Rollup of 5 pull requests
Successful merges:
- #100451 (Do not panic when a test function returns Result::Err.)
- #102098 (Use fetch_update in sync::Weak::upgrade)
- #102538 (Give `def_span` the same SyntaxContext as `span_with_body`.)
- #102556 (Make `feature(const_btree_len)` implied by `feature(const_btree_new)`)
- #102566 (Add a known-bug test for #102498)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
39323a5877