Rollup merge of #60924 - estebank:try-msg, r=petrochenkov

Explain that ? converts the error type using From

Fix #60917.
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Mazdak Farrokhzad 2019-05-19 02:31:39 +02:00 committed by GitHub
commit 80d372f7cd
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4 changed files with 9 additions and 3 deletions

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@ -4,6 +4,7 @@ error[E0277]: `?` couldn't convert the error to `()`
LL | Err(5)?;
| ^ the trait `std::convert::From<{integer}>` is not implemented for `()`
|
= note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
= note: required by `std::convert::From::from`
error: aborting due to previous error

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@ -4,6 +4,7 @@ error[E0277]: `?` couldn't convert the error to `i32`
LL | Err("")?;
| ^ the trait `std::convert::From<&str>` is not implemented for `i32`
|
= note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
= help: the following implementations were found:
<i32 as std::convert::From<bool>>
<i32 as std::convert::From<i16>>

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@ -4,6 +4,7 @@ error[E0277]: `?` couldn't convert the error to `()`
LL | x?;
| ^ the trait `std::convert::From<std::option::NoneError>` is not implemented for `()`
|
= note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
= note: required by `std::convert::From::from`
error[E0277]: the `?` operator can only be used in a function that returns `Result` or `Option` (or another type that implements `std::ops::Try`)