[CodeGen] Add support for IncompleteArrayType in Obj-C ivars.

Fixes an assertion failure when ivar is a struct containing incomplete
array. Also completes support for direct flexible array members.

rdar://problem/21054495

Reviewers: rjmccall, theraven

Reviewed By: rjmccall

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D38774

llvm-svn: 316723

1 files changed, 5 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGObjCMac.cpp b/clang/lib/CodeGen/CGObjCMac.cpp
index 85901a6d65d..992da814093 100644
--- a/clang/lib/CodeGen/CGObjCMac.cpp
+++ b/clang/lib/CodeGen/CGObjCMac.cpp
@@ -5084,6 +5084,11 @@ void IvarLayoutBuilder::visitField(const FieldDecl *field,
 
   // Drill down into arrays.
   uint64_t numElts = 1;
+  if (auto arrayType = CGM.getContext().getAsIncompleteArrayType(fieldType)) {
+    numElts = 0;
+    fieldType = arrayType->getElementType();
+  }
+  // Unlike incomplete arrays, constant arrays can be nested.
   while (auto arrayType = CGM.getContext().getAsConstantArrayType(fieldType)) {
     numElts *= arrayType->getSize().getZExtValue();
     fieldType = arrayType->getElementType();