resetting font-ligatures means passing `nil` as the second argument
of `(set-font-ligatures!)`
Using `ligatures-ignored-major-modes` to cancel ligatures is too
brittle, because "resetting ligatures for `prog-mode`" would have bad
semantics with all its derived modes. The user probably just wants to
remove the default ligatures and then configure `foo-mode`, but pushing
`prog-mode` to `ignored-major-modes` might just disable ligatures across
all modes _derived from_ `prog-mode`.
This commit changes things in 2 ways:
- resetting ligatures now directly manipulates ligature.el internal
state (the `ligature-composition-table` alist)
- in order to work, Doom must maintain an extra invariant on that alist,
multi-modes keys (`'(foo-mode bar-mode)`), cannot be used, only single
modes.
That mostly means that users should _not_ use
`ligature-set-ligatures` themselves in private config, but instead
always rely on `set-font-ligatures!` which does splicing behind
curtains. Failing to do so would be mostly harmless though (it would
just make "resetting ligatures" only partially remove set ligatures).
Fix: #7433
Include ligature.el in a new set-font-ligatures! function, so that
"normal" (read: "font-based") ligatures can
also be controlled on a per-major mode basis from a user function
in configuration.
This commit also drops support for Emacs 27 to reduce the maintenance
burden.
BREAKING CHANGE: font ligatures for Harfbuzz/Coretext composition
table-based ligations are no longer controlled with
`+ligatures-composition-alist`, but is handled with
`+ligatures-prog-mode-list` and `+ligatures-all-modes-list` for most
common cases. See the README for the mode-specific methods
BREAKING CHANGE: the `:ui ligatures` module will not work anymore
with Emacs 27 or older. Also, there is no need to keep patched fonts
(for Fira, Hasklig, Iosevka) if you use the module. Update Emacs if
you want to keep using ligatures, or disable the module (`doom doctor`
will tell you if your current version of Emacs stopped working with
the module)
featurep! will be renamed modulep! in the future, so it's been
deprecated. They have identical interfaces, and can be replaced without
issue.
featurep! was never quite the right name for this macro. It implied that
it had some connection to featurep, which it doesn't (only that it was
similar in purpose; still, Doom modules are not features). To undo such
implications and be consistent with its namespace (and since we're
heading into a storm of breaking changes with the v3 release anyway),
now was the best opportunity to begin the transition.
doom-enlist is now a deprecated alias for ensure-list, which is built
into Emacs 28.1+ and is its drop-in replacement. We've already
backported it for 27.x users in doom-lib (in 4bf4978).
Ref: 4bf49785fd
