Accidental/natural on the same note in a polyphonic staff.

[Pierre Perol-Schneider]

Hi All,

This question comes from the French list:
http://lilypond-french-users.1298960.n2.nabble.com/Deplacer-une-alteration-td7584109.html

Here's the situation:

\version "2.18.2"
\relative c' {
  \omit TupletBracket
  \omit TupletNumber
  \tuplet 3/2 4 { r8 << { fis g } \\ { <c, f!> <c f> } >> }
}

%% My idea to get a readable score: =>
\relative c' {
  \omit TupletBracket
  \omit TupletNumber
  \tuplet 3/2 4 {
    r8
    <<
      {
        fis
        %% ugh, ugly hack:
        \tweak X-offset #2.1
        \tweak extra-offset #'(-2.1 . 0)
        g
      }
      \\
      {
        \once\override NoteColumn.force-hshift = #2.1
        <c, f>
        %% => j'imposerai le bécarre ici afin d'éviter
        %% l'espacement indésirable du silence :
        %% (natural sign placed here to avoid the rest misplacement)
        \once\override Accidental.extra-offset = #'(-2.8 . 0)
        <c f!>
      }
    >>
  }
}

Now I'm sure to have read something about this situation but I cannot find it...

(A much simpler solution).

Any help?

TIA, Cheers,

Pierre