bug#67837: 29.1.90; inhibit-interaction breaks keyboard macros

[Spencer Baugh <sbaugh@janestreet.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Spencer Baugh <sbaugh@janestreet.com>
>> Cc: Stefan Monnier <monnier@iro.umontreal.ca>,  67837@debbugs.gnu.org,
>>    larsi@gnus.org
>> Date: Fri, 15 Dec 2023 14:48:51 -0500
>> 
>> Eli Zaretskii <eliz@gnu.org> writes:
>> 
>> > Please explain why you are removing the calls to
>> > barf_if_interaction_inhibited from many functions.  It looks like they
>> > will now do some work instead of barfing right at the beginning.  Why
>> > is that TRT?
>> 
>> Those calls to barf_if_interaction_inhibited meant inhibit-interaction
>> was checked before the keyboard macro code had a chance to provide
>> input.
>> 
>> I am moving the check on inhibit-interaction to run after checking
>> executing-kbd-macro in the low-level input handling mechanism,
>> read_char.
>
> I'm saying that your proposal of fixing this will cause these
> functions to do some parts of their jobs before they realize that they
> can barf, and this will now happen even when they run not from a
> keyboard macro, and even if the keyboard macro doesn't actually
> provide any input.  This is definitely not TRT.  It affects use cases
> completely unrelated to the ones you wanted to fix, and affects them
> in adverse ways.

I think the effects on other use cases are only positive.  If, for
example, read-char would fail due to reasons other than
inhibit-interaction, it will now fail for those reasons.  Which is good,
because it reduces the need for all code everywhere to think about the
possibility that inhibit-interaction is non-nil.

>> This allows the keyboard macro is allowed to provide input even if
>> inhibit-interaction=t.
>
> Please find a way of fixing the case of a keyboard macro that provides
> input without adversely affecting the other cases where these
> functions are called with inhibit-interaction=t.

How about if those original barf_if_interaction_inhibited calls only
signal if executing-kbd-macro is nil?

>> > And I don't think I understand why we should care about a case when
>> > inhibit-interaction is non-nil, and Emacs needs to execute a keyboard
>> > macro, since executing keyboard macros is basically similar to
>> > interactive invocations of commands.  What are the real-life use cases
>> > for that?
>> 
>> Two concrete, real-life use cases:
>> 
>> - Users write functions using keyboard macros and put them in hooks,
>>   which happen to get invoked by packages which use inhibit-interaction.
>>   Those functions don't actually require interaction, but because they
>>   break, ultimately no code can use inhibit-interaction.
>> 
>> - I run tests in a batch Emacs, frequently using keyboard macros to
>>   provide input.  Sometimes a bug causes code to run which calls
>>   read-char outside of a keyboard macro.  I would like such read-char
>>   calls to error (instead of hanging, which is what they do by default
>>   in batch mode).  If I bind inhibit-interaction=t, then read-char will
>>   exit with an error, but my keyboard macros will also immediately
>>   error.
>
> In both cases, using a function would solve the problem.  So I'm not
> convinced we need to support those marginal cases, unless you can come
> up with a solution that will be both simple and will not affect
> unrelated use cases.

- Are you suggesting that novice users should have to rewrite all their
  keyboard macros in Lisp?  That sounds impractical.

- How can I provide keyboard input to the interactive spec of a command
  I am testing, other than by using keyboard macros?  I'd be pleased to
  have an alternative solution.