#4767 Crash with Completion_heads_engraver and bare durations

[Simon Albrecht]

The following code crashes:

:::TeX
\version "2.19.36"
\layout {
  \context {
    \Voice
    \remove "Note_heads_engraver"
    \consists "Completion_heads_engraver"
  }
}
{ \breve }

Removing Note_heads_engraver is not essential to triggering the bug.

[David Kastrup]

Issue 4767: Crash with Completion_heads_engraver and bare durations

This checks for the existence of a pitch before using it, defaulting
to middle C.

http://codereview.appspot.com/288100043

[Anonymous]

Passes make, make check and a full make doc.

[Anonymous]

Patch on countdown for Feb 15th

[Anonymous]

Patch counted down please push.

[David Kastrup]

Pushed to staging as
commit 0ab926218d76fa487f6935fd846796c902261e94
Author: David Kastrup dak@gnu.org
Date: Mon Feb 8 23:47:47 2016 +0100

Issue 4767: Crash with Completion_heads_engraver and bare durations

This checks for the existence of a pitch before using it, defaulting
to middle C.