[CodeCompletion] Signature help for braced constructor calls

Implementation is based on the "expected type" as used for
designated-initializers in braced init lists. This means it can deduce the type
in some cases where it's not written:

  void foo(Widget);
  foo({ /*help here*/ });

Only basic constructor calls are in scope of this patch, excluded are:
 - aggregate initialization (no help is offered for aggregates)
 - initializer_list initialization (no help is offered for these constructors)

Fixes https://github.com/clangd/clangd/issues/306

Differential Revision: https://reviews.llvm.org/D116317

1 files changed, 3 insertions, 2 deletions

diff --git a/clang/lib/Frontend/ASTUnit.cpp b/clang/lib/Frontend/ASTUnit.cpp
index 5258967..e82b7fe 100644
--- a/clang/lib/Frontend/ASTUnit.cpp
+++ b/clang/lib/Frontend/ASTUnit.cpp
@@ -1922,9 +1922,10 @@ namespace {
     void ProcessOverloadCandidates(Sema &S, unsigned CurrentArg,
                                    OverloadCandidate *Candidates,
                                    unsigned NumCandidates,
-                                   SourceLocation OpenParLoc) override {
+                                   SourceLocation OpenParLoc,
+                                   bool Braced) override {
       Next.ProcessOverloadCandidates(S, CurrentArg, Candidates, NumCandidates,
-                                     OpenParLoc);
+                                     OpenParLoc, Braced);
     }
 
     CodeCompletionAllocator &getAllocator() override {