[clangd] Add option to fold overloads into a single completion item.

Summary:
Adds a CodeCompleteOption to folds together compatible function/method overloads
into a single item. This feels pretty good (for editors with signatureHelp
support), but has limitations.

This happens in the code completion merge step, so there may be inconsistencies
(e.g. if only one overload made it into the index result list, no folding).

We don't want to bundle together completions that have different side-effects
(include insertion), because we can't constructo a coherent CompletionItem.
This may be confusing for users, as the reason for non-bundling may not
be immediately obvious. (Also, the implementation seems a little fragile)

Subscribers: ilya-biryukov, ioeric, MaskRay, jkorous, cfe-commits

Differential Revision: https://reviews.llvm.org/D47957

llvm-svn: 334822

1 files changed, 3 insertions, 0 deletions

diff --git a/clang-tools-extra/clangd/CodeComplete.h b/clang-tools-extra/clangd/CodeComplete.h
index 1d29c31d865..4fb19cb1073 100644
--- a/clang-tools-extra/clangd/CodeComplete.h
+++ b/clang-tools-extra/clangd/CodeComplete.h
@@ -53,6 +53,9 @@ struct CodeCompleteOptions {
   /// For example, private members are usually inaccessible.
   bool IncludeIneligibleResults = false;
 
+  /// Combine overloads into a single completion item where possible.
+  bool BundleOverloads = false;
+
   /// Limit the number of results returned (0 means no limit).
   /// If more results are available, we set CompletionList.isIncomplete.
   size_t Limit = 0;