[MusicXML import] Crash caused by unsupported QVariant

Leon Vinken

• Oct 11, 2018 - 06:44

Reported version

2.3

Type

Functional

Severity

S2 - Critical

Status

closed

Project

MuseScore

Saving a file imported from MusicXML in .mscx or .mscz format sometimes crashes MuseScore with error message "XmlWriter::tag: unsupported type 38 float". Cause is a combination of two things:

1) in file mscore/importmxmlpass1.cpp function updateStyles() style elements lyricsOddFontSize and lyricsEvenFontSize are set to a QVariant(float) instead of QVariant(double)

2) XmlWriter::tag() supports QVariant::Double but does not support QVariant::Float

Changing updateStyles() to use doubles solves the problem (as would supporting QVariant::Float in XmlWriter::tag()

Comments

Jojo-Schmitz

• Oct 11, 2018 - 07:22

As far as I can see QVariant::Float doesn't exist, just QVariant::Double
See http://doc.qt.io/qt-5/qvariant-obsolete.html#Type-enum

Is 3.0 also affected by this?

dmitrio95

• Oct 11, 2018 - 10:16

Still there is a constructor of QVariant for a float value: http://doc.qt.io/qt-5/qvariant.html#QVariant-12
And QMetaType enum contains float either: http://doc.qt.io/qt-5/qmetatype.html#Type-enum
And we seem to be not the only people wondering about this :) See https://stackoverflow.com/q/31290606

So perhaps we should update the code in xmlwriter.cpp to use the new QMetaType list of types?

Leon Vinken

• Oct 11, 2018 - 20:09

Implemented option 1) in PR https://github.com/musescore/MuseScore/pull/4023. Chose this as the MusicXML importer is the part of MuseScore using a Variant containing a float.

This specifically affect 3.0, not sure about 2.3.x.

Jojo is right (I was a bit imprecise): QVariant::Float indeed doesn't exist. That doesn't affect the outcome, as Variant does support float and XmlWriter::tag() doesn't, which causes the issue.

Leon Vinken

• Oct 13, 2018 - 07:18