bug#60428: 29.0.60; ERC 5.4.1: Fix default-port regression in erc-select-read-args

[J.P.]

Tags: patch

To reproduce from emacs -Q, do an M-x erc and accept the default offered
at every prompt. Assuming your IP is not blacklisted by Libera, you
should see a connection failure immediately because a TLS endpoint is
dialed but negotiation never occurs.

This all stems from a lapse in professionalism on my part: an
underrealized feature snuck in with the changes from bug#56514, but
missing logic made it impossible to connect using the default prompt
values, which should probably always succeed because some people don't
care about parameters and just want to get there somehow (so I'm told).
Alternatively, if a deliberate failure is indeed warranted (an arguably
valid position), the error message should at least explain as much.

FWIW, the missing feature was supposed to offer an interactive upgrade
to TLS upon detecting a user's intent to connect to the default server
and, on confirmation, adjust ERC's parameters on the fly. The proposed
patch abandons most of the envisioned niceties and instead employs a
hack to just force a non-local exit and schedule a call to `erc-tls'
when appropriate. It also instructs users to do that themselves in the
future (issue an M-x erc-tls, that is). Hopefully, this makes for an
acceptable compromise.

BTW, a POC patch set far more faithful to the original breadth of the
feature (and way less hacky) is also attached. Perhaps it'll inform
further exploration in this area down the road (but not for Emacs 29).

Thanks.

P.S. Shout out to the Libera users who brought this to my attention.


In GNU Emacs 29.0.60 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 3.24.35, cairo version 1.17.6) of 2022-12-29 built on localhost
Repository revision: d086cd6cf877c6ca7af6712f9b79b52dd0caa934
Repository branch: emacs-29
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0001-Fix-default-port-regression-in-erc-select-read-args.patch
Description: Text Data

0002-POC-Offer-TLS-by-default-for-M-x-erc.patch
Description: Text Data

0003-POC-Display-buffers-differently-for-M-x-erc.patch
Description: Text Data

0004-POC-Optionally-prompt-for-more-ERC-entry-point-param.patch
Description: Text Data