Proportional spacing bug: chained \noBreaks + \newSpacingSection

[Trevor Bača]

Hi,

LilyPond incorrectly compresses consecutive, proportionally spaced measures
when the following conditions hold:

1. first measure in the sequence sets \proportionalNotationDuration; and
2. last measure in sequence is followed by \newSpacingSection; and
3. all measures in sequence carry \noBreak commands.

%%% BEGIN SPACING BUG %%%

\version "2.19.82"

\layout {
    indent = #0
    ragged-right = ##t
}

\new Staff
\with
{
    \remove Time_signature_engraver
}
{

    \time 2/8
    \set Score.proportionalNotationDuration = #(ly:make-moment 1 32)
    c'4
    ^ \markup \with-color #red "First three measures aren't wide enough"
    \noBreak

    c'4
    \noBreak

    c'4
    \noBreak

    \newSpacingSection
    c'4

    c'4

    c'4

    c'4

    c'4

}

%%% END %%%

Output looks like this:

[image: no-break-spacing-bug.png]

Correct output looks like this:

%%% BEGIN NON-BUG %%%

\version "2.19.82"

\layout {
    indent = #0
    ragged-right = ##t
}

\new Staff
\with
{
    \remove Time_signature_engraver
}
{

    \time 2/8
    \set Score.proportionalNotationDuration = #(ly:make-moment 1 32)
    c'4

    c'4

    c'4

    \newSpacingSection
    c'4

    c'4

    c'4

    c'4

    c'4

}

%%% END %%%

Visual:

[image: correct-output.png]

Note, again, that *all* measures spaced incorrectly must carry a \noBreak
command; removing *any one* of the three \noBreak commands in the bug
snippet causes the bug to disappear.


Trevor.

-- 
Trevor Bača
www.trevorbaca.com
soundcloud.com/trevorbaca