Fix for issue #80

lib/Type/Tiny.pm

@@ -814,6 +814,7 @@ sub _perlcode {
 		if $self->can_be_inlined;
 
 	$b ||= do {
+		local $@;
 		require B::Deparse;
 		my $tmp = "B::Deparse"->new;
 		$tmp->ambient_pragmas( strict => "all", warnings => "all" )

t/40-regression/gh80.t

@@ -0,0 +1,51 @@
+=pod
+
+=encoding utf-8
+
+=head1 PURPOSE
+
+Test that stringifying Error::TypeTiny doesn't clobber $@.
+
+=head1 SEE ALSO
+
+L<https://github.com/tobyink/p5-type-tiny/issues/80>.
+
+=head1 AUTHOR
+
+Toby Inkster E<lt>tobyink@cpan.orgE<gt> based on code by @bokutin
+L<https://github.com/bokutin>.
+
+=head1 COPYRIGHT AND LICENCE
+
+This software is copyright (c) 2021 by Toby Inkster.
+
+This is free software; you can redistribute it and/or modify it under
+the same terms as the Perl 5 programming language system itself.
+
+=cut
+
+use strict;
+use warnings;
+use Test::More;
+use Type::Tiny;
+
+# Produces annoying warnings, so don't test by default
+BEGIN {
+	$ENV{EXTENDED_TESTING}
+	or $ENV{AUTHOR_TESTING}
+	or $ENV{RELEASE_TESTING}
+	or plan skip_all => 'EXTENDED_TESTING'
+};
+
+my $Type1 = Type::Tiny->new( name => "Type1", constraint => sub { 0 } );
+
+eval { $Type1->('val1') };
+
+isa_ok( $@, 'Error::TypeTiny', '$@' );
+diag "#### BEGIN EXPECTED WARNINGS ####";
+warn $@;
+warn $@;
+diag "#### END EXPECTED WARNINGS ####";
+like( "$@", qr/did not pass type/, '$@ is still defined and stringifies properly' );
+
+done_testing;