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https://github.com/rust-lang/rust
synced 2024-10-14 20:46:49 +00:00
Allow constraining opaque types during subtyping in the trait system
This commit is contained in:
Oli Scherer
parent
9889a6f5d3
commit
ba4510ece8
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@ -878,9 +878,9 @@ pub fn subtype_predicate(
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self.enter_forall(predicate, |ty::SubtypePredicate { a_is_expected, a, b }| {
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if a_is_expected {
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Ok(self.at(cause, param_env).sub(DefineOpaqueTypes::No, a, b))
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Ok(self.at(cause, param_env).sub(DefineOpaqueTypes::Yes, a, b))
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} else {
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Ok(self.at(cause, param_env).sup(DefineOpaqueTypes::No, b, a))
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Ok(self.at(cause, param_env).sup(DefineOpaqueTypes::Yes, b, a))
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}
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})
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}
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@ -2,58 +2,23 @@
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//! No hidden types are being constrained in the subtyping predicate, but type and
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//! lifetime variables get subtyped in the generic parameter list of the opaque.
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use std::iter;
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//@ check-pass
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mod either {
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pub enum Either<L, R> {
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Left(L),
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Right(R),
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}
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impl<L: Iterator, R: Iterator<Item = L::Item>> Iterator for Either<L, R> {
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type Item = L::Item;
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fn next(&mut self) -> Option<Self::Item> {
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todo!()
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}
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}
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pub use self::Either::{Left, Right};
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}
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pub enum BabeConsensusLogRef<'a> {
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NextEpochData(BabeNextEpochRef<'a>),
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NextConfigData,
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}
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impl<'a> BabeConsensusLogRef<'a> {
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pub fn scale_encoding(
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&self,
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) -> impl Iterator<Item = impl AsRef<[u8]> + Clone + 'a> + Clone + 'a {
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//~^ ERROR is not satisfied
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//~| ERROR is not satisfied
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//~| ERROR is not satisfied
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match self {
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BabeConsensusLogRef::NextEpochData(digest) => either::Left(either::Left(
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digest.scale_encoding().map(either::Left).map(either::Left),
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)),
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BabeConsensusLogRef::NextConfigData => either::Right(
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// The Opaque type from ``scale_encoding` gets used opaquely here, while the `R`
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// generic parameter of `Either` contains type variables that get subtyped and the
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// opaque type contains lifetime variables that get subtyped.
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iter::once(either::Right(either::Left([1])))
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.chain(std::iter::once([1]).map(either::Right).map(either::Right)),
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),
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}
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}
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}
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pub struct BabeNextEpochRef<'a>(&'a ());
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impl<'a> BabeNextEpochRef<'a> {
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pub fn scale_encoding(
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&self,
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) -> impl Iterator<Item = impl AsRef<[u8]> + Clone + 'a> + Clone + 'a {
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std::iter::once([1])
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fn foo() -> impl Default + Copy {
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if false {
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let x = Default::default();
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// add `Subtype(?x, ?y)` obligation
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let y = x;
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// Make a tuple `(?x, ?y)` and equate it with `(impl Default, u32)`.
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// For us to try and prove a `Subtype(impl Default, u32)` obligation,
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// we have to instantiate both `?x` and `?y` without any
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// `select_where_possible` calls inbetween.
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let mut tup = &mut (x, y);
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let assign_tup = &mut (foo(), 1u32);
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tup = assign_tup;
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}
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1u32
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}
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fn main() {}
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@ -1,21 +0,0 @@
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error[E0277]: the trait bound `Either<Either<Map<Map<impl Iterator<Item = impl AsRef<[u8]> + Clone + '_> + Clone + '_, fn(impl AsRef<[u8]> + Clone + '_) -> Either<impl AsRef<[u8]> + Clone + '_, _> {Either::<impl AsRef<[u8]> + Clone + '_, _>::Left}>, fn(Either<impl AsRef<[u8]> + Clone + '_, _>) -> Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>> {Either::<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>::Left}>, _>, std::iter::Chain<std::iter::Once<Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>>, Map<Map<std::iter::Once<[{integer}; 1]>, fn([{integer}; 1]) -> Either<[{integer}; 1], [{integer}; 1]> {Either::<[{integer}; 1], [{integer}; 1]>::Right}>, fn(Either<[{integer}; 1], [{integer}; 1]>) -> Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>> {Either::<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>::Right}>>>: Clone` is not satisfied
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--> $DIR/lazy_subtyping_of_opaques.rs:30:10
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LL | ) -> impl Iterator<Item = impl AsRef<[u8]> + Clone + 'a> + Clone + 'a {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Clone` is not implemented for `Either<Either<Map<Map<impl Iterator<Item = impl AsRef<[u8]> + Clone + '_> + Clone + '_, fn(impl AsRef<[u8]> + Clone + '_) -> Either<impl AsRef<[u8]> + Clone + '_, _> {Either::<impl AsRef<[u8]> + Clone + '_, _>::Left}>, fn(Either<impl AsRef<[u8]> + Clone + '_, _>) -> Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>> {Either::<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>::Left}>, _>, std::iter::Chain<std::iter::Once<Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>>, Map<Map<std::iter::Once<[{integer}; 1]>, fn([{integer}; 1]) -> Either<[{integer}; 1], [{integer}; 1]> {Either::<[{integer}; 1], [{integer}; 1]>::Right}>, fn(Either<[{integer}; 1], [{integer}; 1]>) -> Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>> {Either::<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>::Right}>>>`
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error[E0277]: the trait bound `Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>: AsRef<[u8]>` is not satisfied
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--> $DIR/lazy_subtyping_of_opaques.rs:30:31
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LL | ) -> impl Iterator<Item = impl AsRef<[u8]> + Clone + 'a> + Clone + 'a {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `AsRef<[u8]>` is not implemented for `Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>`
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error[E0277]: the trait bound `Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>: Clone` is not satisfied
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--> $DIR/lazy_subtyping_of_opaques.rs:30:31
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LL | ) -> impl Iterator<Item = impl AsRef<[u8]> + Clone + 'a> + Clone + 'a {
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Clone` is not implemented for `Either<Either<impl AsRef<[u8]> + Clone + '_, _>, Either<[{integer}; 1], [{integer}; 1]>>`
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error: aborting due to 3 previous errors
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For more information about this error, try `rustc --explain E0277`.
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@ -7,9 +7,10 @@
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type Tait = impl FnOnce() -> ();
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fn reify_as_tait() -> Thunk<Tait> {
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//~^ ERROR: expected a `FnOnce()` closure, found `()`
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Thunk::new(|cont| cont)
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//~^ ERROR: mismatched types
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//~| ERROR: mismatched types
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//~| ERROR: expected a `FnOnce()` closure, found `()`
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}
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struct Thunk<F>(F);
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@ -1,26 +1,31 @@
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error[E0308]: mismatched types
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--> $DIR/lazy_subtyping_of_opaques.rs:10:23
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error[E0277]: expected a `FnOnce()` closure, found `()`
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--> $DIR/lazy_subtyping_of_opaques.rs:11:23
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LL | type Tait = impl FnOnce() -> ();
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| ------------------- the found opaque type
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...
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LL | Thunk::new(|cont| cont)
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| ^^^^ expected `()`, found opaque type
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| ^^^^ expected an `FnOnce()` closure, found `()`
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= note: expected unit type `()`
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found opaque type `Tait`
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= help: the trait `FnOnce()` is not implemented for `()`
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= note: wrap the `()` in a closure with no arguments: `|| { /* code */ }`
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error[E0308]: mismatched types
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--> $DIR/lazy_subtyping_of_opaques.rs:10:5
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error[E0277]: expected a `FnOnce()` closure, found `()`
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--> $DIR/lazy_subtyping_of_opaques.rs:9:23
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LL | fn reify_as_tait() -> Thunk<Tait> {
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| ----------- expected `Thunk<_>` because of return type
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| ^^^^^^^^^^^ expected an `FnOnce()` closure, found `()`
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= help: the trait `FnOnce()` is not implemented for `()`
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= note: wrap the `()` in a closure with no arguments: `|| { /* code */ }`
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error[E0308]: mismatched types
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--> $DIR/lazy_subtyping_of_opaques.rs:11:5
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LL | Thunk::new(|cont| cont)
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| ^^^^^^^^^^^^^^^^^^^^^^^ expected `Thunk<_>`, found `()`
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= note: expected struct `Thunk<_>`
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found unit type `()`
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error: aborting due to 2 previous errors
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error: aborting due to 3 previous errors
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For more information about this error, try `rustc --explain E0308`.
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Some errors have detailed explanations: E0277, E0308.
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For more information about an error, try `rustc --explain E0277`.
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