Issue 1291 in lilypond: R2 in single 4/4 measure produces "Object is not a markup." and "I am not spanned!"

[lilypond]

Status: Accepted
Owner: ----
Labels: Warning Type-Defect Priority-High

New issue 1291 by brownian.box: R2 in single 4/4 measure produces "Object  
is not a markup." and "I am not spanned!"
http://code.google.com/p/lilypond/issues/detail?id=1291

Reported by Marnix Klooster and David Kastrup,
http://lists.gnu.org/archive/html/bug-lilypond/2010-10/msg00062.html

%---------------------8<-------------------------------
\version "2.12.4" % the same for 2.13.35
{ R2 }

[...]

We currently get
/tmp/junk2.ly:1:2: warning: barcheck failed at: 1/2
{
  R2 }
Preprocessing graphical objects...
programming error: Multi_measure_rest::get_rods (): I am not spanned!
continuing, cross fingers
programming error: Object is not a markup.
continuing, cross fingers
This object should be a markup: ()
programming error: Multi_measure_rest::get_rods (): I am not spanned!
continuing, cross fingers


Instead, the message better be either
Warning: multimeasure rest fails bar check
(in case that its length _is_ a full bar multiple)
or
Error: multimeasure rest size not a multiple of bar size
(in case that it could not work out anyway).

In case of a warning, error recovery needs to result in something
reasonably sensible.  If that is not feasible, one needs to create an
error instead.

A warning implies that Lilypond is going to do continue with reasonable
results.

--
David Kastrup
%---------------------8<-------------------------------

Again, not sure about priority. "barcheck failed" looks like medium;  
but "programming error" is closer to critical?..