Bernhard Mohr <bernh
...@diagonal.ch> wrote:
> An alias is declared like this (LRM 4.3.3):
> alias_declaration::=
> alias alias_designator [: subtype_indication]
> is name [signature];
> later int the LRM (4.3.3.2 b) there is written:
> A signature is required if the name denotes a subprogram
> (including an operator) or enumberation literal.
> How can a enumeration literal be a name? Is it legal to have
> the following alias defined ?
or a character literal (for example, '0').
An identifier is a name (see Chapter 6).
A character literal can be part of a name; for example, it is part of
a selected name: Std.Standard.'0' (which is ambiguous, since it can
denote either the literal in Std.Standard.Bit or Std.Standard.Character).
But a character literal is not a name (again, see Chapter 6).
> alias zero is true [return boolean];
> alias low is '0' [return bit];
The first example is legal, the second is not (since '0' is not a name).
> Maybe the correct syntax declaration of an alias shoud be
> alias_declaration::=
> alias alias_designator [: subtype_indication]
> is name | enumeration_literal [signature];
Perhaps; the only thing this change allows is to make the second
example legal. Note that
alias low is ieee.std_logic_1164.'0' [return std_ulogic];
is legal in either formulation.
Regards,
Paul
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