4 Slurs can be forced to always attach to note heads.
9 \property Voice.Slur \set #'direction = #1
10 \property Voice.Slur \set #'attachment = #'(head . head)
11 g''16()g()g()g()d'()d()d()d
14 \paper { linewidth = -1.; }
17 \notes\relative c \fragment