2 files changed, 15 insertions, 12 deletions

diff --git a/clang/lib/AST/RecordLayout.cpp b/clang/lib/AST/RecordLayout.cpp
index df5f79c9614..71e44ecf921 100644
--- a/clang/lib/AST/RecordLayout.cpp
+++ b/clang/lib/AST/RecordLayout.cpp
@@ -43,7 +43,7 @@ ASTRecordLayout::ASTRecordLayout(const ASTContext &Ctx, CharUnits size,
 // Constructor for C++ records.
 ASTRecordLayout::ASTRecordLayout(const ASTContext &Ctx,
                                  CharUnits size, CharUnits alignment,
-                                 bool hasOwnVFPtr, bool hasVFPtr,
+                                 bool hasOwnVFPtr, bool hasExtendableVFPtr,
                                  CharUnits vbptroffset,
                                  CharUnits datasize,
                                  const uint64_t *fieldoffsets,
@@ -74,7 +74,7 @@ ASTRecordLayout::ASTRecordLayout(const ASTContext &Ctx,
   CXXInfo->VBaseOffsets = VBaseOffsets;
   CXXInfo->HasOwnVFPtr = hasOwnVFPtr;
   CXXInfo->VBPtrOffset = vbptroffset;
-  CXXInfo->HasVFPtr = hasVFPtr;
+  CXXInfo->HasExtendableVFPtr = hasExtendableVFPtr;
   CXXInfo->BaseSharingVBPtr = BaseSharingVBPtr;
   CXXInfo->AlignAfterVBases = AlignAfterVBases;
 
diff --git a/clang/lib/AST/RecordLayoutBuilder.cpp b/clang/lib/AST/RecordLayoutBuilder.cpp
index d0426fa8dbf..524c3ba254d 100644
--- a/clang/lib/AST/RecordLayoutBuilder.cpp
+++ b/clang/lib/AST/RecordLayoutBuilder.cpp
@@ -2118,8 +2118,10 @@ public:
   const CXXRecordDecl *PrimaryBase;
   /// \brief The class we share our vb-pointer with.
   const CXXRecordDecl *SharedVBPtrBase;
-  /// \brief True if the class has a (not necessarily its own) vftable pointer.
-  bool HasVFPtr : 1;
+  /// \brief True if the class has a vftable pointer that can be extended
+  /// by this class or classes derived from it.  Such a vfptr will always occur
+  /// at offset 0.
+  bool HasExtendableVFPtr : 1;
   /// \brief True if the class has a (not necessarily its own) vbtable pointer.
   bool HasVBPtr : 1;
   /// \brief Offset to the virtual base table pointer (if one exists).
@@ -2226,7 +2228,7 @@ MicrosoftRecordLayoutBuilder::initializeCXXLayout(const CXXRecordDecl *RD) {
 
   // Initialize information about the bases.
   HasVBPtr = false;
-  HasVFPtr = false;
+  HasExtendableVFPtr = false;
   SharedVBPtrBase = 0;
   PrimaryBase = 0;
   VirtualAlignment = CharUnits::One();
@@ -2251,9 +2253,9 @@ MicrosoftRecordLayoutBuilder::initializeCXXLayout(const CXXRecordDecl *RD) {
       continue;
     }
     // We located a primary base class!
-    if (!PrimaryBase && Layout.hasVFPtr()) {
+    if (!PrimaryBase && Layout.hasExtendableVFPtr()) {
       PrimaryBase = BaseDecl;
-      HasVFPtr = true;
+      HasExtendableVFPtr = true;
     }
     // We located a base to share a VBPtr with!
     if (!SharedVBPtrBase && Layout.hasVBPtr()) {
@@ -2279,12 +2281,12 @@ void MicrosoftRecordLayoutBuilder::layoutVFPtr(const CXXRecordDecl *RD) {
 
   // Look at all of our methods to determine if we need a VFPtr.  We need a
   // vfptr if we define a new virtual function.
-  if (!HasVFPtr && RD->isDynamicClass())
+  if (!HasExtendableVFPtr && RD->isDynamicClass())
     for (CXXRecordDecl::method_iterator i = RD->method_begin(),
                                         e = RD->method_end();
-         !HasVFPtr && i != e; ++i)
-      HasVFPtr = i->isVirtual() && i->size_overridden_methods() == 0;
-  if (!HasVFPtr)
+         !HasExtendableVFPtr && i != e; ++i)
+      HasExtendableVFPtr = i->isVirtual() && i->size_overridden_methods() == 0;
+  if (!HasExtendableVFPtr)
     return;
 
   // MSVC 32 (but not 64) potentially over-aligns the vf-table pointer by giving
@@ -2672,7 +2674,8 @@ ASTContext::BuildMicrosoftASTRecordLayout(const RecordDecl *D) const {
     Builder.cxxLayout(RD);
     return new (*this) ASTRecordLayout(
         *this, Builder.Size, Builder.Alignment,
-        Builder.HasVFPtr && !Builder.PrimaryBase, Builder.HasVFPtr,
+        Builder.HasExtendableVFPtr && !Builder.PrimaryBase,
+        Builder.HasExtendableVFPtr,
         Builder.VBPtrOffset, Builder.DataSize, Builder.FieldOffsets.data(),
         Builder.FieldOffsets.size(), Builder.DataSize,
         Builder.NonVirtualAlignment, CharUnits::Zero(), Builder.PrimaryBase,