r360614 - Make more friendly with unions. Reviewed as https://reviews.llvm.org/D61858

[Marshall Clow via cfe-commits]

Author: marshall
Date: Mon May 13 12:29:23 2019
New Revision: 360614

URL: http://llvm.org/viewvc/llvm-project?rev=360614&view=rev
Log:
Make  more friendly with unions. Reviewed as https://reviews.llvm.org/D61858

Modified:
    cfe/trunk/lib/Sema/SemaExprCXX.cpp
    cfe/trunk/test/SemaCXX/type-traits.cpp

Modified: cfe/trunk/lib/Sema/SemaExprCXX.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExprCXX.cpp?rev=360614&r1=360613&r2=360614&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaExprCXX.cpp (original)
+++ cfe/trunk/lib/Sema/SemaExprCXX.cpp Mon May 13 12:29:23 2019
@@ -5118,8 +5118,15 @@ static bool EvaluateBinaryTypeTrait(Sema
     assert(Self.Context.hasSameUnqualifiedType(LhsT, RhsT)
              == (lhsRecord == rhsRecord));
 
+    // Unions are never base classes, and never have base classes.
+    // It doesn't matter if they are complete or not. See PR#41843
+    if (lhsRecord && lhsRecord->getDecl()->isUnion())
+      return false;
+    if (rhsRecord && rhsRecord->getDecl()->isUnion())
+      return false;
+
     if (lhsRecord == rhsRecord)
-      return !lhsRecord->getDecl()->isUnion();
+      return true;
 
     // C++0x [meta.rel]p2:
     //   If Base and Derived are class types and are different types

Modified: cfe/trunk/test/SemaCXX/type-traits.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/type-traits.cpp?rev=360614&r1=360613&r2=360614&view=diff
==============================================================================
--- cfe/trunk/test/SemaCXX/type-traits.cpp (original)
+++ cfe/trunk/test/SemaCXX/type-traits.cpp Mon May 13 12:29:23 2019
@@ -14,6 +14,7 @@ typedef NonPOD NonPODArMB[10][2];
 enum Enum { EV };
 struct POD { Enum e; int i; float f; NonPOD* p; };
 struct Empty {};
+struct IncompleteStruct;
 typedef Empty EmptyAr[10];
 typedef Empty EmptyArNB[];
 typedef Empty EmptyArMB[1][2];
@@ -1915,6 +1916,20 @@ void is_base_of() {
   { int arr[F(__is_base_of(Base, NonderivedTemp<int>))]; }
   { int arr[F(__is_base_of(Base, UndefinedTemp<int>))]; } // expected-error {{implicit instantiation of undefined template 'UndefinedTemp<int>'}}
 
+  { int arr[F(__is_base_of(IncompleteUnion, IncompleteUnion))]; }
+  { int arr[F(__is_base_of(Union, IncompleteUnion))]; }
+  { int arr[F(__is_base_of(IncompleteUnion, Union))]; }
+  { int arr[F(__is_base_of(IncompleteStruct, IncompleteUnion))]; }
+  { int arr[F(__is_base_of(IncompleteUnion, IncompleteStruct))]; }
+  { int arr[F(__is_base_of(Empty, IncompleteUnion))]; }
+  { int arr[F(__is_base_of(IncompleteUnion, Empty))]; }
+  { int arr[F(__is_base_of(int, IncompleteUnion))]; }
+  { int arr[F(__is_base_of(IncompleteUnion, int))]; }
+  { int arr[F(__is_base_of(Empty, Union))]; }
+  { int arr[F(__is_base_of(Union, Empty))]; }
+  { int arr[F(__is_base_of(int, Empty))]; }
+  { int arr[F(__is_base_of(Union, int))]; }
+
   isBaseOfT<Base, Derived>();
   isBaseOfF<Derived, Base>();