Improve customization of arabic-shaper-ZWNJ-handling.

Make the effect of customizing arabic-shaper-ZWNJ-handling appear
immediately.
* lisp/language/misc-lang.el (arabic-shaper-ZWNJ-handling): Add :set
value.
* src/composite.c (Fclear_composition_cache): New function.
(syms_of_composite): Defsubr it.

1 files changed, 4 insertions, 1 deletions

diff --git a/lisp/language/misc-lang.el b/lisp/language/misc-lang.el
index a63c3a21091..cbb581fd19f 100644
--- a/lisp/language/misc-lang.el
+++ b/lisp/language/misc-lang.el
@@ -95,7 +95,10 @@ Customizing the value takes effect when you start Emacs next time."
   :type '(choice
           (const :tag "default" nil)
           (const :tag "as space" as-space)
-          (const :tag "absorb" absorb)))
+          (const :tag "absorb" absorb))
+  :set (lambda (sym val)
+         (set-default sym val)
+         (clear-composition-cache)))
 
 ;; Record error in arabic-change-gstring.
 (defvar arabic-shape-log nil)