From: Rusty Russell <rusty@rustcorp.com.au>
To: ZmnSCPxj <ZmnSCPxj@protonmail.com>,
 Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
In-Reply-To: <wl99_YiLrtFFZuJNlFM19WDz5nkxlTGduefyc1_kCnTNVtkvMcY8xbASSRgoHBylhd9Kne3Uoh6UYfdkswBnel3kTbPeWlkIzY7gKb6vwvc=@protonmail.com>
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Date: Wed, 21 Oct 2020 15:09:32 +1030
Message-ID: <87zh4gxke3.fsf@rustcorp.com.au>
MIME-Version: 1.0
Content-Type: text/plain
Cc: John Barboza <johnbarboza@gmail.com>
Subject: Re: [bitcoin-dev] Progress on bech32 for future Segwit Versions
	(BIP-173)
Precedence: list

ZmnSCPxj <ZmnSCPxj@protonmail.com> writes:
> I believe this is actually my code, which was later refactored by John Barboza when we were standardizing the `param` system.

Ah, sorry!

> This was intended only as a simple precaution against creating non-standard transaction, and not an assumption that future versions should be invalid.
> The intent is that further `else if` branches would be added for newer witness versions and whatever length restrictions they may have, as the `/* Insert other witness versions here.  */` comment implies.

Yes, I mentioned it here because I've found this to be a common
misconception; the *idea* was that application's segwit code would not
have to be reworked for future upgrades, but that information propagated
poorly.

(Just as well, because of overly strict standardness rules, the overflow
bug, and now the proposed validation changes, turns out this lack of
forward compat is a feature!)

Thanks!
Rusty.