1 files changed, 38 insertions, 10 deletions

diff --git a/clang-tools-extra/clangd/ClangdLSPServer.cpp b/clang-tools-extra/clangd/ClangdLSPServer.cpp
index a72e8c7cd9b..78466f4f3ad 100644
--- a/clang-tools-extra/clangd/ClangdLSPServer.cpp
+++ b/clang-tools-extra/clangd/ClangdLSPServer.cpp
@@ -13,6 +13,7 @@
 #include "Trace.h"
 #include "URI.h"
 #include "clang/Tooling/Core/Replacement.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/ADT/ScopeExit.h"
 #include "llvm/Support/Errc.h"
 #include "llvm/Support/Error.h"
@@ -93,6 +94,7 @@ public:
   MessageHandler(ClangdLSPServer &Server) : Server(Server) {}
 
   bool onNotify(llvm::StringRef Method, llvm::json::Value Params) override {
+    WithContext HandlerContext(handlerContext());
     log("<-- {0}", Method);
     if (Method == "exit")
       return false;
@@ -109,6 +111,7 @@ public:
 
   bool onCall(llvm::StringRef Method, llvm::json::Value Params,
               llvm::json::Value ID) override {
+    WithContext HandlerContext(handlerContext());
     // Calls can be canceled by the client. Add cancellation context.
     WithContext WithCancel(cancelableRequestContext(ID));
     trace::Span Tracer(Method);
@@ -129,6 +132,7 @@ public:
 
   bool onReply(llvm::json::Value ID,
                llvm::Expected<llvm::json::Value> Result) override {
+    WithContext HandlerContext(handlerContext());
     // We ignore replies, just log them.
     if (Result)
       log("<-- reply({0})", ID);
@@ -259,6 +263,13 @@ private:
     if (It != RequestCancelers.end())
       It->second.first(); // Invoke the canceler.
   }
+
+  Context handlerContext() const {
+    return Context::current().derive(
+        kCurrentOffsetEncoding,
+        Server.NegotiatedOffsetEncoding.getValueOr(OffsetEncoding::UTF16));
+  }
+
   // We run cancelable requests in a context that does two things:
   //  - allows cancellation using RequestCancelers[ID]
   //  - cleans up the entry in RequestCancelers when it's no longer needed
@@ -302,6 +313,20 @@ void ClangdLSPServer::notify(llvm::StringRef Method, llvm::json::Value Params) {
 
 void ClangdLSPServer::onInitialize(const InitializeParams &Params,
                                    Callback<llvm::json::Value> Reply) {
+  // Determine character encoding first as it affects constructed ClangdServer.
+  if (Params.capabilities.offsetEncoding && !NegotiatedOffsetEncoding) {
+    NegotiatedOffsetEncoding = OffsetEncoding::UTF16; // fallback
+    for (OffsetEncoding Supported : *Params.capabilities.offsetEncoding)
+      if (Supported != OffsetEncoding::UnsupportedEncoding) {
+        NegotiatedOffsetEncoding = Supported;
+        break;
+      }
+  }
+  llvm::Optional<WithContextValue> WithOffsetEncoding;
+  if (NegotiatedOffsetEncoding)
+    WithOffsetEncoding.emplace(kCurrentOffsetEncoding,
+                               *NegotiatedOffsetEncoding);
+
   if (Params.rootUri && *Params.rootUri)
     ClangdServerOpts.WorkspaceRoot = Params.rootUri->file();
   else if (Params.rootPath && !Params.rootPath->empty())
@@ -331,7 +356,7 @@ void ClangdLSPServer::onInitialize(const InitializeParams &Params,
   SupportsHierarchicalDocumentSymbol =
       Params.capabilities.HierarchicalDocumentSymbol;
   SupportFileStatus = Params.initializationOptions.FileStatus;
-  Reply(llvm::json::Object{
+  llvm::json::Object Result{
       {{"capabilities",
         llvm::json::Object{
             {"textDocumentSync", (int)TextDocumentSyncKind::Incremental},
@@ -369,7 +394,10 @@ void ClangdLSPServer::onInitialize(const InitializeParams &Params,
                    ExecuteCommandParams::CLANGD_APPLY_TWEAK}},
              }},
             {"typeHierarchyProvider", true},
-        }}}});
+        }}}};
+  if (NegotiatedOffsetEncoding)
+    Result["offsetEncoding"] = *NegotiatedOffsetEncoding;
+  Reply(std::move(Result));
 }
 
 void ClangdLSPServer::onShutdown(const ShutdownParams &Params,
@@ -875,19 +903,19 @@ void ClangdLSPServer::onSymbolInfo(const TextDocumentPositionParams &Params,
                      std::move(Reply));
 }
 
-ClangdLSPServer::ClangdLSPServer(class Transport &Transp,
-                                 const FileSystemProvider &FSProvider,
-                                 const clangd::CodeCompleteOptions &CCOpts,
-                                 llvm::Optional<Path> CompileCommandsDir,
-                                 bool UseDirBasedCDB,
-                                 const ClangdServer::Options &Opts)
+ClangdLSPServer::ClangdLSPServer(
+    class Transport &Transp, const FileSystemProvider &FSProvider,
+    const clangd::CodeCompleteOptions &CCOpts,
+    llvm::Optional<Path> CompileCommandsDir, bool UseDirBasedCDB,
+    llvm::Optional<OffsetEncoding> ForcedOffsetEncoding,
+    const ClangdServer::Options &Opts)
     : Transp(Transp), MsgHandler(new MessageHandler(*this)),
       FSProvider(FSProvider), CCOpts(CCOpts),
       SupportedSymbolKinds(defaultSymbolKinds()),
       SupportedCompletionItemKinds(defaultCompletionItemKinds()),
       UseDirBasedCDB(UseDirBasedCDB),
-      CompileCommandsDir(std::move(CompileCommandsDir)),
-      ClangdServerOpts(Opts) {
+      CompileCommandsDir(std::move(CompileCommandsDir)), ClangdServerOpts(Opts),
+      NegotiatedOffsetEncoding(ForcedOffsetEncoding) {
   // clang-format off
   MsgHandler->bind("initialize", &ClangdLSPServer::onInitialize);
   MsgHandler->bind("shutdown", &ClangdLSPServer::onShutdown);