#!/usr/bin/perl -w use strict; use Test::More tests => 1; my $warnings; BEGIN { $SIG{__WARN__} = sub { $warnings = join '', @_ }; } { package Foo; use fields qw(thing); } { package Bar; use fields qw(stuff); use base qw(Foo); } ::like $warnings, '/^Bar is inheriting from Foo but already has its own fields!/', 'Inheriting from a base with protected fields warns';