Reland "[lldb][test] TestDataFormatterLibcxxStringSimulator.py: add new padding layout" (#111123)

Relands #108375 which had to be
reverted because it was failing on the Windows buildbot. Trying to
reland this with `msvc::no_unique_address` on Windows.

Author: Michael137

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

@@ -7,6 +7,12 @@
 namespace std {
 namespace __lldb {
 
+#if __has_cpp_attribute(msvc::no_unique_address)
+#define _LLDB_NO_UNIQUE_ADDRESS [[msvc::no_unique_address]]
+#elif __has_cpp_attribute(no_unique_address)
+#define _LLDB_NO_UNIQUE_ADDRESS [[__no_unique_address__]]
+#endif
+
 #if COMPRESSED_PAIR_REV == 0 // Post-c88580c layout
 struct __value_init_tag {};
 struct __default_init_tag {};
@@ -55,7 +61,7 @@ class __compressed_pair : private __compressed_pair_elem<_T1, 0>,
 #elif COMPRESSED_PAIR_REV == 1
 // From libc++ datasizeof.h
 template <class _Tp> struct _FirstPaddingByte {
-  [[no_unique_address]] _Tp __v_;
+  _LLDB_NO_UNIQUE_ADDRESS _Tp __v_;
   char __first_padding_byte_;
 };
 
@@ -75,29 +81,30 @@ template <class _ToPad> class __compressed_pair_padding {
 };
 
 #define _LLDB_COMPRESSED_PAIR(T1, Initializer1, T2, Initializer2)              \
-  [[__gnu__::__aligned__(alignof(T2))]] [[no_unique_address]] T1 Initializer1; \
-  [[no_unique_address]] __compressed_pair_padding<T1> __padding1_;             \
-  [[no_unique_address]] T2 Initializer2;                                       \
-  [[no_unique_address]] __compressed_pair_padding<T2> __padding2_;
+  [[__gnu__::__aligned__(                                                      \
+      alignof(T2))]] _LLDB_NO_UNIQUE_ADDRESS T1 Initializer1;                  \
+  _LLDB_NO_UNIQUE_ADDRESS __compressed_pair_padding<T1> __padding1_;           \
+  _LLDB_NO_UNIQUE_ADDRESS T2 Initializer2;                                     \
+  _LLDB_NO_UNIQUE_ADDRESS __compressed_pair_padding<T2> __padding2_;
 
 #define _LLDB_COMPRESSED_TRIPLE(T1, Initializer1, T2, Initializer2, T3,        \
                                 Initializer3)                                  \
   [[using __gnu__: __aligned__(alignof(T2)),                                   \
-    __aligned__(alignof(T3))]] [[no_unique_address]] T1 Initializer1;          \
-  [[no_unique_address]] __compressed_pair_padding<T1> __padding1_;             \
-  [[no_unique_address]] T2 Initializer2;                                       \
-  [[no_unique_address]] __compressed_pair_padding<T2> __padding2_;             \
-  [[no_unique_address]] T3 Initializer3;                                       \
-  [[no_unique_address]] __compressed_pair_padding<T3> __padding3_;
+    __aligned__(alignof(T3))]] _LLDB_NO_UNIQUE_ADDRESS T1 Initializer1;        \
+  _LLDB_NO_UNIQUE_ADDRESS __compressed_pair_padding<T1> __padding1_;           \
+  _LLDB_NO_UNIQUE_ADDRESS T2 Initializer2;                                     \
+  _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
 #define _LLDB_COMPRESSED_PAIR(T1, Name1, T2, Name2)                            \
-  [[no_unique_address]] T1 Name1;                                              \
-  [[no_unique_address]] T2 Name2
+  _LLDB_NO_UNIQUE_ADDRESS T1 Name1;                                            \
+  _LLDB_NO_UNIQUE_ADDRESS T2 Name2
 
 #define _LLDB_COMPRESSED_TRIPLE(T1, Name1, T2, Name2, T3, Name3)               \
-  [[no_unique_address]] T1 Name1;                                              \
-  [[no_unique_address]] T2 Name2;                                              \
-  [[no_unique_address]] T3 Name3
+  _LLDB_NO_UNIQUE_ADDRESS T1 Name1;                                            \
+  _LLDB_NO_UNIQUE_ADDRESS T2 Name2;                                            \
+  _LLDB_NO_UNIQUE_ADDRESS T3 Name3
 #endif
 } // namespace __lldb
 } // namespace std

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

@@ -27,7 +27,7 @@ def _run_test(self, defines):
 
 
 for v in [None, "ALTERNATE_LAYOUT"]:
-    for r in range(5):
+    for r in range(6):
         for c in range(3):
             name = "test_r%d_c%d" % (r, c)
             defines = ["REVISION=%d" % r, "COMPRESSED_PAIR_REV=%d" % c]

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

@@ -20,7 +20,11 @@
 // Pre-D128285 layout.
 #define PACKED_ANON_STRUCT
 #endif
-// REVISION == 4: current layout
+#if REVISION <= 4
+// Pre-2a1ef74 layout.
+#define NON_STANDARD_PADDING
+#endif
+// REVISION == 5: current layout
 
 #ifdef PACKED_ANON_STRUCT
 #define BEGIN_PACKED_ANON_STRUCT struct __attribute__((packed)) {
@@ -34,13 +38,21 @@
 namespace std {
 namespace __lldb {
 
+#ifdef NON_STANDARD_PADDING
 #if defined(ALTERNATE_LAYOUT) && defined(SUBCLASS_PADDING)
 template <class _CharT, size_t = sizeof(_CharT)> struct __padding {
   unsigned char __xx[sizeof(_CharT) - 1];
 };
 
 template <class _CharT> struct __padding<_CharT, 1> {};
 #endif
+#else // !NON_STANDARD_PADDING
+template <size_t _PaddingSize> struct __padding {
+  char __padding_[_PaddingSize];
+};
+
+template <> struct __padding<0> {};
+#endif
 
 template <class _CharT, class _Traits, class _Allocator> class basic_string {
 public:
@@ -77,7 +89,12 @@ template <class _CharT, class _Traits, class _Allocator> class basic_string {
     };
 #else // !SUBCLASS_PADDING
 
+#ifdef NON_STANDARD_PADDING
     unsigned char __padding[sizeof(value_type) - 1];
+#else
+    _LLDB_NO_UNIQUE_ADDRESS __padding<sizeof(value_type) - 1> __padding_;
+#endif
+
 #ifdef BITMASKS
     unsigned char __size_;
 #else // !BITMASKS
@@ -129,21 +146,26 @@ template <class _CharT, class _Traits, class _Allocator> class basic_string {
     union {
 #ifdef BITMASKS
       unsigned char __size_;
-#else
+#else  // !BITMASKS
       struct {
         unsigned char __is_long_ : 1;
         unsigned char __size_ : 7;
       };
-#endif
+#endif // BITMASKS
       value_type __lx;
     };
-#else
+#else  // !SHORT_UNION
     BEGIN_PACKED_ANON_STRUCT
     unsigned char __is_long_ : 1;
     unsigned char __size_ : 7;
     END_PACKED_ANON_STRUCT
-    char __padding_[sizeof(value_type) - 1];
-#endif
+#ifdef NON_STANDARD_PADDING
+    unsigned char __padding[sizeof(value_type) - 1];
+#else  // !NON_STANDARD_PADDING
+    _LLDB_NO_UNIQUE_ADDRESS __padding<sizeof(value_type) - 1> __padding_;
+#endif // NON_STANDARD_PADDING
+
+#endif // SHORT_UNION
     value_type __data_[__min_cap];
   };