* src/igc.c (read_gens, read_pause_time, read_commit_limit): New.
(make_arena): Use them.

* src/igc.c (Figc__arena_step): New defun.
(arena_step, Vigc_step_interval): Deleted.
(igc_on_idle): Don't call arena_step.
(syms_of_igc): Register Sigc__arena_step.
* lisp/emacs-lisp/igc.el (igc-start-idle-timer): New.
(igc--idle-timer, igc--idle-delay, igc--step-interval)
(igc--predict-idle-time, igc--on-idle): New code for opportunistic Gc.

* src/xterm.c (xi_disable_devices): Move `out' label into the
outermost loop.  (bug#79343)

* lisp/minibuffer.el (define-completion-category): New function.
(completion-category-get): New function, implements completion
category property lookup with (multiple) inheritance.
(completion-metadata-get, completion--styles)
(completion--cycle-threshold): Use it.
(completion-category-defaults): Mention it in docstring.
Remove entry for 'project-buffer' category, and instead...
* lisp/progmodes/project.el: ...have 'project-buffer' inherit
from 'buffer'.
* test/lisp/minibuffer-tests.el
(completion-category-inheritance): New test.
* etc/NEWS: Announce support for category inheritance.

The previous change actually introduced a bug in a closely
related but distinct place.  We need to address the off-by-one
in the 'substring' call, not the 'add-face-text-property'.

* lisp/progmodes/eglot.el (eglot--sig-info): Fixup.

* lisp/isearch.el (isearch-mode): Don't override
'isearch--saved-local-map' when 'overriding-terminal-local-map'
was already set to 'isearch-mode-map' in a previous call.
(with-isearch-suspended): Don't call the function 'isearch-mode'
when the variable 'isearch-mode' is already non-nil.