[Bug fortran/94738] New: C descriptor passed to Fortran from C apepars to have wrong type information.

[longb at cray dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94738

            Bug ID: 94738
           Summary: C descriptor passed to Fortran from C apepars to have
                    wrong type information.
           Product: gcc
           Version: 9.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: longb at cray dot com
  Target Milestone: ---

> cat main.c
#include <errno.h>
#include <string.h>
#include "ISO_Fortran_binding.h"

int main (int argc, char *argv[]) {

    int ret;
    int line;
    int my_errno;
    int i;
    CFI_CDESC_T(1) cdesc;
    CFI_rank_t rank = 1;
    int version = CFI_VERSION;
    CFI_attribute_t attribute = CFI_attribute_allocatable;
    CFI_type_t typ = CFI_type_double;
    CFI_index_t extents[rank];
    CFI_index_t lower_bounds[rank];
    CFI_index_t upper_bounds[rank];
    size_t elem_len; // value doesn't matter
    void sub (CFI_cdesc_t *);

    for (i = 0; i < rank; i++) {
        extents[i] = 100;
        lower_bounds[i] = 1;
        upper_bounds[i] = 100;
    }
ret = CFI_establish ((CFI_cdesc_t *)&cdesc, 0, attribute, typ, elem_len, rank,
extents);
    if (ret != CFI_SUCCESS) {
       line = __LINE__;
       goto done;
    } 
ret = CFI_allocate ((CFI_cdesc_t *)&cdesc, lower_bounds, upper_bounds,
elem_len);
     if (ret != CFI_SUCCESS) {
        line = __LINE__;
        goto done;
     }
     sub ((CFI_cdesc_t *) &cdesc);
     line = 0;

done:

     if (line != 0) {
        asm ("hlt");
     }
     return 0;
}

> cat sub.f90
subroutine sub (a) bind (c)
  use,intrinsic :: iso_c_binding
  real(C_double), allocatable :: a(:)
  do i = 1, size(a, 1)
     a(i) = i
  end do
  print *, a
end subroutine sub
> 
> ftn -c sub.f90
> cc main.c sub.o
> ./a.out
At line 7 of file sub.f90 (unit = 6, file = 'stdout')
Internal Error: list_formatted_write(): Bad type


It appears that the C descriptor, after being converted to a Fortran
descriptor, has the wrong type information encoded.

> cc --version
gcc (GCC) 9.3.0 20200312 (Cray Inc.)
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

> ftn --version
GNU Fortran (GCC) 9.3.0 20200312 (Cray Inc.)
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Output from other compilers:

> module swap PrgEnv-gnu PrgEnv-cray
> ftn -c sub.f90
> cc main.c sub.o
>  ./a.out
 1.,  2.,  3.,  4.,  5.,  6.,  7.,  8.,  9.,  10.,  11.,  12.,  13.,  14., 
15.,  16.,  17.,  18.,  19.,  20.,  21.,  22.,  23.,  24.,  25.,  26.,  27., 
28.,  29.,  30.,  31.,  32.,  33.,  34.,  35.,  36.,  37.,  38.,  39.,  40., 
41.,  42.,  43.,  44.,  45.,  46.,  47.,  48.,  49.,  50.,  51.,  52.,  53., 
54.,  55.,  56.,  57.,  58.,  59.,  60.,  61.,  62.,  63.,  64.,  65.,  66., 
67.,  68.,  69.,  70.,  71.,  72.,  73.,  74.,  75.,  76.,  77.,  78.,  79., 
80.,  81.,  82.,  83.,  84.,  85.,  86.,  87.,  88.,  89.,  90.,  91.,  92., 
93.,  94.,  95.,  96.,  97.,  98.,  99.,  100.
> module swap PrgEnv-cray PrgEnv-intel
> ftn -c sub.f90
> cc main.c sub.o
> ./a.out
   1.00000000000000        2.00000000000000        3.00000000000000     
   4.00000000000000        5.00000000000000        6.00000000000000     
   7.00000000000000        8.00000000000000        9.00000000000000     
   10.0000000000000        11.0000000000000        12.0000000000000     
   13.0000000000000        14.0000000000000        15.0000000000000     
   16.0000000000000        17.0000000000000        18.0000000000000     
   19.0000000000000        20.0000000000000        21.0000000000000     
   22.0000000000000        23.0000000000000        24.0000000000000     
   25.0000000000000        26.0000000000000        27.0000000000000     
   28.0000000000000        29.0000000000000        30.0000000000000     
   31.0000000000000        32.0000000000000        33.0000000000000     
   34.0000000000000        35.0000000000000        36.0000000000000     
   37.0000000000000        38.0000000000000        39.0000000000000     
   40.0000000000000        41.0000000000000        42.0000000000000     
   43.0000000000000        44.0000000000000        45.0000000000000     
   46.0000000000000        47.0000000000000        48.0000000000000     
   49.0000000000000        50.0000000000000        51.0000000000000     
   52.0000000000000        53.0000000000000        54.0000000000000     
   55.0000000000000        56.0000000000000        57.0000000000000     
   58.0000000000000        59.0000000000000        60.0000000000000     
   61.0000000000000        62.0000000000000        63.0000000000000     
   64.0000000000000        65.0000000000000        66.0000000000000     
   67.0000000000000        68.0000000000000        69.0000000000000     
   70.0000000000000        71.0000000000000        72.0000000000000     
   73.0000000000000        74.0000000000000        75.0000000000000     
   76.0000000000000        77.0000000000000        78.0000000000000     
   79.0000000000000        80.0000000000000        81.0000000000000     
   82.0000000000000        83.0000000000000        84.0000000000000     
   85.0000000000000        86.0000000000000        87.0000000000000     
   88.0000000000000        89.0000000000000        90.0000000000000     
   91.0000000000000        92.0000000000000        93.0000000000000     
   94.0000000000000        95.0000000000000        96.0000000000000     
   97.0000000000000        98.0000000000000        99.0000000000000     
   100.000000000000