\version "2.21.0"
\pointAndClickOff
\header { tagline = ##f }
\markup { \bold "LyricExtender syntax with autoextender patch (see issue 4509)"}
\markup "Ah \"\" \"\" buh."
{ c''2 2 2 2 } \addlyrics { Ah "" "" buh. }
\markup "Ah _ \"\" buh."
{ c''2 2 2 2 } \addlyrics { Ah _ "" buh. }
\markup "Ah _ _ buh."
{ c''2 2 2 2 } \addlyrics { Ah _ _ buh. }