When a reference to a field of a struct/union/class is passed to the

__alignof__ operator, make sure to take into account the packed alignment
of the struct/union/class itself. Matches GCC's behavior and fixes PR6362.

llvm-svn: 96884

1 files changed, 6 insertions, 0 deletions

diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index c8caeb62b31..202e3370b67 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -563,6 +563,12 @@ CharUnits ASTContext::getDeclAlign(const Decl *D, bool RefAsPointee) {
 
       Align = std::max(Align, getPreferredTypeAlign(T.getTypePtr()));
     }
+    if (const FieldDecl *FD = dyn_cast<FieldDecl>(VD)) {
+      // In the case of a field in a packed struct, we want the minimum
+      // of the alignment of the field and the alignment of the struct.
+      Align = std::min(Align,
+        getPreferredTypeAlign(FD->getParent()->getTypeForDecl()));
+    }
   }
 
   return CharUnits::fromQuantity(Align / Target.getCharWidth());