Check if dropping an expression may have indirect side-effects (#14594)

It is not enough to check if an expression type implements `Drop` to
determine whether it can have a significant side-effect.

Also, add tests for unchecked cases which were explicitly handled in the
code, such as checking for side effect in a `struct`'s fields, or in its
base expression.

Fix rust-lang/rust-clippy#14592

changelog: [`no_effect_underscore_binding`]: do not propose to remove
the assignment of an object if dropping it might indirectly have a
visible side effect

0 files changed, 0 insertions, 0 deletions