commit 3c989bcda6f9c5dfed78f2c69e364e5eea46e023
author Louis Dionne <ldionne@apple.com> Mon Sep 28 17:29:52 2020 -0400
committer Louis Dionne <ldionne@apple.com> Mon Sep 28 17:44:31 2020 -0400
tree 2aceb091d620feb802c1e3712dad312702e86bef
parent 5ffe515ed655de73515050ae410d53e3d69c3179

[libc++] Fix constexpr dynamic allocation on GCC 10

We're technically not allowed by the Standard to call ::operator new in
constexpr functions like __libcpp_allocate. Clang doesn't seem to complain
about it, but GCC does.

Cr-Mirrored-From: https://chromium.googlesource.com/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: d092c912885cc152bef27019525b8fd0761aaaa2

include/memory

diff --git a/include/memory b/include/memory
index 112ee9d..67a6ddd 100644
--- a/include/memory
+++ b/include/memory
@@ -1678,12 +1678,20 @@
         if (__n > allocator_traits<allocator>::max_size(*this))
             __throw_length_error("allocator<T>::allocate(size_t n)"
                                  " 'n' exceeds maximum supported size");
-        return static_cast<_Tp*>(_VSTD::__libcpp_allocate(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp)));
+        if (__libcpp_is_constant_evaluated()) {
+            return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));
+        } else {
+            return static_cast<_Tp*>(_VSTD::__libcpp_allocate(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp)));
+        }
     }
 
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
     void deallocate(_Tp* __p, size_t __n) _NOEXCEPT {
-        _VSTD::__libcpp_deallocate((void*)__p, __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp));
+        if (__libcpp_is_constant_evaluated()) {
+            ::operator delete(__p);
+        } else {
+            _VSTD::__libcpp_deallocate((void*)__p, __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp));
+        }
     }
 
     // C++20 Removed members
@@ -1751,12 +1759,20 @@
         if (__n > allocator_traits<allocator>::max_size(*this))
             __throw_length_error("allocator<const T>::allocate(size_t n)"
                                  " 'n' exceeds maximum supported size");
-        return static_cast<const _Tp*>(_VSTD::__libcpp_allocate(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp)));
+        if (__libcpp_is_constant_evaluated()) {
+            return static_cast<const _Tp*>(::operator new(__n * sizeof(_Tp)));
+        } else {
+            return static_cast<const _Tp*>(_VSTD::__libcpp_allocate(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp)));
+        }
     }
 
     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
     void deallocate(const _Tp* __p, size_t __n) {
-        _VSTD::__libcpp_deallocate((void*) const_cast<_Tp *>(__p), __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp));
+        if (__libcpp_is_constant_evaluated()) {
+            ::operator delete(const_cast<_Tp*>(__p));
+        } else {
+            _VSTD::__libcpp_deallocate((void*) const_cast<_Tp *>(__p), __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp));
+        }
     }
 
     // C++20 Removed members