Warn about implicit logging in erc-truncate-mode

* etc/ERC-NEWS: Add entry explaining that `erc-truncate-mode' no
longer quasi-activates `erc-log-mode' under certain conditions.
* lisp/erc/erc-log.el
(erc-log--call-when-logging-enabled-sans-module): Add helper for use
by the `truncate' module during initialization.
* lisp/erc/erc-truncate.el (erc-truncate-mode, erc-truncate-enable,
erc-truncate-disable): Warn on `erc-connect-pre-hook' when conditions
exist that would have seen logging transparently activated in older
ERC versions.
(erc-truncate--warn-about-logging): New function to warn about
implicit logging on pre-connect.
(erc-truncate-buffer-to-size): Clarify some comments and revise doc
string.
* test/lisp/erc/erc-scenarios-log.el (erc-scenarios-log--truncate):
Disable `erc-truncate-mode' even though `erc-modules' is shadowed so
that `erc-insert-done-hook' and friends are not contaminated.
`(Bug#60936)

1 files changed, 7 insertions, 0 deletions

diff --git a/etc/ERC-NEWS b/etc/ERC-NEWS
index 94452514e6d..7ee55982b17 100644
--- a/etc/ERC-NEWS
+++ b/etc/ERC-NEWS
@@ -196,6 +196,13 @@ these changes has been the deprecation of the ancient option
 'erc-truncate-buffer-on-save'.  Users of the 'log' module can achieve
 the same effect by issuing a "/CLEAR" at the prompt.
 
+** The 'truncate' module no longer enables logging automatically.
+Users expecting 'truncate' to perform logging based on the option
+'erc-enable-logging' need to instead add 'log' to 'erc-modules' for
+continued integration.  With the existing design, merely loading the
+library 'erc-log' caused 'truncate' to start writing logs, possibly
+against a user's wishes.
+
 ** Miscellaneous UX changes.
 Some minor quality-of-life niceties have finally made their way to
 ERC.  For example, the function 'erc-echo-timestamp' is now