nordic-dev.net/rust
nordic-dev.net/rust
2
0
Fork 0
mirror of https://github.com/rust-lang/rust.git synced 2024-11-28 01:34:21 +00:00
Code Issues Packages Projects Releases Wiki Activity

Stop generating inference vars for nested impl trait and let type equality handle it.

Browse Source 
This means we stop supporting the case where a locally defined trait has only a single impl so we can always use that impl (see nested-tait-inference.rs).
This commit is contained in:
Oli Scherer 2022-01-26 13:02:45 +00:00
parent 7bce50c01a
commit a745797142
9 changed files with 70 additions and 50 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
compiler/rustc_infer/src/infer/opaque_types.rs
View File

@ -1,4 +1,3 @@
use crate::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
use crate::infer::{InferCtxt, InferOk};
use crate::traits::{self, PredicateObligation, PredicateObligations};
use hir::def_id::{DefId, LocalDefId};
@ -604,20 +603,6 @@ struct Instantiator<'a, 'tcx> {
}
impl<'a, 'tcx> Instantiator<'a, 'tcx> {
#[instrument(level = "trace", skip(self))]
fn instantiate_opaque_types(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
if let Some(ty) = self.fold_opaque_ty_new(ty, |infcx, span| {
infcx.next_ty_var(TypeVariableOrigin {
kind: TypeVariableOriginKind::TypeInference,
span,
})
}) {
return ty;
}
ty
}
fn fold_opaque_ty_new(
&mut self,
ty: Ty<'tcx>,
@ -720,7 +705,6 @@ impl<'a, 'tcx> Instantiator<'a, 'tcx> {
ty::Opaque(def_id2, substs2) if def_id == def_id2 && substs == substs2 => {
ty_var
}
ty::Opaque(..) => self.instantiate_opaque_types(ty),
_ => ty,
},
lt_op: |lt| lt,

2
src/test/ui/impl-trait/nested_impl_trait.rs
View File

@ -4,6 +4,7 @@ fn fine(x: impl Into<u32>) -> impl Into<u32> { x }
fn bad_in_ret_position(x: impl Into<u32>) -> impl Into<impl Debug> { x }
//~^ ERROR nested `impl Trait` is not allowed
//~| ERROR `impl Into<u32>` doesn't implement `Debug`
fn bad_in_fn_syntax(x: fn() -> impl Into<impl Debug>) {}
//~^ ERROR nested `impl Trait` is not allowed
@ -16,6 +17,7 @@ struct X;
impl X {
fn bad(x: impl Into<u32>) -> impl Into<impl Debug> { x }
//~^ ERROR nested `impl Trait` is not allowed
//~| ERROR `impl Into<u32>` doesn't implement `Debug`
}
fn allowed_in_assoc_type() -> impl Iterator<Item=impl Fn()> {

38
src/test/ui/impl-trait/nested_impl_trait.stderr
View File

@ -8,7 +8,7 @@ LL | fn bad_in_ret_position(x: impl Into<u32>) -> impl Into<impl Debug> { x }
| outer `impl Trait`
error[E0666]: nested `impl Trait` is not allowed
--> $DIR/nested_impl_trait.rs:8:42
--> $DIR/nested_impl_trait.rs:9:42
|
LL | fn bad_in_fn_syntax(x: fn() -> impl Into<impl Debug>) {}
| ----------^^^^^^^^^^-
@ -17,7 +17,7 @@ LL | fn bad_in_fn_syntax(x: fn() -> impl Into<impl Debug>) {}
| outer `impl Trait`
error[E0666]: nested `impl Trait` is not allowed
--> $DIR/nested_impl_trait.rs:12:37
--> $DIR/nested_impl_trait.rs:13:37
|
LL | fn bad_in_arg_position(_: impl Into<impl Debug>) { }
| ----------^^^^^^^^^^-
@ -26,7 +26,7 @@ LL | fn bad_in_arg_position(_: impl Into<impl Debug>) { }
| outer `impl Trait`
error[E0666]: nested `impl Trait` is not allowed
--> $DIR/nested_impl_trait.rs:17:44
--> $DIR/nested_impl_trait.rs:18:44
|
LL | fn bad(x: impl Into<u32>) -> impl Into<impl Debug> { x }
| ----------^^^^^^^^^^-
@ -35,18 +35,40 @@ LL | fn bad(x: impl Into<u32>) -> impl Into<impl Debug> { x }
| outer `impl Trait`
error[E0562]: `impl Trait` not allowed outside of function and method return types
--> $DIR/nested_impl_trait.rs:8:32
--> $DIR/nested_impl_trait.rs:9:32
|
LL | fn bad_in_fn_syntax(x: fn() -> impl Into<impl Debug>) {}
| ^^^^^^^^^^^^^^^^^^^^^
error[E0562]: `impl Trait` not allowed outside of function and method return types
--> $DIR/nested_impl_trait.rs:25:42
--> $DIR/nested_impl_trait.rs:27:42
|
LL | fn allowed_in_ret_type() -> impl Fn() -> impl Into<u32> {
| ^^^^^^^^^^^^^^
error: aborting due to 6 previous errors
error[E0277]: `impl Into<u32>` doesn't implement `Debug`
--> $DIR/nested_impl_trait.rs:5:70
|
LL | fn bad_in_ret_position(x: impl Into<u32>) -> impl Into<impl Debug> { x }
| ^ `impl Into<u32>` cannot be formatted using `{:?}` because it doesn't implement `Debug`
|
help: consider further restricting this bound
|
LL | fn bad_in_ret_position(x: impl Into<u32> + std::fmt::Debug) -> impl Into<impl Debug> { x }
| +++++++++++++++++
Some errors have detailed explanations: E0562, E0666.
For more information about an error, try `rustc --explain E0562`.
error[E0277]: `impl Into<u32>` doesn't implement `Debug`
--> $DIR/nested_impl_trait.rs:18:58
|
LL | fn bad(x: impl Into<u32>) -> impl Into<impl Debug> { x }
| ^ `impl Into<u32>` cannot be formatted using `{:?}` because it doesn't implement `Debug`
|
help: consider further restricting this bound
|
LL | fn bad(x: impl Into<u32> + std::fmt::Debug) -> impl Into<impl Debug> { x }
| +++++++++++++++++
error: aborting due to 8 previous errors
Some errors have detailed explanations: E0277, E0562, E0666.
For more information about an error, try `rustc --explain E0277`.

2
src/test/ui/type-alias-impl-trait/bound_reduction2.rs
View File

@ -15,5 +15,5 @@ impl<W> Trait<W> for () {}
fn foo_desugared<T: TraitWithAssoc>(_: T) -> Foo<T::Assoc> {
()
//~^ ERROR type annotations needed
//~^ ERROR non-defining opaque type use
}

11
src/test/ui/type-alias-impl-trait/bound_reduction2.stderr
View File

@ -1,8 +1,14 @@
error[E0282]: type annotations needed
error: non-defining opaque type use in defining scope
--> $DIR/bound_reduction2.rs:17:5
|
LL | ()
| ^^ cannot infer type
| ^^
|
note: used non-generic type `<T as TraitWithAssoc>::Assoc` for generic parameter
--> $DIR/bound_reduction2.rs:9:10
|
LL | type Foo<V> = impl Trait<V>;
| ^
error: could not find defining uses
--> $DIR/bound_reduction2.rs:9:15
@ -12,4 +18,3 @@ LL | type Foo<V> = impl Trait<V>;
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0282`.

5
src/test/ui/type-alias-impl-trait/nested-tait-inference.rs
View File

@ -1,18 +1,19 @@
#![feature(type_alias_impl_trait)]
#![allow(dead_code)]
// check-pass
use std::fmt::Debug;
type FooX = impl Debug;
//~^ ERROR could not find defining uses
trait Foo<A> { }
impl Foo<()> for () { }
fn foo() -> impl Foo<FooX> {
// FIXME(type-alias-impl-trait): We could probably make this work.
()
//~^ ERROR: the trait bound `(): Foo<impl Debug>` is not satisfied
}
fn main() { }

18
src/test/ui/type-alias-impl-trait/nested-tait-inference.stderr Normal file
View File

@ -0,0 +1,18 @@
error[E0277]: the trait bound `(): Foo<impl Debug>` is not satisfied
--> $DIR/nested-tait-inference.rs:15:5
|
LL | ()
| ^^ the trait `Foo<impl Debug>` is not implemented for `()`
|
= help: the following implementations were found:
<() as Foo<()>>
error: could not find defining uses
--> $DIR/nested-tait-inference.rs:6:13
|
LL | type FooX = impl Debug;
| ^^^^^^^^^^
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0277`.

3
src/test/ui/type-alias-impl-trait/nested-tait-inference2.rs
View File

@ -13,8 +13,7 @@ impl Foo<u32> for () {}
fn foo() -> impl Foo<FooX> {
()
//~^ ERROR: type annotations needed
//~| ERROR: type annotations needed
//~^ ERROR: the trait bound `(): Foo<impl Debug>` is not satisfied
}
fn main() {}

25
src/test/ui/type-alias-impl-trait/nested-tait-inference2.stderr
View File

@ -1,22 +1,12 @@
error[E0282]: type annotations needed
error[E0277]: the trait bound `(): Foo<impl Debug>` is not satisfied
--> $DIR/nested-tait-inference2.rs:15:5
|
LL | ()
| ^^ cannot infer type
error[E0283]: type annotations needed
--> $DIR/nested-tait-inference2.rs:15:5
| ^^ the trait `Foo<impl Debug>` is not implemented for `()`
|
LL | ()
| ^^ cannot infer type
|
note: multiple `impl`s satisfying `(): Foo<_>` found
--> $DIR/nested-tait-inference2.rs:11:1
|
LL | impl Foo<()> for () {}
| ^^^^^^^^^^^^^^^^^^^
LL | impl Foo<u32> for () {}
| ^^^^^^^^^^^^^^^^^^^^
= help: the following implementations were found:
<() as Foo<()>>
<() as Foo<u32>>
error: could not find defining uses
--> $DIR/nested-tait-inference2.rs:6:13
@ -24,7 +14,6 @@ error: could not find defining uses
LL | type FooX = impl Debug;
| ^^^^^^^^^^
error: aborting due to 3 previous errors
error: aborting due to 2 previous errors
Some errors have detailed explanations: E0282, E0283.
For more information about an error, try `rustc --explain E0282`.
For more information about this error, try `rustc --explain E0277`.