Re: [Patch, Fortran] libgfortran's ISO_Fortran_binding.c: Use GCC11 version for backward-only code [PR108056]

[Richard Biener <richard.guenther@gmail.com>]

On Tue, Dec 13, 2022 at 5:29 PM Tobias Burnus <tobias@codesourcery.com> wrote:
>
> This is a 12/13 regression as come changes to fix the GFC/CFI descriptor
> that went into GCC 12 fail with the (bogus) descriptor passed via by a
> GCC-11-compiled program.
>
> As later GCC 12 changes moved the descriptor to the front end, those
> functions are only in libgomp.so to cater for old program. Richard
> suggested in the PR that the best way is to move to the GCC 11 version,
> such that libgfortran.so won't regress.
>
> I now did so - except for three fixes (cf. changelog). See also
> PR: https://gcc.gnu.org/PR108056
>
> There is no testcase as it needs to be compiled by GCC <= 11 and then
> run with linking (dynamically) to a GCC 12 or 13 libgfortran.
>
> OK for mainline and GCC 12?

OK for the branch if approved for trunk.

Richard.

>   * * *
>
> Note: It is strongly recommended to use GCC 12 (or 13) with array-descriptor
> C interop as many issues were fixed. Like for the testcase in the PR; in GCC 11
> the type arriving in libgomp is BT_ASSUME ('type(*)'). But as the effective
> argument is passed as array descriptor through out, the 'float' (real(4)) type
> info is actually preservable (as GCC 12 cf. testcase of comment 0 and my comment
> in the PR for the C part of the testcase).(*)
>
> Tobias
>
> ((*) This is not possible if using a scalar 'type(*)' or a non-array-descriptor
> array in between. I think GCC 12 uses 'CFI_other' in the information-is-lost case.)
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