Rollup of 4 pull requests Successful merges: - #124520 (Document that `create_dir_all` calls `mkdir`/`CreateDirW` multiple times) - #124724 (Prefer lower vtable candidates in select in new solver) - #124771 (Don't consider candidates with no failing where clauses when refining obligation causes in new solver) - #124808 (Use `super_fold` in `RegionsToStatic` visitor) r? `@ghost` `@rustbot` modify labels: rollup