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rust/tests/ui/suggestions/chain-method-call-mutation-in-place.stderr

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Add explanation for `&mut self` method call when expecting `-> Self` When a user tries to use a method as if it returned a new value of the same type as its receiver, we will emit a type error. Try to detect this and provide extra explanation that the method modifies the receiver in-place. This has confused people in the wild, like in https://users.rust-lang.org/t/newbie-why-the-commented-line-stops-the-snippet-from-compiling/47322
2020-08-16 20:33:30 -05:00
error[E0308]: mismatched types
--> $DIR/chain-method-call-mutation-in-place.rs:3:5
|
LL | fn foo(mut s: String) -> String {
pretty: trim paths of unique symbols If a symbol name can only be imported from one place for a type, and as long as it was not glob-imported anywhere in the current crate, we can trim its printed path and print only the name. This has wide implications on error messages with types, for example, shortening `std::vec::Vec` to just `Vec`, as long as there is no other `Vec` importable anywhere. This adds a new '-Z trim-diagnostic-paths=false' option to control this feature. On the good path, with no diagnosis printed, we should try to avoid issuing this query, so we need to prevent trimmed_def_paths query on several cases. This change also relies on a previous commit that differentiates between `Debug` and `Display` on various rustc types, where the latter is trimmed and presented to the user and the former is not.
2020-09-02 02:40:56 -05:00
| ------ expected `String` because of return type
Add explanation for `&mut self` method call when expecting `-> Self` When a user tries to use a method as if it returned a new value of the same type as its receiver, we will emit a type error. Try to detect this and provide extra explanation that the method modifies the receiver in-place. This has confused people in the wild, like in https://users.rust-lang.org/t/newbie-why-the-commented-line-stops-the-snippet-from-compiling/47322
2020-08-16 20:33:30 -05:00
LL | s.push_str("asdf")
pretty: trim paths of unique symbols If a symbol name can only be imported from one place for a type, and as long as it was not glob-imported anywhere in the current crate, we can trim its printed path and print only the name. This has wide implications on error messages with types, for example, shortening `std::vec::Vec` to just `Vec`, as long as there is no other `Vec` importable anywhere. This adds a new '-Z trim-diagnostic-paths=false' option to control this feature. On the good path, with no diagnosis printed, we should try to avoid issuing this query, so we need to prevent trimmed_def_paths query on several cases. This change also relies on a previous commit that differentiates between `Debug` and `Display` on various rustc types, where the latter is trimmed and presented to the user and the former is not.
2020-09-02 02:40:56 -05:00
| ^^^^^^^^^^^^^^^^^^ expected struct `String`, found `()`
Add explanation for `&mut self` method call when expecting `-> Self` When a user tries to use a method as if it returned a new value of the same type as its receiver, we will emit a type error. Try to detect this and provide extra explanation that the method modifies the receiver in-place. This has confused people in the wild, like in https://users.rust-lang.org/t/newbie-why-the-commented-line-stops-the-snippet-from-compiling/47322
2020-08-16 20:33:30 -05:00
|
note: method `push_str` modifies its receiver in-place
--> $DIR/chain-method-call-mutation-in-place.rs:3:7
|
LL | s.push_str("asdf")
| - ^^^^^^^^ this call modifies `s` in-place
| |
| you probably want to use this value after calling the method...
= note: ...instead of the `()` output of method `push_str`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0308`.
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