Rollup of 8 pull requests Successful merges: - #107902 (fix: improve the suggestion on future not awaited) - #107913 (Update broken link in cargo style guide) - #107942 (Tighter spans for bad inherent `impl` self types) - #107948 (Allow shortcuts to directories to be used for ./x.py fmt) - #107971 (Clearly document intentional UB in mir-opt tests) - #107985 (Added another error to be processed in fallback) - #108002 (Update books) - #108013 (rustdoc: use a string with one-character codes for search index types) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup