rustc should output "fix-its" like clang does. Here are some ideas:

• Incorrect use of numeric literals.

   auto i = 0u; i += 3; // suggest "3u" 

• Use of for where for each was meant.

   for (v in foo.iter()) // suggest "for each" 

• Typos on record field names.

   fn f(rec(int foo, int bar) r) { ... } f(rec(foo=1, baz=2)); // suggest "bar"