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From: "burnus at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug fortran/113997] Bogus 'Warning: Interface mismatch in global
 procedure' with C binding
Date: Mon, 19 Feb 2024 18:13:47 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113997

--- Comment #3 from Tobias Burnus <burnus at gcc dot gnu.org> ---
> Anyway, renaming the binding label, like
>    subroutine acc_attach_c(x) bind(C, name=3D"acc_attach_renamed")
> makes the code compile.

Well, the code *does* compile as it is only a warning.

* * *

I think the problem here is a bit that on the Fortran-user side ('acc_attac=
h'
vs. 'acc_attach_c') and on the assembler-level side ('acc_attach_' vs.
'acc_attach') everything is fine (except with -fno-underscore) but, admitte=
dly,
not from the Fortran lanaguage side.

(On the other hand, Fortran itself is perfectly happy with:
'subroutine foo' and 'subroutine bar() Bind(C, name=3D'foo_')' but that will
break with most Fortran compilers.)

Thus, the question is whether we (gfortran) want to do something here - or =
are
happy with issuing the semi-correct/semi-bogus warning here.

* * *

And renaming "acc_attach_c" does not really help as 'acc_attach' with C bin=
ding
does exist. In this case it exists as:
=20
https://gcc.gnu.org/git/?p=3Dgcc.git;a=3Dblob;f=3Dlibgomp/oacc-mem.c;hb=3Dr=
efs/heads/master#l944
and renaming would just add another wrapper around it.


However, an alternative is the following - which is (nearly) identical, exc=
ept
that GCC does some GFC-CFC and back conversations =E2=80=93 independent whe=
ther
implemented in C or in Fortran:

subroutine acc_attach(x) bind(C, name=3D"acc_attach_")
  use iso_c_binding, only : c_loc
  implicit none (external, type)

  type(*), dimension(..), target :: x

  interface
    subroutine acc_attach_c(x) bind(C, name=3D"acc_attach")
      use iso_c_binding
      type(c_ptr) :: x
    end subroutine
  end interface

  call acc_attach_c(c_loc(x))
end=