Re: *Ping* patch, fortran] Warn about constant integer divisions

[Jerry DeLisle <jvdelisle at charter dot net>]

On 06/23/2015 01:36 AM, Janne Blomqvist wrote:
> On Sun, Jun 21, 2015 at 4:57 PM, Thomas Koenig <tkoenig@netcologne.de> wrote:
>> *ping*
>>
>> https://gcc.gnu.org/ml/gcc-patches/2015-06/msg00966.html
>>
>>
>>> Hello world,
>>>
>>> the attached patch emits a warning for constant integer division.
>>> While correct according to the standard, I cannot really think
>>> of a legitimate reason why people would want to write 3/5 where
>>> they could have written 0 , so my preference would be to put
>>> this under -Wconversion (like in the attached patch).
>>>
>>> However, I am open to discussion on that.  It is easy enough to
>>> change.
>>>
>>> Regression-tested.  Opinions?  Comments?  Would somebody rather
>>> have -Wconversion-extra?  OK for trunk?
> 
> I'm a bit uncomfortable about this. IIRC I have code where I'm
> iterating over some kind of grid, and I'm using integer division and
> relying on truncation to calculate array indices. I can certainly
> imagine that others have used it as well, and even that it's not a
> particularly uncommon pattern.
> 
> Furthermore, I think it's confusing that you have it under
> -Wconversion, as there is no type conversion going on.
> -Winteger-truncation maybe?
> 
> Any other opinions?
> 

I am not sure it is worth warning about. I don't think it justifies its own
compilation warning option. I have no objection to -Wconversion, 3/5 being
converted to zero in a sense. It would help users catch a missing decimal point
when they meant 3./5

Regards,

Jerry

Jerry