bug#55668: Extending the `C-x 8' map to include macrons

[Eli Zaretskii <eliz@gnu.org>]

> Cc: "55668@debbugs.gnu.org" <55668@debbugs.gnu.org>
> From: Tor Kringeland <tor.kringeland@ntnu.no>
> Date: Fri, 27 May 2022 12:49:40 +0000
> 
> Kévin Le Gouguec <kevin.legouguec@gmail.com> writes:
> 
> > From the peanut gallery (I don't use macrons much in my writing, so
> > please disregard if not helpful): if we are going to displace an
> > existing binding, why not `C-x 8 ='?  It's currently bound to ¯
> > (MACRON), and the = prefix is reminiscent of TeX, where \=o yields ō
> > (which is usable right now with the TeX input method).
> 
> Didn't know about this one.  I think it'd be better to use it instead of
> `C-x 8 -', then, since the change in behavior is not so different.

Does the below fit the bill?

diff --git a/lisp/international/iso-transl.el b/lisp/international/iso-transl.el
index b90c065..bdfe9b1 100644
--- a/lisp/international/iso-transl.el
+++ b/lisp/international/iso-transl.el
@@ -134,7 +134,19 @@ iso-transl-char-map
     ("*<"   . [?«])
     ("<"    . [?«])
     ("*="   . [?¯])
-    ("="    . [?¯])
+    ("=="   . [?¯])
+    ("=A"   . [?Ā])
+    ("=a"   . [?ā])
+    ("=E"   . [?Ē])
+    ("=e"   . [?ē])
+    ("=I"   . [?Ī])
+    ("=i"   . [?ī])
+    ("=O"   . [?Ō])
+    ("=o"   . [?ō])
+    ("=U"   . [?Ū])
+    ("=u"   . [?ū])
+    ("=Y"   . [?Ȳ])
+    ("=y"   . [?ȳ])
     ("*>"   . [?»])
     (">"    . [?»])
     ("*?"   . [?¿])