I've now seen meson fail to find Qt6 in many environments. That might be because of the meson version, while namely supporting Qt6, having the support broken with newer Qt6 releases. E.g. https://github.com/mesonbuild/meson/pull/9988 suggests that meson-0.62.1 would be the minimum version to have it actually working.
For the reference, ubuntu-22.04 released about a month ago, has meson-0.61.2.
In S3_1 we might just accept the situation - 1) meson is not nearly as supported build method there as autotools, 2) we still have a good Qt5 support for affected people to fall back instead of using Qt6.
For master this is more serious. We'd like to be moving away from both autotools and Qt5 -> to meson and Qt6. That's also a reason we can't make minimum meson requirement too extreme - if people are supposed to be using it, we shouldn't require tool versions that almost nobody has yet.
While meson-0.62.1 resolved the issue for CI ubuntu runner, e.g., in crosser environment it does not. As it attempts to use pkg-config to find Qt6, things might start to work only when crosser has Qt-6.4: https://bugreports.qt.io/browse/QTBUG-86080
I've now seen meson fail to find Qt6 in many environments. That might be because of the meson version, while namely supporting Qt6, having the support broken with newer Qt6 releases. E.g. https://github.com/mesonbuild/meson/pull/9988 suggests that meson-0.62.1 would be the minimum version to have it actually working.
For the reference, ubuntu-22.04 released about a month ago, has meson-0.61.2.
In S3_1 we might just accept the situation - 1) meson is not nearly as supported build method there as autotools, 2) we still have a good Qt5 support for affected people to fall back instead of using Qt6.
For master this is more serious. We'd like to be moving away from both autotools and Qt5 -> to meson and Qt6. That's also a reason we can't make minimum meson requirement too extreme - if people are supposed to be using it, we shouldn't require tool versions that almost nobody has yet.