Re: Use aligned-on-x-parent instead of other callbacks for some grobs (issue 127860043 by address@hidden)

[dak]

https://codereview.appspot.com/127860043/diff/80001/lily/note-column.cc
File lily/note-column.cc (right):

https://codereview.appspot.com/127860043/diff/80001/lily/note-column.cc#newcode167
lily/note-column.cc:167: Grob *main_head;
This is a catastrophic error.  If get_stem (me) returns 0 and there are
no grobs in note-heads, main_head is not initialized at all but gets a
random value.  The rest of the code more likely than not then calls
Grob::extent on this random value.

It would have been easy to notice this error: GCC puts out a quite
accurate warning.

Ignoring GCC's warnings is rarely a good idea.

https://codereview.appspot.com/127860043/