Only the first zero-length bitfield decides alignment of

the followup data member in an ms_struct struct.
// rdar:// 8823265



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@130795 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 6 insertions, 3 deletions

diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index 8316ea68e9..287c8b2af6 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -546,7 +546,8 @@ bool ASTContext::ZeroBitfieldFollowsNonBitfield(const FieldDecl *FD,
 bool ASTContext::ZeroBitfieldFollowsBitfield(const FieldDecl *FD,
                                              const FieldDecl *LastFD) const {
   return (FD->isBitField() && LastFD && LastFD->isBitField() &&
-          FD->getBitWidth()-> EvaluateAsInt(*this).getZExtValue() == 0);
+          FD->getBitWidth()-> EvaluateAsInt(*this).getZExtValue() == 0 &&
+          LastFD->getBitWidth()-> EvaluateAsInt(*this).getZExtValue() != 0);
 
 }
 
diff --git a/lib/AST/RecordLayoutBuilder.cpp b/lib/AST/RecordLayoutBuilder.cpp
index 810f11b6e3..2203ed1324 100644
--- a/lib/AST/RecordLayoutBuilder.cpp
+++ b/lib/AST/RecordLayoutBuilder.cpp
@@ -1359,9 +1359,11 @@ void RecordLayoutBuilder::LayoutBitField(const FieldDecl *D) {
       std::pair<uint64_t, unsigned> FieldInfo = 
         Context.getTypeInfo(ZeroLengthBitfield->getType());
       unsigned ZeroLengthBitfieldAlignment = FieldInfo.second;
-      if (ZeroLengthBitfieldAlignment > FieldAlign)
+      // Ignore alignment of subsequent zero-length bitfields.
+      if ((ZeroLengthBitfieldAlignment > FieldAlign) || (FieldSize == 0))
         FieldAlign = ZeroLengthBitfieldAlignment;
-      ZeroLengthBitfield = 0;
+      if (FieldSize)
+        ZeroLengthBitfield = 0;
     }
   }