[clangd] Hide inlay hints capability behind a command-line flag

[sammccall]

clang-tools-extra/clangd/ClangdLSPServer.cpp

1482

I think we only need to suppress the capability, not the method itself, right?

(This is what we usually do, folding-ranges is different... it's seriously crashy and even then probably should bind regardless)

clang-tools-extra/clangd/ClangdServer.h

167 ↗

(On Diff #340424)

I think this should go in ClangdLSPServer::Options, again i'm not sure why FoldingRanges does what it does.

[njames93]

clang-tools-extra/clangd/tool/ClangdMain.cpp

313

Does it make sense to hide this flag? This is a feature that's basically in a shippable state disregarding any LSP standardization.

[sammccall]

clang-tools-extra/clangd/tool/ClangdMain.cpp

313

We may or may not *want* to ship it without further standardization, it can make maintenance more complicated.

But I agree if it's behind a flag it doesn't necessarily need to be hidden, esp if we plan to make a call closer to the release cut.

[nridge]

Address review comments, including making the flag not hidden

clang-tools-extra/clangd/ClangdLSPServer.h

struct Options : ClangdServer::Options {
     /// Per-feature options. Generally ClangdServer lets these vary
     /// per-request, but LSP allows limited/no customizations.
     clangd::CodeCompleteOptions CodeComplete;
     clangd::RenameOptions Rename;
     /// Returns true if the tweak should be enabled.
     std::function<bool(const Tweak &)> TweakFilter = [](const Tweak &T) {
       return !T.hidden(); // only enable non-hidden tweaks.
     };
+
+    /// Enable preview of InlayHints feature.
+    bool InlayHints = false;
   };
 
   ClangdLSPServer(Transport &Transp, const ThreadsafeFS &TFS,
                   const ClangdLSPServer::Options &Opts);
   /// The destructor blocks on any outstanding background tasks.
   ~ClangdLSPServer();
 
   /// Run LSP server loop, communicating with the Transport provided in the

clang-tools-extra/clangd/ClangdLSPServer.cpp

llvm::json::Object ServerCaps{
        }},
       {"hoverProvider", true},
       {"selectionRangeProvider", true},
       {"documentSymbolProvider", true},
       {"workspaceSymbolProvider", true},
       {"referencesProvider", true},
       {"astProvider", true}, // clangd extension
       {"typeHierarchyProvider", true},
-      {"clangdInlayHintsProvider", true},
       {"memoryUsageProvider", true}, // clangd extension
       {"compilationDatabase",        // clangd extension
        llvm::json::Object{{"automaticReload", true}}},
       {"callHierarchyProvider", true},
   };
 
   {
     LSPBinder Binder(Handlers, *this);
ServerCaps["codeActionProvider"] =
                                 {CodeAction::QUICKFIX_KIND,
                                  CodeAction::REFACTOR_KIND,
                                  CodeAction::INFO_KIND}}}
           : llvm::json::Value(true);
 
   if (Opts.FoldingRanges)
     ServerCaps["foldingRangeProvider"] = true;
 
+  if (Opts.InlayHints)
+    ServerCaps["clangdInlayHintsProvider"] = true;
+
   std::vector<llvm::StringRef> Commands;
   for (llvm::StringRef Command : Handlers.CommandHandlers.keys())
     Commands.push_back(Command);
   llvm::sort(Commands);
   ServerCaps["executeCommandProvider"] =
       llvm::json::Object{{"commands", Commands}};
 
   llvm::json::Object Result{
void ClangdLSPServer::bindMethods(LSPBinder &Bind,
   Bind.method("typeHierarchy/resolve", this, &ClangdLSPServer::onResolveTypeHierarchy);
   Bind.method("textDocument/prepareCallHierarchy", this, &ClangdLSPServer::onPrepareCallHierarchy);
   Bind.method("callHierarchy/incomingCalls", this, &ClangdLSPServer::onCallHierarchyIncomingCalls);
   Bind.method("callHierarchy/outgoingCalls", this, &ClangdLSPServer::onCallHierarchyOutgoingCalls);
   Bind.method("textDocument/selectionRange", this, &ClangdLSPServer::onSelectionRange);
   Bind.method("textDocument/documentLink", this, &ClangdLSPServer::onDocumentLink);
   Bind.method("textDocument/semanticTokens/full", this, &ClangdLSPServer::onSemanticTokens);
   Bind.method("textDocument/semanticTokens/full/delta", this, &ClangdLSPServer::onSemanticTokensDelta);
   Bind.method("clangd/inlayHints", this, &ClangdLSPServer::onInlayHints);
   Bind.method("$/memoryUsage", this, &ClangdLSPServer::onMemoryUsage);
   if (Opts.FoldingRanges)
     Bind.method("textDocument/foldingRange", this, &ClangdLSPServer::onFoldingRange);
   Bind.command(APPLY_FIX_COMMAND, this, &ClangdLSPServer::onCommandApplyEdit);
   Bind.command(APPLY_TWEAK_COMMAND, this, &ClangdLSPServer::onCommandApplyTweak);
 
   ApplyWorkspaceEdit = Bind.outgoingMethod("workspace/applyEdit");
   PublishDiagnostics = Bind.outgoingNotification("textDocument/publishDiagnostics");

clang-tools-extra/clangd/tool/ClangdMain.cpp

 opt<bool> FoldingRanges{
     "folding-ranges",
     cat(Features),
     desc("Enable preview of FoldingRanges feature"),
     init(false),
     Hidden,
 };
 
+opt<bool> InlayHints{"inlay-hints", cat(Features),
+                     desc("Enable preview of InlayHints feature"), init(false)};
+
 opt<unsigned> WorkerThreadsCount{
     "j",
     cat(Misc),
     desc("Number of async workers used by clangd. Background index also "
          "uses this many workers."),
     init(getDefaultAsyncThreadsCount()),
 };
 
if (StaticIdx) {
     IdxStack.emplace_back(
         std::make_unique<MergedIndex>(PAI.get(), IdxStack.back().get()));
     Opts.StaticIndex = IdxStack.back().get();
   } else {
     Opts.StaticIndex = PAI.get();
   }
   Opts.AsyncThreadsCount = WorkerThreadsCount;
   Opts.FoldingRanges = FoldingRanges;
+  Opts.InlayHints = InlayHints;
   Opts.MemoryCleanup = getMemoryCleanupFunction();
 
   Opts.CodeComplete.IncludeIneligibleResults = IncludeIneligibleResults;
   Opts.CodeComplete.Limit = LimitResults;
   if (CompletionStyle.getNumOccurrences())
     Opts.CodeComplete.BundleOverloads = CompletionStyle != Detailed;
   Opts.CodeComplete.ShowOrigins = ShowOrigins;
   Opts.CodeComplete.InsertIncludes = HeaderInsertion;