[EXTERNAL] Re: [Patch, F03, RFC] FINAL support in 4.8

[Tobias Burnus]

Janus Weil wrote:
>> I don't think that it is a good idea to finalize SAVE variables by 
>> default, if they declared in the main program. 
> In fact, the current patch does it only for non-SAVE variables
> (although SAVE should not really make much of a difference for
> variables declared in the main program, right?).

In terms of the Fortran standard (F2008, 5.3.16 SAVE attribute), the 
non-SAVE doesn't make sense as:

"A variable, common block, or procedure pointer declared in the scoping 
unit of a main program, module, or submodule implicitly has the SAVE 
attribute, which may be confirmed by explicit specification."

In other words, your patch doesn't finalizes main-program variables 
which have an explicit SAVE attribute, except for those which got it 
implicitly, but, I presume, not if they got it via a SAVE
statement without a saved entity list. ;-)


>> I concur that it is unclear why the
>> standard is as it is, but I don't think to break the standard with default
>> options (-std=gnu is the default) is a good idea.
> Well, yeah. I guess one can argue about this.
>
> On one hand, a good Fortran compiler should clearly obey the Fortran
> standard. And with the -std=... switch, we even have a nice way of
> supporting different versions of the standard.
>
> On the other hand, I'd rather implement something that "makes sense"
> than something that blindly obeys some (screwed-up) standard. So, the
> first thing should be of course to find out whether this was in fact
> "screwed up" in the standard, or if it was done on purpose (and if
> yes, for what reason).

I think it was done on purpose - or at least consciously. The only 
purpose might be that it was done for consistency as variables SAVE or 
it might have a deeper reason.

You should really ask at the J3 mailing list, maybe they have a good answer.

Regarding extensions: The idea of extensions is usually to provide 
additional features without breaking the (current) standard. Your 
proposal on purpose breaks the standard.

> My idea behind implementing it as an extension was to support both
> options, and let the user choose which one he wants. However, I agree
> that using the non-standard version by default may be dangerous. Since
> we probably don't want to make -std=f2008 the default (for reasons of
> backward compatibility), one alternative might be to add a separate
> switch ("-finalize-main" or whatever).

I wouldn't oppose against an extra flag; although, I probably wouldn't 
use it.

>> It is a patch, you proposed in some regression PR.
> Me, really? I don't quite remember this ;)

PR 53718.

Tobias