Re: Moving from lilypond 2.18 to 2.19

[Matt Wallis]

On 17/11/2017 15:57, David Kastrup wrote:

Matt Wallis <address@hidden> writes:

On 17/11/2017 14:15, David Kastrup wrote:

There are no error messages referring to my own lilypond source files,
which makes me wonder what's going on here.

Your source is triggering an error in the library.  Have you called
convert-ly -ed on your source in order to upgrade its syntax?

I understand that the lilypond-devel package is not intended to be
stable, and so bugs may appear. Is that what's happening here? If not,
I'm happy to try to create a small example that exposes this error.

First try convert-ly.

When I tried lilypond 2.19 on a different score, I had the above
error, but also some relating to my own .ly files. I guess there are
changes that I need to make to my source (even though I have `\version
"2.18.2"` in the source). Is that right? Is there a guide to these
changes?

<http://lilypond.org/doc/v2.19/Documentation/usage/invoking-convert_002dly.en.html>

Many thanks David,

That looks like exactly what I need :-)

If it turns out that this does the trick, it would be interesting to see
just what construct triggered the problem in 2.19 and what convert-ly
changed.  Because I currently have no good guess at what might have
happened here.

I tried convert-ly. It changed nothing other than the version number, and unsurprisingly the error persisted.

So I made experimental changes to the source until I found the cause of the error.
Here is a small example:

\include "english.ly"

global = {
  \time 4/4
  \tempo 4 = 96
}
\score {
  \new Staff {
    \clef treble
    \global
    \relative c' { c1 }
  }
  \midi { \global }
}

... that provokes this error in 2.19.80:

GNU LilyPond 2.19.80
Processing `PianoScore.ly'
Parsing.../opt/local/share/lilypond/2.19.80/scm/lily-library.scm:375:14: In procedure ly:add-context-mod in _expression_ (ly:add-context-mod mods (list # #)):
/opt/local/share/lilypond/2.19.80/scm/lily-library.scm:375:14: Wrong type argument in position 1 (expecting Context_mod): #f

... but works fine in 2.18.2

The error is triggered by the use of \global in the midi block when global contains "\time 4/4". Incidentally, if the midi block contains a \key signature, but no \time, then it works fine in 2.19.80.

I can understand that \time is irrelevant to midi (as is \key?), but I've used this lazily in the past because it works.
I'd be interested to know if you think the correct fix is to restore the original 2.18.2 behaviour, or to output an error message that identifies the line that causes the problem.

Matt Wallis