\version "2.18.2"

% triplets played by the flute
flute = \new Staff \with {
  \tupletSpan 8
  beamExceptions = #'((end .
                        (
                          ((1 . 24) . (3 3 3 3 3 3 3 3))
                          )))
} \tuplet 3/2 {
  gis'16( f'' e'') d''( c'' b') a'( gis' fis')
}

% sung words with grace notes
melody = \new Staff \new Voice {
  \autoBeamOff
  d''8 \grace {c''16(}  bis'8) \grace {a'16(}  gis'8)
} \addlyrics { Je -- su, ach! }

% in this score, the grace notes produce gaps between the tuplets
\score {
  <<
    \flute
    \melody
  >>
}

% in this score the grace notes collide with the accidentals
\score {
  <<
    \flute
    \melody
  >>
  \layout {
    \context {
      \Score
      proportionalNotationDuration = #(ly:make-moment 1/24)
      \override SpacingSpanner.strict-note-spacing = ##t
    }
  }
}