moc: use C++ constexpr to generate the meta object string data

This avoids having to rely on moc precalculating everything and getting
its sums right, as the main integer table only has a string index
(unlike my original 5.0 plan which would have stored the offset).

For example, for:

  struct Object : QObject { Q_OBJECT signals: void changed(const QVariant &v); }

moc now generates:

  struct qt_meta_stringdata_Object_t {};
  static constexpr auto qt_meta_stringdata_Object = QtMocHelpers::stringData(
      "Object",
      "foobar",
      "",
      "v"
  );

Notes on the implementation:

* the old code is retained because we need moc 6.5 to generate code
  compatible with QtCore 6.2-6.4. It's marked for removal in Qt 6.9.
* the struct qt_meta_stringdata_%s_t remains because we need a
  TU-specific type for QtPrivate::is_complete (via
  qt_incomplete_metaTypeArray). This can be cleaned up.
* after this change, GDB complains while loading QtCore:
    warning: internal error: string "StringData<long sequence of numbers>" failed to be canonicalized
  but debugging does not appear to be impacted. It's just annoying
  because it shows up when QtTest detects a crash too.

Change-Id: Id0fb9ab0089845ee8843fffd16f9d5493e9bd708
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

0 files changed, 0 insertions, 0 deletions