bug#62412: 29.0.60; strange c++ indentation behavior with tree sitter

[Herman]

That's the difference. c++-ts-mode appends "{}():;,#" to 
electric-indent-chars, while c++-mode doesn't do this.

Nevertheless, I think that the calculated intendation should be a 
correct number. Even if the user turns off electric-indent-mode, but 
dedices to call re-indenting manually for a half-written for loop, emacs 
should re-intent the line properly. At least, this specific example 
works OK with c++-mode.

(note that I understand that this problem is not trivial, tree 
sitter/emacs may get confused if the buffer cannot be properly parsed)

On 3/25/23 09:53, João Távora wrote:
> On Fri, Mar 24, 2023 at 10:02 PM Theodor Thornhill via Bug reports for
> GNU Emacs, the Swiss army knife of text editors
> <bug-gnu-emacs@gnu.org> wrote:
> e about the original purpose for this rule, CC’ing Theo.
> > > Yuan
> > I'll look more deeply into the cause of this, but the rule is covering some 
> > preproc directives iirc.
> >
> > Unfortunately tree-sitter behaves better when auto pairs is used. I would 
> > advise people to use electric-pairs-mode (if that's the correct name, on mobile 
> > now) to avoid these sorts of issues.
> electric-pair-mode, it's not on by default.
>
> But, for some reason, electric-indent-mode _is_ on by default,
> at least in c++-ts-mode.
>
> So this has nothing to do with tree-sitter IMO, it's just
> electric-pair-mode doing its thing.
>
> Why is it on by default?  A fair number of users don't like
> this electricity, or prefer to have it toned down.  At least
> this has been the  argument for not turning on electric-pair-mode
> by default, which is a much less jarring mode IMO, and one which
> would solve these problems.
>
> João