* lisp/hi-lock.el (hi-lock-unface-buffer): Use hi-lock--hashcons
only on strings, not lists.
* test/lisp/hi-lock-tests.el (hi-lock-bug26666): Revert previous change,
use "a" instead of "b".
(hi-lock-unhighlight): New test.
* lisp/hi-lock.el (hi-lock--regexps-at-point): Handle font-lock faces.
(hi-lock-unface-buffer): Simplify default value handling.
(hi-lock-set-pattern): Add either lighter or regexp to
hi-lock-interactive-lighters.
(hi-lock-set-pattern): Put overlay prop hi-lock-overlay-regexp to
either lighter or regexp.
* test/lisp/hi-lock-tests.el (hi-lock-bug26666): Use "b" instead of "a".
(hi-lock-case-fold): New test.
Most of this change is to boilerplate commentary such as license URLs.
This change was prompted by ftp://ftp.gnu.org's going-away party,
planned for November. Change these FTP URLs to https://ftp.gnu.org
instead. Make similar changes for URLs to other organizations moving
away from FTP. Also, change HTTP to HTTPS for URLs to gnu.org and
fsf.org when this works, as this will further help defend against
man-in-the-middle attacks (for this part I omitted the MS-DOS and
MS-Windows sources and the test tarballs to keep the workload down).
HTTPS is not fully working to lists.gnu.org so I left those URLs alone
for now.
If font-lock-mode is disabled in the current buffer, and
there are no matches for REGEXP, then keep FACE available
for a next search.
* lisp/hi-lock.el (hi-lock-set-pattern): Add FACE into
hi-lock--unused-faces if font-lock-mode is disabled and
there are no matches.
* test/lisp/hi-lock-tests.el (hi-lock-test-set-pattern): Add test.
* lisp/hi-lock.el (hi-lock-set-pattern): If REGEXP is already
highlighted, then push FACE into hi-lock--unused-faces (Bug#26666).
* test/lisp/hi-lock-tests.el (hi-lock-bug26666): Add test.
