graphia doesn't build

[nsajko]

With graphia from Git master and qt 5.15.2.

It seems the bug is in thirdparty/SortFilterProxyModel.

Errors:

 1886 | inline bool operator< (QChar lhs, const QString &rhs) noexcept
      |                        ~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1897:13: note: candidate: ‘bool operator<(const QString&, QChar)’
 1897 | inline bool operator< (const QString &lhs, QChar rhs) noexcept { return   rhs >  lhs; }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1897:39: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const QString&’
 1897 | inline bool operator< (const QString &lhs, QChar rhs) noexcept { return   rhs >  lhs; }
      |                        ~~~~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1905:13: note: candidate: ‘bool operator<(QChar, const QStringRef&)’
 1905 | inline bool operator< (QChar lhs, const QStringRef &rhs) noexcept
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1905:30: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QChar’
 1905 | inline bool operator< (QChar lhs, const QStringRef &rhs) noexcept
      |                        ~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1916:13: note: candidate: ‘bool operator<(const QStringRef&, QChar)’
 1916 | inline bool operator< (const QStringRef &lhs, QChar rhs) noexcept { return   rhs >  lhs; }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1916:42: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const QStringRef&’
 1916 | inline bool operator< (const QStringRef &lhs, QChar rhs) noexcept { return   rhs >  lhs; }
      |                        ~~~~~~~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1924:13: note: candidate: ‘bool operator<(QChar, QLatin1String)’
 1924 | inline bool operator< (QChar lhs, QLatin1String rhs) noexcept
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1924:30: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QChar’
 1924 | inline bool operator< (QChar lhs, QLatin1String rhs) noexcept
      |                        ~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1935:13: note: candidate: ‘bool operator<(QLatin1String, QChar)’
 1935 | inline bool operator< (QLatin1String lhs, QChar rhs) noexcept { return   rhs >  lhs; }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1935:38: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QLatin1String’
 1935 | inline bool operator< (QLatin1String lhs, QChar rhs) noexcept { return   rhs >  lhs; }
      |                        ~~~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1943:13: note: candidate: ‘bool operator<(QStringView, QStringView)’
 1943 | inline bool operator< (QStringView lhs, QStringView rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) <  0; }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1943:36: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QStringView’
 1943 | inline bool operator< (QStringView lhs, QStringView rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) <  0; }
      |                        ~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1951:13: note: candidate: ‘bool operator<(QStringView, QChar)’
 1951 | inline bool operator< (QStringView lhs, QChar rhs) noexcept { return lhs <  QStringView(&rhs, 1); }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1951:36: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QStringView’
 1951 | inline bool operator< (QStringView lhs, QChar rhs) noexcept { return lhs <  QStringView(&rhs, 1); }
      |                        ~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1958:13: note: candidate: ‘bool operator<(QChar, QStringView)’
 1958 | inline bool operator< (QChar lhs, QStringView rhs) noexcept { return QStringView(&lhs, 1) <  rhs; }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1958:30: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QChar’
 1958 | inline bool operator< (QChar lhs, QStringView rhs) noexcept { return QStringView(&lhs, 1) <  rhs; }
      |                        ~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1966:13: note: candidate: ‘bool operator<(QStringView, QLatin1String)’
 1966 | inline bool operator< (QStringView lhs, QLatin1String rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) <  0; }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1966:36: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QStringView’
 1966 | inline bool operator< (QStringView lhs, QLatin1String rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) <  0; }
      |                        ~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1973:13: note: candidate: ‘bool operator<(QLatin1String, QStringView)’
 1973 | inline bool operator< (QLatin1String lhs, QStringView rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) <  0; }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1973:38: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QLatin1String’
 1973 | inline bool operator< (QLatin1String lhs, QStringView rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) <  0; }
      |                        ~~~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1982:32: note: candidate: ‘bool operator<(const QStringRef&, const QByteArray&)’
 1982 | inline QT_ASCII_CAST_WARN bool operator< (const QStringRef &lhs, const QByteArray &rhs) { return lhs.compare(rhs) <  0; }
      |                                ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1982:61: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const QStringRef&’
 1982 | inline QT_ASCII_CAST_WARN bool operator< (const QStringRef &lhs, const QByteArray &rhs) { return lhs.compare(rhs) <  0; }
      |                                           ~~~~~~~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1989:32: note: candidate: ‘bool operator<(const QByteArray&, const QStringRef&)’
 1989 | inline QT_ASCII_CAST_WARN bool operator< (const QByteArray &lhs, const QStringRef &rhs) { return rhs.compare(lhs) >  0; }
      |                                ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1989:61: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const QByteArray&’
 1989 | inline QT_ASCII_CAST_WARN bool operator< (const QByteArray &lhs, const QStringRef &rhs) { return rhs.compare(lhs) >  0; }
      |                                           ~~~~~~~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:2012:32: note: candidate: ‘bool operator<(const char*, const QStringRef&)’
 2012 | inline QT_ASCII_CAST_WARN bool operator<(const char *s1, const QStringRef &s2)
      |                                ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:2012:54: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const char*’
 2012 | inline QT_ASCII_CAST_WARN bool operator<(const char *s1, const QStringRef &s2)
      |                                          ~~~~~~~~~~~~^~
/home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.cpp:64:19: error: no match for ‘operator>’ (operand types are ‘QVariant’ and ‘QVariant’)
   64 |     if (leftValue > rightValue)
      |         ~~~~~~~~~ ^ ~~~~~~~~~~
      |         |           |
      |         QVariant    QVariant
In file included from /usr/include/qt/QtCore/qhashfunctions.h:45,
                 from /usr/include/qt/QtCore/qlist.h:47,
                 from /usr/include/qt/QtCore/qobject.h:49,
                 from /usr/include/qt/QtCore/QObject:1,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/sorter.h:4,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.h:4,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.cpp:1:
/usr/include/qt/QtCore/qpair.h:130:41: note: candidate: ‘template<class T1, class T2> constexpr bool operator>(const QPair<T1, T2>&, const QPair<T1, T2>&)’
  130 | Q_DECL_CONSTEXPR Q_INLINE_TEMPLATE bool operator>(const QPair<T1, T2> &p1, const QPair<T1, T2> &p2)
      |                                         ^~~~~~~~
/usr/include/qt/QtCore/qpair.h:130:41: note:   template argument deduction/substitution failed:
/home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.cpp:64:21: note:   ‘QVariant’ is not derived from ‘const QPair<T1, T2>’
   64 |     if (leftValue > rightValue)
      |                     ^~~~~~~~~~
In file included from /usr/include/qt/QtCore/qlist.h:48,
                 from /usr/include/qt/QtCore/qobject.h:49,
                 from /usr/include/qt/QtCore/QObject:1,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/sorter.h:4,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.h:4,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.cpp:1:
/usr/include/qt/QtCore/qvector.h:1089:13: note: candidate: ‘template<class T> bool operator>(const QVector<T>&, const QVector<T>&)’
 1089 | inline bool operator>(const QVector<T> &lhs, const QVector<T> &rhs)
      |             ^~~~~~~~
/usr/include/qt/QtCore/qvector.h:1089:13: note:   template argument deduction/substitution failed:
/home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.cpp:64:21: note:   ‘QVariant’ is not derived from ‘const QVector<T>’
   64 |     if (leftValue > rightValue)
      |                     ^~~~~~~~~~
In file included from /usr/include/qt/QtCore/qobject.h:49,
                 from /usr/include/qt/QtCore/QObject:1,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/sorter.h:4,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.h:4,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.cpp:1:
/usr/include/qt/QtCore/qlist.h:1173:13: note: candidate: ‘template<class T> bool operator>(const QList<T>&, const QList<T>&)’
 1173 | inline bool operator>(const QList<T> &lhs, const QList<T> &rhs)
      |             ^~~~~~~~
/usr/include/qt/QtCore/qlist.h:1173:13: note:   template argument deduction/substitution failed:
/home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.cpp:64:21: note:   ‘QVariant’ is not derived from ‘const QList<T>’
   64 |     if (leftValue > rightValue)
      |                     ^~~~~~~~~~
In file included from /usr/include/qt/QtCore/qmetatype.h:48,
                 from /usr/include/qt/QtCore/qobject.h:54,
                 from /usr/include/qt/QtCore/QObject:1,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/sorter.h:4,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.h:4,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.cpp:1:
/usr/include/qt/QtCore/qvarlengtharray.h:585:13: note: candidate: ‘template<class T, int Prealloc1, int Prealloc2> bool operator>(const QVarLengthArray<T, Prealloc1>&, const QVarLengthArray<T, Prealloc2>&)’
  585 | inline bool operator>(const QVarLengthArray<T, Prealloc1> &lhs, const QVarLengthArray<T, Prealloc2> &rhs)
      |             ^~~~~~~~
/usr/include/qt/QtCore/qvarlengtharray.h:585:13: note:   template argument deduction/substitution failed:
/home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.cpp:64:21: note:   ‘QVariant’ is not derived from ‘const QVarLengthArray<T, Prealloc1>’
   64 |     if (leftValue > rightValue)
      |                     ^~~~~~~~~~
In file included from /usr/include/qt/QtCore/qstring.h:49,
                 from /usr/include/qt/QtCore/qobject.h:47,
                 from /usr/include/qt/QtCore/QObject:1,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/sorter.h:4,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.h:4,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.cpp:1:
/usr/include/qt/QtCore/qchar.h:66:30: note: candidate: ‘constexpr bool operator>(char, QLatin1Char)’
   66 | Q_DECL_CONSTEXPR inline bool operator> (char lhs, QLatin1Char rhs) noexcept { return lhs >  rhs.toLatin1(); }
      |                              ^~~~~~~~
/usr/include/qt/QtCore/qchar.h:66:46: note:   no known conversion for argument 1 from ‘QVariant’ to ‘char’
   66 | Q_DECL_CONSTEXPR inline bool operator> (char lhs, QLatin1Char rhs) noexcept { return lhs >  rhs.toLatin1(); }
      |                                         ~~~~~^~~
/usr/include/qt/QtCore/qchar.h:73:30: note: candidate: ‘constexpr bool operator>(QLatin1Char, char)’
   73 | Q_DECL_CONSTEXPR inline bool operator> (QLatin1Char lhs, char rhs) noexcept { return lhs.toLatin1() >  rhs; }
      |                              ^~~~~~~~
/usr/include/qt/QtCore/qchar.h:73:53: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QLatin1Char’
   73 | Q_DECL_CONSTEXPR inline bool operator> (QLatin1Char lhs, char rhs) noexcept { return lhs.toLatin1() >  rhs; }
      |                                         ~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qchar.h:642:30: note: candidate: ‘constexpr bool operator>(QChar, QChar)’
  642 | Q_DECL_CONSTEXPR inline bool operator> (QChar c1, QChar c2) noexcept { return  operator< (c2, c1); }
      |                              ^~~~~~~~
/usr/include/qt/QtCore/qchar.h:642:47: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QChar’
  642 | Q_DECL_CONSTEXPR inline bool operator> (QChar c1, QChar c2) noexcept { return  operator< (c2, c1); }
      |                                         ~~~~~~^~
/usr/include/qt/QtCore/qchar.h:653:30: note: candidate: ‘constexpr bool operator>(QChar, std::nullptr_t)’
  653 | Q_DECL_CONSTEXPR inline bool operator> (QChar lhs, std::nullptr_t) noexcept { return  operator< (nullptr, lhs); }
      |                              ^~~~~~~~
/usr/include/qt/QtCore/qchar.h:653:47: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QChar’
  653 | Q_DECL_CONSTEXPR inline bool operator> (QChar lhs, std::nullptr_t) noexcept { return  operator< (nullptr, lhs); }
      |                                         ~~~~~~^~~
/usr/include/qt/QtCore/qchar.h:658:30: note: candidate: ‘constexpr bool operator>(std::nullptr_t, QChar)’
  658 | Q_DECL_CONSTEXPR inline bool operator> (std::nullptr_t, QChar rhs) noexcept { return  operator< (rhs, nullptr); }
      |                              ^~~~~~~~
/usr/include/qt/QtCore/qchar.h:658:41: note:   no known conversion for argument 1 from ‘QVariant’ to ‘std::nullptr_t’
  658 | Q_DECL_CONSTEXPR inline bool operator> (std::nullptr_t, QChar rhs) noexcept { return  operator< (rhs, nullptr); }
      |                                         ^~~~~~~~~~~~~~
In file included from /usr/include/qt/QtCore/qstring.h:50,
                 from /usr/include/qt/QtCore/qobject.h:47,
                 from /usr/include/qt/QtCore/QObject:1,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/sorter.h:4,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.h:4,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.cpp:1:
/usr/include/qt/QtCore/qbytearray.h:708:13: note: candidate: ‘bool operator>(const QByteArray&, const QByteArray&)’
  708 | inline bool operator>(const QByteArray &a1, const QByteArray &a2) noexcept
      |             ^~~~~~~~
/usr/include/qt/QtCore/qbytearray.h:708:41: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const QByteArray&’
  708 | inline bool operator>(const QByteArray &a1, const QByteArray &a2) noexcept
      |                       ~~~~~~~~~~~~~~~~~~^~
/usr/include/qt/QtCore/qbytearray.h:710:13: note: candidate: ‘bool operator>(const QByteArray&, const char*)’
  710 | inline bool operator>(const QByteArray &a1, const char *a2) noexcept
      |             ^~~~~~~~
/usr/include/qt/QtCore/qbytearray.h:710:41: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const QByteArray&’
  710 | inline bool operator>(const QByteArray &a1, const char *a2) noexcept
      |                       ~~~~~~~~~~~~~~~~~~^~
/usr/include/qt/QtCore/qbytearray.h:712:13: note: candidate: ‘bool operator>(const char*, const QByteArray&)’
  712 | inline bool operator>(const char *a1, const QByteArray &a2) noexcept
      |             ^~~~~~~~
/usr/include/qt/QtCore/qbytearray.h:712:35: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const char*’
  712 | inline bool operator>(const char *a1, const QByteArray &a2) noexcept
      |                       ~~~~~~~~~~~~^~
In file included from /usr/include/qt/QtCore/qobject.h:47,
                 from /usr/include/qt/QtCore/QObject:1,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/sorter.h:4,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.h:4,
                 from /home/nsajko/src/github.com/graphia-app/graphia/source/thirdparty/SortFilterProxyModel/sorters/rolesorter.cpp:1:
/usr/include/qt/QtCore/qstring.h:1396:13: note: candidate: ‘bool operator>(QLatin1String, QLatin1String)’
 1396 | inline bool operator>(QLatin1String s1, QLatin1String s2) noexcept
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1396:37: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QLatin1String’
 1396 | inline bool operator>(QLatin1String s1, QLatin1String s2) noexcept
      |                       ~~~~~~~~~~~~~~^~
/usr/include/qt/QtCore/qstring.h:1436:32: note: candidate: ‘bool operator>(const char*, const QString&)’
 1436 | inline QT_ASCII_CAST_WARN bool operator>(const char *s1, const QString &s2)
      |                                ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1436:54: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const char*’
 1436 | inline QT_ASCII_CAST_WARN bool operator>(const char *s1, const QString &s2)
      |                                          ~~~~~~~~~~~~^~
/usr/include/qt/QtCore/qstring.h:1449:32: note: candidate: ‘bool operator>(const char*, QLatin1String)’
 1449 | inline QT_ASCII_CAST_WARN bool operator>(const char *s1, QLatin1String s2)
      |                                ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1449:54: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const char*’
 1449 | inline QT_ASCII_CAST_WARN bool operator>(const char *s1, QLatin1String s2)
      |                                          ~~~~~~~~~~~~^~
/usr/include/qt/QtCore/qstring.h:1825:13: note: candidate: ‘bool operator>(const QStringRef&, const QStringRef&)’
 1825 | inline bool operator>(const QStringRef &s1, const QStringRef &s2) noexcept
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1825:41: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const QStringRef&’
 1825 | inline bool operator>(const QStringRef &s1, const QStringRef &s2) noexcept
      |                       ~~~~~~~~~~~~~~~~~~^~
/usr/include/qt/QtCore/qstring.h:1836:13: note: candidate: ‘bool operator>(const QString&, const QStringRef&)’
 1836 | inline bool operator> (const QString &lhs, const QStringRef &rhs) noexcept { return lhs.compare(rhs) >  0; }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1836:39: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const QString&’
 1836 | inline bool operator> (const QString &lhs, const QStringRef &rhs) noexcept { return lhs.compare(rhs) >  0; }
      |                        ~~~~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1843:13: note: candidate: ‘bool operator>(const QStringRef&, const QString&)’
 1843 | inline bool operator> (const QStringRef &lhs, const QString &rhs) noexcept { return rhs <  lhs; }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1843:42: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const QStringRef&’
 1843 | inline bool operator> (const QStringRef &lhs, const QString &rhs) noexcept { return rhs <  lhs; }
      |                        ~~~~~~~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1872:13: note: candidate: ‘bool operator>(QLatin1String, const QStringRef&)’
 1872 | inline bool operator> (QLatin1String lhs, const QStringRef &rhs) noexcept { return rhs.compare(lhs) <  0; }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1872:38: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QLatin1String’
 1872 | inline bool operator> (QLatin1String lhs, const QStringRef &rhs) noexcept { return rhs.compare(lhs) <  0; }
      |                        ~~~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1879:13: note: candidate: ‘bool operator>(const QStringRef&, QLatin1String)’
 1879 | inline bool operator> (const QStringRef &lhs, QLatin1String rhs) noexcept { return rhs <  lhs; }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1879:42: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const QStringRef&’
 1879 | inline bool operator> (const QStringRef &lhs, QLatin1String rhs) noexcept { return rhs <  lhs; }
      |                        ~~~~~~~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1888:13: note: candidate: ‘bool operator>(QChar, const QString&)’
 1888 | inline bool operator> (QChar lhs, const QString &rhs) noexcept
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1888:30: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QChar’
 1888 | inline bool operator> (QChar lhs, const QString &rhs) noexcept
      |                        ~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1898:13: note: candidate: ‘bool operator>(const QString&, QChar)’
 1898 | inline bool operator> (const QString &lhs, QChar rhs) noexcept { return   rhs <  lhs; }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1898:39: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const QString&’
 1898 | inline bool operator> (const QString &lhs, QChar rhs) noexcept { return   rhs <  lhs; }
      |                        ~~~~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1907:13: note: candidate: ‘bool operator>(QChar, const QStringRef&)’
 1907 | inline bool operator> (QChar lhs, const QStringRef &rhs) noexcept
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1907:30: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QChar’
 1907 | inline bool operator> (QChar lhs, const QStringRef &rhs) noexcept
      |                        ~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1917:13: note: candidate: ‘bool operator>(const QStringRef&, QChar)’
 1917 | inline bool operator> (const QStringRef &lhs, QChar rhs) noexcept { return   rhs <  lhs; }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1917:42: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const QStringRef&’
 1917 | inline bool operator> (const QStringRef &lhs, QChar rhs) noexcept { return   rhs <  lhs; }
      |                        ~~~~~~~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1926:13: note: candidate: ‘bool operator>(QChar, QLatin1String)’
 1926 | inline bool operator> (QChar lhs, QLatin1String rhs) noexcept
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1926:30: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QChar’
 1926 | inline bool operator> (QChar lhs, QLatin1String rhs) noexcept
      |                        ~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1936:13: note: candidate: ‘bool operator>(QLatin1String, QChar)’
 1936 | inline bool operator> (QLatin1String lhs, QChar rhs) noexcept { return   rhs <  lhs; }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1936:38: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QLatin1String’
 1936 | inline bool operator> (QLatin1String lhs, QChar rhs) noexcept { return   rhs <  lhs; }
      |                        ~~~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1945:13: note: candidate: ‘bool operator>(QStringView, QStringView)’
 1945 | inline bool operator> (QStringView lhs, QStringView rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) >  0; }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1945:36: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QStringView’
 1945 | inline bool operator> (QStringView lhs, QStringView rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) >  0; }
      |                        ~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1953:13: note: candidate: ‘bool operator>(QStringView, QChar)’
 1953 | inline bool operator> (QStringView lhs, QChar rhs) noexcept { return lhs >  QStringView(&rhs, 1); }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1953:36: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QStringView’
 1953 | inline bool operator> (QStringView lhs, QChar rhs) noexcept { return lhs >  QStringView(&rhs, 1); }
      |                        ~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1960:13: note: candidate: ‘bool operator>(QChar, QStringView)’
 1960 | inline bool operator> (QChar lhs, QStringView rhs) noexcept { return QStringView(&lhs, 1) >  rhs; }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1960:30: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QChar’
 1960 | inline bool operator> (QChar lhs, QStringView rhs) noexcept { return QStringView(&lhs, 1) >  rhs; }
      |                        ~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1968:13: note: candidate: ‘bool operator>(QStringView, QLatin1String)’
 1968 | inline bool operator> (QStringView lhs, QLatin1String rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) >  0; }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1968:36: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QStringView’
 1968 | inline bool operator> (QStringView lhs, QLatin1String rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) >  0; }
      |                        ~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1975:13: note: candidate: ‘bool operator>(QLatin1String, QStringView)’
 1975 | inline bool operator> (QLatin1String lhs, QStringView rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) >  0; }
      |             ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1975:38: note:   no known conversion for argument 1 from ‘QVariant’ to ‘QLatin1String’
 1975 | inline bool operator> (QLatin1String lhs, QStringView rhs) noexcept { return QtPrivate::compareStrings(lhs, rhs) >  0; }
      |                        ~~~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1983:32: note: candidate: ‘bool operator>(const QStringRef&, const QByteArray&)’
 1983 | inline QT_ASCII_CAST_WARN bool operator> (const QStringRef &lhs, const QByteArray &rhs) { return lhs.compare(rhs) >  0; }
      |                                ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1983:61: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const QStringRef&’
 1983 | inline QT_ASCII_CAST_WARN bool operator> (const QStringRef &lhs, const QByteArray &rhs) { return lhs.compare(rhs) >  0; }
      |                                           ~~~~~~~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:1990:32: note: candidate: ‘bool operator>(const QByteArray&, const QStringRef&)’
 1990 | inline QT_ASCII_CAST_WARN bool operator> (const QByteArray &lhs, const QStringRef &rhs) { return rhs.compare(lhs) <  0; }
      |                                ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:1990:61: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const QByteArray&’
 1990 | inline QT_ASCII_CAST_WARN bool operator> (const QByteArray &lhs, const QStringRef &rhs) { return rhs.compare(lhs) <  0; }
      |                                           ~~~~~~~~~~~~~~~~~~^~~
/usr/include/qt/QtCore/qstring.h:2016:32: note: candidate: ‘bool operator>(const char*, const QStringRef&)’
 2016 | inline QT_ASCII_CAST_WARN bool operator>(const char *s1, const QStringRef &s2)
      |                                ^~~~~~~~
/usr/include/qt/QtCore/qstring.h:2016:54: note:   no known conversion for argument 1 from ‘QVariant’ to ‘const char*’
 2016 | inline QT_ASCII_CAST_WARN bool operator>(const char *s1, const QStringRef &s2)
      |                                          ~~~~~~~~~~~~^~
make[2]: *** [source/thirdparty/CMakeFiles/thirdparty.dir/build.make:4878: source/thirdparty/CMakeFiles/thirdparty.dir/SortFilterProxyModel/sorters/rolesorter.cpp.o] Error 1
[ 68%] Linking CXX static library libthirdparty_static.a
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[ 68%] Automatic RCC for resources.qrc
[ 68%] Building CXX object source/crashreporter/CMakeFiles/CrashReporter.dir/CrashReporter_autogen/mocs_compilation.cpp.o
[ 68%] Building CXX object source/crashreporter/CMakeFiles/CrashReporter.dir/main.cpp.o
[ 68%] Building CXX object source/crashreporter/CMakeFiles/CrashReporter.dir/__/app/rendering/openglfunctions.cpp.o
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[ 69%] Building CXX object source/crashreporter/CMakeFiles/CrashReporter.dir/__/shared/utils/static_block.cpp.o
[ 69%] Building CXX object source/crashreporter/CMakeFiles/CrashReporter.dir/CrashReporter_autogen/EWIEGA46WW/qrc_resources.cpp.o
[ 69%] Linking CXX executable ../../CrashReporter
[ 69%] Built target CrashReporter
make[1]: *** [CMakeFiles/Makefile2:314: source/thirdparty/CMakeFiles/thirdparty.dir/all] Error 2
make: *** [Makefile:136: all] Error 2

[nsajko]

This seems to be the relevant bug report: oKcerG/SortFilterProxyModel#77

This pull request claims to fix the issue: oKcerG/SortFilterProxyModel#81

This fork merged that and some other pull requests: https://github.com/CasparKielwein/SortFilterProxyModel

[timangus]

Yep, I'm aware of that issue, but we're actually stuck on 5.14 for other reasons (https://bugreports.qt.io/browse/QTBUG-88111) so haven't bothered addressing this. The Qt company have (rightly or wrongly) basically killed off any further development on Qt 5, so we really need to move to Qt 6/Qt Quick 2. This is obviously not a trivial task though.

[timangus]

Graphia has now been ported to Qt 6.