MusicXML: xml file causes crash due to failed assertion

• Apr 20, 2018 - 16:31
Reported version
3.0
Type
Functional
Severity
S2 - Critical
Status
closed
Project
MuseScore
Tags
3.0alpha
musicxml

Came up in https://musescore.org/en/node/271604, the xml file there, created by Sibelius directly, not via Dolet, (attached here too) crashes 2.1 and master (287f99d), 2.2.1 loads it without problems though.

Failed assertion:
Fatal: ASSERT: "e == 0 || e->isText()" in file .../MuseScore/libmscore/scoreElement.h, line 511 (.../MuseScore/libmscore/scoreElement.h:511, )

This is the toText() macro, so got to be happening either in mscore/musicxmlsupport.cpp, line 223, domError(), or in mscore/musicxmlsupport.cpp, line 250, domNotImplemented(), which are the only 2 places in the entire score what that macro is used.
Well not quite. it is the only places where that marco is used without a parameter, but as a method of Element?!?

Might have to do with lyrics on grace notes (which in not supported by MuseScore currently), as the 'famos last words just before the assertion are:
Debug: Info at line 14802 col 64: ignoring lyrics on grace notes (...\MuseScore\mscore\importmxmllogger.cpp:49, void Ms::log(Ms::MxmlLogger::Level, const QString&, const QXmlStreamReader*))

Attachment Size
TRAVIATA ACT 1 BRINDISI and on.xml 438.24 KB

Comments

• Apr 20, 2018 - 18:37

The crash occurs in Timeline::tempo_meta() in mscore/timeline.cpp when casting an object that is known to be of type TempoText to type Text. Replacing the line

Text* text = toText(element);

with

TempoText* text = toTempoText(element);

will prevent the crash. But later, when autosave kicks in, another crash occurs when XmlWriter::tag(const QString& name, QVariant data) encounters a data object with a typeName() of "float". This crash is prevented by adding

else if (strcmp(type, "float") == 0) {
*this << "<" << name << ">";
*this << data.toFloat();
*this << "\n";
}

right before the final else in the function.

Reply

• Apr 20, 2018 - 21:33

Whatever bug was causing the crash in 2.1 must have been fixed in 2.2. The casting macros are new in 3.0, and so is mscore/timeline.cpp, so it must not have been the same bug.

Reply

• Apr 21, 2018 - 12:50

Not really sure about your 2nd change. (it crashes not only when autosave kicks in, but also on a regular save or save as BTW).
For one it might better be

                  else if (strcmp(type, "float") == 0)
                        *this << QString("<%1>%2</%1>\n").arg(name).arg(data.toFloat());

just one term and also having an end tag, but maybe it should get handled further up, together with QVariant::Double
Here that float is used for LyricsOddFontSize and LyricsEvenFontSize, so the better fix might be in mscore/importmxml.cpp to change from

            score->style().set(Sid::lyricsOddFontSize, fLyricSize);
            score->style().set(Sid::lyricsEvenFontSize, fLyricSize);

to

            score->style().set(Sid::lyricsOddFontSize, QVariant(fLyricSize));
            score->style().set(Sid::lyricsEvenFontSize, QVariant(fLyricSize));

Reply

• Apr 21, 2018 - 13:43

It makes sense to rewrite it as you say. I had copied the code from the QVariant::Double case. The end tag somehow got lost when I pasted it here. Perhaps the cases that don't already use this format could be rewritten as well.

There is no such thing as a QVariant::Float, so I figured floats had to be handled in the default case for data.type().

Reply