Disable aligned new/delete on Apple platforms without posix_memalign

[EricWF]

Summary

This patch disables the aligned new/delet overloads on Apple platforms without posix_memalign. This fixes libc++.dylib build regressions on such platforms.
This fixes http://llvm.org/PR31448.

This patch should also be merged into the 4.0 release branch

[EricWF]

• Remove NFC parts of this patch and commit them to master.

[EricWF]

• Remove <Availability.h> include in place of defining the required macros manually.

[EricWF]

• Move __config block lower down in the file as suggested by Marshall.

[mclow.lists]

LGTM. Thanks!

[rsmith]

Does OS X have the C11 aligned_alloc function? Perhaps we could use that instead, when available.

[gparker42]

No, the old versions of OS X that lack posix_memalign also lack aligned_alloc.

[EricWF]

@rsmith I looked for an alternative provider for aligned allocation but couldn't find one, which is quite unfortunate. Is this going to mess up the __libcpp_version detection Clang does?

include/__config

 // is just a placeholder until Clang implements such macros. For now assume
 // that Windows compilers pretending to be MSVC++ target the microsoft ABI.
 #if defined(_WIN32) && defined(_MSC_VER)
 # define _LIBCPP_ABI_MICROSOFT
 #else
 # define _LIBCPP_ABI_ITANIUM
 #endif
 
+#if defined(__APPLE__)
+# if !defined(__MAC_OS_X_VERSION_MIN_REQUIRED) && \
+     defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__)
+#   define __MAC_OS_X_VERSION_MIN_REQUIRED __ENVIROMENT_MAC_OS_X_VERSION_MIN_REQUIRED__
+# endif
+# if defined(__MAC_OS_X_VERSION_MIN_REQUIRED)
+#   if __MAC_OS_X_VERSION_MIN_REQUIRED < 1060
+#     define _LIBCPP_HAS_NO_ALIGNED_ALLOCATION
+#   endif
+# endif
+#endif // defined(__APPLE__)
+
 // Need to detect which libc we're using if we're on Linux.
 #if defined(__linux__)
 #include <features.h>
 #if !defined(__GLIBC_PREREQ)
 #define __GLIBC_PREREQ(a, b) 0
 #endif // !defined(__GLIBC_PREREQ)
 #endif // defined(__linux__)
 

include/new

 #pragma GCC system_header
 #endif
 
 #if !(defined(_LIBCPP_BUILDING_NEW) || _LIBCPP_STD_VER >= 14 || \
     (defined(__cpp_sized_deallocation) && __cpp_sized_deallocation >= 201309))
 # define _LIBCPP_HAS_NO_SIZED_DEALLOCATION
 #endif
 
-#if !(defined(_LIBCPP_BUILDING_NEW) || _LIBCPP_STD_VER > 14 || \
-    (defined(__cpp_aligned_new) && __cpp_aligned_new >= 201606))
+#if !defined(_LIBCPP_HAS_NO_ALIGNED_ALLOCATION) && \
+    (!(defined(_LIBCPP_BUILDING_NEW) || _LIBCPP_STD_VER > 14 || \
+    (defined(__cpp_aligned_new) && __cpp_aligned_new >= 201606)))
 # define _LIBCPP_HAS_NO_ALIGNED_ALLOCATION
 #endif
 
 namespace std  // purposefully not using versioning namespace
 {
 
 class _LIBCPP_EXCEPTION_ABI bad_alloc
     : public exception

src/new.cpp

 
 _LIBCPP_WEAK
 void
 operator delete[] (void* ptr, size_t) _NOEXCEPT
 {
     ::operator delete[](ptr);
 }
 
+#if !defined(_LIBCPP_HAS_NO_ALIGNED_ALLOCATION)
+
 _LIBCPP_WEAK
 void *
 operator new(std::size_t size, std::align_val_t alignment) _THROW_BAD_ALLOC
 {
     if (size == 0)
         size = 1;
     if (static_cast<size_t>(alignment) < sizeof(void*))
       alignment = std::align_val_t(sizeof(void*));

 
 _LIBCPP_WEAK
 void
 operator delete[] (void* ptr, size_t, std::align_val_t alignment) _NOEXCEPT
 {
     ::operator delete[](ptr, alignment);
 }
 
+#endif // !defined(_LIBCPP_HAS_NO_ALIGNED_ALLOCATION)
+
 #endif // !__GLIBCXX__
 
 namespace std
 {
 
 #ifndef __GLIBCXX__
 const nothrow_t nothrow = {};
 #endif