Re: Language lawyer needed

[dlc@ddsdx2.jhuapl.edu (Dave Collard x7468)]

In <1993Apr1.215753.3147@oracorp.com> davidg@oracorp.com (David Guaspari) writes:

>Here's a question for language lawyers.

>Consider the following pathological program:

>   procedure Q(x : integer) is  
>   begin
>     declare
>       x : integer;   -- (1)
>     begin
>       Q(x => 0);     -- (2)
>     end;
>   end Q;

>My question concerns the legality of Q (forgetting about the fact that
>its execution won't terminate).  One way to apply chapter 8 in the
>reference manual goes as follows:

>  The declaration of x in (1) hides the declaration of x as a formal
>  parameter of Q.

>  Therefore, by the visibility rules, the occurrence of x in (2) has
>  exactly one possible meaning, namely that given by the declaration
>  in (1). 

>  However, the declaration in (1) is not visible by selection at the
>  point at which x occurs in (2).

>  Therefore the call in (2) is illegal.

The 'x' in (2) does not refer to a variable -- it is
part of a named parameter association and has
nothing to do with the visibility of either the formal parameter
'x' or the 'x' declared in (1).  Q is visible at (2)
with the correct parameter and result type profile -- that is
the name 'x' is indeed a formal parameter of Q and the actual 
0 matches the integer type of that parameter.


--Thor
dlc@ddsdx2.jhuapl.edu