Rollup merge of #37244 - senior:add-error-desc-182-230-399, r=GuillaumeGomez
Add error explaination for E0182, E0230 and E0399 This PR adds some error descriptions requested in issue https://github.com/rust-lang/rust/issues/32777. r? @GuillaumeGomez Specifically this adds descriptions for E0182 - unexpected binding of associated item in expression path E0230 - missing type parameter from on_unimplemented description E0399 - overriding a trait type without re-implementing default methods
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@ -1915,6 +1915,45 @@ More details can be found in [RFC 438].
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[RFC 438]: https://github.com/rust-lang/rfcs/pull/438
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"##,
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E0182: r##"
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You bound an associated type in an expression path which is not
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allowed.
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Erroneous code example:
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```compile_fail,E0182
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trait Foo {
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type A;
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fn bar() -> isize;
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}
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impl Foo for isize {
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type A = usize;
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fn bar() -> isize { 42 }
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}
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// error: unexpected binding of associated item in expression path
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let x: isize = Foo::<A=usize>::bar();
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```
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To give a concrete type when using the Universal Function Call Syntax,
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use "Type as Trait". Example:
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```
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trait Foo {
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type A;
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fn bar() -> isize;
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}
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impl Foo for isize {
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type A = usize;
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fn bar() -> isize { 42 }
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}
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let x: isize = <isize as Foo>::bar(); // ok!
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```
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"##,
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E0184: r##"
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Explicitly implementing both Drop and Copy for a type is currently disallowed.
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This feature can make some sense in theory, but the current implementation is
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@ -2752,6 +2791,30 @@ fn main() {
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```
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"##,
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E0230: r##"
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The trait has more type parameters specified than appear in its definition.
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Erroneous example code:
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```compile_fail,E0230
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#![feature(on_unimplemented)]
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#[rustc_on_unimplemented = "Trait error on `{Self}` with `<{A},{B},{C}>`"]
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// error: there is no type parameter C on trait TraitWithThreeParams
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trait TraitWithThreeParams<A,B>
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{}
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```
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Include the correct number of type parameters and the compilation should
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proceed:
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```
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#![feature(on_unimplemented)]
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#[rustc_on_unimplemented = "Trait error on `{Self}` with `<{A},{B},{C}>`"]
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trait TraitWithThreeParams<A,B,C> // ok!
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{}
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```
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"##,
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E0232: r##"
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The attribute must have a value. Erroneous code example:
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@ -3587,6 +3650,44 @@ fn together_we_will_rule_the_galaxy(son: &A<i32>) {} // Ok!
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```
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"##,
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E0399: r##"
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You implemented a trait, overriding one or more of its associated types but did
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not reimplement its default methods.
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Example of erroneous code:
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```compile_fail,E0399
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#![feature(associated_type_defaults)]
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pub trait Foo {
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type Assoc = u8;
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fn bar(&self) {}
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}
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impl Foo for i32 {
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// error - the following trait items need to be reimplemented as
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// `Assoc` was overridden: `bar`
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type Assoc = i32;
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}
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```
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To fix this, add an implementation for each default method from the trait:
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```
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#![feature(associated_type_defaults)]
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pub trait Foo {
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type Assoc = u8;
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fn bar(&self) {}
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}
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impl Foo for i32 {
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type Assoc = i32;
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fn bar(&self) {} // ok!
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}
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```
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"##,
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E0439: r##"
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The length of the platform-intrinsic function `simd_shuffle`
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wasn't specified. Erroneous code example:
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@ -4074,7 +4175,6 @@ register_diagnostics! {
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// E0168,
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// E0173, // manual implementations of unboxed closure traits are experimental
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// E0174,
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E0182,
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E0183,
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// E0187, // can't infer the kind of the closure
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// E0188, // can not cast an immutable reference to a mutable pointer
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@ -4098,7 +4198,6 @@ register_diagnostics! {
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E0226, // only a single explicit lifetime bound is permitted
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E0227, // ambiguous lifetime bound, explicit lifetime bound required
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E0228, // explicit lifetime bound required
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E0230, // there is no type parameter on trait
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E0231, // only named substitution parameters are allowed
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// E0233,
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// E0234,
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@ -4120,8 +4219,6 @@ register_diagnostics! {
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// E0372, // coherence not object safe
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E0377, // the trait `CoerceUnsized` may only be implemented for a coercion
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// between structures with the same definition
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E0399, // trait items need to be implemented because the associated
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// type `{}` was overridden
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E0436, // functional record update requires a struct
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E0521, // redundant default implementations of trait
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E0533, // `{}` does not name a unit variant, unit struct or a constant
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