https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90539
--- Comment #25 from Martin Liška <marxin at gcc dot gnu.org> ---
(In reply to Thomas Koenig from comment #22)
> I've been trying out some things, and I cannot construct a failing
> test case.
>
> A sane way to build such an interface would be
>
> cat tst.f90
> module x
> use, intrinsic :: iso_c_binding, only : c_double
> implicit none
> interface
> subroutine foo(a) bind(c)
> import
> real(kind=c_double) :: a(*)
> end subroutine foo
> end interface
> private
> public :: bar
>
> contains
> subroutine bar(a)
> real(kind=c_double), dimension(:) :: a
> a = 42._c_double
> call foo(a)
> end subroutine bar
> end module x
>
> program main
> use, intrinsic :: iso_c_binding, only : c_double
> use x
> implicit none
> real(kind=c_double), dimension(1) :: a
> call bar(a)
> end program main
> $ cat foo.c
> #include <stdio.h>
>
> void foo (double *a)
> {
> printf("%f\n", *a);
> }
> $ gfortran -flto -O tst.f90 foo.c
> $ ./a.out
> 42.000000
>
> This works as expected.
>
> What I do not understand is (comment #17)
>
> (gdb) p debug(fsym)
> || symbol: '_formal_107'
> type spec : (REAL 8)
> attributes: (VARIABLE DIMENSION DUMMY)
> Array spec:(0 [0])
>
>
> This means that the dummy parameter has rank zero. How, then,
> is it possible to pass a rank-1 argument to it?
>
> (gdb) p debug(expr)
> nf90_put_var_1d_eightbytereal:values(FULL) (REAL 8)
>
> (gdb) p *expr->ref
> $8 = {
> type = REF_ARRAY,
> u = {
> ar = {
> type = AR_FULL,
> dimen = 1,
> codimen = 0,
>
> Something very fishy going on here.
>
> Please look up the Fortran interface to the C function that is called,
> nc_put_vara_double.
>
> Also, please break on gfc_conv_procedure_call for the call
> in question and do
>
> $ call debug(sym)
> $ p args
> $ call debug(args->expr)
> $ p args->next
> $ call debug(args->next->expr)
(gdb) call debug(sym)
|| symbol: 'nf_put_vara_double'
type spec : (INTEGER 4)
attributes: (PROCEDURE EXTERNAL-PROC IMPLICIT-SAVE EXTERNAL FUNCTION)
result: nf_put_vara_double
Formal arglist: _formal_103 _formal_104 _formal_105 _formal_106 _formal_107
(gdb) p args
$4 = (gfc_actual_arglist *) 0x2a766f0
(gdb) call debug(args->expr)
nf90_put_var_1d_eightbytereal:ncid (INTEGER 4)
(gdb) p args->next
$5 = (gfc_actual_arglist *) 0x2a72150
(gdb) call debug(args->next->expr)
nf90_put_var_1d_eightbytereal:varid (INTEGER 4)
(gdb) call debug(args->next->next->expr)
nf90_put_var_1d_eightbytereal:localstart(FULL) (INTEGER 4)
(gdb) call debug(args->next->next->next->expr)
nf90_put_var_1d_eightbytereal:localcount(FULL) (INTEGER 4)
(gdb) call debug(args->next->next->next->next->expr)
nf90_put_var_1d_eightbytereal:values(FULL) (REAL 8)
>
> ... and so on, until args->...->next becomes a null pointer.
>
> I am starting do suspect that this is, in fact, another piece of SPEC
> bugware where they made some sort of broken interface between C
> and Fortran, which is exposed by my patch.
That's likely :) Hope my remove gdb session helped.
>
> Hmpf...
