16 Library introduction [library]

16.5 Library-wide requirements [requirements]

16.5.3 Requirements on types and expressions [utility.requirements]

16.5.3.5 Cpp17Allocator requirements [allocator.requirements]

16.5.3.5.1 Allocator completeness requirements [allocator.requirements.completeness]

If X is an allocator class for type T, X additionally satisfies the allocator completeness requirements if, whether or not T is a complete type: