use utf8与Method::Signatures::Simple冲突原因及共存方案咨询

以下是一段Perl代码：

use 5.034;
use warnings;
#use utf8;
binmode(STDOUT, ':encoding(utf-8)');

package User {
        use Method::Signatures::Simple;
        use Moose;
        has 'name' => (is => 'rw', isa => 'Str', default => sub { return 'foo' });
        method xname { return "čč" . $self->name . "ňň"; }
}

my $u = User->new;
say $u->xname;

这段代码能正常运行，但由于源码包含UTF-8字符，输出结果并不完全正确。取消注释use utf8;后，执行perl -c会抛出如下错误：

Couldn't find declarator 'method' at /u/ae/envs/plenv/versions/5.38.2/lib/perl5/site_perl/5.38.2/amd64-freebsd/Devel/Declare/Context/Simple.pm line 47.
    Devel::Declare::Context::Simple::skip_declarator(Method::Signatures::Simple=HASH(0x8292a3fa8)) called at /u/ae/envs/plenv/versions/5.38.2/lib/perl5/site_perl/5.38.2/amd64-freebsd/Devel/Declare/MethodInstaller/Simple.pm line 62
    Devel::Declare::MethodInstaller::Simple::parser(Method::Signatures::Simple=HASH(0x8292a3fa8), "method", 1, 1) called at /u/ae/envs/plenv/versions/5.38.2/lib/perl5/site_perl/5.38.2/amd64-freebsd/Devel/Declare/MethodInstaller/Simple.pm line 25
    Devel::Declare::MethodInstaller::Simple::__ANON__("method", 1) called at /u/ae/envs/plenv/versions/5.38.2/lib/perl5/site_perl/5.38.2/amd64-freebsd/Devel/Declare.pm line 277
    Devel::Declare::linestr_callback("const", "method", 1) called at t line 10

问题 #

1. 为何use utf8编译指示会与Method::Signatures::Simple模块产生冲突？
2. 如何让Method::Signatures::Simple与use utf8配合使用？

编辑补充 #

有人推荐了Function::Parameters模块，该模块能很好支持use utf8，但存在一个限制：无法在Moose的builder子程序中使用method关键字。

例如，以下代码无法运行：

has 'foo' => (is => 'rw', isa => 'Str', default => sub { return 'foo' });
has 'foobar' => (is => 'rw', isa => 'Str', builder => '_buildfoobar');
method _buildfoobar {return $self->foo . 'bar' } # 注意这里用了method

必须改用标准的sub并手动通过shift获取$self：

has 'foo' => (is => 'rw', isa => 'Str', default => sub { return 'foo' });
has 'foobar' => (is => 'rw', isa => 'Str', builder => '_buildfoobar');
sub _buildfoobar {my $self=shift; return $self->foo . 'bar' }

如果没有更好的方案，这个办法可以作为替代。

内容的提问来源于stack exchange，提问作者clt60