Issue: object ref-count ignored when moving std::unique_ptr

[rhaschke]

Inspecting the unit tests of #2904 in more detail, I noticed that the smart holder code is actually ignoring an object's ref-count, although there is this test:

pybind11/include/pybind11/detail/smart_holder_type_casters.h

Line 380 in 784092d

holder().ensure_use_count_1(context);

Nevertheless, as shown in this example, the refcount of the object before moving it, is 3! Something weird is going on there. Moving should fail in this case, shouldn't it? @rwgk

Having that said, I actually want to have the possibility to move an object with a refcount > 1. Otherwise, I couldn't move a variable, but only "rvalues". There are extra checks in place to ensure that I don't access a disowned object again...

[rwgk]

holder().ensure_use_count_1(context);

Hi @rhaschke, this is the std::shared_ptr::use_count, which has basically nothing to do with the Python refcount, although conceptually both are very similar.

[rhaschke]

Ah. Ok. Sorry for the noise.