[CodeComplete] Fix accessibilty of protected members from base class.

Summary:
Currently, protected members from base classes are marked as
inaccessible when completing in derived class. This patch fixes the problem by
setting the naming class correctly when looking up results in base class
according to [11.2.p5].

Reviewers: aaron.ballman, sammccall, rsmith

Reviewed By: aaron.ballman

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D49421

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@337453 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 27 insertions, 2 deletions

diff --git a/lib/Sema/SemaCodeComplete.cpp b/lib/Sema/SemaCodeComplete.cpp
index 700f5a2fee..ae5183408f 100644
--- a/lib/Sema/SemaCodeComplete.cpp
+++ b/lib/Sema/SemaCodeComplete.cpp
@@ -1303,8 +1303,33 @@ namespace {
     void FoundDecl(NamedDecl *ND, NamedDecl *Hiding, DeclContext *Ctx,
                    bool InBaseClass) override {
       bool Accessible = true;
-      if (Ctx)
-        Accessible = Results.getSema().IsSimplyAccessible(ND, Ctx);
+      if (Ctx) {
+        DeclContext *AccessingCtx = Ctx;
+        // If ND comes from a base class, set the naming class back to the
+        // derived class if the search starts from the derived class (i.e.
+        // InBaseClass is true).
+        //
+        // Example:
+        //   class B { protected: int X; }
+        //   class D : public B { void f(); }
+        //   void D::f() { this->^; }
+        // The completion after "this->" will have `InBaseClass` set to true and
+        // `Ctx` set to "B", when looking up in `B`. We need to set the actual
+        // accessing context (i.e. naming class) to "D" so that access can be
+        // calculated correctly.
+        if (InBaseClass && isa<CXXRecordDecl>(Ctx)) {
+          CXXRecordDecl *RC = nullptr;
+          // Get the enclosing record.
+          for (DeclContext *DC = CurContext; !DC->isFileContext();
+               DC = DC->getParent()) {
+            if ((RC = dyn_cast<CXXRecordDecl>(DC)))
+              break;
+          }
+          if (RC)
+            AccessingCtx = RC;
+        }
+        Accessible = Results.getSema().IsSimplyAccessible(ND, AccessingCtx);
+      }
 
       ResultBuilder::Result Result(ND, Results.getBasePriority(ND), nullptr,
                                    false, Accessible, FixIts);