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e75660dad3
In this new version of Arbitrary Self Types, we no longer use the Deref trait exclusively when working out which self types are valid. Instead, we follow a chain of Receiver traits. This enables methods to be called on smart pointer types which fundamentally cannot support Deref (for instance because they are wrappers for pointers that don't follow Rust's aliasing rules). This includes: * Changes to tests appropriately * New tests for: * The basics of the feature * Ensuring lifetime elision works properly * Generic Receivers * A copy of the method subst test enhanced with Receiver This is really the heart of the 'arbitrary self types v2' feature, and is the most critical commit in the current PR. Subsequent commits are focused on: * Detecting "shadowing" problems, where a smart pointer type can hide methods in the pointee. * Diagnostics and cleanup. Naming: in this commit, the "Autoderef" type is modified so that it no longer solely focuses on the "Deref" trait, but can now consider the "Receiver" trait instead. Should it be renamed, to something like "TraitFollower"? This was considered, but rejected, because * even in the Receiver case, it still considers built-in derefs * the name Autoderef is short and snappy.
169 lines
8.4 KiB
Plaintext
169 lines
8.4 KiB
Plaintext
error[E0801]: invalid generic `self` parameter type: `R`
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--> $DIR/arbitrary-self-from-method-substs.rs:9:43
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LL | fn get<R: Deref<Target = Self>>(self: R) -> u32 {
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| ^
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= note: type of `self` must not be a method generic parameter type
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= help: use a concrete type such as `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
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error[E0801]: invalid generic `self` parameter type: `&R`
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--> $DIR/arbitrary-self-from-method-substs.rs:13:44
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LL | fn get1<R: Deref<Target = Self>>(self: &R) -> u32 {
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| ^^
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= note: type of `self` must not be a method generic parameter type
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= help: use a concrete type such as `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
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error[E0801]: invalid generic `self` parameter type: `&mut R`
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--> $DIR/arbitrary-self-from-method-substs.rs:17:44
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LL | fn get2<R: Deref<Target = Self>>(self: &mut R) -> u32 {
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| ^^^^^^
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= note: type of `self` must not be a method generic parameter type
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= help: use a concrete type such as `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
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error[E0801]: invalid generic `self` parameter type: `Rc<R>`
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--> $DIR/arbitrary-self-from-method-substs.rs:21:44
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LL | fn get3<R: Deref<Target = Self>>(self: std::rc::Rc<R>) -> u32 {
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| ^^^^^^^^^^^^^^
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= note: type of `self` must not be a method generic parameter type
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= help: use a concrete type such as `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
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error[E0801]: invalid generic `self` parameter type: `&Rc<R>`
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--> $DIR/arbitrary-self-from-method-substs.rs:25:44
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LL | fn get4<R: Deref<Target = Self>>(self: &std::rc::Rc<R>) -> u32 {
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| ^^^^^^^^^^^^^^^
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= note: type of `self` must not be a method generic parameter type
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= help: use a concrete type such as `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
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error[E0801]: invalid generic `self` parameter type: `Rc<&R>`
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--> $DIR/arbitrary-self-from-method-substs.rs:29:44
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LL | fn get5<R: Deref<Target = Self>>(self: std::rc::Rc<&R>) -> u32 {
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| ^^^^^^^^^^^^^^^
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= note: type of `self` must not be a method generic parameter type
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= help: use a concrete type such as `self`, `&self`, `&mut self`, `self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, or `self: Pin<P>` (where P is one of the previous types except `Self`)
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error[E0658]: `<FR as FindReceiver>::Receiver` cannot be used as the type of `self` without the `arbitrary_self_types` feature
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--> $DIR/arbitrary-self-from-method-substs.rs:33:37
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LL | fn get6<FR: FindReceiver>(self: FR::Receiver, other: FR) -> u32 {
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| ^^^^^^^^^^^^
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= note: see issue #44874 <https://github.com/rust-lang/rust/issues/44874> for more information
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= help: add `#![feature(arbitrary_self_types)]` to the crate attributes to enable
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= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
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= help: consider changing to `self`, `&self`, `&mut self`, or a type implementing `Receiver` such as `self: Box<Self>`, `self: Rc<Self>`, or `self: Arc<Self>`
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error[E0658]: `R` cannot be used as the type of `self` without the `arbitrary_self_types` feature
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--> $DIR/arbitrary-self-from-method-substs.rs:61:18
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LL | fn get(self: R) {}
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| ^
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= note: see issue #44874 <https://github.com/rust-lang/rust/issues/44874> for more information
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= help: add `#![feature(arbitrary_self_types)]` to the crate attributes to enable
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= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
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= help: consider changing to `self`, `&self`, `&mut self`, or a type implementing `Receiver` such as `self: Box<Self>`, `self: Rc<Self>`, or `self: Arc<Self>`
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error[E0271]: type mismatch resolving `<Silly as FindReceiver>::Receiver == Foo`
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--> $DIR/arbitrary-self-from-method-substs.rs:92:9
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LL | foo.get6(Silly);
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| ^^^^ type mismatch resolving `<Silly as FindReceiver>::Receiver == Foo`
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note: expected this to be `Foo`
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--> $DIR/arbitrary-self-from-method-substs.rs:71:21
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LL | type Receiver = std::rc::Rc<Foo>;
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| ^^^^^^^^^^^^^^^^
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= note: expected struct `Foo`
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found struct `Rc<Foo>`
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error[E0271]: type mismatch resolving `<Silly as FindReceiver>::Receiver == &Foo`
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--> $DIR/arbitrary-self-from-method-substs.rs:96:9
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LL | foo.get6(Silly);
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| ^^^^ type mismatch resolving `<Silly as FindReceiver>::Receiver == &Foo`
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note: expected this to be `&Foo`
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--> $DIR/arbitrary-self-from-method-substs.rs:71:21
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LL | type Receiver = std::rc::Rc<Foo>;
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| ^^^^^^^^^^^^^^^^
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= note: expected reference `&Foo`
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found struct `Rc<Foo>`
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error[E0599]: the method `get` exists for struct `Rc<Bar<_>>`, but its trait bounds were not satisfied
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--> $DIR/arbitrary-self-from-method-substs.rs:100:7
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LL | struct Bar<R>(std::marker::PhantomData<R>);
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| ------------- doesn't satisfy `Bar<_>: Deref`
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...
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LL | t.get();
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| ^^^ method cannot be called on `Rc<Bar<_>>` due to unsatisfied trait bounds
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note: the following trait bounds were not satisfied:
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`<&Bar<_> as Deref>::Target = Bar<&Bar<_>>`
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`<&Rc<Bar<_>> as Deref>::Target = Bar<&Rc<Bar<_>>>`
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`<&mut Bar<_> as Deref>::Target = Bar<&mut Bar<_>>`
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`<&mut Rc<Bar<_>> as Deref>::Target = Bar<&mut Rc<Bar<_>>>`
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`<Rc<Bar<_>> as Deref>::Target = Bar<Rc<Bar<_>>>`
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`Bar<_>: Deref`
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--> $DIR/arbitrary-self-from-method-substs.rs:60:9
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LL | impl<R: std::ops::Deref<Target = Self>> Bar<R> {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ------
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| | |
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| | unsatisfied trait bound introduced here
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| unsatisfied trait bound introduced here
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note: the trait `Deref` must be implemented
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--> $SRC_DIR/core/src/ops/deref.rs:LL:COL
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= help: items from traits can only be used if the trait is implemented and in scope
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= note: the following trait defines an item `get`, perhaps you need to implement it:
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candidate #1: `SliceIndex`
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error[E0599]: the method `get` exists for reference `&Rc<Bar<_>>`, but its trait bounds were not satisfied
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--> $DIR/arbitrary-self-from-method-substs.rs:108:7
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LL | struct Bar<R>(std::marker::PhantomData<R>);
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| ------------- doesn't satisfy `Bar<_>: Deref`
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...
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LL | t.get();
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| ^^^ method cannot be called on `&Rc<Bar<_>>` due to unsatisfied trait bounds
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note: the following trait bounds were not satisfied:
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`<&&Rc<Bar<_>> as Deref>::Target = Bar<&&Rc<Bar<_>>>`
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`<&Bar<_> as Deref>::Target = Bar<&Bar<_>>`
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`<&Rc<Bar<_>> as Deref>::Target = Bar<&Rc<Bar<_>>>`
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`<&mut &Rc<Bar<_>> as Deref>::Target = Bar<&mut &Rc<Bar<_>>>`
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`<&mut Bar<_> as Deref>::Target = Bar<&mut Bar<_>>`
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`<&mut Rc<Bar<_>> as Deref>::Target = Bar<&mut Rc<Bar<_>>>`
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`<Rc<Bar<_>> as Deref>::Target = Bar<Rc<Bar<_>>>`
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`Bar<_>: Deref`
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--> $DIR/arbitrary-self-from-method-substs.rs:60:9
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LL | impl<R: std::ops::Deref<Target = Self>> Bar<R> {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ------
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| | |
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| | unsatisfied trait bound introduced here
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| unsatisfied trait bound introduced here
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note: the trait `Deref` must be implemented
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--> $SRC_DIR/core/src/ops/deref.rs:LL:COL
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= help: items from traits can only be used if the trait is implemented and in scope
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= note: the following trait defines an item `get`, perhaps you need to implement it:
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candidate #1: `SliceIndex`
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error: aborting due to 12 previous errors
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Some errors have detailed explanations: E0271, E0599, E0658, E0801.
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For more information about an error, try `rustc --explain E0271`.
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