SUMMARY

SyntaxHighlighter(QObject* parent = nullptr) calls QSyntaxHighlighter(parent).

If parent == nullptr, this crashes because QSyntaxHighlighter(QObject *parent) dereferences parent without checking for nullptr. This could be considered a bug in QSyntaxHighlighter. However, QSyntaxHighlighter does not have a default argument nullptr but SyntaxHighlighter does.

I do not see a way to fix SyntaxHighlighter so that SyntaxHighlighter() can be called without crashing. Ideally, one would do this:

SyntaxHighlighter::SyntaxHighlighter(QObject* parent) :
    QSyntaxHighlighter(parent ?QSyntaxHighlighter(parent) :QSyntaxHighlighter((QTextDocument*)0)),
    AbstractHighlighter(new SyntaxHighlighterPrivate)
{
    qRegisterMetaType<QTextBlock>();
}

but that does not compile.

Is there a way to choose what superclass constructor to call at runtime?