MODULE testcfstr_mod
  IMPLICIT none (external, type)
  PRIVATE
!
  ABSTRACT INTERFACE
    INTEGER(KIND=C_INT) FUNCTION strlen_z(ptr) BIND(C)
    USE ISO_C_BINDING, ONLY : C_INT, C_PTR
    TYPE(C_PTR),VALUE :: ptr
    END FUNCTION strlen_z
  END INTERFACE
  PROCEDURE(strlen_z),PUBLIC, BIND(C, NAME='strlen') :: strlen
!
  END MODULE testcfstr_mod
!
  PROGRAM testcfstr
  USE ISO_C_BINDING, ONLY   : C_PTR, C_LOC, C_F_STRPOINTER, F_C_STRING, C_ASSOCIATED
  USE ISO_FORTRAN_ENV, ONLY : COMPILER_VERSION
  USE testcfstr_mod, ONLY   : strlen
  IMPLICIT none (external, type)

  CHARACTER(LEN=9),TARGET  :: string_in
  CHARACTER(LEN=:),POINTER :: string_out
  TYPE(C_PTR)              :: pString
  INTEGER                  :: length
  INTEGER                  :: iPos
!
  write(*,*) 'Compiler version: ', COMPILER_VERSION()
!
  string_in = F_C_STRING("abcdefgh")
  pString = C_LOC(string_in)
  write(*,*) 'c_associated: ', C_ASSOCIATED(pString)
  length = strlen(pString)
  write(*,*) 'length:', length
  CALL C_F_STRPOINTER(pString, string_out, length)
  write(*,*) 'associated: ', ASSOCIATED(string_out)     !  <<<<<<<<<<<<<<<<<<<<<<<  wrong?
  write(*,*) 'string out: ', string_out//"<<"           ! works fine here, but fails elsewhere
  iPos = INDEX(string_out, "bc")                        ! works fine here, but fails elsewhere
  write(*,*)'ipos', ipos

!
  STOP
  END PROGRAM testcfstr