Bug#904717: rosegarden "Tie Notes at Barlines" has no effect on some imported MIDI

[Jamin Hoggard]

Package: rosegarden
Version: 1:16.06-1+b1

After opening or importing some midi files, if there are tracks with
notes that span barlines (e.g. a half-note on beat 4 of a 4/4 bar),
selecting the note(s) and executing the command:
Adjust -> Notes -> Tie Notes at Barlines
 has no effect.

It is expected that the note would be split into shorter, tied notes,
in accordance with the documentation (e.g. two tied quarter-notes in
the example above; see "Splitting very long notes" at
https://rosegardenmusic.com/wiki/doc:notation-en).

Interestingly, if the long note is deleted and a note of equal
duration is inserted in place of it, the inserted note can then be
split properly using "Tie Notes at Barlines".

Example MIDI files that exhibit this bug (look for red barlines,
indicating an improper number of beats in the bar):

https://upload.wikimedia.org/wikipedia/commons/a/a0/Bass_sample.mid
http://scores.ccarh.org/corelli/op2/corelli-op2n01-1.mid (see tracks 5 and 6),
https://imslp.org/wiki/Special:ImagefromIndex/186184

This bug was not present in Rosegarden 14.02, but is present in
Rosegarden 15.10 in other distributions (as well as 16.06, of course
in Debian).

Sometimes it appears that "Fix Note Quantization" fixes the notation
(many red bar lines disappear), but it actually shortens the notes
spanning the barlines to do this, instead of adding ties across
barlines and preserving the correct note durations.

The change that caused this bug may be in the makeThisNoteViable
function of src/base/SegmentNotationHelper.cpp, where similar bugs
have been caused in the past.

Thanks for your attention in fixing this.