[libc++] Refactor max_size.pass.cpp

[ldionne]

Summary

Reorganize the test and simplify the #ifdefs. Fix a typo in powerpc64
as a fly-by, and also add a test for the unstable ABI.

[philnik]

Is there any way we could let this test error if it's run in CI and the system isn't listed here? This seems like one of the tests that could easily be forgotten to update when supporting a new platform.

[ldionne]

Fail if we don't know the arch.

[philnik]

LGTM if you update the summary.

[Mordante]

LGTM, but one question.

libcxx/test/libcxx/strings/basic.string/string.capacity/max_size.pass.cpp

13

Is there a separate test for ABI v2?

[ldionne]

Address comments.

[ldionne]

libcxx/test/libcxx/strings/basic.string/string.capacity/max_size.pass.cpp

13

No, we don't have one right now, but let me try to also test for other ABI versions in this test.

libcxx/test/libcxx/strings/basic.string/string.capacity/max_size.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 
 // <string>
 
 // This test ensures that the correct max_size() is returned depending on the platform.
 
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
 #include <string>
 
 #include "test_macros.h"
 
 // alignment of the string heap buffer is hardcoded to 16
 static const size_t alignment = 16;
#ifndef TEST_HAS_NO_UNICODE_CHARS
   std::u16string u16str;
   std::u32string u32str;
   assert(u16str.max_size() == std::numeric_limits<size_t>::max() / 2 - alignment);
   assert(u32str.max_size() == std::numeric_limits<size_t>::max() / 4 - alignment);
 #endif
 }
 
 bool test() {
-#if _LIBCPP_ABI_VERSION == 1
-#ifdef __APPLE__
 
-#  ifdef __aarch64__
-  half_size();
-#  elif defined(__x86_64__)
-  full_size();
-#  else
-#    error "Your target system seems to be unsupported."
-#  endif
-
-#elif defined(__linux__)
+#if _LIBCPP_ABI_VERSION == 1
 
-#  ifdef  __x86_64__
+# if defined(__x86_64__)
   full_size();
-#  elif defined(__arm__) || defined(__aarch64__)
-#    ifdef __BIG_ENDIAN__
+# elif defined(__APPLE__) && defined(__aarch64__)
+  half_size();
+# elif defined(__arm__) || defined(__aarch64__)
+#   ifdef __BIG_ENDIAN__
   half_size();
-#    else
+#   else
   full_size();
-#    endif
-
-#  else
-#    error "Your target system seems to be unsupported."
-#  endif
-
-#elif defined(__powerpc__)
+#   endif
+# elif defined(__powerpc__) || defined(__powerpc64__)
   half_size();
-#elif defined(__powepc64__)
-  half_size();
-
-#elif defined(_WIN64)
-
-#  ifdef __x86_64__
-  full_size();
-#  else
-#    error "Your target system seems to be unsupported."
-#  endif
+# else
+#   error "Your target system seems to be unsupported."
+# endif
 
 #else
-#  error "Your target system seems to be unsupported."
-#endif
+
+  half_size();
 
 #endif
 
   return true;
 }
 
 int main(int, char**) {
   test();
 #if TEST_STD_VER > 17
   // static_assert(test());
 #endif
 
   return 0;
 }