[lldb][test] Synchronize __compressed_pair_padding with libc++ (#142516)

This PR mirrors changes of `__compressed_pair_padding` in libc++ into
lldb test suite.

Related PR for libc++:
- #108956
- #109028
- #142125

Author: frederick-vs-ja

lldb/packages/Python/lldbsuite/test/make/libcxx-simulators-common/compressed_pair.h

@@ -58,7 +58,7 @@ class __compressed_pair : private __compressed_pair_elem<_T1, 0>,
 
   _T1 &first() { return static_cast<_Base1 &>(*this).__get(); }
 };
-#elif COMPRESSED_PAIR_REV == 1
+#elif COMPRESSED_PAIR_REV == 1 || COMPRESSED_PAIR_REV == 2
 // From libc++ datasizeof.h
 template <class _Tp> struct _FirstPaddingByte {
   _LLDB_NO_UNIQUE_ADDRESS _Tp __v_;
@@ -72,13 +72,35 @@ inline const size_t __datasizeof_v =
 template <class _Tp>
 struct __lldb_is_final : public integral_constant<bool, __is_final(_Tp)> {};
 
+// The legacy layout has been patched, see
+// https://github.com/llvm/llvm-project/pull/142516.
+#if COMPRESSED_PAIR_REV == 1
 template <class _ToPad> class __compressed_pair_padding {
   char __padding_[((is_empty<_ToPad>::value &&
                     !__lldb_is_final<_ToPad>::value) ||
                    is_reference<_ToPad>::value)
                       ? 0
                       : sizeof(_ToPad) - __datasizeof_v<_ToPad>];
 };
+#else
+template <class _ToPad>
+inline const bool __is_reference_or_unpadded_object =
+    (std::is_empty<_ToPad>::value && !__lldb_is_final<_ToPad>::value) ||
+    sizeof(_ToPad) == __datasizeof_v<_ToPad>;
+
+template <class _Tp>
+inline const bool __is_reference_or_unpadded_object<_Tp &> = true;
+
+template <class _Tp>
+inline const bool __is_reference_or_unpadded_object<_Tp &&> = true;
+
+template <class _ToPad, bool _Empty = __is_reference_or_unpadded_object<_ToPad>>
+class __compressed_pair_padding {
+  char __padding_[sizeof(_ToPad) - __datasizeof_v<_ToPad>] = {};
+};
+
+template <class _ToPad> class __compressed_pair_padding<_ToPad, true> {};
+#endif
 
 #define _LLDB_COMPRESSED_PAIR(T1, Initializer1, T2, Initializer2)              \
   [[__gnu__::__aligned__(                                                      \
@@ -96,7 +118,7 @@ template <class _ToPad> class __compressed_pair_padding {
   _LLDB_NO_UNIQUE_ADDRESS __compressed_pair_padding<T2> __padding2_;           \
   _LLDB_NO_UNIQUE_ADDRESS T3 Initializer3;                                     \
   _LLDB_NO_UNIQUE_ADDRESS __compressed_pair_padding<T3> __padding3_;
-#elif COMPRESSED_PAIR_REV == 2
+#elif COMPRESSED_PAIR_REV == 3
 #define _LLDB_COMPRESSED_PAIR(T1, Name1, T2, Name2)                            \
   _LLDB_NO_UNIQUE_ADDRESS T1 Name1;                                            \
   _LLDB_NO_UNIQUE_ADDRESS T2 Name2

lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/invalid-vector/main.cpp

@@ -1,4 +1,4 @@
-#define COMPRESSED_PAIR_REV 2
+#define COMPRESSED_PAIR_REV 3
 #include <libcxx-simulators-common/compressed_pair.h>
 
 namespace std {

lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/string/TestDataFormatterLibcxxStringSimulator.py

@@ -28,7 +28,7 @@ def _run_test(self, defines):
 
 for v in [None, "ALTERNATE_LAYOUT"]:
     for r in range(6):
-        for c in range(3):
+        for c in range(4):
             name = "test_r%d_c%d" % (r, c)
             defines = ["REVISION=%d" % r, "COMPRESSED_PAIR_REV=%d" % c]
             if v:

lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/string/main.cpp

@@ -209,22 +209,22 @@ template <class _CharT, class _Traits, class _Allocator> class basic_string {
   __long &getLongRep() {
 #if COMPRESSED_PAIR_REV == 0
     return __r_.first().__l;
-#elif COMPRESSED_PAIR_REV <= 2
+#elif COMPRESSED_PAIR_REV <= 3
     return __rep_.__l;
 #endif
   }
 
   __short &getShortRep() {
 #if COMPRESSED_PAIR_REV == 0
     return __r_.first().__s;
-#elif COMPRESSED_PAIR_REV <= 2
+#elif COMPRESSED_PAIR_REV <= 3
     return __rep_.__s;
 #endif
   }
 
 #if COMPRESSED_PAIR_REV == 0
   std::__lldb::__compressed_pair<__rep, allocator_type> __r_;
-#elif COMPRESSED_PAIR_REV <= 2
+#elif COMPRESSED_PAIR_REV <= 3
   _LLDB_COMPRESSED_PAIR(__rep, __rep_, allocator_type, __alloc_);
 #endif
 

lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/unique_ptr/TestDataFormatterLibcxxUniquePtrSimulator.py

@@ -26,7 +26,7 @@ def _run_test(self, defines):
         )
 
 
-for r in range(3):
+for r in range(4):
     name = "test_r%d" % r
     defines = ["COMPRESSED_PAIR_REV=%d" % r]
 

lldb/test/API/functionalities/data-formatter/data-formatter-stl/libcxx-simulators/unique_ptr/main.cpp

@@ -20,7 +20,8 @@ template <class _Tp, class _Dp = default_delete<_Tp>> class unique_ptr {
   std::__lldb::__compressed_pair<pointer, deleter_type> __ptr_;
   explicit unique_ptr(pointer __p) noexcept
       : __ptr_(__p, std::__lldb::__value_init_tag()) {}
-#elif COMPRESSED_PAIR_REV == 1 || COMPRESSED_PAIR_REV == 2
+#elif COMPRESSED_PAIR_REV == 1 || COMPRESSED_PAIR_REV == 2 ||                  \
+    COMPRESSED_PAIR_REV == 3
   _LLDB_COMPRESSED_PAIR(pointer, __ptr_, deleter_type, __deleter_);
   explicit unique_ptr(pointer __p) noexcept : __ptr_(__p), __deleter_() {}
 #endif