master 918a5ea 1/2: Make font locking work in mercury-mode

[Lars Ingebrigtsen]

branch: master
commit 918a5eae179f7998e4872cc5cf2f301a21c36587
Author: k3tu0isui <k3tu0isui@gmail.com>
Commit: Lars Ingebrigtsen <larsi@gnus.org>

    Make font locking work in mercury-mode
    
    * lisp/progmodes/prolog.el (prolog-font-lock-keywords): Work in
    all modes derived from prolog-mode (bug#45747).
    (mercury-mode): Set up variables based on the Prolog system (bug#45747).
    
    Copyright-paperwork-exempt: yes
---
 lisp/progmodes/prolog.el | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lisp/progmodes/prolog.el b/lisp/progmodes/prolog.el
index c8f6c12..9f5f9ed 100644
--- a/lisp/progmodes/prolog.el
+++ b/lisp/progmodes/prolog.el
@@ -1201,7 +1201,9 @@ Commands:
 (define-derived-mode mercury-mode prolog-mode "Prolog[Mercury]"
   "Major mode for editing Mercury programs.
 Actually this is just customized `prolog-mode'."
-  (setq-local prolog-system 'mercury))
+  (setq-local prolog-system 'mercury)
+  ;; Run once more to set up based on `prolog-system'
+  (prolog-mode-variables))
 
 
 ;;-------------------------------------------------------------------
@@ -2082,7 +2084,7 @@ Argument BOUND is a buffer position limiting searching."
     (delq
      nil
      (cond
-      ((eq major-mode 'prolog-mode)
+      ((derived-mode-p 'prolog-mode)
        (list
         head-predicates
         head-predicates-1