X error handler

Currently, if Emacs receives an X protocol error and
x_catch_errors
has not been called, Emacs will kill itself (x_error_handler
calls
x_error_quitter, which calls x_connection_closed).  This
seems
unnecessary.

Xlib defines two types of X error handlers.  The protocol
error
handler (for us, this is x_error_handler) is intended for
non-fatal X
protocol errors.  Fatal errors such as losing the connection
to the X
server invoke a different handler, the X IO error handler
(for us,
this is x_io_error_quitter), which really is supposed to
kill Emacs.

Currently, about half the uses of x_catch_errors in Emacs
code occur
where we want to make an Xlib call that can produce protocol
errors---we don't want those to kill Emacs, but we don't
actually care
about whatever error messages are emitted.  It makes little
sense to
go through xmalloc'ing an error message storage stack,
etc., for this.

It seems to me cleaner to make the protocol error handler do
nothing
by default (rather than kill Emacs).  When x_catch_errors is
on, we
can carry out the current behavior, i.e., storing the error
string
etc.


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    It seems to me cleaner to make the protocol error
handler do nothing
    by default (rather than kill Emacs).  When
x_catch_errors is on, we
    can carry out the current behavior, i.e., storing the
error string
    etc.

This might be a good idea, but I tend to think there must
have been
some reason for writing the code originally not to do so.

Can anyone think of a drawback for this?

One possible drawback is that bugs get ignored rather than
fixed.
But I am not sure that really matters.


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Richard Stallman <rmsgnu.org> writes:

>     It seems to me cleaner to make the protocol error
handler do nothing
>     by default (rather than kill Emacs).  When
x_catch_errors is on, we
>     can carry out the current behavior, i.e., storing
the error string
>     etc.
>
> This might be a good idea, but I tend to think there
must have been
> some reason for writing the code originally not to do
so.
>
> Can anyone think of a drawback for this?
>
> One possible drawback is that bugs get ignored rather
than fixed.
> But I am not sure that really matters.

We can always make the default error handler print to stderr
when
ENABLE_CHECKING is on.

But since this seems like a non-trivial change, and doesn't
fix any
bug, I guess we can put it off till after the release.


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