1 error[E0277]: `?` couldn't convert the error to `u8`
2 --> $DIR/bad-interconversion.rs:6:20
4 LL | fn result_to_result() -> Result<u64, u8> {
5 | --------------- expected `u8` because of this
7 | ^ the trait `From<i32>` is not implemented for `u8`
9 = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
10 = help: the following other types implement trait `From<T>`:
20 = note: required for `Result<u64, u8>` to implement `FromResidual<Result<Infallible, i32>>`
22 error[E0277]: the `?` operator can only be used on `Result`s, not `Option`s, in a function that returns `Result`
23 --> $DIR/bad-interconversion.rs:11:12
25 LL | / fn option_to_result() -> Result<u64, String> {
27 | | ^ use `.ok_or(...)?` to provide an error compatible with `Result<u64, String>`
31 | |_- this function returns a `Result`
33 = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `Result<u64, String>`
34 = help: the following other types implement trait `FromResidual<R>`:
35 <Result<T, F> as FromResidual<Result<Infallible, E>>>
36 <Result<T, F> as FromResidual<Yeet<E>>>
38 error[E0277]: the `?` operator can only be used on `Result`s in a function that returns `Result`
39 --> $DIR/bad-interconversion.rs:17:31
41 LL | / fn control_flow_to_result() -> Result<u64, String> {
42 LL | | Ok(ControlFlow::Break(123)?)
43 | | ^ this `?` produces `ControlFlow<{integer}, Infallible>`, which is incompatible with `Result<u64, String>`
46 | |_- this function returns a `Result`
48 = help: the trait `FromResidual<ControlFlow<{integer}, Infallible>>` is not implemented for `Result<u64, String>`
49 = help: the following other types implement trait `FromResidual<R>`:
50 <Result<T, F> as FromResidual<Result<Infallible, E>>>
51 <Result<T, F> as FromResidual<Yeet<E>>>
53 error[E0277]: the `?` operator can only be used on `Option`s, not `Result`s, in a function that returns `Option`
54 --> $DIR/bad-interconversion.rs:22:22
56 LL | / fn result_to_option() -> Option<u16> {
57 LL | | Some(Err("hello")?)
58 | | ^ use `.ok()?` if you want to discard the `Result<Infallible, &str>` error information
61 | |_- this function returns an `Option`
63 = help: the trait `FromResidual<Result<Infallible, &str>>` is not implemented for `Option<u16>`
64 = help: the following other types implement trait `FromResidual<R>`:
65 <Option<T> as FromResidual<Yeet<()>>>
66 <Option<T> as FromResidual>
68 error[E0277]: the `?` operator can only be used on `Option`s in a function that returns `Option`
69 --> $DIR/bad-interconversion.rs:27:33
71 LL | / fn control_flow_to_option() -> Option<u64> {
72 LL | | Some(ControlFlow::Break(123)?)
73 | | ^ this `?` produces `ControlFlow<{integer}, Infallible>`, which is incompatible with `Option<u64>`
76 | |_- this function returns an `Option`
78 = help: the trait `FromResidual<ControlFlow<{integer}, Infallible>>` is not implemented for `Option<u64>`
79 = help: the following other types implement trait `FromResidual<R>`:
80 <Option<T> as FromResidual<Yeet<()>>>
81 <Option<T> as FromResidual>
83 error[E0277]: the `?` operator can only be used on `ControlFlow`s in a function that returns `ControlFlow`
84 --> $DIR/bad-interconversion.rs:32:39
86 LL | / fn result_to_control_flow() -> ControlFlow<String> {
87 LL | | ControlFlow::Continue(Err("hello")?)
88 | | ^ this `?` produces `Result<Infallible, &str>`, which is incompatible with `ControlFlow<String>`
91 | |_- this function returns a `ControlFlow`
93 = help: the trait `FromResidual<Result<Infallible, &str>>` is not implemented for `ControlFlow<String>`
94 = help: the trait `FromResidual` is implemented for `ControlFlow<B, C>`
96 error[E0277]: the `?` operator can only be used on `ControlFlow`s in a function that returns `ControlFlow`
97 --> $DIR/bad-interconversion.rs:37:12
99 LL | / fn option_to_control_flow() -> ControlFlow<u64> {
101 | | ^ this `?` produces `Option<Infallible>`, which is incompatible with `ControlFlow<u64>`
103 LL | | ControlFlow::Break(10)
105 | |_- this function returns a `ControlFlow`
107 = help: the trait `FromResidual<Option<Infallible>>` is not implemented for `ControlFlow<u64>`
108 = help: the trait `FromResidual` is implemented for `ControlFlow<B, C>`
110 error[E0277]: the `?` operator in a function that returns `ControlFlow<B, _>` can only be used on other `ControlFlow<B, _>`s (with the same Break type)
111 --> $DIR/bad-interconversion.rs:43:29
113 LL | / fn control_flow_to_control_flow() -> ControlFlow<i64> {
114 LL | | ControlFlow::Break(4_u8)?;
115 | | ^ this `?` produces `ControlFlow<u8, Infallible>`, which is incompatible with `ControlFlow<i64>`
117 LL | | ControlFlow::Continue(())
119 | |_- this function returns a `ControlFlow`
121 = help: the trait `FromResidual<ControlFlow<u8, Infallible>>` is not implemented for `ControlFlow<i64>`
122 = note: unlike `Result`, there's no `From`-conversion performed for `ControlFlow`
123 = help: the trait `FromResidual` is implemented for `ControlFlow<B, C>`
125 error: aborting due to 8 previous errors
127 For more information about this error, try `rustc --explain E0277`.