bug#71282: 30.0.50; hl-line overlay priority has no affect

[Mohsin Kaleem <mohkale@kisara.moe>]

Hi there,

Looks like there's no way to give hl-line a higher priority than other
text overlays. This impacts things like eglot-inlay-hints-mode or
overlay-error-string among other modes and has the affect of making
hints or annotations from these modes look out of place. I can reproduce
this with something as minimal as:

$ emacs -Q
$ M-:
(progn
  (setq hl-line-overlay-priority 10)
  (hl-line-mode)
  (erase-buffer)
  (insert ";; This buffer is for text that is not saved, and for Lisp evaluation.
;; To create a file, visit it with ‘SPC f f’ and enter text in its buffer.")
  (let ((ov (make-overlay (+ (point-min) 2) (+ (point-min) 3))))
    (overlay-put ov 'before-string "foo")
    (overlay-put ov 'priority 5)))

If you move the point to the first line you can see the overlay and its
face background completely disregards hl-lines background despite having
a lower priority.

In GNU Emacs 30.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 3.24.41, cairo version 1.18.0) of 2024-05-08 built on mk-desktop
Repository revision: 840c33070dc789d5095a47fa65f4f77564cd6e59
Repository branch: master
System Description: Arch Linux

Configured using:
 'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --mandir=/usr/share/man --with-gameuser=:games
 --with-modules --without-m17n-flt --without-gconf
 --with-native-compilation=yes --with-xinput2 --with-x-toolkit=gtk3
 --without-xaw3d --with-sound=no --with-tree-sitter --without-gpm
 --without-compress-install
 '--program-transform-name=s/\([ec]tags\)/\1.emacs/'
 'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fno-plt -fexceptions
 -Wp,-D_FORTIFY_SOURCE=3 -Wformat -Werror=format-security
 -fstack-clash-protection -fcf-protection -fno-omit-frame-pointer
 -mno-omit-leaf-frame-pointer -g
 -ffile-prefix-map=/home/mohkale/.cache/yay/emacs-git/src=/usr/src/debug/emacs-git
 -flto=auto' 'LDFLAGS=-Wl,-O1 -Wl,--sort-common -Wl,--as-needed
 -Wl,-z,relro -Wl,-z,now -Wl,-z,pack-relative-relocs -flto=auto''

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG
LCMS2 LIBOTF LIBSYSTEMD LIBXML2 MODULES NATIVE_COMP NOTIFY INOTIFY
PDUMPER PNG RSVG SECCOMP SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS
TREE_SITTER WEBP X11 XDBE XIM XINPUT2 XPM GTK3 ZLIB

Important settings:
  value of $LC_MESSAGES: C
  value of $LC_TIME: en_GB.UTF-8
  value of $LANG: en_GB.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  hl-line-mode: t
  straight-use-package-mode: t
  straight-package-neutering-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  minibuffer-regexp-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message mailcap yank-media puny dired
dired-loaddefs rfc822 mml mml-sec password-cache epa derived epg rfc6068
epg-config gnus-util time-date mm-decode mm-bodies mm-encode mail-parse
rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045
ietf-drums mm-util mail-prsvr mail-utils hl-line compile
text-property-search comint ansi-osc ansi-color ring comp-run
comp-common rx straight-autoloads cl-seq cl-extra help-mode straight
cl-macs cl-loaddefs cl-lib +core-setup-paths xdg subr-x term/st
term/xterm xterm byte-opt gv bytecomp byte-compile rmc iso-transl
tooltip cconv eldoc paren electric uniquify ediff-hook vc-hooks
lisp-float-type elisp-mode mwheel term/x-win x-win term/common-win x-dnd
touch-screen tool-bar dnd fontset image regexp-opt fringe tabulated-list
replace newcomment text-mode lisp-mode prog-mode register page tab-bar
menu-bar rfn-eshadow isearch easymenu timer select scroll-bar mouse
jit-lock font-lock syntax font-core term/tty-colors frame minibuffer
nadvice seq simple cl-generic indonesian philippine cham georgian
utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao korean
japanese eucjp-ms cp51932 hebrew greek romanian slovak czech european
ethiopic indian cyrillic chinese composite emoji-zwj charscript charprop
case-table epa-hook jka-cmpr-hook help abbrev obarray oclosure
cl-preloaded button loaddefs theme-loaddefs faces cus-face macroexp
files window text-properties overlay sha1 md5 base64 format env
code-pages mule custom widget keymap hashtable-print-readable backquote
threads dbusbind inotify lcms2 dynamic-setting system-font-setting
font-render-setting cairo gtk x-toolkit xinput2 x multi-tty move-toolbar
make-network-process native-compile emacs)

Memory information:
((conses 16 135391 97166) (symbols 48 12063 45)
 (strings 32 37667 9732) (string-bytes 1 2453600) (vectors 16 17732)
 (vector-slots 8 966098 204470) (floats 8 37 12)
 (intervals 56 463 162) (buffers 992 13))

-- 
Mohsin Kaleem