[fpc-devel] [Suggestion] Enumeration range-check intrinsic

[Michael Van Canneyt]

On Sat, 6 Jul 2019, Ondrej Pokorny wrote:

> On 05.07.2019 22:44, J. Gareth Moreton wrote:
>> 
>> In the meantime, I've extended your AS/IS patch over here 
>> <https://bugs.freepascal.org/view.php?id=33603> to create efficient code 
>> for x86 platforms, although currently it only does a range check and won't 
>> correctly handle enumerations with holes.  If non-contiguous enumerations 
>> are going to be allowed, we'll need to design an algorithm that can cover 
>> these holes with the smallest number of Boolean conditions.
>> 
> IMO handling holes in enumerations is just a pure waste of time and energy. 
> Delphi documents them as valid and the FPC compiler handles them as valid as 
> well. IMO it is just an unnecessary extra added limitation to disable IS/AS 
> on them. Furthermore they are used mainly for very specific needs, so are 
> very marginal. The effort to make this work just doesn't pay off.

After considering what Ondrej pointed out about the behaviour of FPC and
delphi, I agree that checking lower and upper bounds should be sufficient.

Michael.