...In general, we are looking to limit areas of instability; in particular, post-1.0, the formatting of most code should not change as Rustfmt improves. However, there are some things that Rustfmt can't do or can't do well (and thus where formatting might change significantly, even post-1.0). We would like to reduce the list of limitations over time. You can run Rustfmt by just typing rustfmt filename if you used cargo install. This runs rustfmt on the given file, if the file includes out of line modules, then we reformat those too.