Compilers supporting generation of C function prototypes

Among Fortran compilers, gfortran can be instructed to emit C function prototypes which can be put in a header file. Here’s how to do it with gfortran (see section Options for interoperability with other languages):

$ gfortran -fc-prototypes -fsyntax-only foo.f90 > foo.h

As an example, running the command above on the file

! foo.f90
module foo
  use, intrinsic :: iso_c_binding, only: c_float
  implicit none
contains
  real(c_float) function foo_sqr(x) bind(c)
    real(c_float), intent(in) :: x
    foo_sqr = x**2
  end function
  subroutine foo_print(x) bind(c)
    real(c_float), intent(in) :: x(:)
    write(*,*) x
  end subroutine
end module

will produce the header file:

#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

void foo_print (const float *x);
float foo_sqr (const float *x);

#ifdef __cplusplus
}
#endif

For incompatible types, gfortran will issue a friendly warning.

Question: Do any other compiler vendors support this feature?

3 Likes