no warnings qw( pack );

So, you'd have us throw away all the useful warnings that pack can emit when I do something wrong in order to disable the stupid warning emitted when it does something wrong. Cool-io. Not.

You're getting an overflow warning.

Oh sure. "Wide character" says 'overflow', like super-injunction says right to privacy for all.

It has nothing to do with Unicode.

Really? Can you guess where this direct quote " A Unicode character number." comes from?

I don't give flying fig whether you want to conflate the term 'unicode' with that multiplicitous cock-up of formats that hide behind the moniker 'The Unicode Standard'(*), and can't see that I used the former as a short-hand for 'multi-byte character sets'.

Which should of course be 'The Multicode Standards:Everything including the (7 different) kitchen sinks'

* — Not even "U" has any understanding of Unicode. >perl -wE"say sprintf '%X', unpack 'U', pack 'U', 0x200000" 200000

Wadday'know. If you pack with U and unpack with U you get back what you packed. D'uh. A pointless example of nothing much.

This is the problem.

perl -wE"$s=pack 'U*', 257; say length $s; print for unpack 'C*', $s;"
1
257
[download]

That totally devalues the purpose of having two different template characters.

• one for C   An unsigned char (octet) value.
• one for U   A Unicode character number.  Encodes to a character in character mode and UTF-8 ... in byte mode.

That should not happen. And I shouldn't have to state that I don't want it to happen:

>perl -Mbytes -wE"$s=pack 'U*', 257; say length $s; say for unpack 'C*
+', $s;"
2
196
129
[download]

It breaks backward compatibility in the very worst way.

• Screaming when you are doing nothing wrong.

  Breaking both existing, working code and existing expectations. And causing people to disable important and useful warnings to silence it.

• And saying nothing at all when it does it wrong thing.

  Just silently breaking previously working, 'best practice' code violating every expectation and rule of change and enhancement.

The Unicode Standard is a cock-up. And the Perl implementation worse.