https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119419
Bug ID: 119419
Summary: C prototype generation for functions returning
C_FUNPTR incorrect
Product: gcc
Version: 14.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: ryan.gambord at oregonstate dot edu
Target Milestone: ---
Created attachment 60849
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=60849&action=edit
Collected source files
When compiled with -fc-prototypes, the emitted function signature is incorrect,
==> MRE.f90 <==
function f(idx) bind(C)
use, intrinsic :: ISO_C_BINDING
type(C_FUNPTR) :: f
integer(C_INT) :: idx
end function f
======
Emits `int (*f()) (int)` rather than `int (*f(int)) ()`
I have attached a sample fortran "library" and C program that illustrates the
issue:
==> lookup.f90 <==
MODULE test
USE, INTRINSIC :: ISO_C_BINDING
CONTAINS
FUNCTION lookup(idx) BIND(C)
type(C_FUNPTR) :: lookup
integer(C_INT), VALUE :: idx
SELECT CASE (idx)
CASE (1)
lookup = C_FUNLOC(x1)
CASE (2)
lookup = C_FUNLOC(x2)
CASE DEFAULT
lookup = C_NULL_FUNPTR
end SELECT
END FUNCTION lookup
subroutine x1()
print *, "x1"
end subroutine x1
subroutine x2()
print *, "x2"
end subroutine x2
END MODULE test
==> test.c <==
#include <stdio.h>
/* Incorrect prototype */
/* #include "lookup.h" */
/* Correct function prototype */
void (*lookup(int))();
int main()
{
lookup(1)(); /* "x1" */
lookup(2)(); /* "x2" */
}
The generated function prototype in lookup.h is: `int (*lookup()) (int idx);`
