[libcxx-commits] [libcxx] 2a83cf5 - [libc++] Add tests for the ABI break introduced by switching to _LIBCPP_COMPRESSED_PAIR (#154559)

via libcxx-commits libcxx-commits at lists.llvm.org
Fri Aug 22 06:25:54 PDT 2025


Author: Nikolas Klauser
Date: 2025-08-22T09:25:50-04:00
New Revision: 2a83cf5d0e592890f74c5d5ff4a30ae4cf54b61b

URL: https://github.com/llvm/llvm-project/commit/2a83cf5d0e592890f74c5d5ff4a30ae4cf54b61b
DIFF: https://github.com/llvm/llvm-project/commit/2a83cf5d0e592890f74c5d5ff4a30ae4cf54b61b.diff

LOG: [libc++] Add tests for the ABI break introduced by switching to _LIBCPP_COMPRESSED_PAIR (#154559)

This patch adds unit tests to catch the regression described in #154146.
At the moment, these tests are pinning down the post-break ABI.

Added: 
    libcxx/test/libcxx/containers/associative/map/abi.compile.pass.cpp
    libcxx/test/libcxx/containers/associative/set/abi.compile.pass.cpp
    libcxx/test/libcxx/containers/sequences/forwardlist/abi.compile.pass.cpp
    libcxx/test/libcxx/containers/strings/basic.string/abi.compile.pass.cpp

Modified: 
    libcxx/test/libcxx/containers/associative/unord.map/abi.compile.pass.cpp
    libcxx/test/libcxx/containers/associative/unord.set/abi.compile.pass.cpp
    libcxx/test/libcxx/containers/sequences/deque/abi.compile.pass.cpp
    libcxx/test/libcxx/containers/sequences/list/abi.compile.pass.cpp
    libcxx/test/libcxx/containers/sequences/vector.bool/abi.compile.pass.cpp
    libcxx/test/libcxx/containers/sequences/vector/abi.compile.pass.cpp

Removed: 
    


################################################################################
diff  --git a/libcxx/test/libcxx/containers/associative/map/abi.compile.pass.cpp b/libcxx/test/libcxx/containers/associative/map/abi.compile.pass.cpp
new file mode 100644
index 0000000000000..04c1802bc84f6
--- /dev/null
+++ b/libcxx/test/libcxx/containers/associative/map/abi.compile.pass.cpp
@@ -0,0 +1,161 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: libcpp-abi-no-compressed-pair-padding
+
+// XFAIL: FROZEN-CXX03-HEADERS-FIXME
+
+#include <cstdint>
+#include <map>
+
+#include "min_allocator.h"
+#include "test_allocator.h"
+#include "test_macros.h"
+
+template <class T>
+class small_pointer {
+  std::uint16_t offset;
+};
+
+template <class T>
+class small_iter_allocator {
+public:
+  using value_type      = T;
+  using pointer         = small_pointer<T>;
+  using size_type       = std::uint16_t;
+  using 
diff erence_type = std::int16_t;
+
+  small_iter_allocator() TEST_NOEXCEPT {}
+
+  template <class U>
+  small_iter_allocator(small_iter_allocator<U>) TEST_NOEXCEPT {}
+
+  T* allocate(std::size_t n);
+  void deallocate(T* p, std::size_t);
+
+  friend bool operator==(small_iter_allocator, small_iter_allocator) { return true; }
+  friend bool operator!=(small_iter_allocator, small_iter_allocator) { return false; }
+};
+
+template <class T>
+class final_small_iter_allocator final {
+public:
+  using value_type      = T;
+  using pointer         = small_pointer<T>;
+  using size_type       = std::uint16_t;
+  using 
diff erence_type = std::int16_t;
+
+  final_small_iter_allocator() TEST_NOEXCEPT {}
+
+  template <class U>
+  final_small_iter_allocator(final_small_iter_allocator<U>) TEST_NOEXCEPT {}
+
+  T* allocate(std::size_t n);
+  void deallocate(T* p, std::size_t);
+
+  friend bool operator==(final_small_iter_allocator, final_small_iter_allocator) { return true; }
+  friend bool operator!=(final_small_iter_allocator, final_small_iter_allocator) { return false; }
+};
+
+struct allocator_base {};
+
+// Make sure that types with a common base type don't get broken. See https://llvm.org/PR154146
+template <class T>
+struct common_base_allocator : allocator_base {
+  using value_type = T;
+
+  common_base_allocator() TEST_NOEXCEPT {}
+
+  template <class U>
+  common_base_allocator(common_base_allocator<U>) TEST_NOEXCEPT {}
+
+  T* allocate(std::size_t n);
+  void deallocate(T* p, std::size_t);
+
+  friend bool operator==(common_base_allocator, common_base_allocator) { return true; }
+  friend bool operator!=(common_base_allocator, common_base_allocator) { return false; }
+};
+
+template <class T, class Alloc>
+using map_alloc = std::map<T, T, std::less<T>, Alloc>;
+
+struct user_struct {
+  map_alloc<int, common_base_allocator<std::pair<const int, int> > > v;
+  [[no_unique_address]] common_base_allocator<int> a;
+};
+
+#if __SIZE_WIDTH__ == 64
+static_assert(sizeof(user_struct) == 32, "");
+static_assert(TEST_ALIGNOF(user_struct) == 8, "");
+
+static_assert(sizeof(map_alloc<int, std::allocator<std::pair<const int, int> > >) == 24, "");
+static_assert(sizeof(map_alloc<int, min_allocator<std::pair<const int, int> > >) == 24, "");
+static_assert(sizeof(map_alloc<int, test_allocator<std::pair<const int, int> > >) == 40, "");
+static_assert(sizeof(map_alloc<int, small_iter_allocator<std::pair<const int, int> > >) == 6, "");
+static_assert(sizeof(map_alloc<int, final_small_iter_allocator<std::pair<const int, int> > >) == 8, "");
+
+static_assert(sizeof(map_alloc<char, std::allocator<std::pair<const char, char> > >) == 24, "");
+static_assert(sizeof(map_alloc<char, min_allocator<std::pair<const char, char> > >) == 24, "");
+static_assert(sizeof(map_alloc<char, test_allocator<std::pair<const char, char> > >) == 40, "");
+static_assert(sizeof(map_alloc<char, small_iter_allocator<std::pair<const char, char> > >) == 6, "");
+static_assert(sizeof(map_alloc<char, final_small_iter_allocator<std::pair<const char, char> > >) == 8, "");
+
+static_assert(TEST_ALIGNOF(map_alloc<int, std::allocator<std::pair<const int, int> > >) == 8, "");
+static_assert(TEST_ALIGNOF(map_alloc<int, min_allocator<std::pair<const int, int> > >) == 8, "");
+static_assert(TEST_ALIGNOF(map_alloc<int, test_allocator<std::pair<const int, int> > >) == 8, "");
+static_assert(TEST_ALIGNOF(map_alloc<int, small_iter_allocator<std::pair<const int, int> > >) == 2, "");
+static_assert(TEST_ALIGNOF(map_alloc<int, final_small_iter_allocator<std::pair<const int, int> > >) == 2, "");
+
+static_assert(TEST_ALIGNOF(map_alloc<char, std::allocator<std::pair<const char, char> > >) == 8, "");
+static_assert(TEST_ALIGNOF(map_alloc<char, min_allocator<std::pair<const char, char> > >) == 8, "");
+static_assert(TEST_ALIGNOF(map_alloc<char, test_allocator<std::pair<const char, char> > >) == 8, "");
+static_assert(TEST_ALIGNOF(map_alloc<char, small_iter_allocator<std::pair<const char, char> > >) == 2, "");
+static_assert(TEST_ALIGNOF(map_alloc<char, final_small_iter_allocator<std::pair<const char, char> > >) == 2, "");
+
+struct TEST_ALIGNAS(32) AlignedLess {};
+
+// This part of the ABI has been broken between LLVM 19 and LLVM 20.
+static_assert(sizeof(std::map<int, int, AlignedLess>) == 64, "");
+static_assert(TEST_ALIGNOF(std::map<int, int, AlignedLess>) == 32, "");
+
+#elif __SIZE_WIDTH__ == 32
+static_assert(sizeof(user_struct) == 16, "");
+static_assert(TEST_ALIGNOF(user_struct) == 4, "");
+
+static_assert(sizeof(map_alloc<int, std::allocator<std::pair<const int, int> > >) == 12, "");
+static_assert(sizeof(map_alloc<int, min_allocator<std::pair<const int, int> > >) == 12, "");
+static_assert(sizeof(map_alloc<int, test_allocator<std::pair<const int, int> > >) == 24, "");
+static_assert(sizeof(map_alloc<int, small_iter_allocator<std::pair<const int, int> > >) == 6, "");
+static_assert(sizeof(map_alloc<int, final_small_iter_allocator<std::pair<const int, int> > >) == 8, "");
+
+static_assert(sizeof(map_alloc<char, std::allocator<std::pair<const char, char> > >) == 12, "");
+static_assert(sizeof(map_alloc<char, min_allocator<std::pair<const char, char> > >) == 12, "");
+static_assert(sizeof(map_alloc<char, test_allocator<std::pair<const char, char> > >) == 24, "");
+static_assert(sizeof(map_alloc<char, small_iter_allocator<std::pair<const char, char> > >) == 6, "");
+static_assert(sizeof(map_alloc<char, final_small_iter_allocator<std::pair<const char, char> > >) == 8, "");
+
+static_assert(TEST_ALIGNOF(map_alloc<int, std::allocator<std::pair<const int, int> > >) == 4, "");
+static_assert(TEST_ALIGNOF(map_alloc<int, min_allocator<std::pair<const int, int> > >) == 4, "");
+static_assert(TEST_ALIGNOF(map_alloc<int, test_allocator<std::pair<const int, int> > >) == 4, "");
+static_assert(TEST_ALIGNOF(map_alloc<int, small_iter_allocator<std::pair<const int, int> > >) == 2, "");
+static_assert(TEST_ALIGNOF(map_alloc<int, final_small_iter_allocator<std::pair<const int, int> > >) == 2, "");
+
+static_assert(TEST_ALIGNOF(map_alloc<char, std::allocator<std::pair<const char, char> > >) == 4, "");
+static_assert(TEST_ALIGNOF(map_alloc<char, min_allocator<std::pair<const char, char> > >) == 4, "");
+static_assert(TEST_ALIGNOF(map_alloc<char, test_allocator<std::pair<const char, char> > >) == 4, "");
+static_assert(TEST_ALIGNOF(map_alloc<char, small_iter_allocator<std::pair<const char, char> > >) == 2, "");
+static_assert(TEST_ALIGNOF(map_alloc<char, final_small_iter_allocator<std::pair<const char, char> > >) == 2, "");
+
+struct TEST_ALIGNAS(32) AlignedLess {};
+
+static_assert(sizeof(std::map<int, int, AlignedLess>) == 64);
+static_assert(TEST_ALIGNOF(std::map<int, int, AlignedLess>) == 32);
+
+#else
+#  error std::size_t has an unexpected size
+#endif

diff  --git a/libcxx/test/libcxx/containers/associative/set/abi.compile.pass.cpp b/libcxx/test/libcxx/containers/associative/set/abi.compile.pass.cpp
new file mode 100644
index 0000000000000..1b85bb7c93773
--- /dev/null
+++ b/libcxx/test/libcxx/containers/associative/set/abi.compile.pass.cpp
@@ -0,0 +1,161 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: libcpp-abi-no-compressed-pair-padding
+
+// XFAIL: FROZEN-CXX03-HEADERS-FIXME
+
+#include <cstdint>
+#include <set>
+
+#include "min_allocator.h"
+#include "test_allocator.h"
+#include "test_macros.h"
+
+template <class T>
+class small_pointer {
+  std::uint16_t offset;
+};
+
+template <class T>
+class small_iter_allocator {
+public:
+  using value_type      = T;
+  using pointer         = small_pointer<T>;
+  using size_type       = std::uint16_t;
+  using 
diff erence_type = std::int16_t;
+
+  small_iter_allocator() TEST_NOEXCEPT {}
+
+  template <class U>
+  small_iter_allocator(small_iter_allocator<U>) TEST_NOEXCEPT {}
+
+  T* allocate(std::size_t n);
+  void deallocate(T* p, std::size_t);
+
+  friend bool operator==(small_iter_allocator, small_iter_allocator) { return true; }
+  friend bool operator!=(small_iter_allocator, small_iter_allocator) { return false; }
+};
+
+template <class T>
+class final_small_iter_allocator final {
+public:
+  using value_type      = T;
+  using pointer         = small_pointer<T>;
+  using size_type       = std::uint16_t;
+  using 
diff erence_type = std::int16_t;
+
+  final_small_iter_allocator() TEST_NOEXCEPT {}
+
+  template <class U>
+  final_small_iter_allocator(final_small_iter_allocator<U>) TEST_NOEXCEPT {}
+
+  T* allocate(std::size_t n);
+  void deallocate(T* p, std::size_t);
+
+  friend bool operator==(final_small_iter_allocator, final_small_iter_allocator) { return true; }
+  friend bool operator!=(final_small_iter_allocator, final_small_iter_allocator) { return false; }
+};
+
+struct allocator_base {};
+
+// Make sure that types with a common base type don't get broken. See https://llvm.org/PR154146
+template <class T>
+struct common_base_allocator : allocator_base {
+  using value_type = T;
+
+  common_base_allocator() TEST_NOEXCEPT {}
+
+  template <class U>
+  common_base_allocator(common_base_allocator<U>) TEST_NOEXCEPT {}
+
+  T* allocate(std::size_t n);
+  void deallocate(T* p, std::size_t);
+
+  friend bool operator==(common_base_allocator, common_base_allocator) { return true; }
+  friend bool operator!=(common_base_allocator, common_base_allocator) { return false; }
+};
+
+template <class T, class Alloc>
+using set_alloc = std::set<T, std::less<T>, Alloc>;
+
+struct user_struct {
+  set_alloc<int, common_base_allocator<int> > v;
+  [[no_unique_address]] common_base_allocator<int> a;
+};
+
+#if __SIZE_WIDTH__ == 64
+static_assert(sizeof(user_struct) == 32, "");
+static_assert(TEST_ALIGNOF(user_struct) == 8, "");
+
+static_assert(sizeof(set_alloc<int, std::allocator<int> >) == 24, "");
+static_assert(sizeof(set_alloc<int, min_allocator<int> >) == 24, "");
+static_assert(sizeof(set_alloc<int, test_allocator<int> >) == 40, "");
+static_assert(sizeof(set_alloc<int, small_iter_allocator<int> >) == 6, "");
+static_assert(sizeof(set_alloc<int, final_small_iter_allocator<int> >) == 8, "");
+
+static_assert(sizeof(set_alloc<char, std::allocator<char> >) == 24, "");
+static_assert(sizeof(set_alloc<char, min_allocator<char> >) == 24, "");
+static_assert(sizeof(set_alloc<char, test_allocator<char> >) == 40, "");
+static_assert(sizeof(set_alloc<char, small_iter_allocator<char> >) == 6, "");
+static_assert(sizeof(set_alloc<char, final_small_iter_allocator<char> >) == 8, "");
+
+static_assert(TEST_ALIGNOF(set_alloc<int, std::allocator<int> >) == 8, "");
+static_assert(TEST_ALIGNOF(set_alloc<int, min_allocator<int> >) == 8, "");
+static_assert(TEST_ALIGNOF(set_alloc<int, test_allocator<int> >) == 8, "");
+static_assert(TEST_ALIGNOF(set_alloc<int, small_iter_allocator<int> >) == 2, "");
+static_assert(TEST_ALIGNOF(set_alloc<int, final_small_iter_allocator<int> >) == 2, "");
+
+static_assert(TEST_ALIGNOF(set_alloc<char, std::allocator<char> >) == 8, "");
+static_assert(TEST_ALIGNOF(set_alloc<char, min_allocator<char> >) == 8, "");
+static_assert(TEST_ALIGNOF(set_alloc<char, test_allocator<char> >) == 8, "");
+static_assert(TEST_ALIGNOF(set_alloc<char, small_iter_allocator<char> >) == 2, "");
+static_assert(TEST_ALIGNOF(set_alloc<char, final_small_iter_allocator<char> >) == 2, "");
+
+struct TEST_ALIGNAS(32) AlignedLess {};
+
+// This part of the ABI has been broken between LLVM 19 and LLVM 20.
+static_assert(sizeof(std::set<int, AlignedLess>) == 64, "");
+static_assert(TEST_ALIGNOF(std::set<int, AlignedLess>) == 32, "");
+
+#elif __SIZE_WIDTH__ == 32
+static_assert(sizeof(user_struct) == 16, "");
+static_assert(TEST_ALIGNOF(user_struct) == 4, "");
+
+static_assert(sizeof(set_alloc<int, std::allocator<int> >) == 12, "");
+static_assert(sizeof(set_alloc<int, min_allocator<int> >) == 12, "");
+static_assert(sizeof(set_alloc<int, test_allocator<int> >) == 24, "");
+static_assert(sizeof(set_alloc<int, small_iter_allocator<int> >) == 6, "");
+static_assert(sizeof(set_alloc<int, final_small_iter_allocator<int> >) == 8, "");
+
+static_assert(sizeof(set_alloc<char, std::allocator<char> >) == 12, "");
+static_assert(sizeof(set_alloc<char, min_allocator<char> >) == 12, "");
+static_assert(sizeof(set_alloc<char, test_allocator<char> >) == 24, "");
+static_assert(sizeof(set_alloc<char, small_iter_allocator<char> >) == 6, "");
+static_assert(sizeof(set_alloc<char, final_small_iter_allocator<char> >) == 8, "");
+
+static_assert(TEST_ALIGNOF(set_alloc<int, std::allocator<int> >) == 4, "");
+static_assert(TEST_ALIGNOF(set_alloc<int, min_allocator<int> >) == 4, "");
+static_assert(TEST_ALIGNOF(set_alloc<int, test_allocator<int> >) == 4, "");
+static_assert(TEST_ALIGNOF(set_alloc<int, small_iter_allocator<int> >) == 2, "");
+static_assert(TEST_ALIGNOF(set_alloc<int, final_small_iter_allocator<int> >) == 2, "");
+
+static_assert(TEST_ALIGNOF(set_alloc<char, std::allocator<char> >) == 4, "");
+static_assert(TEST_ALIGNOF(set_alloc<char, min_allocator<char> >) == 4, "");
+static_assert(TEST_ALIGNOF(set_alloc<char, test_allocator<char> >) == 4, "");
+static_assert(TEST_ALIGNOF(set_alloc<char, small_iter_allocator<char> >) == 2, "");
+static_assert(TEST_ALIGNOF(set_alloc<char, final_small_iter_allocator<char> >) == 2, "");
+
+struct TEST_ALIGNAS(32) AlignedLess {};
+
+static_assert(sizeof(std::set<int, AlignedLess>) == 64);
+static_assert(TEST_ALIGNOF(std::set<int, AlignedLess>) == 32);
+
+#else
+#  error std::size_t has an unexpected size
+#endif

diff  --git a/libcxx/test/libcxx/containers/associative/unord.map/abi.compile.pass.cpp b/libcxx/test/libcxx/containers/associative/unord.map/abi.compile.pass.cpp
index 55d42a8d017e1..0476872487036 100644
--- a/libcxx/test/libcxx/containers/associative/unord.map/abi.compile.pass.cpp
+++ b/libcxx/test/libcxx/containers/associative/unord.map/abi.compile.pass.cpp
@@ -66,10 +66,36 @@ class final_small_iter_allocator final {
   friend bool operator!=(final_small_iter_allocator, final_small_iter_allocator) { return false; }
 };
 
+struct allocator_base {};
+
+// Make sure that types with a common base type don't get broken. See https://llvm.org/PR154146
+template <class T>
+struct common_base_allocator : allocator_base {
+  using value_type = T;
+
+  common_base_allocator() TEST_NOEXCEPT {}
+
+  template <class U>
+  common_base_allocator(common_base_allocator<U>) TEST_NOEXCEPT {}
+
+  T* allocate(std::size_t n);
+  void deallocate(T* p, std::size_t);
+
+  friend bool operator==(common_base_allocator, common_base_allocator) { return true; }
+  friend bool operator!=(common_base_allocator, common_base_allocator) { return false; }
+};
+
 template <class T, class Alloc>
 using unordered_map_alloc = std::unordered_map<T, T, std::hash<T>, std::equal_to<T>, Alloc>;
 
+struct user_struct {
+  unordered_map_alloc<int, common_base_allocator<std::pair<const int, int> > > v;
+  [[no_unique_address]] common_base_allocator<int> a;
+};
+
 #if __SIZE_WIDTH__ == 64
+static_assert(sizeof(user_struct) == 48, "");
+static_assert(TEST_ALIGNOF(user_struct) == 8, "");
 
 static_assert(sizeof(unordered_map_alloc<int, std::allocator<std::pair<const int, int> > >) == 40, "");
 static_assert(sizeof(unordered_map_alloc<int, min_allocator<std::pair<const int, int> > >) == 40, "");
@@ -104,6 +130,8 @@ static_assert(sizeof(std::unordered_map<int, int, AlignedHash, UnalignedEqualTo>
 static_assert(TEST_ALIGNOF(std::unordered_map<int, int, AlignedHash, UnalignedEqualTo>) == 32, "");
 
 #elif __SIZE_WIDTH__ == 32
+static_assert(sizeof(user_struct) == 24, "");
+static_assert(TEST_ALIGNOF(user_struct) == 4, "");
 
 static_assert(sizeof(unordered_map_alloc<int, std::allocator<std::pair<const int, int> > >) == 20, "");
 static_assert(sizeof(unordered_map_alloc<int, min_allocator<std::pair<const int, int> > >) == 20, "");

diff  --git a/libcxx/test/libcxx/containers/associative/unord.set/abi.compile.pass.cpp b/libcxx/test/libcxx/containers/associative/unord.set/abi.compile.pass.cpp
index bee2012bbea29..e9d88a126de6c 100644
--- a/libcxx/test/libcxx/containers/associative/unord.set/abi.compile.pass.cpp
+++ b/libcxx/test/libcxx/containers/associative/unord.set/abi.compile.pass.cpp
@@ -66,10 +66,36 @@ class final_small_iter_allocator final {
   friend bool operator!=(final_small_iter_allocator, final_small_iter_allocator) { return false; }
 };
 
+struct allocator_base {};
+
+// Make sure that types with a common base type don't get broken. See https://llvm.org/PR154146
+template <class T>
+struct common_base_allocator : allocator_base {
+  using value_type = T;
+
+  common_base_allocator() TEST_NOEXCEPT {}
+
+  template <class U>
+  common_base_allocator(common_base_allocator<U>) TEST_NOEXCEPT {}
+
+  T* allocate(std::size_t n);
+  void deallocate(T* p, std::size_t);
+
+  friend bool operator==(common_base_allocator, common_base_allocator) { return true; }
+  friend bool operator!=(common_base_allocator, common_base_allocator) { return false; }
+};
+
 template <class T, class Alloc>
 using unordered_set_alloc = std::unordered_set<T, std::hash<T>, std::equal_to<T>, Alloc>;
 
+struct user_struct {
+  unordered_set_alloc<int, common_base_allocator<int> > v;
+  [[no_unique_address]] common_base_allocator<int> a;
+};
+
 #if __SIZE_WIDTH__ == 64
+static_assert(sizeof(user_struct) == 48, "");
+static_assert(TEST_ALIGNOF(user_struct) == 8, "");
 
 static_assert(sizeof(unordered_set_alloc<int, std::allocator<int> >) == 40, "");
 static_assert(sizeof(unordered_set_alloc<int, min_allocator<int> >) == 40, "");
@@ -103,6 +129,8 @@ static_assert(sizeof(std::unordered_set<int, AlignedHash, UnalignedEqualTo>) ==
 static_assert(TEST_ALIGNOF(std::unordered_set<int, AlignedHash, UnalignedEqualTo>) == 32, "");
 
 #elif __SIZE_WIDTH__ == 32
+static_assert(sizeof(user_struct) == 24, "");
+static_assert(TEST_ALIGNOF(user_struct) == 4, "");
 
 static_assert(sizeof(unordered_set_alloc<int, std::allocator<int> >) == 20, "");
 static_assert(sizeof(unordered_set_alloc<int, min_allocator<int> >) == 20, "");

diff  --git a/libcxx/test/libcxx/containers/sequences/deque/abi.compile.pass.cpp b/libcxx/test/libcxx/containers/sequences/deque/abi.compile.pass.cpp
index 30586d8b2422c..38f957f416c87 100644
--- a/libcxx/test/libcxx/containers/sequences/deque/abi.compile.pass.cpp
+++ b/libcxx/test/libcxx/containers/sequences/deque/abi.compile.pass.cpp
@@ -8,6 +8,8 @@
 
 // UNSUPPORTED: libcpp-abi-no-compressed-pair-padding
 
+// XFAIL: FROZEN-CXX03-HEADERS-FIXME
+
 #include <cstdint>
 #include <deque>
 
@@ -60,6 +62,25 @@ class final_small_iter_allocator final {
   friend bool operator!=(final_small_iter_allocator, final_small_iter_allocator) { return false; }
 };
 
+struct allocator_base {};
+
+// Make sure that types with a common base type don't get broken. See https://llvm.org/PR154146
+template <class T>
+struct common_base_allocator : allocator_base {
+  using value_type = T;
+
+  common_base_allocator() TEST_NOEXCEPT {}
+
+  template <class U>
+  common_base_allocator(common_base_allocator<U>) TEST_NOEXCEPT {}
+
+  T* allocate(std::size_t n);
+  void deallocate(T* p, std::size_t);
+
+  friend bool operator==(common_base_allocator, common_base_allocator) { return true; }
+  friend bool operator!=(common_base_allocator, common_base_allocator) { return false; }
+};
+
 #if __SIZE_WIDTH__ == 64
 
 static_assert(sizeof(std::deque<int>) == 48, "");
@@ -67,24 +88,28 @@ static_assert(sizeof(std::deque<int, min_allocator<int> >) == 48, "");
 static_assert(sizeof(std::deque<int, test_allocator<int> >) == 80, "");
 static_assert(sizeof(std::deque<int, small_iter_allocator<int> >) == 12, "");
 static_assert(sizeof(std::deque<int, final_small_iter_allocator<int> >) == 16, "");
+static_assert(sizeof(std::deque<int, common_base_allocator<int> >) == 56, "");
 
 static_assert(sizeof(std::deque<char>) == 48, "");
 static_assert(sizeof(std::deque<char, min_allocator<char> >) == 48, "");
 static_assert(sizeof(std::deque<char, test_allocator<char> >) == 80, "");
 static_assert(sizeof(std::deque<char, small_iter_allocator<char> >) == 12, "");
 static_assert(sizeof(std::deque<char, final_small_iter_allocator<char> >) == 16, "");
+static_assert(sizeof(std::deque<char, common_base_allocator<char> >) == 56, "");
 
 static_assert(TEST_ALIGNOF(std::deque<int>) == 8, "");
 static_assert(TEST_ALIGNOF(std::deque<int, min_allocator<int> >) == 8, "");
 static_assert(TEST_ALIGNOF(std::deque<int, test_allocator<int> >) == 8, "");
 static_assert(TEST_ALIGNOF(std::deque<int, small_iter_allocator<int> >) == 2, "");
 static_assert(TEST_ALIGNOF(std::deque<int, final_small_iter_allocator<int> >) == 2, "");
+static_assert(TEST_ALIGNOF(std::deque<int, common_base_allocator<int> >) == 8, "");
 
 static_assert(TEST_ALIGNOF(std::deque<char>) == 8, "");
 static_assert(TEST_ALIGNOF(std::deque<char, min_allocator<char> >) == 8, "");
 static_assert(TEST_ALIGNOF(std::deque<char, test_allocator<char> >) == 8, "");
 static_assert(TEST_ALIGNOF(std::deque<char, small_iter_allocator<char> >) == 2, "");
 static_assert(TEST_ALIGNOF(std::deque<char, final_small_iter_allocator<char> >) == 2, "");
+static_assert(TEST_ALIGNOF(std::deque<char, common_base_allocator<char> >) == 8, "");
 
 #elif __SIZE_WIDTH__ == 32
 
@@ -93,24 +118,28 @@ static_assert(sizeof(std::deque<int, min_allocator<int> >) == 24, "");
 static_assert(sizeof(std::deque<int, test_allocator<int> >) == 48, "");
 static_assert(sizeof(std::deque<int, small_iter_allocator<int> >) == 12, "");
 static_assert(sizeof(std::deque<int, final_small_iter_allocator<int> >) == 16, "");
+static_assert(sizeof(std::deque<int, common_base_allocator<int> >) == 28, "");
 
 static_assert(sizeof(std::deque<char>) == 24, "");
 static_assert(sizeof(std::deque<char, min_allocator<char> >) == 24, "");
 static_assert(sizeof(std::deque<char, test_allocator<char> >) == 48, "");
 static_assert(sizeof(std::deque<char, small_iter_allocator<char> >) == 12, "");
 static_assert(sizeof(std::deque<char, final_small_iter_allocator<char> >) == 16, "");
+static_assert(sizeof(std::deque<char, common_base_allocator<char> >) == 28, "");
 
 static_assert(TEST_ALIGNOF(std::deque<int>) == 4, "");
 static_assert(TEST_ALIGNOF(std::deque<int, min_allocator<int> >) == 4, "");
 static_assert(TEST_ALIGNOF(std::deque<int, test_allocator<int> >) == 4, "");
 static_assert(TEST_ALIGNOF(std::deque<int, small_iter_allocator<int> >) == 2, "");
 static_assert(TEST_ALIGNOF(std::deque<int, final_small_iter_allocator<int> >) == 2, "");
+static_assert(TEST_ALIGNOF(std::deque<int, common_base_allocator<int> >) == 4, "");
 
 static_assert(TEST_ALIGNOF(std::deque<char>) == 4, "");
 static_assert(TEST_ALIGNOF(std::deque<char, min_allocator<char> >) == 4, "");
 static_assert(TEST_ALIGNOF(std::deque<char, test_allocator<char> >) == 4, "");
 static_assert(TEST_ALIGNOF(std::deque<char, small_iter_allocator<char> >) == 2, "");
 static_assert(TEST_ALIGNOF(std::deque<char, final_small_iter_allocator<char> >) == 2, "");
+static_assert(TEST_ALIGNOF(std::deque<char, common_base_allocator<char> >) == 4, "");
 
 #else
 #  error std::size_t has an unexpected size

diff  --git a/libcxx/test/libcxx/containers/sequences/forwardlist/abi.compile.pass.cpp b/libcxx/test/libcxx/containers/sequences/forwardlist/abi.compile.pass.cpp
new file mode 100644
index 0000000000000..cb500f9c4d61b
--- /dev/null
+++ b/libcxx/test/libcxx/containers/sequences/forwardlist/abi.compile.pass.cpp
@@ -0,0 +1,115 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <cstdint>
+#include <forward_list>
+
+#include "min_allocator.h"
+#include "test_allocator.h"
+#include "test_macros.h"
+
+template <class T>
+class small_pointer {
+  std::uint16_t offset;
+};
+
+template <class T>
+class small_iter_allocator {
+public:
+  using value_type      = T;
+  using pointer         = small_pointer<T>;
+  using size_type       = std::int16_t;
+  using 
diff erence_type = std::int16_t;
+
+  small_iter_allocator() TEST_NOEXCEPT {}
+
+  template <class U>
+  small_iter_allocator(small_iter_allocator<U>) TEST_NOEXCEPT {}
+
+  T* allocate(std::size_t n);
+  void deallocate(T* p, std::size_t);
+
+  friend bool operator==(small_iter_allocator, small_iter_allocator) { return true; }
+  friend bool operator!=(small_iter_allocator, small_iter_allocator) { return false; }
+};
+
+struct allocator_base {};
+
+// Make sure that types with a common base type don't get broken. See https://llvm.org/PR154146
+template <class T>
+struct common_base_allocator : allocator_base {
+  using value_type = T;
+
+  common_base_allocator() TEST_NOEXCEPT {}
+
+  template <class U>
+  common_base_allocator(common_base_allocator<U>) TEST_NOEXCEPT {}
+
+  T* allocate(std::size_t n);
+  void deallocate(T* p, std::size_t);
+
+  friend bool operator==(common_base_allocator, common_base_allocator) { return true; }
+  friend bool operator!=(common_base_allocator, common_base_allocator) { return false; }
+};
+
+struct user_struct {
+  std::forward_list<int, common_base_allocator<int> > v;
+  [[no_unique_address]] common_base_allocator<int> a;
+};
+
+#if __SIZE_WIDTH__ == 64
+static_assert(sizeof(user_struct) == 16, "");
+static_assert(TEST_ALIGNOF(user_struct) == 8, "");
+
+static_assert(sizeof(std::forward_list<int>) == 8, "");
+static_assert(sizeof(std::forward_list<int, min_allocator<int> >) == 8, "");
+static_assert(sizeof(std::forward_list<int, test_allocator<int> >) == 24, "");
+static_assert(sizeof(std::forward_list<int, small_iter_allocator<int> >) == 2, "");
+
+static_assert(sizeof(std::forward_list<char>) == 8, "");
+static_assert(sizeof(std::forward_list<char, min_allocator<char> >) == 8, "");
+static_assert(sizeof(std::forward_list<char, test_allocator<char> >) == 24, "");
+static_assert(sizeof(std::forward_list<char, small_iter_allocator<char> >) == 2, "");
+
+static_assert(TEST_ALIGNOF(std::forward_list<int>) == 8, "");
+static_assert(TEST_ALIGNOF(std::forward_list<int, min_allocator<int> >) == 8, "");
+static_assert(TEST_ALIGNOF(std::forward_list<int, test_allocator<int> >) == 8, "");
+static_assert(TEST_ALIGNOF(std::forward_list<int, small_iter_allocator<int> >) == 2, "");
+
+static_assert(TEST_ALIGNOF(std::forward_list<char>) == 8, "");
+static_assert(TEST_ALIGNOF(std::forward_list<char, min_allocator<char> >) == 8, "");
+static_assert(TEST_ALIGNOF(std::forward_list<char, test_allocator<char> >) == 8, "");
+static_assert(TEST_ALIGNOF(std::forward_list<char, small_iter_allocator<char> >) == 2, "");
+
+#elif __SIZE_WIDTH__ == 32
+static_assert(sizeof(user_struct) == 8, "");
+static_assert(TEST_ALIGNOF(user_struct) == 4, "");
+
+static_assert(sizeof(std::forward_list<int>) == 4, "");
+static_assert(sizeof(std::forward_list<int, min_allocator<int> >) == 4, "");
+static_assert(sizeof(std::forward_list<int, test_allocator<int> >) == 16, "");
+static_assert(sizeof(std::forward_list<int, small_iter_allocator<int> >) == 2, "");
+
+static_assert(sizeof(std::forward_list<char>) == 4, "");
+static_assert(sizeof(std::forward_list<char, min_allocator<char> >) == 4, "");
+static_assert(sizeof(std::forward_list<char, test_allocator<char> >) == 16, "");
+static_assert(sizeof(std::forward_list<char, small_iter_allocator<char> >) == 2, "");
+
+static_assert(TEST_ALIGNOF(std::forward_list<int>) == 4, "");
+static_assert(TEST_ALIGNOF(std::forward_list<int, min_allocator<int> >) == 4, "");
+static_assert(TEST_ALIGNOF(std::forward_list<int, test_allocator<int> >) == 4, "");
+static_assert(TEST_ALIGNOF(std::forward_list<int, small_iter_allocator<int> >) == 2, "");
+
+static_assert(TEST_ALIGNOF(std::forward_list<char>) == 4, "");
+static_assert(TEST_ALIGNOF(std::forward_list<char, min_allocator<char> >) == 4, "");
+static_assert(TEST_ALIGNOF(std::forward_list<char, test_allocator<char> >) == 4, "");
+static_assert(TEST_ALIGNOF(std::forward_list<char, small_iter_allocator<char> >) == 2, "");
+
+#else
+#  error std::size_t has an unexpected size
+#endif

diff  --git a/libcxx/test/libcxx/containers/sequences/list/abi.compile.pass.cpp b/libcxx/test/libcxx/containers/sequences/list/abi.compile.pass.cpp
index a16ae1d527921..1737497ab159e 100644
--- a/libcxx/test/libcxx/containers/sequences/list/abi.compile.pass.cpp
+++ b/libcxx/test/libcxx/containers/sequences/list/abi.compile.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// XFAIL: FROZEN-CXX03-HEADERS-FIXME
+
 #include <cstdint>
 #include <list>
 
@@ -38,7 +40,33 @@ class small_iter_allocator {
   friend bool operator!=(small_iter_allocator, small_iter_allocator) { return false; }
 };
 
+struct allocator_base {};
+
+// Make sure that types with a common base type don't get broken. See https://llvm.org/PR154146
+template <class T>
+struct common_base_allocator : allocator_base {
+  using value_type = T;
+
+  common_base_allocator() TEST_NOEXCEPT {}
+
+  template <class U>
+  common_base_allocator(common_base_allocator<U>) TEST_NOEXCEPT {}
+
+  T* allocate(std::size_t n);
+  void deallocate(T* p, std::size_t);
+
+  friend bool operator==(common_base_allocator, common_base_allocator) { return true; }
+  friend bool operator!=(common_base_allocator, common_base_allocator) { return false; }
+};
+
+struct user_struct {
+  std::list<int, common_base_allocator<int> > v;
+  [[no_unique_address]] common_base_allocator<int> a;
+};
+
 #if __SIZE_WIDTH__ == 64
+static_assert(sizeof(user_struct) == 32, "");
+static_assert(TEST_ALIGNOF(user_struct) == 8, "");
 
 static_assert(sizeof(std::list<int>) == 24, "");
 static_assert(sizeof(std::list<int, min_allocator<int> >) == 24, "");
@@ -61,6 +89,8 @@ static_assert(TEST_ALIGNOF(std::list<char, test_allocator<char> >) == 8, "");
 static_assert(TEST_ALIGNOF(std::list<char, small_iter_allocator<char> >) == 2, "");
 
 #elif __SIZE_WIDTH__ == 32
+static_assert(sizeof(user_struct) == 16, "");
+static_assert(TEST_ALIGNOF(user_struct) == 4, "");
 
 static_assert(sizeof(std::list<int>) == 12, "");
 static_assert(sizeof(std::list<int, min_allocator<int> >) == 12, "");

diff  --git a/libcxx/test/libcxx/containers/sequences/vector.bool/abi.compile.pass.cpp b/libcxx/test/libcxx/containers/sequences/vector.bool/abi.compile.pass.cpp
index cc6b0d94e7daf..97e09ab4ca868 100644
--- a/libcxx/test/libcxx/containers/sequences/vector.bool/abi.compile.pass.cpp
+++ b/libcxx/test/libcxx/containers/sequences/vector.bool/abi.compile.pass.cpp
@@ -8,6 +8,8 @@
 
 // UNSUPPORTED: libcpp-abi-no-compressed-pair-padding
 
+// XFAIL: FROZEN-CXX03-HEADERS-FIXME
+
 #include <cstdint>
 #include <vector>
 
@@ -40,7 +42,33 @@ class small_iter_allocator {
   friend bool operator!=(small_iter_allocator, small_iter_allocator) { return false; }
 };
 
+struct allocator_base {};
+
+// Make sure that types with a common base type don't get broken. See https://llvm.org/PR154146
+template <class T>
+struct common_base_allocator : allocator_base {
+  using value_type = T;
+
+  common_base_allocator() TEST_NOEXCEPT {}
+
+  template <class U>
+  common_base_allocator(common_base_allocator<U>) TEST_NOEXCEPT {}
+
+  T* allocate(std::size_t n);
+  void deallocate(T* p, std::size_t);
+
+  friend bool operator==(common_base_allocator, common_base_allocator) { return true; }
+  friend bool operator!=(common_base_allocator, common_base_allocator) { return false; }
+};
+
+struct user_struct {
+  std::vector<bool, common_base_allocator<bool> > v;
+  [[no_unique_address]] common_base_allocator<bool> a;
+};
+
 #if __SIZE_WIDTH__ == 64
+static_assert(sizeof(user_struct) == 32, "");
+static_assert(TEST_ALIGNOF(user_struct) == 8, "");
 
 static_assert(sizeof(std::vector<bool>) == 24, "");
 static_assert(sizeof(std::vector<bool, min_allocator<bool> >) == 24, "");
@@ -53,6 +81,8 @@ static_assert(TEST_ALIGNOF(std::vector<bool, test_allocator<bool> >) == 8, "");
 static_assert(TEST_ALIGNOF(std::vector<bool, small_iter_allocator<bool> >) == 2, "");
 
 #elif __SIZE_WIDTH__ == 32
+static_assert(sizeof(user_struct) == 16, "");
+static_assert(TEST_ALIGNOF(user_struct) == 4, "");
 
 static_assert(sizeof(std::vector<bool>) == 12, "");
 static_assert(sizeof(std::vector<bool, min_allocator<bool> >) == 12, "");

diff  --git a/libcxx/test/libcxx/containers/sequences/vector/abi.compile.pass.cpp b/libcxx/test/libcxx/containers/sequences/vector/abi.compile.pass.cpp
index 57684951c8e8e..879e143510752 100644
--- a/libcxx/test/libcxx/containers/sequences/vector/abi.compile.pass.cpp
+++ b/libcxx/test/libcxx/containers/sequences/vector/abi.compile.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+// XFAIL: FROZEN-CXX03-HEADERS-FIXME
+
 #include <cstdint>
 #include <vector>
 
@@ -46,7 +48,33 @@ class small_iter_allocator {
   friend bool operator!=(small_iter_allocator, small_iter_allocator) { return false; }
 };
 
+struct allocator_base {};
+
+// Make sure that types with a common base type don't get broken. See https://llvm.org/PR154146
+template <class T>
+struct common_base_allocator : allocator_base {
+  using value_type = T;
+
+  common_base_allocator() TEST_NOEXCEPT {}
+
+  template <class U>
+  common_base_allocator(common_base_allocator<U>) TEST_NOEXCEPT {}
+
+  T* allocate(std::size_t n);
+  void deallocate(T* p, std::size_t);
+
+  friend bool operator==(common_base_allocator, common_base_allocator) { return true; }
+  friend bool operator!=(common_base_allocator, common_base_allocator) { return false; }
+};
+
+struct user_struct {
+  std::vector<int, common_base_allocator<int> > v;
+  [[no_unique_address]] common_base_allocator<int> a;
+};
+
 #if __SIZE_WIDTH__ == 64
+static_assert(sizeof(user_struct) == 32, "");
+static_assert(TEST_ALIGNOF(user_struct) == 8, "");
 
 static_assert(sizeof(std::vector<int>) == 24, "");
 static_assert(sizeof(std::vector<int, min_allocator<int> >) == 24, "");
@@ -69,6 +97,8 @@ static_assert(TEST_ALIGNOF(std::vector<char, test_allocator<char> >) == 8, "");
 static_assert(TEST_ALIGNOF(std::vector<char, small_iter_allocator<char> >) == 2, "");
 
 #elif __SIZE_WIDTH__ == 32
+static_assert(sizeof(user_struct) == 16, "");
+static_assert(TEST_ALIGNOF(user_struct) == 4, "");
 
 static_assert(sizeof(std::vector<int>) == 12, "");
 static_assert(sizeof(std::vector<int, min_allocator<int> >) == 12, "");

diff  --git a/libcxx/test/libcxx/containers/strings/basic.string/abi.compile.pass.cpp b/libcxx/test/libcxx/containers/strings/basic.string/abi.compile.pass.cpp
new file mode 100644
index 0000000000000..cf802e214d07c
--- /dev/null
+++ b/libcxx/test/libcxx/containers/strings/basic.string/abi.compile.pass.cpp
@@ -0,0 +1,106 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <cstdint>
+#include <string>
+
+#include "min_allocator.h"
+#include "test_allocator.h"
+#include "test_macros.h"
+
+template <class T>
+class small_pointer {
+public:
+  using value_type        = T;
+  using 
diff erence_type   = std::int16_t;
+  using pointer           = small_pointer;
+  using reference         = T&;
+  using iterator_category = std::random_access_iterator_tag;
+
+private:
+  std::uint16_t offset;
+};
+
+template <class T>
+class small_iter_allocator {
+public:
+  using value_type      = T;
+  using pointer         = small_pointer<T>;
+  using size_type       = std::int16_t;
+  using 
diff erence_type = std::int16_t;
+
+  small_iter_allocator() TEST_NOEXCEPT {}
+
+  template <class U>
+  small_iter_allocator(small_iter_allocator<U>) TEST_NOEXCEPT {}
+
+  T* allocate(std::size_t n);
+  void deallocate(T* p, std::size_t);
+
+  friend bool operator==(small_iter_allocator, small_iter_allocator) { return true; }
+  friend bool operator!=(small_iter_allocator, small_iter_allocator) { return false; }
+};
+
+struct allocator_base {};
+
+// Make sure that types with a common base type don't get broken. See https://llvm.org/PR154146
+template <class T>
+struct common_base_allocator : allocator_base {
+  using value_type = T;
+
+  common_base_allocator() TEST_NOEXCEPT {}
+
+  template <class U>
+  common_base_allocator(common_base_allocator<U>) TEST_NOEXCEPT {}
+
+  T* allocate(std::size_t n);
+  void deallocate(T* p, std::size_t);
+
+  friend bool operator==(common_base_allocator, common_base_allocator) { return true; }
+  friend bool operator!=(common_base_allocator, common_base_allocator) { return false; }
+};
+
+template <class Alloc>
+using string_alloc = std::basic_string<char, std::char_traits<char>, Alloc>;
+
+struct user_struct {
+  string_alloc<common_base_allocator<char> > v;
+  [[no_unique_address]] common_base_allocator<int> a;
+};
+
+#if __SIZE_WIDTH__ == 64
+static_assert(sizeof(user_struct) == 32, "");
+static_assert(TEST_ALIGNOF(user_struct) == 8, "");
+
+static_assert(sizeof(string_alloc<std::allocator<char> >) == 24, "");
+static_assert(sizeof(string_alloc<min_allocator<char> >) == 24, "");
+static_assert(sizeof(string_alloc<test_allocator<char> >) == 32, "");
+static_assert(sizeof(string_alloc<small_iter_allocator<char> >) == 6, "");
+
+static_assert(TEST_ALIGNOF(string_alloc<std::allocator<char> >) == 8, "");
+static_assert(TEST_ALIGNOF(string_alloc<min_allocator<char> >) == 8, "");
+static_assert(TEST_ALIGNOF(string_alloc<test_allocator<char> >) == 8, "");
+static_assert(TEST_ALIGNOF(string_alloc<small_iter_allocator<char> >) == 2, "");
+
+#elif __SIZE_WIDTH__ == 32
+static_assert(sizeof(user_struct) == 16, "");
+static_assert(TEST_ALIGNOF(user_struct) == 4, "");
+
+static_assert(sizeof(string_alloc<std::allocator<char> >) == 12, "");
+static_assert(sizeof(string_alloc<min_allocator<char> >) == 12, "");
+static_assert(sizeof(string_alloc<test_allocator<char> >) == 24, "");
+static_assert(sizeof(string_alloc<small_iter_allocator<char> >) == 6, "");
+
+static_assert(TEST_ALIGNOF(string_alloc<std::allocator<char> >) == 4, "");
+static_assert(TEST_ALIGNOF(string_alloc<min_allocator<char> >) == 4, "");
+static_assert(TEST_ALIGNOF(string_alloc<test_allocator<char> >) == 4, "");
+static_assert(TEST_ALIGNOF(string_alloc<small_iter_allocator<char> >) == 2, "");
+
+#else
+#  error std::size_t has an unexpected size
+#endif


        


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