[clangd] Don't send semanticHighlights to clients that support semanticTokens.

Summary: This allows the standard mechanism to gracefully displace the old one.

Reviewers: hokein

Subscribers: ilya-biryukov, MaskRay, jkorous, arphaman, kadircet, usaxena95, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D77206

clang-tools-extra/clangd/ClangdLSPServer.cpp

@@ -480,6 +480,13 @@ void ClangdLSPServer::onInitialize(const InitializeParams &Params,
 
   ClangdServerOpts.TheiaSemanticHighlighting =
       Params.capabilities.TheiaSemanticHighlighting;
+  if (Params.capabilities.TheiaSemanticHighlighting &&
+      Params.capabilities.SemanticTokens) {
+    log("Client supports legacy semanticHighlights notification and standard "
+        "semanticTokens request, choosing the latter (no notifications).");
+    ClangdServerOpts.TheiaSemanticHighlighting = false;
+  }
+
   if (Params.rootUri && *Params.rootUri)
     ClangdServerOpts.WorkspaceRoot = std::string(Params.rootUri->file());
   else if (Params.rootPath && !Params.rootPath->empty())
@@ -612,7 +619,7 @@ void ClangdLSPServer::onInitialize(const InitializeParams &Params,
         }}}};
   if (NegotiatedOffsetEncoding)
     Result["offsetEncoding"] = *NegotiatedOffsetEncoding;
-  if (Params.capabilities.TheiaSemanticHighlighting)
+  if (ClangdServerOpts.TheiaSemanticHighlighting)
     Result.getObject("capabilities")
         ->insert(
             {"semanticHighlighting",

clang-tools-extra/clangd/ClangdServer.h

@@ -145,7 +145,7 @@ public:
     /// fetch system include path.
     std::vector<std::string> QueryDriverGlobs;
 
-    /// Enable semantic highlighting features.
+    /// Enable notification-based semantic highlighting.
     bool TheiaSemanticHighlighting = false;
 
     /// Returns true if the tweak should be enabled.

clang-tools-extra/clangd/Protocol.cpp

@@ -297,6 +297,8 @@ bool fromJSON(const llvm::json::Value &Params, ClientCapabilities &R) {
               SemanticHighlighting->getBoolean("semanticHighlighting"))
         R.TheiaSemanticHighlighting = *SemanticHighlightingSupport;
     }
+    if (auto *SemanticHighlighting = TextDocument->getObject("semanticTokens"))
+      R.SemanticTokens = true;
     if (auto *Diagnostics = TextDocument->getObject("publishDiagnostics")) {
       if (auto CategorySupport = Diagnostics->getBoolean("categorySupport"))
         R.DiagnosticCategory = *CategorySupport;

clang-tools-extra/clangd/Protocol.h

@@ -433,8 +433,13 @@ struct ClientCapabilities {
   /// textDocument.codeAction.codeActionLiteralSupport.
   bool CodeActionStructure = false;
 
+  /// Client advertises support for the semanticTokens feature.
+  /// We support the textDocument/semanticTokens request in any case.
+  /// textDocument.semanticTokens
+  bool SemanticTokens = false;
   /// Client supports Theia semantic highlighting extension.
   /// https://github.com/microsoft/vscode-languageserver-node/pull/367
+  /// This will be ignored if the client also supports semanticTokens.
   /// textDocument.semanticHighlightingCapabilities.semanticHighlighting
   /// FIXME: drop this support once clients support LSP 3.16 Semantic Tokens.
   bool TheiaSemanticHighlighting = false;

clang-tools-extra/clangd/test/semantic-tokens.test

@@ -1,5 +1,10 @@
-# RUN: clangd -lit-test < %s | FileCheck -strict-whitespace %s
-{"jsonrpc":"2.0","id":0,"method":"initialize","params":{}}
+# RUN: clangd -lit-test < %s | FileCheck -strict-whitespace %s -implicit-check-not=semanticHighlight
+# Send capabilities for both Theia semanticHighlight & standard semanticTokens.
+# clangd should not use/acknowledge the Theia protocol in this case.
+{"jsonrpc":"2.0","id":0,"method":"initialize","params":{"capabilities":{"textDocument":{
+  "semanticHighlightingCapabilities":{"semanticHighlighting":true},
+  "semanticTokens":{"dynamicRegistration":true}
+}}}}
 ---
 {"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.cpp","languageId":"cpp","text":"int x = 2;"}}}
 ---