454 # ===== basic utility routines
    455 
    456 sub writelog;


    640 sub writelog($) {
    641     my $arg = shift;
[download]

Your forward declaration of writelog does not include a prototype and therefore the effects of the prototype do not apply until after it is declared.

No prototype:

$ perl -le'
use warnings;
use strict;
my @x = 14 .. 19;
sub writelog;    
writelog @x;
writelog "F" .. "J";
sub writelog ($) {
    my $arg = shift;
    print "\@_ = @_\t\t\$arg = $arg";
    }
writelog @x;
writelog "F" .. "J";
'
Useless use of range (or flop) in void context at -e line 13.
@_ = 15 16 17 18 19             $arg = 14
@_ = G H I J            $arg = F
@_ =            $arg = 6
@_ =            $arg = F
Argument "J" isn't numeric in range (or flop) at -e line 13.
Use of uninitialized value $. in range (or flop) at -e line 13.
[download]

With Prototype:

$ perl -le'
use warnings;
use strict;
my @x = 14 .. 19;
sub writelog ($);
writelog @x;
writelog "F" .. "J";
sub writelog ($) {
    my $arg = shift;
    print "\@_ = @_\t\t\$arg = $arg";
    }
writelog @x;
writelog "F" .. "J";
'
Useless use of range (or flop) in void context at -e line 7.
Useless use of range (or flop) in void context at -e line 13.
@_ =            $arg = 6
@_ =            $arg = F
Argument "J" isn't numeric in range (or flop) at -e line 7.
Use of uninitialized value $. in range (or flop) at -e line 7.
@_ =            $arg = 6
@_ =            $arg = F
Argument "J" isn't numeric in range (or flop) at -e line 13.
Use of uninitialized value $. in range (or flop) at -e line 13.
[download]