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

[FX]

Reading the thread, and in particular this:

>> Thomas, please following Janne's suggestion of adding a new
>> -W option (I'll suggest -Winteger-division) and add this
>> to -Wall.
> 
> After following this discussion, I think this is what makes the most
> sense.

and this:

>   i = 4 / 2
>       1
> Warning: Integer division simplifies to constant '2' at (1) [-Wconversion]
> a.f90:9:7:
> 
> In compiling LAPACK, there are few n*(n+1)/2 type warnings.
> So, yes, it might produce an annoying warning.  So be it.

I don’t think the proposed warning belongs to -Wall at all, probably more like -Wextra.

The doc for -Wall says: “warning options pertaining to usage that we recommend avoiding and that we believe are easy to avoid”. Do we consider integer division bad practice? I think there are cases where it’s actually good practice, such as the n*(n+1)/2 example mentionned. Moreover, it’s not easily avoided (defining another named constant with the numeric value? not really good practice if you ask me).

Adding “borderline useful" warnings to -Wall just means people will use it less, decreases its value.


FX