[CodeComplete] Add an option to omit results from the preamble.

Summary:
Enumerating the contents of a namespace or global scope will omit any
decls that aren't already loaded, instead of deserializing them from the
PCH.

This allows a fast hybrid code completion where symbols from headers are
provided by an external index. (Sema already exposes the information
needed to do a reasonabl job of filtering them).
Clangd plans to implement this hybrid.

This option is just a hint - callers still need to postfilter results if
they want to *avoid* completing decls outside the main file.

Reviewers: bkramer, ilya-biryukov

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D41989

llvm-svn: 322371

1 files changed, 2 insertions, 0 deletions

diff --git a/clang/tools/libclang/CIndexCodeCompletion.cpp b/clang/tools/libclang/CIndexCodeCompletion.cpp
index d4af0870c0b..ba2c818cca3 100644
--- a/clang/tools/libclang/CIndexCodeCompletion.cpp
+++ b/clang/tools/libclang/CIndexCodeCompletion.cpp
@@ -643,6 +643,7 @@ clang_codeCompleteAt_Impl(CXTranslationUnit TU, const char *complete_filename,
                           ArrayRef<CXUnsavedFile> unsaved_files,
                           unsigned options) {
   bool IncludeBriefComments = options & CXCodeComplete_IncludeBriefComments;
+  bool SkipPreamble = options & CXCodeComplete_SkipPreamble;
 
 #ifdef UDP_CODE_COMPLETION_LOGGER
 #ifdef UDP_CODE_COMPLETION_LOGGER_PORT
@@ -689,6 +690,7 @@ clang_codeCompleteAt_Impl(CXTranslationUnit TU, const char *complete_filename,
   // Create a code-completion consumer to capture the results.
   CodeCompleteOptions Opts;
   Opts.IncludeBriefComments = IncludeBriefComments;
+  Opts.LoadExternal = !SkipPreamble;
   CaptureCompletionResults Capture(Opts, *Results, &TU);
 
   // Perform completion.