Re: Division by zero

[Christoph Grein <Christoph.Grein@eurocopter.com>]

  declare
    C: constant := 0;
    D: constant := 1;
    A: constant Integer := D / C;  -- static, illegal
    function "/" (Left, Right: Integer) return Integer is
    begin
      return 1;
    end "/";
    E: constant := D / C;          -- static, illegal
    F: constant Integer := D / C;  -- legal, not static, uses overridden "/"
  begin
    null;
  end;

Lurker wrote:

>"Robert A Duff" <bobduff@shell01.TheWorld.com> wrote in message
>news:wccy88ugorw.fsf@shell01.TheWorld.com...
>
>  
>
>>11.6(5) is all about run time effects.  If divide by zero were illegal
>>(which means at compile time), then 11.6 would not apply.  11.6 is also
>>(as you said) all about implementation permissions -- i.e. not
>>portable.  I would hope a legality rule in this area would be portable.
>>    
>>
>
>OK, I don't want to get *too* deep into the language wars sort
>of thing. My surprise was quite pragmatic - I was called in (as a
>consultant) to investigate and fix a problem that led to actual program
>crash in production. The reason for that crash, as it happened, was
>division by zero in some obscure and rarely used part of the code.
>Now, I would understand it if it was a variable which is generally
>unsolvable. But a constant? At first I thought it must be a bug in this
>particular compiler version. But since then I've had quite a few replies
>stating that's how it should be. So I don't know anymore...
>
>
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