\version "2.24.0"

global= {
  \time 4/4
  \clef "treble_8"
  \key c \major
}

basse = \relative c {
  \global
  \voiceTwo
  c4 g'4 s s
  e2\5 g\4
}

melodie = \relative c' {
  \global
  \voiceOne
  c4 g8 g'~g f\2 e4
  e4\2 f\2 a e\2
}

\score{ 
  <<       
    \new StaffGroup = "classique et Tab"  
    << 
      \new Staff = "guitare traditionnelle" 
      <<
        \context Voice = "la mélodie" \melodie
        \context Voice = "la basse" \basse
      >>
      \new TabStaff = "guitare TAB" 
      <<
        \context TabVoice = "la basse" \basse
        \context TabVoice = "la mélodie" \melodie
      >>   
    >>
  >>
  \layout { }
}