Check this test out:

https://github.com/vlang/v/blob/master/vlib/v/tests/valgrind...

It has lots of comments and will give you a good picture.

I think having actual documentation about how the memory system is supposed to work would do a lot more to answer questions than linking to the tests.

For example:

x = [1, 2, 3] // is this stack or heap allocated?

foo(&x) // how does the compiler know if x needs to be ref counted or not?

return &x // is this valid or UB or a compilation error?