Re: [PATCH] On the nasty "ghost key" problem on NS

[Kai Ma]

On Nov 4, 2022, at 23:09, Stefan Monnier <monnier@iro.umontreal.ca> wrote:

I'm glad we found a way to make the code work, apparently, but
Here we need a comment explaining why we do this gymnastic of
`safe_call` + `inhibit_quit` + `waiting_for_input`.

It's very unusual to have to do that.

Thanks for the pointer, this indeed turned out unnecessary (and dangerous).

A tester informed me of a problem in the v3 patch:

  safe_call (0, Qns_in_echo_area)

is incorrect. The 0 should be 1, or nargs will be -1 for funcall_general.  

This will cause an error to be signaled, which explains why 

`waiting_for_input` has to be masked.

[ I guess we could add an assertion that numargs >= 0 in funcall_general or

  somewhere else? ]

This patch should be correct even without the ugly `waiting_for_input` hack.

I’ve been running patched Emacs for some time without issues.

With the current understanding of the bug, I guess the comment line could be

  /* Protect against throw-on-input. */

WDYT?

fix-ghost-key-v4.patch
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