I'm not aware of any way to directly declare option dependencies with Getopt::Long.

In theory, you could do ugly things like replacing the option handlers while processing the options, but whether that's "better" than your attempt is questionable... :)

my $result = GetOptions (
          "c=s" => \&COMPT1,
          "t=s" => \&COMPT2,
          '<>' => sub {print "\nThat is not a valid parameter\n";},
    );

sub COMPT1 {
    my ($optname, $value) = @_;
    print "Option -$optname is value=$value\n";

    # replace error handler for -t with real handler
    $optname->{linkage}{t} = sub {
        my ($optname, $value) = @_;
        print "Option -$optname is value=$value\n";
    };
};

sub COMPT2 { # error handler
    print "Option -t requires option -c\n";
};

__END__
$ ./888928.pl -c foo -t bar
Option -c is value=foo
Option -t is value=bar

$ ./888928.pl  -t bar
Option -t requires option -c
[download]

Note that $optname is an object¹, via which you can access the bindings, for example. (I just Data::Dumper'ed the object to see what's in it — maybe you can find a way to do it properly with (documented) methods when you peruse the docs carefully enough...)

Also, the dependency is only "one-way", i.e. it's assumed that -c comes before -t on the command line, and that -c alone makes sense...  If you want "-c without -t" to also be an error, you'll necessarily have to wait until the entire command line has been processed, before checking for failed dependencies.

___

¹

• with newer versions of the module only
• the object strigifies to the option name