[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

3 files changed, 67 insertions, 16 deletions

diff --git a/lib/Sema/SemaAccess.cpp b/lib/Sema/SemaAccess.cpp
index 44d41ea4b0..9fbae2ca29 100644
--- a/lib/Sema/SemaAccess.cpp
+++ b/lib/Sema/SemaAccess.cpp
@@ -11,6 +11,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "clang/Basic/Specifiers.h"
 #include "clang/Sema/SemaInternal.h"
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/CXXInheritance.h"
@@ -1856,29 +1857,31 @@ void Sema::CheckLookupAccess(const LookupResult &R) {
   }
 }
 
-/// Checks access to Decl from the given class. The check will take access
+/// Checks access to Target from the given class. The check will take access
 /// specifiers into account, but no member access expressions and such.
 ///
-/// \param Decl the declaration to check if it can be accessed
+/// \param Target the declaration to check if it can be accessed
 /// \param Ctx the class/context from which to start the search
-/// \return true if the Decl is accessible from the Class, false otherwise.
-bool Sema::IsSimplyAccessible(NamedDecl *Decl, DeclContext *Ctx) {
+/// \return true if the Target is accessible from the Class, false otherwise.
+bool Sema::IsSimplyAccessible(NamedDecl *Target, DeclContext *Ctx) {
   if (CXXRecordDecl *Class = dyn_cast<CXXRecordDecl>(Ctx)) {
-    if (!Decl->isCXXClassMember())
+    if (!Target->isCXXClassMember())
       return true;
 
+    if (Target->getAccess() == AS_public)
+      return true;
     QualType qType = Class->getTypeForDecl()->getCanonicalTypeInternal();
+    // The unprivileged access is AS_none as we don't know how the member was
+    // accessed, which is described by the access in DeclAccessPair.
+    // `IsAccessible` will examine the actual access of Target (i.e.
+    // Decl->getAccess()) when calculating the access.
     AccessTarget Entity(Context, AccessedEntity::Member, Class,
-                        DeclAccessPair::make(Decl, Decl->getAccess()),
-                        qType);
-    if (Entity.getAccess() == AS_public)
-      return true;
-
+                        DeclAccessPair::make(Target, AS_none), qType);
     EffectiveContext EC(CurContext);
     return ::IsAccessible(*this, EC, Entity) != ::AR_inaccessible;
   }
-  
-  if (ObjCIvarDecl *Ivar = dyn_cast<ObjCIvarDecl>(Decl)) {
+
+  if (ObjCIvarDecl *Ivar = dyn_cast<ObjCIvarDecl>(Target)) {
     // @public and @package ivars are always accessible.
     if (Ivar->getCanonicalAccessControl() == ObjCIvarDecl::Public ||
         Ivar->getCanonicalAccessControl() == ObjCIvarDecl::Package)
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);
diff --git a/test/Index/complete-access-checks.cpp b/test/Index/complete-access-checks.cpp
index 7eec41ec56..54d9640f6f 100644
--- a/test/Index/complete-access-checks.cpp
+++ b/test/Index/complete-access-checks.cpp
@@ -36,10 +36,10 @@ void Y::doSomething() {
 
 // CHECK-SUPER-ACCESS: CXXMethod:{ResultType void}{TypedText doSomething}{LeftParen (}{RightParen )} (34)
 // CHECK-SUPER-ACCESS: CXXMethod:{ResultType void}{Informative X::}{TypedText func1}{LeftParen (}{RightParen )} (36)
-// CHECK-SUPER-ACCESS: CXXMethod:{ResultType void}{Informative X::}{TypedText func2}{LeftParen (}{RightParen )} (36) (inaccessible)
+// CHECK-SUPER-ACCESS: CXXMethod:{ResultType void}{Informative X::}{TypedText func2}{LeftParen (}{RightParen )} (36)
 // CHECK-SUPER-ACCESS: CXXMethod:{ResultType void}{Informative X::}{TypedText func3}{LeftParen (}{RightParen )} (36) (inaccessible)
 // CHECK-SUPER-ACCESS: FieldDecl:{ResultType int}{Informative X::}{TypedText member1} (37)
-// CHECK-SUPER-ACCESS: FieldDecl:{ResultType int}{Informative X::}{TypedText member2} (37) (inaccessible)
+// CHECK-SUPER-ACCESS: FieldDecl:{ResultType int}{Informative X::}{TypedText member2} (37)
 // CHECK-SUPER-ACCESS: FieldDecl:{ResultType int}{Informative X::}{TypedText member3} (37) (inaccessible)
 // CHECK-SUPER-ACCESS: CXXMethod:{ResultType Y &}{TypedText operator=}{LeftParen (}{Placeholder const Y &}{RightParen )} (79)
 // CHECK-SUPER-ACCESS: CXXMethod:{ResultType X &}{Text X::}{TypedText operator=}{LeftParen (}{Placeholder const X &}{RightParen )} (81)
@@ -87,3 +87,26 @@ void f(P x, Q y) {
 // CHECK-USING-ACCESSIBLE: ClassDecl:{TypedText Q}{Text ::} (75)
 // CHECK-USING-ACCESSIBLE: CXXDestructor:{ResultType void}{Informative P::}{TypedText ~P}{LeftParen (}{RightParen )} (81)
 // CHECK-USING-ACCESSIBLE: CXXDestructor:{ResultType void}{TypedText ~Q}{LeftParen (}{RightParen )} (79)
+
+class B {
+protected:
+  int member;
+};
+
+class C : private B {};
+
+
+class D : public C {
+ public:
+  void f(::B *b);
+};
+
+void D::f(::B *that) {
+  // RUN: c-index-test -code-completion-at=%s:106:9 %s | FileCheck -check-prefix=CHECK-PRIVATE-SUPER-THIS %s
+  this->;
+// CHECK-PRIVATE-SUPER-THIS: FieldDecl:{ResultType int}{Informative B::}{TypedText member} (37) (inaccessible)
+
+  // RUN: c-index-test -code-completion-at=%s:110:9 %s | FileCheck -check-prefix=CHECK-PRIVATE-SUPER-THAT %s
+  that->;
+// CHECK-PRIVATE-SUPER-THAT: FieldDecl:{ResultType int}{TypedText member} (35) (inaccessible)
+}