Re: Does a null pointer always raise Constraint_Error?

["Ken Garlington" <Ken.Garlington@computer.org>]

"Lutz Donnerhacke" <lutz@iks-jena.de> wrote in message
news:slrn93eect.i1.lutz@taranis.iks-jena.de...
: * Robert Dewar wrote:
: [access to empty arrays represent as Null (System.Address)]
: >   subtype n is string (1 .. 0);
: >   type np is access n;
: >   a, b : np;
: >
: >   if a.all = b.all then ...
: >
: >it is a common compiler bug to translate this as
: >
: >   for j in n'range loop
: >     if a.all (j) = b.all (j) ....
: >
: >and the null loop causes no checks to be made :-)
:
: I do not see the bug.

Probably explains why it's so common...

(I'm guessing it might have something to do with the case where a or b are
null. Presumably, no exception would be raised if the compiler generated
this kind of code, due to n'range causing the body of the loop to be skipped
altogether?)