https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64958
--- Comment #9 from MarkEggleston <mark.eggleston at codethink dot com> ---
using -Wimplicit-interface helps:
7 | call dusty(n)
| 1
Warning: Procedure 'dusty' called with an implicit interface at (1)
[-Wimplicit-interface]
Adding in an interface block:
module foo
implicit none
interface
subroutine dusty(n)
integer, intent(inout) :: n
end subroutine
end interface
contains
subroutine bar(n)
integer, intent(in) :: n
print *,"bar before dusty", n
call dusty(n)
print *,"bar after dusty", n
end subroutine bar
end module foo
program main
use foo
implicit none
integer :: n
n = 5
call bar(6)
end program main
subroutine dusty(n)
integer :: n
n = n - 1
end
Resulting in two errors:
14 | call dusty(n)
| 1
Error: Dummy argument 'n' with INTENT(IN) in variable definition context
(actual argument to INTENT = OUT/INOUT) at (1)
here
pr64598.f90:21:6:
21 | use foo
| 1
Fatal Error: Cannot open module file 'foo.mod' for reading at (1): No such file
o
If intent(inout) is omitted from the interface block the program will compile
with the fault unidentified. I'm working on a patch that will warn about
modification of dummy variables that have no intent which will warn in this
case. (PR fortran/88079).
