emacs erlang broken: Error during redisplay: (jit-lock-function 504) signaled (void-function case)

[Andreas Schultz]

Opening an Erlang source in emacs with erlang-mode renders the file with incomplete syntax highlighting. At the same time a error message is logged in emacs:

  Error during redisplay: (jit-lock-function 504) signaled (void-function case)

A Lisp backtrace for this:

Debugger entered--Lisp error: (void-function case)
  (case (nth 3 state) (34 font-lock-string-face) (39 'default))
  (cond ((nth 3 state) (case (nth 3 state) (34 font-lock-string-face) (39 'default))) (t font-lock-comment-face))
  erlang-syntactic-face-function((1 938 nil 34 nil nil 0 nil 939 (938) nil))
  font-lock-fontify-syntactically-region(503 1016 nil)
  font-lock-default-fontify-region(503 1003 nil)
  font-lock-fontify-region(503 1003)
  #f(compiled-function (fun) #<bytecode 0x155ae4b55765>)(font-lock-fontify-region)
  run-hook-wrapped(#f(compiled-function (fun) #<bytecode 0x155ae4b55765>) font-lock-fontify-region)
  jit-lock--run-functions(503 1003)
  jit-lock-fontify-now(503 1003)
  jit-lock-function(503)
  window-end(#<window 9 on ggsn_gn.erl> t)
  linum-update-window(#<window 9 on ggsn_gn.erl>)
  mapc(linum-update-window (#<window 9 on ggsn_gn.erl>))
  linum-update(#<buffer ggsn_gn.erl>)
  linum-after-scroll(#<window 9 on ggsn_gn.erl> 1)
  set-window-buffer(#<window 9 on ggsn_gn.erl> #<buffer ggsn_gn.erl>)
  window--display-buffer(#<buffer ggsn_gn.erl> #<window 9 on ggsn_gn.erl> reuse ((inhibit-same-window)))
  display-buffer-same-window(#<buffer ggsn_gn.erl> ((inhibit-same-window)))
  display-buffer(#<buffer ggsn_gn.erl> (display-buffer-same-window (inhibit-same-window)))
  pop-to-buffer(#<buffer ggsn_gn.erl> (display-buffer-same-window (inhibit-same-window)) nil)
  pop-to-buffer-same-window(#<buffer ggsn_gn.erl>)
  find-file("ggsn_gn.er..." t)
  funcall-interactively(find-file "ggsn_gn.er..." t)
  call-interactively(find-file nil nil)
  command-execute(find-file)

The backtrace points to the erlang-syntactic-face-function in erlang.el. That function is added by a patch that is only present in the Debian and Ubuntu packages.

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: erlang-mode 1:24.1.5+dfsg-1ubuntu1
Uname: Linux 5.15.13-051513-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu75
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: XFCE
Date: Wed Jan 12 10:30:48 2022
Dependencies: emacsen-common 3.0.4
InstallationDate: Installed on 2017-09-26 (1568 days ago)
InstallationMedia: Ubuntu-Server 17.10 "Artful Aardvark" - Alpha amd64 (20170924)
PackageArchitecture: all
SourcePackage: erlang
UpgradeStatus: Upgraded to jammy on 2021-12-30 (12 days ago)

[Andreas Schultz (aschultz)]

In case anyone cares (and I looks like the maintainer does not), backing out debian/patches/atomsfontlock.patch from the source package fixes the problem.

Erlang syntax highlighting works as expected after that.