Re: Any way to get a warning if a non-boolean type is used in an if expression?
Re: Any way to get a warning if a non-boolean type is used in an if expression?
- Subject: Re: Any way to get a warning if a non-boolean type is used in an if expression?
- From: Sean McBride <email@hidden>
- Date: Fri, 18 Oct 2013 11:56:36 -0400
- Organization: Rogue Research Inc.
On Fri, 18 Oct 2013 08:48:58 -0700, Jens Alfke said:
>> Relatedly, I think a lack of warning on this is even worse:
>>
>> BOOL x = ...
>> if (x == YES)
>> ...
>
>Ouch, I’ve run into that before, especially with bit-tests like
> BOOL x = flags & (1<<kFlagBit);
>If kFlagBit isn’t zero, the example you gave doesn’t work right. (A
>related even worse case is where kFlagBit > 7, in which case x always
>ends up as 0 because the flag gets truncated out of the 8-bit BOOL value
>entirely, so even a correctly-written ‘if’ statement fails.)
>
>My understanding is that with the ‘bool’ type my example would work
>correctly, because the assignment would do an implicit “!= 0”
>comparison, and maybe that was the justification for bool’s weird
>behavior. I’d much rather get a warning.
Yes, it would work with 'bool'. Hopefully Obj-C will one day change BOOL from char to bool.
I filed this bug a few years ago: <http://llvm.org/PR9194> Maybe I should file it in the black hole too...
One day I hope to have time to muck around in clang and try to add it. :)
Cheers,
--
____________________________________________________________
Sean McBride, B. Eng email@hidden
Rogue Research www.rogue-research.com
Mac Software Developer Montréal, Québec, Canada
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