bug#67767: 30.0.50; ERC 5.6: Add track integration to the nicks module

[J.P.]

Tags: patch

ERC's `nicks' module doesn't currently play nice with `track'. Enabling
it breaks the cycling effect normally occurring among faces in
`erc-track-faces-normal-list' [1]. To address this, I'm proposing we
expose two internal seams:

  1. A function-valued variable for modifying or discarding faces
     gleaned in the narrowed buffer while `track' visits a message.

  2. A buffer-local hash table created on init from the contents of
     `erc-track-faces-normal-list'.

The first brings a small performance penalty and the second a small UX
hiccup [2]. The proposed implementation offsets the first by passing
around more refined data to cut down on some waste during processing.
The second is only currently addressed via doc string, although there's
a public compatibility flag to revert to a related historical behavior,
which dispenses with the issue indirectly.

The only actual addition to the `nicks' module is a user option named
`erc-nicks-track-faces'. It's a boolean that lets you opt out of seeing
nick colors as faces in the mode line indicator. There's also a loosely
related patch that adds some caching to the uniquified name shortening
performed by `track', although it should mainly benefit batch processing
and history playback. Suggestions welcome, as always.

Thanks.


[1] Although, what we typically perceive as this effect is somewhat
    illusory, if not underrealized. See comments preceding the new tests
    in the first patch.

[2] Users will have to toggle the module's minor-mode to update the
    variable mid-session, but we can provide a Custom :set function to
    help with this. Also, there's actually a resource penalty that comes
    with this change too. We can probably use per-server instead of
    per-channel hash tables, or only go per-channel if a local value for
    `erc-track-faces-normal-list' exists on `erc-track-mode' init.


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0001-5.6-Always-promote-normal-faces-in-erc-track.patch
Description: Text Data

0002-5.6-Cache-shortened-channel-names-in-erc-track.patch
Description: Text Data

0003-5.6-Add-erc-track-integration-to-erc-nicks.patch
Description: Text Data