lilypond-bin hung

[Nicolas Sceaux]

I've encountered a problem that outreach my knowledge: with the
following ly file, lilypond-bin (current CVS) hangs:

#(define foo #{ #})
#(define quux #{ #})
\score { \notes { c' } }

If I comment out the second line for instance, all is fine.
When I C-c C-c in a GDB session:

« /tmp/hang.ly » maintenant en traitement
Analyse...
Interprétation en cours de la musique...[1]
Pré-traitement des éléments graphiques... 
Program received signal SIGINT, Interrupt.
[Switching to Thread 1077093632 (LWP 11317)]
0x40269672 in mallopt () from /lib/tls/libc.so.6
(gdb) 

The last step that I can track is in grob.hh:127:
    DECLARE_SMOBS (Grob,foo);
some steps after a call to Grob::calculate_dependencies()

I cannot understand what's happening.
nicolas