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Auto merge of #9649 - Alexendoo:from-over-into-suggestion, r=llogiq
Add a suggestion and a note about orphan rules for `from_over_into` Adds a machine applicable suggestion to convert the `Into` impl into a `From` one to `from_over_into` Also adds a note explaining that `impl From<Local> for Foreign` is fine if the `Into` type is foreign Closes #7444 Addresses half of #9638 changelog: [`from_over_into`] Add a suggestion and a note about orphan rules
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,62 @@ | ||
// run-rustfix | ||
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#![warn(clippy::from_over_into)] | ||
#![allow(unused)] | ||
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// this should throw an error | ||
struct StringWrapper(String); | ||
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impl From<String> for StringWrapper { | ||
fn from(val: String) -> Self { | ||
StringWrapper(val) | ||
} | ||
} | ||
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struct SelfType(String); | ||
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impl From<String> for SelfType { | ||
fn from(val: String) -> Self { | ||
SelfType(String::new()) | ||
} | ||
} | ||
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#[derive(Default)] | ||
struct X; | ||
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impl X { | ||
const FOO: &'static str = "a"; | ||
} | ||
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struct SelfKeywords; | ||
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impl From<X> for SelfKeywords { | ||
fn from(val: X) -> Self { | ||
let _ = X::default(); | ||
let _ = X::FOO; | ||
let _: X = val; | ||
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SelfKeywords | ||
} | ||
} | ||
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struct ExplicitPaths(bool); | ||
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impl core::convert::From<crate::ExplicitPaths> for bool { | ||
fn from(mut val: crate::ExplicitPaths) -> Self { | ||
let in_closure = || val.0; | ||
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val.0 = false; | ||
val.0 | ||
} | ||
} | ||
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// this is fine | ||
struct A(String); | ||
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impl From<String> for A { | ||
fn from(s: String) -> A { | ||
A(s) | ||
} | ||
} | ||
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fn main() {} |
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Original file line number | Diff line number | Diff line change |
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@@ -1,11 +1,62 @@ | ||
error: an implementation of `From` is preferred since it gives you `Into<_>` for free where the reverse isn't true | ||
--> $DIR/from_over_into.rs:6:1 | ||
--> $DIR/from_over_into.rs:9:1 | ||
| | ||
LL | impl Into<StringWrapper> for String { | ||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| | ||
= help: consider to implement `From<std::string::String>` instead | ||
= note: `-D clippy::from-over-into` implied by `-D warnings` | ||
help: replace the `Into` implentation with `From<std::string::String>` | ||
| | ||
LL ~ impl From<String> for StringWrapper { | ||
LL ~ fn from(val: String) -> Self { | ||
LL ~ StringWrapper(val) | ||
| | ||
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error: an implementation of `From` is preferred since it gives you `Into<_>` for free where the reverse isn't true | ||
--> $DIR/from_over_into.rs:17:1 | ||
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LL | impl Into<SelfType> for String { | ||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| | ||
help: replace the `Into` implentation with `From<std::string::String>` | ||
| | ||
LL ~ impl From<String> for SelfType { | ||
LL ~ fn from(val: String) -> Self { | ||
LL ~ SelfType(String::new()) | ||
| | ||
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error: an implementation of `From` is preferred since it gives you `Into<_>` for free where the reverse isn't true | ||
--> $DIR/from_over_into.rs:32:1 | ||
| | ||
LL | impl Into<SelfKeywords> for X { | ||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| | ||
help: replace the `Into` implentation with `From<X>` | ||
| | ||
LL ~ impl From<X> for SelfKeywords { | ||
LL ~ fn from(val: X) -> Self { | ||
LL ~ let _ = X::default(); | ||
LL ~ let _ = X::FOO; | ||
LL ~ let _: X = val; | ||
| | ||
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error: an implementation of `From` is preferred since it gives you `Into<_>` for free where the reverse isn't true | ||
--> $DIR/from_over_into.rs:44:1 | ||
| | ||
LL | impl core::convert::Into<bool> for crate::ExplicitPaths { | ||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| | ||
= help: `impl From<Local> for Foreign` is allowed by the orphan rules, for more information see | ||
https://doc.rust-lang.org/reference/items/implementations.html#trait-implementation-coherence | ||
help: replace the `Into` implentation with `From<ExplicitPaths>` | ||
| | ||
LL ~ impl core::convert::From<crate::ExplicitPaths> for bool { | ||
LL ~ fn from(mut val: crate::ExplicitPaths) -> Self { | ||
LL ~ let in_closure = || val.0; | ||
LL | | ||
LL ~ val.0 = false; | ||
LL ~ val.0 | ||
| | ||
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error: aborting due to previous error | ||
error: aborting due to 4 previous errors | ||
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