Previously it output `partially moved` to eagerly. This updates it to be more
accurate and output `collaterally moved` for use of values that were invalidated
by moves out of different fields in the same struct.
Closes#15630.
Currently analyze_move_out_from checks all restrictions on all base
paths of the move path, but it only needs to check restrictions from
loans of the base paths, and can disregard restrictions from loans of
extensions of those base paths.
Instead of calling a borrow() function that takes a pointer type, just
create a local pointer and dereference it. The dereference is there to
outsmart any future liveness analysis in borrowck.
The move_after_borrow / fu_move_after_borrow tests in
run-pass/borrowck-field-sensitivity.rs are not testing the right thing,
since the scope of the borrow is limited to the call to borrow(). When
fixed, these tests fail and thus should be moved to the corresponding
compile-fail test file.
Some of the borrowck field-sensitivity test functions have 'use' in
their name, but they don't refer to the specific kind of use (whether a
copy or a deref). It would be better if the name more precisely
reflected what the function is testing.
