User-Defined Attributes (UDA) are compile-time expressions introduced by the
@ token that can be attached to a declaration. These attributes can
then be queried, extracted, and manipulated at compile time.
GNU D provides a number of extra special attributes to control specific
compiler behavior that may help the compiler optimize or check code more
carefully for correctness. The attributes are defined in the
gcc.attributes module.
There is some overlap between the purposes of attributes and pragmas. It has
been found more convenient to use @attribute to achieve a natural
attachment of attributes to their corresponding declarations, whereas
pragma is of use for compatibility with other compilers or constructs
that do not naturally form part of the grammar.