bug#72736: 31.0.50; ERC 5.6.1: Keep ban lists in sync

[J.P.]

Tags: patch

The function `erc-banlist-update' conditionally modifies the local
variable `erc-channel-banlist'." As originally envisioned, this list
remains synced with the server's because `erc-banlist-update' runs
whenever the client receives a MODE command. But due to a bug in the
logic surrounding an internal flag (meant to regulate meaningful action
by the function), synchronization is inconsistent and difficult to
predict, which makes `erc-channel-banlist' ultimately unreliable.

Much of this can be solved by simply wiring in ban-list syncing to the
MODE-handling "framework" introduced by bug#67220. So instead of the
current situation, in which `erc-banlist-update' only understands "+b"
or "-b" but not "+mb", etc., we'll have a reliable solution for handling
all such permutations. This *should* have been addressed by bug#67220
along with everything else in that arena, but unscrambling all the
aforementioned state-flag business seemed a chore too many at the time,
ISTR.

The last two of the attached patches aim to improve the situation by
updating `erc-channel-banlist' on a rolling basis, unconditionally. On
the UX side, they provide third-party modules with a new function,
`erc-sync-banlist', that effectively guarantees `erc-channel-banlist'
will remain in sync for the remainder of the session, once invoked.

I've also run into some related issues on the interactive side with the
slash commands /BANLIST and /MASSUNBAN. Currently, issuing a /MASSUNBAN
corrupts synchronization, potentially across all sessions. For example,
issuing a subsequent /BANLIST won't send a "MODE #chan b" to refresh
`erc-channel-banlist' as it usually does. Instead, it will proceed in
listing the variable's stale contents, which could potentially confuse a
channel operator and lead to unfortunate social situations.

The first few patches in the set are mostly unrelated fixes. The second
tackles a memory leak introduced by Bug#67677, which added the "msg
props" internal framework for organizing per-message text props. The
third patch is of a supporting nature and internally binds the current
`erc-response' object for hooks and handlers, to allow easier access
toward the business end of the call stack. I was hoping to avoid such a
change until 5.7, but circumstances dictate otherwise.

Thanks.

In GNU Emacs 31.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
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Repository revision: a876c4d7a17df152e3e78800c76ddf158f632ee5
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0001-5.6.1-Rename-internal-variable-in-erc-fill.patch
Description: Text Data

0002-5.6.1-Store-one-string-per-user-in-erc-spkr-msg-prop.patch
Description: Text Data

0003-5.6.1-Bind-current-erc-response-around-all-handlers.patch
Description: Text Data

0004-5.6.1-Use-5.6-MODE-framework-to-update-erc-channel-b.patch
Description: Text Data

0005-5.6.1-Fix-inconsistent-handling-of-ban-lists-in-ERC.patch
Description: Text Data