Re: Lilypond crash related to tuplets

[Aaron Hill]

On 2019-03-23 3:39 pm, Thomas Morley wrote:
> Am Sa., 23. März 2019 um 21:41 Uhr schrieb Aaron Hill
> <address@hidden>:
> > %%%%
> >    \override TupletBracket.X-positions = #(lambda (grob)
> >      (let ((xpos (ly:tuplet-bracket::calc-x-positions grob)))
> >        (if (> (car xpos) (cdr xpos))
> >          (format #t "\nwarning: Inverted X-positions ~a" xpos))
>
> We have `ordered-cons´ for:
>
> >        (cons (min (car xpos) (cdr xpos)) (max (car xpos) (cdr 
> > xpos)))))
> > %%%%

Thanks, Harm.  Would it be reasonable for Internals to include 
documentation on the various helper functions in lily-library.scm?  Some 
have documentation strings already, but even just a list of all 
define-public procedures could be useful.  That, or I just need to 
review that file enough to commit it to memory.

----

Here's a pathological example to trigger bad behavior:

%%%%
\version "2.19.82"
\paper { indent = 0 ragged-right = ##t }
\layout {
  \set tupletFullLength = ##t
  \set tupletFullLengthNote = ##t
  \override Staff.TupletBracket.X-positions = #(lambda (grob)
    (let ((xpos (ly:tuplet-bracket::calc-x-positions grob)))
      (if (> (car xpos) (cdr xpos))
        (format #t "\nwarning: Inverted X-positions ~a" xpos))
      (ordered-cons (car xpos) (cdr xpos))))
}
{ \tuplet 1/1 { b'1 } \break <b' c''>4 }
%%%%

It should be possible to avoid this with the following change to 
tuplet-bracket.cc:

====
241,243c241
<           coord = max (coord, x_span[LEFT]);
<
<           x_span[d] = coord - padding;
---
>           x_span[d] = max (coord - padding, x_span[LEFT]);
====

This does make break-overshoot take priority over full-length-padding, 
as the left bound is computed first.

-- Aaron Hill