From 93fdb3f356ea25490d6eb3b8abf0f1c540b7cd4b Mon Sep 17 00:00:00 2001
From: David Majnemer <david.majnemer@gmail.com>
Date: Thu, 22 Oct 2015 18:04:22 +0000
Subject: [PATCH] [MS ABI] Don't crash when inheriting from base with trailing
 empty array member

We got this right for Itanium but not MSVC because CGRecordLayoutBuilder
was checking if the base's size was zero when it should have been
checking the non-virtual size.

This fixes PR21040.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@251036 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/CGRecordLayoutBuilder.cpp         |  2 +-
 test/Layout/ms-x86-empty-nonvirtual-bases.cpp | 26 ++++++++++++++++++-
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/lib/CodeGen/CGRecordLayoutBuilder.cpp b/lib/CodeGen/CGRecordLayoutBuilder.cpp
index f91ecebd09..375b59c5cb 100644
--- a/lib/CodeGen/CGRecordLayoutBuilder.cpp
+++ b/lib/CodeGen/CGRecordLayoutBuilder.cpp
@@ -454,7 +454,7 @@ void CGRecordLowering::accumulateBases() {
     // contain only a trailing array member.
     const CXXRecordDecl *BaseDecl = Base.getType()->getAsCXXRecordDecl();
     if (!BaseDecl->isEmpty() &&
-        !Context.getASTRecordLayout(BaseDecl).getSize().isZero())
+        !Context.getASTRecordLayout(BaseDecl).getNonVirtualSize().isZero())
       Members.push_back(MemberInfo(Layout.getBaseClassOffset(BaseDecl),
           MemberInfo::Base, getStorageType(BaseDecl), BaseDecl));
   }
diff --git a/test/Layout/ms-x86-empty-nonvirtual-bases.cpp b/test/Layout/ms-x86-empty-nonvirtual-bases.cpp
index 00906e9862..07be1d836e 100644
--- a/test/Layout/ms-x86-empty-nonvirtual-bases.cpp
+++ b/test/Layout/ms-x86-empty-nonvirtual-bases.cpp
@@ -159,6 +159,28 @@ struct __declspec(align(32)) H : B0, B1, B2, B3, B4 {
 // CHECK-NEXT:      | [sizeof=64, align=32
 // CHECK-NEXT:      |  nvsize=40, nvalign=32]
 
+struct I {
+  int i0[0];
+};
+
+// CHECK: *** Dumping AST Record Layout
+// CHECK-NEXT:    0 | struct I
+// CHECK-NEXT:    0 |   int [0] i0
+// CHECK-NEXT:      | [sizeof={{1|4}}, align=4,
+// CHECK-NEXT:      |  nvsize=0, nvalign=4]
+
+struct J : I {
+  int j;
+};
+
+// CHECK: *** Dumping AST Record Layout
+// CHECK-NEXT:   0 | struct J
+// CHECK-NEXT:   0 |   struct I (base)
+// CHECK-NEXT:   0 |     int [0] i0
+// CHECK-NEXT:   0 |   int j
+// CHECK-NEXT:     | [sizeof=4, align=4,
+// CHECK-NEXT:     |  nvsize=4, nvalign=4]
+
 int a[
 sizeof(A)+
 sizeof(B)+
@@ -167,4 +189,6 @@ sizeof(D)+
 sizeof(E)+
 sizeof(F)+
 sizeof(G)+
-sizeof(H)];
+sizeof(H)+
+sizeof(I)+
+sizeof(J)];
-- 
2.40.0