[CodeComplete] Fix the crash in code completion on access checking

Started crashing in r337453. See the added test case for the crash repro.

The fix reverts part of r337453 that causes the crash and does
not actually break anything when reverted.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@338255 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Sema/SemaCodeComplete.cpp

@@ -1303,34 +1303,8 @@ namespace {
     void FoundDecl(NamedDecl *ND, NamedDecl *Hiding, DeclContext *Ctx,
                    bool InBaseClass) override {
       bool Accessible = true;
-      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);
-      }
-
+      if (Ctx)
+        Accessible = Results.getSema().IsSimplyAccessible(ND, Ctx);
       ResultBuilder::Result Result(ND, Results.getBasePriority(ND), nullptr,
                                    false, Accessible, FixIts);
       Results.AddResult(Result, CurContext, Hiding, InBaseClass);

test/Index/complete-access-checks-crash.cpp

@@ -0,0 +1,13 @@
+struct Base {
+protected:
+  bool bar();
+};
+struct Derived : Base {
+};
+
+struct X {
+  int foo() {
+    Derived(). // RUN: c-index-test -code-completion-at=%s:10:15 %s | FileCheck %s
+    // CHECK: bar{{.*}}(inaccessible)
+  }
+};