On Wed, Jan 10, 2024 at 04:24:42PM -0500, Jason Merrill wrote:
> On 1/10/24 15:59, Marek Polacek wrote:
> > On Wed, Jan 10, 2024 at 02:58:03PM -0500, Jason Merrill via Gcc wrote:
> > > What formatting style do we want for non-trivial lambdas in GCC sources?
> > > I'm thinking the most consistent choice would be
> > >
> > > auto l = [&] (parms) // space between ] (
> > > { // brace on new line, indented two spaces
> > > return stuff;
> > > };
> >
> > Sure, why not. Consistency is what matters. Thus far we seem
> > to have been very inconsistent. ;)
> > > By default, recent emacs lines up the { with the previous line, like an
> > > in-class function definition; I talked it into the above indentation with
> > >
> > > (defun lambda-offset (elem)
> > > (if (assq 'inline-open c-syntactic-context) '+ 0))
> > > (add-to-hook 'c++-mode-hook '(c-set-offset 'inlambda 'lambda-offset))
> > >
> > > I think we probably want the same formatting for lambdas in function
> > > argument lists, e.g.
> > >
> > > algorithm ([] (parms)
> > > {
> > > return foo;
> > > });
> >
> > And what about lambdas in conditions:
> >
> > if (foo ()
> > && [&] (params) mutable
> > {
> > return 42;
> > } ())
> >
> > should the { go just below [?
>
> I think we don't want the { to go below the [ in general; that was the old
> emacs default behavior, and it produced lambda bodies with excessive
> indentation.
>
> With my adjustment above, emacs indents the { two spaces from the &&, which
> seems a bit arbitrary but reasonable.
Fair enough, I think that's better.
I suppose we should add a note wrt lambdas to
https://gcc.gnu.org/codingconventions.html#Cxx_Conventions
Marek
