-* a program where any part of the program does not parse (parsing is an early
- stage of compilation and in Rust includes macro expansion).
-* Macro declarations and uses (current status: some macro declarations and uses
- are formatted).
-* Comments, including any AST node with a comment 'inside' (Rustfmt does not
- currently attempt to format comments, it does format code with comments inside, but that formatting may change in the future).
-* Rust code in code blocks in comments.
-* Any fragment of a program (i.e., stability guarantees only apply to whole
- programs, even where fragments of a program can be formatted today).
-* Code containing non-ascii unicode characters (we believe Rustfmt mostly works
- here, but do not have the test coverage or experience to be 100% sure).
-* Bugs in Rustfmt (like any software, Rustfmt has bugs, we do not consider bug
- fixes to break our stability guarantees).