[CodeComplete] Collect visited contexts when scope specifier is invalid.

Summary:
This will allow completion consumers to guess the specified scope by
putting together scopes in the context with the specified scope (e.g. when the
specified namespace is not imported yet).

Reviewers: ilya-biryukov

Subscribers: jdoerfert, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D58446

llvm-svn: 354570

1 files changed, 14 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
index a042abb6f5f..cebf97a09ab 100644
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -5061,7 +5061,20 @@ void Sema::CodeCompleteQualifiedId(Scope *S, CXXScopeSpec &SS,
   if (SS.isInvalid()) {
     CodeCompletionContext CC(CodeCompletionContext::CCC_Symbol);
     CC.setCXXScopeSpecifier(SS);
-    HandleCodeCompleteResults(this, CodeCompleter, CC, nullptr, 0);
+    // As SS is invalid, we try to collect accessible contexts from the current
+    // scope with a dummy lookup so that the completion consumer can try to
+    // guess what the specified scope is.
+    ResultBuilder DummyResults(*this, CodeCompleter->getAllocator(),
+                               CodeCompleter->getCodeCompletionTUInfo(), CC);
+    if (S->getEntity()) {
+      CodeCompletionDeclConsumer Consumer(DummyResults, S->getEntity(),
+                                          BaseType);
+      LookupVisibleDecls(S, LookupOrdinaryName, Consumer,
+                         /*IncludeGlobalScope=*/false,
+                         /*LoadExternal=*/false);
+    }
+    HandleCodeCompleteResults(this, CodeCompleter,
+                              DummyResults.getCompletionContext(), nullptr, 0);
     return;
   }
   // Always pretend to enter a context to ensure that a dependent type