1 error[E0308]: mismatched types
2 --> $DIR/tail-typeck.rs:3:26
4 LL | fn f() -> isize { return g(); }
5 | ----- ^^^ expected `isize`, found `usize`
7 | expected `isize` because of return type
9 help: you can convert a `usize` to an `isize` and panic if the converted value doesn't fit
11 LL | fn f() -> isize { return g().try_into().unwrap(); }
12 | ++++++++++++++++++++
14 error: aborting due to previous error
16 For more information about this error, try `rustc --explain E0308`.