set modes
} {auto crlf}
test io-39.22 {Tcl_SetChannelOption, invariance} {unix} {
    file delete $path(test1)
    set f1 [open $path(test1) w+]
    set l ""
    lappend l [fconfigure $f1 -eofchar]
    fconfigure $f1 -eofchar {ON {}}
    fconfigure $f1 -eofchar {O {}}
    lappend l [fconfigure $f1 -eofchar]
    fconfigure $f1 -eofchar D
    lappend l [fconfigure $f1 -eofchar]
    close $f1
    set l
} {{{}} O D}
test io-39.22a {Tcl_SetChannelOption, invariance} {
    file delete $path(test1)
    set f1 [open $path(test1) w+]
    set l [list]
    fconfigure $f1 -eofchar {ON {}}
    fconfigure $f1 -eofchar {O {}}
    lappend l [fconfigure $f1 -eofchar]
    fconfigure $f1 -eofchar D
    lappend l [fconfigure $f1 -eofchar]
    lappend l [list [catch {fconfigure $f1 -eofchar {1 2 3}} msg] $msg]
    close $f1
    set l
} {O D {1 {bad value for -eofchar: should be a list of zero, one, or two elements}}}