Bug: nested alist accessor syntax broken for TextSpanner #'bound-details #'[left, right]-broken

[Trevor Bača]

Hi Valentin,

Another one for the tracker. I suspect this one relates very closely to the
previous bug I mailed in less than an hour ago, but I'm not certain. Maybe
add to the tracker as two separate IDs, but referencing each other? Either
way, these two mail given info that should wind up as two separate
regression tests once a fix shows up later on.

Again there is a workaround included towards the bottom, so lower priority.

All examples 2.11.34.


===


NR 1.8.3.2 "Text and line spanners" uses the following syntax for setting
TextSpanner #'bound-details #'left-broken and TextSpanner #'bound-details
#'right-broken:

   \override TextSpanner #'bound-details #'left-broken #'text =
"cotinuation"

This sytax does indeed work, as we can see in the following example:

   \new Staff {
      \override TextSpanner #'bound-details #'left-broken #'text =
"cotinuation"
      \override TextSpanner #'bound-details #'left #'text = "start"
      c'4 \startTextSpan c'4 c'4 c'4 \break
      c'4 c'4 c'4 c'4 \stopTextSpan
   }


Furthermore, we can see this same syntax working here in this second
example:

   \new Staff {
      \override TextSpanner #'bound-details #'left-broken #'X = #30
      \override TextSpanner #'bound-details #'left #'text = "start"
      c'4 \startTextSpan c'4 c'4 c'4 \break
      c'4 c'4 c'4 c'4 \stopTextSpan
   }


But now observe that we get a bug when we try to combine these first two
examples together at one time:

   \new Staff {
      \override TextSpanner #'bound-details #'left-broken #'X = #30
      \override TextSpanner #'bound-details #'left-broken #'text =
"continuation" % BUG -- this setting junked
      \override TextSpanner #'bound-details #'left #'text = "start"
      c'4 \startTextSpan c'4 c'4 c'4 \break
      c'4 c'4 c'4 c'4 \stopTextSpan
   }


There is a workaround. Setting the alist directly works:

   \new Staff {
      \override TextSpanner #'bound-details #'left-broken =
         #'((X . 30) (text . "continuation"))
      \override TextSpanner #'bound-details #'left #'text = "start"
      c'4 \startTextSpan c'4 c'4 c'4 \break
      c'4 c'4 c'4 c'4 \stopTextSpan
   }


Note that this alist syntax is not available in NR. This syntax is available
in the IR ... but with no reference to left-broken and right-broken.

Maybe the best way to summarize this bug is that the code written to afford
access to the nested sublists living inside of bound-details breaks when the
user appends to the #'left-broken and #'right-broken sublists (but works
fine when the user appends to the #'left and #'right sublists).



-- 
Trevor Bača
address@hidden