2.0 KiB
[dcl.attr.nouniqueaddr]
9 Declarations [dcl]
9.13 Attributes [dcl.attr]
9.13.11 No unique address attribute [dcl.attr.nouniqueaddr]
The attribute-token no_unique_address specifies that a non-static data member is a potentially-overlapping subobject ([intro.object]).
No attribute-argument-clause shall be present.
The attribute may appertain to a non-static data member other than a bit-field.
[Note 1:
The non-static data member can share the address of another non-static data member or that of a base class, and any padding that would normally be inserted at the end of the object can be reused as storage for other members.
â end note]
Recommended practice: The value of a has-attribute-expression for the no_unique_address attribute should be 0 for a given implementation unless this attribute can cause a potentially-overlapping subobject to have zero size.
[Example 1: template<typename Key, typename Value, typename Hash, typename Pred, typename Allocator>class hash_map {no_unique_address Hash hasher; no_unique_address Pred pred; no_unique_address Allocator alloc; Bucket *buckets; // ...public:// ...};
Here, hasher, pred, and alloc could have the same address as buckets if their respective types are all empty.
â end example]