Add an optional testfn parameter to assoc

* src/fns.c (assoc): New optional testfn parameter used for comparison
when provided.
* test/src/fns-tests.el (test-assoc-testfn): Add tests for the new
'testfn' parameter.
* src/buffer.c:
* src/coding.c:
* src/dbusbind.c:
* src/font.c:
* src/fontset.c:
* src/gfilenotify.c:
* src/image.c:
* src/keymap.c:
* src/process.c:
* src/w32fns.c:
* src/w32font.c:
* src/w32notify.c:
* src/w32term.c:
* src/xdisp.c:
* src/xfont.c: Add a third argument to Fassoc calls.
* etc/NEWS:
* doc/lispref/lists.texi: Document the new 'testfn' parameter.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/xfont.c b/src/xfont.c
index b73596ce7ce..85fccf0dafd 100644
--- a/src/xfont.c
+++ b/src/xfont.c
@@ -505,7 +505,8 @@ xfont_list (struct frame *f, Lisp_Object spec)
       Lisp_Object alter;
 
       if ((alter = Fassoc (SYMBOL_NAME (registry),
-                           Vface_alternative_font_registry_alist),
+                           Vface_alternative_font_registry_alist,
+                           Qnil),
            CONSP (alter)))
         {
           /* Pointer to REGISTRY-ENCODING field.  */