[clangd] Code completion uses Sema for NS-level things in the current file.

Summary:
To stay fast, it avoids deserializing anything outside the current file, by
disabling the LoadExternal code completion option added in r322377, when the
index is enabled.

Reviewers: hokein

Subscribers: klimek, ilya-biryukov, cfe-commits

Differential Revision: https://reviews.llvm.org/D41996

llvm-svn: 322387

1 files changed, 4 insertions, 2 deletions

diff --git a/clang-tools-extra/clangd/CodeComplete.cpp b/clang-tools-extra/clangd/CodeComplete.cpp
index e2fc5019708..fa6c5d18a71 100644
--- a/clang-tools-extra/clangd/CodeComplete.cpp
+++ b/clang-tools-extra/clangd/CodeComplete.cpp
@@ -642,8 +642,10 @@ clang::CodeCompleteOptions CodeCompleteOptions::getClangCompleteOpts() const {
   Result.IncludeGlobals = IncludeGlobals;
   Result.IncludeBriefComments = IncludeBriefComments;
 
-  // Enable index-based code completion when Index is provided.
-  Result.IncludeNamespaceLevelDecls = !Index;
+  // When an is used, Sema is responsible for completing the main file,
+  // the index can provide results from the preamble.
+  // Tell Sema not to deserialize the preamble to look for results.
+  Result.LoadExternal = !Index;
 
   return Result;
 }