Re: Emacs crashes when displaying the Euro character

[Richard Stallman]

    The X error seems to be coming from the call to XPending.  The X
    libraries manual does not state that XPending can signal an X error,
    but maybe this is a documentation flaw in the X manual.  In any case,
    try this patch; it should eliminate this particular crash.

That patch would not be correct.  What the manual means is probably
that XPending can't _cause_ an error.  And this error was not caused
by XPending.  But XPending looks for input from the X server, so it
notices that a message indicating an error has arrived.  Only the
functions that check input can detect a pending error.

The patch you wrote would be a way of ignoring the error--not just
this error, but all X errors.  If we wanted to do that, the cleaner
way would be to change x_error_handler.  But we don't want to do that.
Normally an X error is the result of a bug in Emacs, calling the Xlib
functions wrong.  We need to track down which Xlib call actually
causes the error.  If it is a bug in Emacs, we can fix it.  If it is
not a bug, then we need to do x_catch_errors around that Xlib call.