Re: Memory overwrite?

["Theodore E. Dennison" <dennison@escmail.mmc.orl.com>]

bill@valiant (R.A.L Williams) wrote:
>
> In article <1995Jan18.182039.7324@wdl.loral.com> Mark Biggar wrote:
> 
> [original post and a reply deleted]
> 
> : Actually the most likely reason for this is an uninitialized variable used

> OK, I can see how an optimiser *could* do that, and, of course, RM9x
> section 3.3.1 says that 'There is no implicit initial value defined
> for a scalar subtype ... might have a value which does not belong to
> that subtype' (para 21). I'm a little suprised, however, that the
> compiler isn't expected to perform a simple data flow analysis and
> generate a warning about use of uninitialised variables. You're quite
> right though, I can't find anything in RM9x which says it should, and
> I'm pretty sure there was nothing in the Ada83 LRM.

You are right that Ada 83 did not REQUIRE this. Howerver, all four Ada
compilers that I have used generated warnings when uninitialized
variables were read or passed as "in" or "in out" parameters. Unless
you are the type that ignores compiler warnings, this situation is 
unlikely to arise. It is still worth checking out, but I would hardly
call it the "most likely reason" for the crashing behavior.  My vote
is still on misuse of either a "for use at" clause or address-access
UNCHECKED_CONVERSION.

Did you ever figure it out, Mark?

T.E.D.