[drop tracking] Use parent expression for scope

Previously we were just using the parent node as the scope for a
temporary value, but it turns out this is too narrow. For example, in
an expression like

    Foo {
        b: &42,
        a: async { 0 }.await,
    }

the scope for the &42 was set to the ExprField node for `b: &42`, when
we actually want to use the Foo struct expression.

We fix this by recursively searching through parent nodes until we find
a Node::Expr. It may be that we don't find one, and if so that's okay,
we will just fall back on the enclosing temporary scope which is always
sufficient.

0 files changed, 0 insertions, 0 deletions