[clangd] Allow specifying -resource-dir

[krasimir]

Summary

This patch allows clangd to specify its -resource-dir.

[bkramer]

Looks good.

clangd/ClangdLSPServer.h

 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_CLANGDLSPSERVER_H
 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_CLANGDLSPSERVER_H
 
 #include "ClangdServer.h"
 #include "GlobalCompilationDatabase.h"
 #include "Path.h"
 #include "Protocol.h"
 #include "clang/Tooling/Core/Replacement.h"
+#include "llvm/ADT/Optional.h"
 
 namespace clang {
 namespace clangd {
 
 class JSONOutput;
 
 /// This class provides implementation of an LSP server, glueing the JSON
 /// dispatch and ClangdServer together.
 class ClangdLSPServer {
 public:
-  ClangdLSPServer(JSONOutput &Out, bool RunSynchronously);
+ ClangdLSPServer(JSONOutput &Out, bool RunSynchronously,
+                 llvm::Optional<StringRef> ResourceDir);
 
   /// Run LSP server loop, receiving input for it from \p In. \p In must be
   /// opened in binary mode. Output will be written using Out variable passed to
   /// class constructor. This method must not be executed more than once for
   /// each instance of ClangdLSPServer.
   void run(std::istream &In);
 
 private:

clangd/ClangdLSPServer.cpp

void ClangdLSPServer::LSPProtocolCallbacks::onGoToDefinition(
   }
   if (!Locations.empty())
     Locations.pop_back();
   Out.writeMessage(
       R"({"jsonrpc":"2.0","id":)" + ID.str() +
       R"(,"result":[)" + Locations + R"(]})");
 }
 
-ClangdLSPServer::ClangdLSPServer(JSONOutput &Out, bool RunSynchronously)
+ClangdLSPServer::ClangdLSPServer(JSONOutput &Out, bool RunSynchronously,
+                                 llvm::Optional<StringRef> ResourceDir)
     : Out(Out), DiagConsumer(*this),
-      Server(CDB, DiagConsumer, FSProvider, RunSynchronously) {}
+      Server(CDB, DiagConsumer, FSProvider, RunSynchronously, ResourceDir) {}
 
 void ClangdLSPServer::run(std::istream &In) {
   assert(!IsDone && "Run was called before");
 
   // Set up JSONRPCDispatcher.
   LSPProtocolCallbacks Callbacks(*this);
   JSONRPCDispatcher Dispatcher(llvm::make_unique<Handler>(Out));
   regiterCallbackHandlers(Dispatcher, Out, Callbacks);

clangd/tool/ClangdMain.cpp

 using namespace clang;
 using namespace clang::clangd;
 
 static llvm::cl::opt<bool>
     RunSynchronously("run-synchronously",
                      llvm::cl::desc("parse on main thread"),
                      llvm::cl::init(false), llvm::cl::Hidden);
 
+static llvm::cl::opt<std::string>
+    ResourceDir("resource-dir",
+                llvm::cl::desc("directory for system clang headers"),
+                llvm::cl::init(""), llvm::cl::Hidden);
+
 int main(int argc, char *argv[]) {
   llvm::cl::ParseCommandLineOptions(argc, argv, "clangd");
 
   llvm::raw_ostream &Outs = llvm::outs();
   llvm::raw_ostream &Logs = llvm::errs();
   JSONOutput Out(Outs, Logs);
 
   // Change stdin to binary to not lose \r\n on windows.
   llvm::sys::ChangeStdinToBinary();
 
-  ClangdLSPServer LSPServer(Out, RunSynchronously);
+  llvm::Optional<StringRef> ResourceDirRef = None;
+  if (!ResourceDir.empty())
+    ResourceDirRef = ResourceDir;
+  ClangdLSPServer LSPServer(Out, RunSynchronously, ResourceDirRef);
   LSPServer.run(std::cin);
 }