1 files changed, 27 insertions, 2 deletions
diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
index 700f5a2fee2..ae5183408f1 100644
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/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);