Comment 3 for bug 1842164

Detected :

$ cat z2.f90
program p
integer(len((c)) :: n
end

$ cat z5.f90
implicit none
integer(len((c)) :: n
end

$ gfortran-9-20181216 -c z2.f90 -fimplicit-none
z2.f90:2:14:

    2 | integer(len((c)) :: n
      | 1
Error: Symbol 'c' at (1) has no IMPLICIT type