[Bug fortran/96220] New: -fc-prototypes forgets types for doubles

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96220

            Bug ID: 96220
           Summary: -fc-prototypes forgets types for doubles
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tkoenig at gcc dot gnu.org
  Target Milestone: ---

$ cat foo.f90 
module f_global_vars_m
use, intrinsic :: iso_c_binding, sp => c_float, dp => c_double
implicit none
real(dp), bind(c) :: one= 1.0_dp, four= 4.0_dp ! Error in gfortran v.10.1
end module f_global_vars_m
$ gfortran -fc-prototypes -c foo.f90 
#include <stddef.h>
#ifdef __cplusplus
#include <complex>
#define __GFORTRAN_FLOAT_COMPLEX std::complex<float>
#define __GFORTRAN_DOUBLE_COMPLEX std::complex<double>
#define __GFORTRAN_LONG_DOUBLE_COMPLEX std::complex<long double>
extern "C" {
#else
#define __GFORTRAN_FLOAT_COMPLEX float _Complex
#define __GFORTRAN_DOUBLE_COMPLEX double _Complex
#define __GFORTRAN_LONG_DOUBLE_COMPLEX long double _Complex
#endif

extern  four;
extern  one;

#ifdef __cplusplus
}
#endif