[4.5, Fortran, Patch] PR 38432 - Add warning for loops which are never executed

[Daniel Kraft]

Hi Tobias,

Tobias Burnus wrote:
> the patch adds a warning for loops which have zero iterations, e.g.
> 
> do i = 1, 0
>    ! never reached
> end do
> 
> (/ i, i=1,2,-1 /)  ! Empty array
> 
> The question is whether the warning should be printed always (like
> currently) or only with -W* (-Wsurprising)? For normal loops there are
> nearly alway not intended; for array constructors they can be used on
> purpose to construct zero-sized arrays; I don't think that happens often
> with real-world code, but some (few) programs could have a lot of those.

My opinion is that we should go for always printing the warning, unless 
-w is given of course.  On the other hand, I'm not aware of many 
warnings (that is, none except the non-polymorphic passed-object 
warning) being printed without any -W flag, so maybe -Wsurprising is in 
fact the better choice.  But both is ok for me.

> Build and tested on x86-64-linux.
> OK for 4.5?

OK for 4.5, thanks for the patch!

Yours,
Daniel

-- 
Done:  Arc-Bar-Cav-Rog-Sam-Val-Wiz
To go: Hea-Kni-Mon-Pri-Ran-Tou