Figured bass brackets (bug?)

[Jean-Charles Malahieude]

Hi!

I'm trying to reproduce editorial markings in figured bass like in the 
enclosed image, but get nowhere even after having read the sources.

I admit I don't fully get the add_brackets function in 
lily/figured-bass-engraver.cc and need someone to correct my commenting 
of these lines I find in scm/define-music-display-methods.scm;


(define-display-method BassFigureEvent (figure parser)
;;a figure may be composed of 4 elements
  (let ((alteration (ly:music-property figure 'alteration))       ;;an 
alteration
        (fig (ly:music-property figure 'figure))                  ;;a 
figure (number)
        (bracket-start (ly:music-property figure 'bracket-start)) ;;an 
opening bracket
        (bracket-stop (ly:music-property figure 'bracket-stop)))  ;;a 
closing bracket
;;that should be follow this order
    (format #f "~a~a~a~a"
            (if (null? bracket-start) "" "[")  ;;optional editorial
            (cond ((null? fig) "_")  ;;reserved place in the column
                  ((markup? fig) (second fig)) ;; fig: (<number-markup> 
"number")
                  (else fig))
            (if (null? alteration)
                ""  ;;no accidental
                (cond  ;;the different permitted accidentals
                 ((= alteration DOUBLE-FLAT) "--")
                 ((= alteration FLAT) "-")
                 ((= alteration NATURAL) "!")
                 ((= alteration SHARP) "+")
                 ((= alteration DOUBLE-SHARP) "++")
                 (else "")))
            (if (null? bracket-stop) "" "]"))))  ;;optional editorial


I don't find anything wrong in my code

\version "2.17.22"
\new Staff <<
   \new Voice { g'1 }
   \new FiguredBass \figuremode { <[6 5]>2 <6 5]> } >>

but don't see the last closing bracket despite its announcement.

Could anyone help me finish this BWV246 project?
TIA,
Jean-Charles

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