[dcl.attr.deprecated]

9 Declarations [dcl]

9.13 Attributes [dcl.attr]

9.13.4 Deprecated attribute [dcl.attr.deprecated]

The attribute-token deprecated can be used to mark names and entities whose use is still allowed, but is discouraged for some reason.

[Note 1:

In particular, deprecated is appropriate for names and entities that are deemed obsolescent or unsafe.

— end note]

The attribute may be applied to the declaration of a class, a type alias, a variable, a non-static data member, a function, a namespace, an enumeration, an enumerator, a concept, or a template specialization.

An entity declared without the deprecated attribute can later be redeclared with the attribute and vice-versa.

[Note 3:

Thus, an entity initially declared without the attribute can be marked as deprecated by a subsequent redeclaration.

However, after an entity is marked as deprecated, later redeclarations do not un-deprecate the entity.

— end note]

Recommended practice: Implementations should use the deprecated attribute to produce a diagnostic message in case the program refers to a name or entity other than to declare it, after a declaration that specifies the attribute.

The diagnostic message should include the text provided within the attribute-argument-clause of any deprecated attribute applied to the name or entity.

The value of a has-attribute-expression for the deprecated attribute should be 0 unless the implementation can issue such diagnostic messages.