1 files changed, 19 insertions, 7 deletions

diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
index 7ee24b114cc..3dd3c9f59e4 100644
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -4603,9 +4603,19 @@ void Sema::CodeCompleteAssignmentRHS(Scope *S, Expr *LHS) {
 
 void Sema::CodeCompleteQualifiedId(Scope *S, CXXScopeSpec &SS,
                                    bool EnteringContext) {
-  if (!SS.getScopeRep() || !CodeCompleter)
+  if (SS.isEmpty() || !CodeCompleter)
     return;
 
+  // We want to keep the scope specifier even if it's invalid (e.g. the scope
+  // "a::b::" is not corresponding to any context/namespace in the AST), since
+  // it can be useful for global code completion which have information about
+  // contexts/symbols that are not in the AST.
+  if (SS.isInvalid()) {
+    CodeCompletionContext CC(CodeCompletionContext::CCC_Name);
+    CC.setCXXScopeSpecifier(SS);
+    HandleCodeCompleteResults(this, CodeCompleter, CC, nullptr, 0);
+    return;
+  }
   // Always pretend to enter a context to ensure that a dependent type
   // resolves to a dependent record.
   DeclContext *Ctx = computeDeclContext(SS, /*EnteringContext=*/true);
@@ -4621,7 +4631,7 @@ void Sema::CodeCompleteQualifiedId(Scope *S, CXXScopeSpec &SS,
                         CodeCompleter->getCodeCompletionTUInfo(),
                         CodeCompletionContext::CCC_Name);
   Results.EnterNewScope();
-  
+
   // The "template" keyword can follow "::" in the grammar, but only
   // put it into the grammar if the nested-name-specifier is dependent.
   NestedNameSpecifier *NNS = SS.getScopeRep();
@@ -4635,16 +4645,18 @@ void Sema::CodeCompleteQualifiedId(Scope *S, CXXScopeSpec &SS,
   // qualified-id completions.
   if (!EnteringContext)
     MaybeAddOverrideCalls(*this, Ctx, Results);
-  Results.ExitScope();  
-  
+  Results.ExitScope();
+
   CodeCompletionDeclConsumer Consumer(Results, CurContext);
   LookupVisibleDecls(Ctx, LookupOrdinaryName, Consumer,
                      /*IncludeGlobalScope=*/true,
                      /*IncludeDependentBases=*/true);
 
-  HandleCodeCompleteResults(this, CodeCompleter, 
-                            Results.getCompletionContext(),
-                            Results.data(),Results.size());
+  auto CC = Results.getCompletionContext();
+  CC.setCXXScopeSpecifier(SS);
+
+  HandleCodeCompleteResults(this, CodeCompleter, CC, Results.data(),
+                            Results.size());
 }
 
 void Sema::CodeCompleteUsing(Scope *S) {