std::scoped_allocator_adaptor<OuterAlloc,InnerAlloc...>::outermost, outermost-construct, outermost-destroy

std::scoped_allocator_adaptor<OuterAlloc,InnerAlloc...>::outermost, outermost-construct, outermost-destroy - cppreference.com

From cppreference.com

`template< class Alloc > /* unspecified / /outermost/( Alloc&& alloc = this );`	(1)	(exposition only*)
`template< class T, class... Args > void /outermost-construct/( T* p, Args&&... args );`	(2)	(exposition only*)
`template< class T > void /outermost-destroy/( T* p );`	(3)	(exposition only*)

These exposition-only helper member function templates are used in member functions construct() and destroy().

1) Obtains the outermost allocator of alloc.

If the expression alloc.outer_allocator() is valid, returns outermost (alloc.outer_allocator()).
Otherwise, returns alloc.

2,3) Constructs or destroys an object using the outermost allocator of *this.

Given the type std::allocator_traits<std::remove_reference_t<decltype(outermost ())>> as outermost_traits:

2) Equivalent to outermost_traits::construct(outermost (), p, std::forward<Args>(args)...);.

3) Equivalent to outermost_traits::destroy(outermost (), p);.

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 3116	C++11	the recursion condition for `outermost` was “`alloc` has the member function `outer_allocator()`”	changed to “the expression `alloc.outer_allocator()` is valid”

	constructs an object in the allocated storage (function template) [edit]
	destructs an object stored in the allocated storage (function template) [edit]