Re: GNAT 4.4.5 order of conditional processing?

[Adam Beneschan <adam@irvine.com>]

On Nov 16, 2:40 pm, Adam Beneschan <a...@irvine.com> wrote:
> For instance:
>
>   subtype Index_Subtype is Integer range 1 .. 10;
>   Arr : array (Index_Subtype) of Float;
>   Curr_Index : Index_Subtype;
>
>   if Curr_Index_Initialized and Arr(Curr_Index) < -1.0 then ...
>
> Suppose Curr_Index_Initialized is FALSE and Curr_Index has never been
> initialized to anything.  The result is that if the right side is
> evaluated, Curr_Index's uninitialized value may be a value outside the
> range 1..10, and then the code will read an element of Arr that is
> outside the bounds of Arr.  Big deal.  That's not likely to make a
> program fail.  (Unless the bit pattern it reads happens to be a
> Signaling NaN, maybe!!)

Clarification: Depending on how Curr_Index is represented (some
compilers would fit it into an 8-bit byte while others would make it
as big as an Integer), evaluating Arr(Curr_Index) could make the
program fail if Curr_Index is big enough to put the element's address
out of the program's memory space.  So it's more likely to fail than I
first claimed.  Keep in mind that this is just my example and I don't
know that the OP was doing any array indexing.

                           -- Adam