diff --git a/src/clang_complete.cc b/src/clang_complete.cc
index af7e936c..5328437e 100644
--- a/src/clang_complete.cc
+++ b/src/clang_complete.cc
@@ -346,15 +346,19 @@ public:
     }
   }
 
+  void ProcessOverloadCandidates(Sema &S, unsigned CurrentArg,
+                                 OverloadCandidate *Candidates,
+                                 unsigned NumCandidates) override {}
+
   CodeCompletionAllocator &getAllocator() override { return *Alloc; }
 
   CodeCompletionTUInfo &getCodeCompletionTUInfo() override { return CCTUInfo;}
 };
 
-void TryEnsureDocumentParsed(ClangCompleteManager* manager,
+void TryEnsureDocumentParsed(ClangCompleteManager *manager,
                              std::shared_ptr<CompletionSession> session,
-                             std::unique_ptr<ClangTranslationUnit>* tu,
-                             bool emit_diag) {
+                             std::unique_ptr<ClangTranslationUnit> *tu,
+                             bool diagnostic) {
   // Nothing to do. We already have a translation unit.
   if (*tu)
     return;
@@ -365,7 +369,8 @@ void TryEnsureDocumentParsed(ClangCompleteManager* manager,
 
   LOG_S(INFO) << "Creating completion session with arguments "
               << StringJoin(args, " ");
-  *tu = ClangTranslationUnit::Create(session->file.filename, args, snapshot);
+  *tu = ClangTranslationUnit::Create(session->file.filename, args, snapshot,
+                                     diagnostic);
 }
 
 void CompletionPreloadMain(ClangCompleteManager* completion_manager) {
@@ -392,7 +397,7 @@ void CompletionPreloadMain(ClangCompleteManager* completion_manager) {
       continue;
 
     std::unique_ptr<ClangTranslationUnit> parsing;
-    TryEnsureDocumentParsed(completion_manager, session, &parsing, true);
+    TryEnsureDocumentParsed(completion_manager, session, &parsing, false);
 
     // Activate new translation unit.
     std::lock_guard<std::mutex> lock(tu->lock);
@@ -454,33 +459,30 @@ void CompletionQueryMain(ClangCompleteManager* completion_manager) {
                              request->position.character + 1, Remapped,
                              /*IncludeMacros=*/true,
                              /*IncludeCodePatterns=*/false,
-                             /*IncludeBriefComments=*/true, capture, tu->PCHCO,
-                             *Diag, LangOpts, *SrcMgr, *FileMgr, Diagnostics,
-                             TemporaryBuffers);
+                             /*IncludeBriefComments=*/g_config->index.comments,
+                             capture, tu->PCHCO, *Diag, LangOpts, *SrcMgr,
+                             *FileMgr, Diagnostics, TemporaryBuffers);
       request->on_complete(capture.ls_items, false /*is_cached_result*/);
       // completion_manager->on_diagnostic_(session->file.filename, Diags.take());
     }
   }
 }
 
-void DiagnosticQueryMain(ClangCompleteManager* completion_manager) {
+void DiagnosticQueryMain(ClangCompleteManager *manager) {
   while (true) {
     // Fetching the completion request blocks until we have a request.
     ClangCompleteManager::DiagnosticRequest request =
-        completion_manager->diagnostic_request_.Dequeue();
+        manager->diagnostic_request_.Dequeue();
     if (!g_config->diagnostics.onType)
       continue;
     std::string path = request.document.uri.GetPath();
 
-    std::shared_ptr<CompletionSession> session =
-        completion_manager->TryGetSession(path, true /*mark_as_completion*/,
-                                          true /*create_if_needed*/);
+    std::shared_ptr<CompletionSession> session = manager->TryGetSession(
+        path, true /*mark_as_completion*/, true /*create_if_needed*/);
 
     // At this point, we must have a translation unit. Block until we have one.
     std::lock_guard<std::mutex> lock(session->diagnostics.lock);
-    TryEnsureDocumentParsed(completion_manager, session,
-                            &session->diagnostics.tu,
-                            false /*emit_diagnostics*/);
+    TryEnsureDocumentParsed(manager, session, &session->diagnostics.tu, true);
 
     // It is possible we failed to create the document despite
     // |TryEnsureDocumentParsed|.
@@ -489,7 +491,7 @@ void DiagnosticQueryMain(ClangCompleteManager* completion_manager) {
       continue;
 
     WorkingFiles::Snapshot snapshot =
-        completion_manager->working_files_->AsSnapshot({StripFileType(path)});
+        manager->working_files_->AsSnapshot({StripFileType(path)});
     llvm::CrashRecoveryContext CRC;
     if (tu->Reparse(CRC, snapshot)) {
       LOG_S(ERROR) << "Reparsing translation unit for diagnostics failed for "
@@ -497,13 +499,16 @@ void DiagnosticQueryMain(ClangCompleteManager* completion_manager) {
       continue;
     }
 
-    auto &SM = tu->Unit->getSourceManager();
     auto &LangOpts = tu->Unit->getLangOpts();
     std::vector<lsDiagnostic> ls_diags;
     for (ASTUnit::stored_diag_iterator I = tu->Unit->stored_diag_begin(),
                                        E = tu->Unit->stored_diag_end();
          I != E; ++I) {
       FullSourceLoc FLoc = I->getLocation();
+      const auto &SM = FLoc.getManager();
+
+      const FileEntry *FE = SM.getFileEntryForID(SM.getFileID(FLoc));
+      if (!FE || FileName(*FE) != path) continue;
       SourceRange R;
       for (const auto &CR : I->getRanges()) {
         auto RT = Lexer::makeFileCharRange(CR, SM, LangOpts);
@@ -520,11 +525,10 @@ void DiagnosticQueryMain(ClangCompleteManager* completion_manager) {
       switch (I->getLevel()) {
       case DiagnosticsEngine::Ignored:
         // llvm_unreachable
-        break;
       case DiagnosticsEngine::Note:
       case DiagnosticsEngine::Remark:
         ls_diag.severity = lsDiagnosticSeverity::Information;
-        break;
+        continue;
       case DiagnosticsEngine::Warning:
         ls_diag.severity = lsDiagnosticSeverity::Warning;
         break;
@@ -543,7 +547,7 @@ void DiagnosticQueryMain(ClangCompleteManager* completion_manager) {
       }
       ls_diags.push_back(ls_diag);
     }
-    completion_manager->on_diagnostic_(path, ls_diags);
+    manager->on_diagnostic_(path, ls_diags);
   }
 }
 
diff --git a/src/clang_tu.cc b/src/clang_tu.cc
index 092caab4..9e2b3ac2 100644
--- a/src/clang_tu.cc
+++ b/src/clang_tu.cc
@@ -64,14 +64,14 @@ GetRemapped(const WorkingFiles::Snapshot &snapshot) {
   return Remapped;
 }
 
-std::unique_ptr<ClangTranslationUnit>
-ClangTranslationUnit::Create(const std::string &filepath,
-                             const std::vector<std::string> &args,
-                             const WorkingFiles::Snapshot &snapshot) {
+std::unique_ptr<ClangTranslationUnit> ClangTranslationUnit::Create(
+    const std::string &filepath, const std::vector<std::string> &args,
+    const WorkingFiles::Snapshot &snapshot, bool diagnostic) {
   std::vector<const char *> Args;
   for (auto& arg : args)
     Args.push_back(arg.c_str());
   Args.push_back("-fno-spell-checking");
+  Args.push_back("-fallow-editor-placeholders");
 
   auto ret = std::make_unique<ClangTranslationUnit>();
   IntrusiveRefCntPtr<DiagnosticsEngine> Diags(
@@ -86,9 +86,10 @@ ClangTranslationUnit::Create(const std::string &filepath,
         Args.data(), Args.data() + Args.size(),
         /*PCHContainerOpts=*/ret->PCHCO, Diags,
         /*ResourceFilePath=*/"", /*OnlyLocalDecls=*/false,
-        /*CaptureDiagnostics=*/true, Remapped,
-        /*RemappedFilesKeepOriginalName=*/true, 1, TU_Prefix,
-        /*CacheCodeCompletionResults=*/true, true,
+        /*CaptureDiagnostics=*/diagnostic, Remapped,
+        /*RemappedFilesKeepOriginalName=*/true, 1,
+        diagnostic ? TU_Complete : TU_Prefix,
+        /*CacheCodeCompletionResults=*/true, g_config->index.comments,
         /*AllowPCHWithCompilerErrors=*/true,
 #if LLVM_VERSION_MAJOR >= 7
         SkipFunctionBodiesScope::None,
diff --git a/src/clang_tu.h b/src/clang_tu.h
index 17b4b0e2..741d9a40 100644
--- a/src/clang_tu.h
+++ b/src/clang_tu.h
@@ -34,8 +34,8 @@ bool RunSafely(llvm::CrashRecoveryContext &CRC, Fn &&fn) {
 
 struct ClangTranslationUnit {
   static std::unique_ptr<ClangTranslationUnit>
-  Create(const std::string &filepath, const std::vector<std::string> &arguments,
-         const WorkingFiles::Snapshot &snapshot);
+  Create(const std::string &filepath, const std::vector<std::string> &args,
+         const WorkingFiles::Snapshot &snapshot, bool diagnostic);
 
   int Reparse(llvm::CrashRecoveryContext &CRC,
               const WorkingFiles::Snapshot &snapshot);
diff --git a/src/indexer.cc b/src/indexer.cc
index d624935b..ce4eee67 100644
--- a/src/indexer.cc
+++ b/src/indexer.cc
@@ -1125,7 +1125,8 @@ std::vector<std::unique_ptr<IndexFile>> Index(
         std::move(CI), PCHCO, Diags, IndexAction.get(), Unit.get(),
         /*Persistent=*/true, /*ResourceDir=*/"",
         /*OnlyLocalDecls=*/true,
-        /*CaptureDiagnostics=*/true, 0, false, false, true);
+        /*CaptureDiagnostics=*/true, 0, false, false,
+        /*UserFilesAreVolatile=*/true);
   };
   if (!RunSafely(CRC, compile)) {
     LOG_S(ERROR) << "clang crashed for " << file;
diff --git a/src/project.cc b/src/project.cc
index 7140e082..da24705c 100644
--- a/src/project.cc
+++ b/src/project.cc
@@ -17,11 +17,9 @@ using namespace ccls;
 #include <clang/Frontend/CompilerInstance.h>
 #include <clang/Tooling/CompilationDatabase.h>
 #include <llvm/ADT/ArrayRef.h>
-#include <llvm/Support/MemoryBuffer.h>
 #include <llvm/Support/LineIterator.h>
 using namespace clang;
 using namespace llvm;
-using namespace llvm::opt;
 
 #include <rapidjson/writer.h>
 
@@ -156,7 +154,8 @@ Project::Entry GetCompilationEntryFromCompileCommandEntry(
       continue;
     }
 
-  if (HeaderOpts.ResourceDir.empty() && HeaderOpts.UseBuiltinIncludes)
+  if (!sys::path::is_absolute(HeaderOpts.ResourceDir) &&
+      HeaderOpts.UseBuiltinIncludes)
     args.push_back("-resource-dir=" + g_config->clang.resourceDir);
   if (CI->getFileSystemOpts().WorkingDir.empty())
     args.push_back("-working-directory=" + entry.directory);