Errors with slashed grace notes in LilyPond

Question

Here's a strange issue with typesetting (in LilyPond) a work that begins with slashed grace notes (acciaccatura). First of all, I get the following error message in my console when I run lilypond (but it does finish, creating a PDF):

warning: articulation failed to steal 9/640 note backward at beginning of music; stealing forward instead

Then, I get the below awkward and incorrect notation in the score (see red and blue circles):

Below is the code in my .ly file:

\version "2.18.2"
\include "english.ly"

% some other code here [omitted]

topVoice =
{
  \clef treble
  \numericTimeSignature
  \time 4/4
  \key g \major
  \tempo "Bedächtig. Nicht eilen." 4=88
  \relative c''
  {
    \repeat unfold 8 { \acciaccatura g'16( <b, fs'>8)-. }
    \repeat unfold 8 { \acciaccatura g'16( <b, fs'>8)-. }

    % rest of top staff notes here (omitted)
  }
}

bottomVoice =
{
  \clef bass
  \numericTimeSignature
  \time 4/4
  \key g \major
  \relative c
  {
    R1
    fs16( g fs g fs8-.) b,-. fs'16( g fs g fs8-.) b,16( b')

    % rest of bottom staff notes here (omitted)
  }
}

\score
{
  <<
    \new PianoStaff
    {
      <<
        \new Staff = "up"
        {
          \topVoice
        }

        \new Staff = "down"
        {
          \bottomVoice
        }
      >>
    }
  >>

  \layout
  {
    \context
    {
      \PianoStaff
    }
  }
}

Any ideas how to fix this? I'm using LilyPond version 2.18.2.

Answer 1

That's issue 34 in the issue tracker, old, infamous, obstinate, annoying. When starting staves on grace notes, all need to start at the same point of time. Start the notes of the bottom voice with \grace s16 in order to let it match the start time of the top voices.