3 files changed, 35 insertions, 33 deletions

diff --git a/include/clang/AST/Type.h b/include/clang/AST/Type.h
index c2d492b3bb..c1b8a775a6 100644
--- a/include/clang/AST/Type.h
+++ b/include/clang/AST/Type.h
@@ -1179,6 +1179,10 @@ public:
   /// (C++0x [basic.types]p9)
   bool isTrivialType() const;
 
+  /// \brief Test if this type is a standard-layout type.
+  /// (C++0x [basic.type]p9)
+  bool isStandardLayoutType() const;
+
   /// isCXX11PODType() - Return true if this is a POD type according to the
   /// more relaxed rules of the C++11 standard, regardless of the current
   /// compilation's language.
@@ -2842,9 +2846,6 @@ public:
   // const, it needs to return false.
   bool hasConstFields() const { return false; }
 
-  /// \brief Whether this class has standard layout
-  bool hasStandardLayout() const;
-
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
diff --git a/lib/AST/Type.cpp b/lib/AST/Type.cpp
index 55f01e5822..dbced252aa 100644
--- a/lib/AST/Type.cpp
+++ b/lib/AST/Type.cpp
@@ -943,9 +943,36 @@ bool Type::isTrivialType() const {
   return false;
 }
 
-// This is effectively the intersection of isTrivialType and hasStandardLayout.
-// We implement it dircetly to avoid redundant conversions from a type to
-// a CXXRecordDecl.
+bool Type::isStandardLayoutType() const {
+  if (isIncompleteType())
+    return false;
+
+  // C++0x [basic.types]p9:
+  //   Scalar types, standard-layout class types, arrays of such types, and
+  //   cv-qualified versions of these types are collectively called
+  //   standard-layout types.
+  const Type *BaseTy = getBaseElementTypeUnsafe();
+  assert(BaseTy && "NULL element type");
+  if (BaseTy->isScalarType()) return true;
+  if (const RecordType *RT = BaseTy->getAs<RecordType>()) {
+    if (const CXXRecordDecl *ClassDecl =
+        dyn_cast<CXXRecordDecl>(RT->getDecl()))
+      if (!ClassDecl->hasStandardLayout())
+        return false;
+
+    // Default to 'true' for non-C++ class types.
+    // FIXME: This is a bit dubious, but plain C structs should trivially meet
+    // all the requirements of standard layout classes.
+    return true;
+  }
+
+  // No other types can match.
+  return false;
+}
+
+// This is effectively the intersection of isTrivialType and
+// isStandardLayoutType. We implement it dircetly to avoid redundant
+// conversions from a type to a CXXRecordDecl.
 bool Type::isCXX11PODType() const {
   if (isIncompleteType())
     return false;
@@ -1448,17 +1475,6 @@ static uint64_t countBasesWithFields(QualType BaseType) {
   return BasesWithFields;
 }
 
-bool RecordType::hasStandardLayout() const {
-  CXXRecordDecl *RD = cast<CXXRecordDecl>(getDecl());
-  if (! RD) {
-    assert(cast<RecordDecl>(getDecl()) &&
-           "RecordType does not have a corresponding RecordDecl");
-    return true;
-  }
-
-  return RD->hasStandardLayout();
-}
-
 bool EnumType::classof(const TagType *TT) {
   return isa<EnumDecl>(TT->getDecl());
 }
diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index d975a155cd..d87752081b 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -2438,22 +2438,7 @@ static bool EvaluateUnaryTypeTrait(Sema &Self, UnaryTypeTrait UTT, QualType T,
   case UTT_IsSigned:
     return T->isSignedIntegerType();
   case UTT_IsStandardLayout:
-    // Error if T is an incomplete type.
-    if (Self.RequireCompleteType(KeyLoc, T, diag::err_incomplete_typeid))
-      return false;
-
-    // A standard layout type is:
-    // - a scalar type
-    // - an array of standard layout types
-    // - a standard layout class type:
-    if (EvaluateUnaryTypeTrait(Self, UTT_IsScalar, T, KeyLoc))
-      return true;
-    if (EvaluateUnaryTypeTrait(Self, UTT_IsScalar, C.getBaseElementType(T),
-                               KeyLoc))
-      return true;
-    if (const RecordType *RT = C.getBaseElementType(T)->getAs<RecordType>())
-      return RT->hasStandardLayout();
-    return false;
+    return T->isStandardLayoutType();
   case UTT_IsUnsigned:
     return T->isUnsignedIntegerType();
   case UTT_IsVoid: