST) {
     if (!InpAST)
       return CB(InpAST.takeError());
     auto Changes = renameWithinFile(InpAST->AST, File, Pos, NewName, Index);
     if (!Changes)
       return CB(Changes.takeError());
 
+    if (WantFormat) {
       auto Style = getFormatStyleForFile(File, InpAST->Inputs.Contents,
                                          InpAST->Inputs.FS.get());
       if (auto Formatted =
               cleanupAndFormat(InpAST->Inputs.Contents, *Changes, Style))
         *Changes = std::move(*Formatted);
       else
         elog("Failed to format replacements: {0}", Formatted.takeError());
+    }
 
     std::vector<TextEdit> Edits;
     for (const auto &Rep : *Changes)
       Edits.push_back(replacementToEdit(InpAST->Inputs.Contents, Rep));
     return CB(std::move(Edits));
   };
 
   WorkScheduler.runWithAST(

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

runFindDocumentHighlights(ClangdServer &Server, PathRef File, Position Pos) {
   Server.findDocumentHighlights(File, Pos, capture(Result));
   return std::move(*Result);
 }
 
 llvm::Expected<std::vector<TextEdit>> runRename(ClangdServer &Server,
                                                 PathRef File, Position Pos,
                                                 llvm::StringRef NewName) {
   llvm::Optional<llvm::Expected<std::vector<TextEdit>>> Result;
-  Server.rename(File, Pos, NewName, capture(Result));
+  Server.rename(File, Pos, NewName, /*WantFormat=*/true, capture(Result));
   return std::move(*Result);
 }
 
 std::string runDumpAST(ClangdServer &Server, PathRef File) {
   llvm::Optional<std::string> Result;
   Server.dumpAST(File, capture(Result));
   return std::move(*Result);
 }