1 files changed, 47 insertions, 0 deletions
diff --git a/test/Layout/watchos-standard-layout.cpp b/test/Layout/watchos-standard-layout.cpp
new file mode 100644
index 0000000000000..bd7bb1a434bdf
--- /dev/null
+++ b/test/Layout/watchos-standard-layout.cpp
@@ -0,0 +1,47 @@
+// RUN: %clang_cc1 -fsyntax-only -triple armv7k-apple-darwin-watchos -fdump-record-layouts %s | FileCheck %s
+
+// WatchOS, 64-bit iOS, and WebAssembly use the C++11 definition of POD to
+// determine whether we can reuse the tail padding of a struct (POD is
+// "trivially copyable and standard layout"). The definition of standard
+// layout changed some time around C++17; check that we still use the old
+// ABI rule.
+
+// B is not standard-layout, but it was under C++11's rule, so we pack
+// C::d into its tail padding anyway.
+struct A { int : 0; };
+struct B : A { int n; char c[3]; };
+struct C : B { char d; };
+int c = sizeof(C);
+static_assert(!__is_standard_layout(B));
+
+// CHECK:*** Dumping AST Record Layout
+// CHECK:          0 | struct C
+// CHECK-NEXT:     0 |   struct B (base)
+// CHECK-NEXT:     0 |     struct A (base) (empty)
+// CHECK-NEXT:   0:- |       int 
+// CHECK-NEXT:     0 |     int n
+// CHECK-NEXT:     4 |     char [3] c
+// CHECK-NEXT:     8 |   char d
+// CHECK-NEXT:       | [sizeof=12, dsize=9, align=4,
+// CHECK-NEXT:       |  nvsize=9, nvalign=4]
+
+// F is not standard-layout due to the repeated D base class, but it was under
+// C++11's rule, so we pack G::d into its tail padding anyway.
+struct D {};
+struct E : D {};
+struct F : D, E { int n; char c[3]; };
+struct G : F { G(const G&); char d; };
+int g = sizeof(G);
+static_assert(!__is_standard_layout(F));
+
+// CHECK:*** Dumping AST Record Layout
+// CHECK:          0 | struct G
+// CHECK-NEXT:     0 |   struct F (base)
+// CHECK-NEXT:     0 |     struct D (base) (empty)
+// CHECK-NEXT:     1 |     struct E (base) (empty)
+// CHECK-NEXT:     1 |       struct D (base) (empty)
+// CHECK-NEXT:     0 |     int n
+// CHECK-NEXT:     4 |     char [3] c
+// CHECK-NEXT:     8 |   char d
+// CHECK-NEXT:       | [sizeof=12, dsize=9, align=4,
+// CHECK-NEXT:       |  nvsize=9, nvalign=4]