Re: [Patch] Fortran: Avoid var initialization in interfaces [PR54753]

[Harald Anlauf <anlauf@gmx.de>]

Hi Tobias,

Am 29.09.21 um 10:53 schrieb Tobias Burnus:
> Found when looking at F2018:C839 / PR54753.
> 
> For INTENT(OUT) the dummy variable (might) also be default initialized
> or deallocated. However, with assumed rank, that causes issues, which
> C839 prevents. In the current GCC implementation, missing C839 constraint
> diagnostic, but also rejects-valid/ice-on-valid appears.
> 
> There are three issues, this patch solves the first:
> 
> * reject-valid issue due to adding the initializer also to a dummy
>    argument which is in an INTERFACE block. Having initializers in
>    INTERFACE blocks is pointless and causes for the attached testcase
>    the bogus error:
>    "Assumed-rank variable y at (1) may only be used as actual argument"

ACK.

> (Except for wasting resources and this error, they should be ignored
> in trans*.c and usually do not cause any further harm.)
> 
> 
> I think Sandra has a nearly ready patch to do the C839 constraint
> diagnostic, which needs the attached patch to do the checks.
> 
> The third issue is that GCC currently gives either an ICE or the
> above error message when declaring a procedure with a valid
> assumed-rank intent(out) dummy. This has still to be solved as well.
> But first I wanted to unblock Sandra's C839 work with this patch :-)
> 
> 
> Regarding the patch, '!= IFSRC_IFBODY' has to be used; "== IFSRC_DECL"
> won't work as the the generatedy ENTRY master function has IFSRC_UNKNOWN.

I have to admit that the code touched is hard to understand for me.
The conditions involved are unfortunately already dense, long lists.

(There are PRs related to *missing* default initializations (e.g.
PR100440), which I looked at before in that area until I got lost...
Of course this needs to be addressed elsewhere.)

> OK for mainline?

No objections here; the patch seems to work.  The commit message has
a non-ASCII character (hyphen).  Not sure whether that was intended.

You may nevertheless want a second opinion.

Thanks for the patch!

Harald

> Tobias
> 
> PS: Some patch reviews are that fast that it is impossible to send the OK;
> at least, I did not manage to do for Harald's last two - for the last one
> I was at least 4min too late. ;-)
> 
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