This looks strange to me... I wonder on which system and in which shell you are doing this.

It looks like rel2abs is - on your system - a shell command (I don't have it). So I assume you are testing in the shell.

IMHO: Your shell should handle the expansion of ~ to the correct path. If it does not, try to fix your shell or try a different shell.

Tests in my shell (/bin/bash):

$ perl /tmp/t.pl ~/.vimrc ~user/.vimrc ~root/.vimrc
/home/linuxer/.vimrc
/home/user/.vimrc
/root/.vimrc
[download]

/tmp/t.pl:

#! /usr/bin/env perl
use strict;
use warnings;
use 5.020;

say $_ for @ARGV;
[download]