Pragma Attribute_Definition (GNAT Reference Manual)

### 2.22 Pragma Attribute_Definition ¶

Syntax:

    pragma Attribute_Definition
      ([Attribute  =>] ATTRIBUTE_DESIGNATOR,
       [Entity     =>] LOCAL_NAME,
       [Expression =>] EXPRESSION | NAME);

If `Attribute` is a known attribute name, this pragma is equivalent to the attribute definition clause:

    for Entity'Attribute use Expression;

If `Attribute` is not a recognized attribute name, the pragma is ignored, and a warning is emitted. This allows source code to be written that takes advantage of some new attribute, while remaining compilable with earlier compilers.