bug#60711: Compose fails to generate ≤ and ≥ (only those two! and only in emacs!)

[Po Lu via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Gregory Heytings <gregory@heytings.org> writes:

> What do you mean?  Conceptually the code does this:
>
> while (XPending (display))
>   {
>     XNextEvent (display, &event);
>     if (XFilterEvent (&event, None) == True)
>       continue;
>     if (event.type == KeyPress)
>       {
>         XmbLookupString(input_context, &event.xkey, buffer, sizeof (buffer) - 1, &keysym, &status);
>         if (status == XLookupChars)
>           {
>             /* do something with buffer */
>           }
>       }
>   }
>
> There is nothing that must be kept around in that code.

Where do you think the text that is stored in buffer comes from?  And
what if the input method choses to commit a keysym?

What if the Xlib character encoding routines do not understand that
particular character?

> I'm sure there are possible complications, but AFAIU they do not
> change the pattern outlined above.

If you get XLookupChars, then half the time the key event you receive is
not a real key event.  Many things can go wrong there, so it is
impossible to debug this without knowing exactly what events are being
sent.