bug#68265: 30.0.50; ERC 5.6: Simplify alternate text insertion for outgoing messages

[J.P.]

Tags: patch

Spoofing messages submitted at the prompt is currently a chore. By this,
I mean inserting chat content that differs from what's actually sent.
For years, users have resorted to all manner of awkward finagling
(typically in `erc-send-modify-hook' members) to accomplish "simple"
things, like finding where the leading speaker portion ends and the
message proper begins.

The proposal here is to add an "alternate text" slot to the `erc-input'
object passed around by `erc-pre-send-functions'. Use cases include

 - language translation
 - sub-protocol encoding
 - the IRCv3 multiline extension

For the upcoming release, users will already have to recompile their
dependent packages, so we might as well seize this opportunity to modify
core schemata (if truly warranted).

Demo implementation for an existing third-party package forthcoming.

Thanks.


In GNU Emacs 30.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 3.24.38, cairo version 1.17.6) of 2024-01-04 built on localhost
Repository revision: 1081e975c9370999df1a288b117bfd9053050d21
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12014000
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0001-5.6-Make-erc-send-input-lines-a-normal-function.patch
Description: Text Data

0002-5.6-Allow-setting-erc-split-line-length-to-zero.patch
Description: Text Data

0003-5.6-Make-ERC-s-format-catalogs-more-extensible.patch
Description: Text Data

0004-5.6-Add-replacement-text-field-to-erc-input-struct.patch
Description: Text Data