[fpc-devel] Dangerous optimization in CASE..OF

[Martok]

Hi all,

Am 02.07.2017 um 22:02 schrieb Florian Klämpfl:
> Am 02.07.2017 um 21:40 schrieb Martok:
>> Honestly, I still don't understand why we're even having this discussion.
> Because it is a fundamental question: if there is any defined behavior possible if a variable
> contains an invalid value. I consider a value outside of the declared range as invalid
So, as this is the core of all this, I have spent the last few days asking
various users of pascal languages in different compilers, intentionally without
telling them what this was about. Not a single one considered out-of-range
ordinal values as something bad (though not terribly useful), especially not
causing undefined behaviour: all assumed that they would continue to behave like
ordinals in comparisons.

Something I hadn't known, and which I find quite funny: that group apparently
includes Anders Hejlsberg, who wrote the original Turbo Pascal compiler and
years later specifically defined C# enums contrary to your assumption. In fact,
this entire thread's topic is an actual example in the language reference:
<https://docs.microsoft.com/en-gb/dotnet/csharp/language-reference/keywords/enum>

I haven't yet told all of them why I asked (one set of answers comes from a
forum thread that I don't want to spoil yet, maybe tomorrow evening), but those
who I asked in private all have at some point written code that relies on that
concept and are "irritated" why that wouldn't work in FPC.

All that seems to leave only one conclusion...


Kind regards,

Martok