https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126485
Bug ID: 126485
Summary: Regression caused by r16-8455 / `64e03b96dfe`:
Fortran: fix resolution of generic interface with
TYPE(C_PTR) [PR66973]
Product: gcc
Version: 16.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: henri at henrimenke dot de
Target Milestone: ---
Created attachment 65169
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=65169&action=edit
Minimal (probably insufficient) patch
The reproducer needs two files:
! mod_a.f90
module mod_a
use iso_c_binding
implicit none
end module mod_a
! bug.f90
subroutine s1(x)
use mod_a ! C_LOC reached indirectly, via a .mod
real, target :: x
call foo(c_loc(x)) ! first call: interface is synthesised here
end subroutine s1
subroutine s2(y)
use mod_a
real, target :: y
call foo(c_loc(y)) ! second call: checked against it -> bogus error
end subroutine s2
Compiling the two gives a bogus error about a dummy argument '_formal_0' that
doesn't exist. The same code compiled correctly with GCC 15.1. Since PR66973
was backported to GCC 15, I think GCC 15.2 is affected as well.
$ gfortran --version
GNU Fortran (GCC) 16.1.0
[...]
$ gfortran -c mod_a.f90
$ gfortran -c bug.f90
bug.f90:10:11:
10 | call foo(c_loc(y)) ! second call: checked against it -> bogus error
| 1
Error: ISO_C_BINDING function actual argument at (1) requires dummy argument
‘_formal_0’ to have a matching type from ISO_C_BINDING
