Revert "Revert "When checking whether an impl applies, constrain hidden types of opaque types.""

oli-obk · oli-obk · commit d8596e1f2615 · 2024-12-03T11:35:18.000Z
This reverts commit ad00868.
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -2543,7 +2543,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
         let InferOk { obligations, .. } = self
             .infcx
             .at(&cause, obligation.param_env)
-            .eq(DefineOpaqueTypes::No, placeholder_obligation_trait_ref, impl_trait_ref)
+            .eq(DefineOpaqueTypes::Yes, placeholder_obligation_trait_ref, impl_trait_ref)
             .map_err(|e| {
                 debug!("match_impl: failed eq_trait_refs due to `{}`", e.to_string(self.tcx()))
             })?;
diff --git a/tests/ui/auto-traits/opaque_type_candidate_selection.rs b/tests/ui/auto-traits/opaque_type_candidate_selection.rs
@@ -0,0 +1,29 @@
+//! used to ICE: #119272
+
+#![feature(type_alias_impl_trait)]
+mod defining_scope {
+    use super::*;
+    pub type Alias<T> = impl Sized;
+
+    pub fn cast<T>(x: Container<Alias<T>, T>) -> Container<T, T> {
+        x
+    }
+}
+
+struct Container<T: Trait<U>, U> {
+    x: <T as Trait<U>>::Assoc,
+}
+
+trait Trait<T> {
+    type Assoc;
+}
+
+impl<T> Trait<T> for T {
+    type Assoc = Box<u32>;
+}
+impl<T> Trait<T> for defining_scope::Alias<T> {
+    //~^ ERROR: conflicting implementations
+    type Assoc = usize;
+}
+
+fn main() {}
diff --git a/tests/ui/auto-traits/opaque_type_candidate_selection.stderr b/tests/ui/auto-traits/opaque_type_candidate_selection.stderr
@@ -0,0 +1,12 @@
+error[E0119]: conflicting implementations of trait `Trait<_>`
+  --> $DIR/opaque_type_candidate_selection.rs:24:1
+   |
+LL | impl<T> Trait<T> for T {
+   | ---------------------- first implementation here
+...
+LL | impl<T> Trait<T> for defining_scope::Alias<T> {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0119`.
diff --git a/tests/ui/impl-trait/call_method_on_inherent_impl_on_rigid_type.current.stderr b/tests/ui/impl-trait/call_method_on_inherent_impl_on_rigid_type.current.stderr
diff --git a/tests/ui/impl-trait/call_method_on_inherent_impl_on_rigid_type.next.stderr b/tests/ui/impl-trait/call_method_on_inherent_impl_on_rigid_type.next.stderr
@@ -1,5 +1,5 @@
 error[E0282]: type annotations needed for `&_`
-  --> $DIR/call_method_on_inherent_impl_on_rigid_type.rs:14:13
+  --> $DIR/call_method_on_inherent_impl_on_rigid_type.rs:15:13
    |
 LL |         let x = &my_foo();
    |             ^
diff --git a/tests/ui/impl-trait/call_method_on_inherent_impl_on_rigid_type.rs b/tests/ui/impl-trait/call_method_on_inherent_impl_on_rigid_type.rs
@@ -1,5 +1,6 @@
 //@ revisions: current next
 //@[next] compile-flags: -Znext-solver
+//@[current] check-pass
 
 trait MyDebug {
     fn my_debug(&self);
@@ -14,7 +15,6 @@ fn my_foo() -> impl std::fmt::Debug {
         let x = &my_foo();
         //[next]~^ ERROR: type annotations needed
         x.my_debug();
-        //[current]~^ ERROR: no method named `my_debug`
     }
     ()
 }
diff --git a/tests/ui/impl-trait/equality.rs b/tests/ui/impl-trait/equality.rs
@@ -22,7 +22,7 @@ fn sum_to(n: u32) -> impl Foo {
         0
     } else {
         n + sum_to(n - 1)
-        //~^ ERROR cannot add `impl Foo` to `u32`
+        //~^ ERROR cannot satisfy `<u32 as Add<impl Foo>>::Output == i32`
     }
 }
 
diff --git a/tests/ui/impl-trait/equality.stderr b/tests/ui/impl-trait/equality.stderr
@@ -22,20 +22,13 @@ help: change the type of the numeric literal from `u32` to `i32`
 LL |     0_i32
    |       ~~~
 
-error[E0277]: cannot add `impl Foo` to `u32`
+error[E0284]: type annotations needed: cannot satisfy `<u32 as Add<impl Foo>>::Output == i32`
   --> $DIR/equality.rs:24:11
    |
 LL |         n + sum_to(n - 1)
-   |           ^ no implementation for `u32 + impl Foo`
-   |
-   = help: the trait `Add<impl Foo>` is not implemented for `u32`
-   = help: the following other types implement trait `Add<Rhs>`:
-             `&u32` implements `Add<u32>`
-             `&u32` implements `Add`
-             `u32` implements `Add<&u32>`
-             `u32` implements `Add`
+   |           ^ cannot satisfy `<u32 as Add<impl Foo>>::Output == i32`
 
 error: aborting due to 2 previous errors; 1 warning emitted
 
-Some errors have detailed explanations: E0277, E0308.
-For more information about an error, try `rustc --explain E0277`.
+Some errors have detailed explanations: E0284, E0308.
+For more information about an error, try `rustc --explain E0284`.
diff --git a/tests/ui/impl-trait/nested_impl_trait.rs b/tests/ui/impl-trait/nested_impl_trait.rs
@@ -5,7 +5,7 @@ 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 the trait bound `impl Debug: From<impl Into<u32>>` is not satisfied
+//~| ERROR the trait bound `impl Into<u32>: Into<impl Debug>` is not satisfied
 
 fn bad_in_fn_syntax(x: fn() -> impl Into<impl Debug>) {}
 //~^ ERROR nested `impl Trait` is not allowed
@@ -18,7 +18,7 @@ struct X;
 impl X {
     fn bad(x: impl Into<u32>) -> impl Into<impl Debug> { x }
     //~^ ERROR nested `impl Trait` is not allowed
-    //~| ERROR the trait bound `impl Debug: From<impl Into<u32>>` is not satisfied
+    //~| ERROR the trait bound `impl Into<u32>: Into<impl Debug>` is not satisfied
 }
 
 fn allowed_in_assoc_type() -> impl Iterator<Item=impl Fn()> {
diff --git a/tests/ui/impl-trait/nested_impl_trait.stderr b/tests/ui/impl-trait/nested_impl_trait.stderr
@@ -42,27 +42,27 @@ LL | fn bad_in_fn_syntax(x: fn() -> impl Into<impl Debug>) {}
    |
    = note: `impl Trait` is only allowed in arguments and return types of functions and methods
 
-error[E0277]: the trait bound `impl Debug: From<impl Into<u32>>` is not satisfied
+error[E0277]: the trait bound `impl Into<u32>: Into<impl Debug>` is not satisfied
   --> $DIR/nested_impl_trait.rs:6:46
    |
 LL | fn bad_in_ret_position(x: impl Into<u32>) -> impl Into<impl Debug> { x }
-   |                                              ^^^^^^^^^^^^^^^^^^^^^   - return type was inferred to be `impl Into<u32>` here
-   |                                              |
-   |                                              the trait `From<impl Into<u32>>` is not implemented for `impl Debug`
+   |                                              ^^^^^^^^^^^^^^^^^^^^^ the trait `Debug` is not implemented for `impl Into<u32>`
    |
-   = help: the trait `Into<U>` is implemented for `T`
-   = note: required for `impl Into<u32>` to implement `Into<impl 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 }
+   |                                          +++++++++++++++++
 
-error[E0277]: the trait bound `impl Debug: From<impl Into<u32>>` is not satisfied
+error[E0277]: the trait bound `impl Into<u32>: Into<impl Debug>` is not satisfied
   --> $DIR/nested_impl_trait.rs:19:34
    |
 LL |     fn bad(x: impl Into<u32>) -> impl Into<impl Debug> { x }
-   |                                  ^^^^^^^^^^^^^^^^^^^^^   - return type was inferred to be `impl Into<u32>` here
-   |                                  |
-   |                                  the trait `From<impl Into<u32>>` is not implemented for `impl Debug`
+   |                                  ^^^^^^^^^^^^^^^^^^^^^ the trait `Debug` is not implemented for `impl Into<u32>`
+   |
+help: consider further restricting this bound
    |
-   = help: the trait `Into<U>` is implemented for `T`
-   = note: required for `impl Into<u32>` to implement `Into<impl Debug>`
+LL |     fn bad(x: impl Into<u32> + std::fmt::Debug) -> impl Into<impl Debug> { x }
+   |                              +++++++++++++++++
 
 error: aborting due to 7 previous errors
 
diff --git a/tests/ui/impl-trait/recursive-bound-eval.current.stderr b/tests/ui/impl-trait/recursive-bound-eval.current.stderr
@@ -0,0 +1,9 @@
+error[E0282]: type annotations needed
+  --> $DIR/recursive-bound-eval.rs:18:28
+   |
+LL |     move || recursive_fn().parse()
+   |                            ^^^^^ cannot infer type
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/tests/ui/impl-trait/recursive-bound-eval.next.stderr b/tests/ui/impl-trait/recursive-bound-eval.next.stderr
@@ -1,5 +1,5 @@
 error[E0282]: type annotations needed
-  --> $DIR/recursive-bound-eval.rs:20:13
+  --> $DIR/recursive-bound-eval.rs:18:13
    |
 LL |     move || recursive_fn().parse()
    |             ^^^^^^^^^^^^^^ cannot infer type
diff --git a/tests/ui/impl-trait/recursive-bound-eval.rs b/tests/ui/impl-trait/recursive-bound-eval.rs
@@ -4,8 +4,6 @@
 //@revisions: next current
 //@[next] compile-flags: -Znext-solver
 
-//@[current] check-pass
-
 pub trait Parser<E> {
     fn parse(&self) -> E;
 }
@@ -18,7 +16,7 @@ impl<E, T: Fn() -> E> Parser<E> for T {
 
 pub fn recursive_fn<E>() -> impl Parser<E> {
     move || recursive_fn().parse()
-    //[next]~^ ERROR: type annotations needed
+    //~^ ERROR: type annotations needed
 }
 
 fn main() {}
diff --git a/tests/ui/impl-trait/recursive-type-alias-impl-trait-declaration.rs b/tests/ui/impl-trait/recursive-type-alias-impl-trait-declaration.rs
@@ -11,7 +11,7 @@ impl PartialEq<(Bar, i32)> for Bar {
 }
 
 fn foo() -> Foo {
-    //~^ ERROR can't compare `Bar` with `(Foo, i32)`
+    //~^ ERROR overflow evaluating the requirement `Bar: PartialEq<(Foo, i32)>`
     Bar
 }
 
diff --git a/tests/ui/impl-trait/recursive-type-alias-impl-trait-declaration.stderr b/tests/ui/impl-trait/recursive-type-alias-impl-trait-declaration.stderr
@@ -1,15 +1,9 @@
-error[E0277]: can't compare `Bar` with `(Foo, i32)`
+error[E0275]: overflow evaluating the requirement `Bar: PartialEq<(Foo, i32)>`
   --> $DIR/recursive-type-alias-impl-trait-declaration.rs:13:13
    |
 LL | fn foo() -> Foo {
-   |             ^^^ no implementation for `Bar == (Foo, i32)`
-LL |
-LL |     Bar
-   |     --- return type was inferred to be `Bar` here
-   |
-   = help: the trait `PartialEq<(Foo, i32)>` is not implemented for `Bar`
-   = help: the trait `PartialEq<(Bar, i32)>` is implemented for `Bar`
+   |             ^^^
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0277`.
+For more information about this error, try `rustc --explain E0275`.
diff --git a/tests/ui/type-alias-impl-trait/constrain_in_projection.current.stderr b/tests/ui/type-alias-impl-trait/constrain_in_projection.current.stderr
diff --git a/tests/ui/type-alias-impl-trait/constrain_in_projection.rs b/tests/ui/type-alias-impl-trait/constrain_in_projection.rs
@@ -4,7 +4,7 @@
 //@ revisions: current next
 //@ ignore-compare-mode-next-solver (explicit revisions)
 //@[next] compile-flags: -Znext-solver
-//@[next]check-pass
+//@check-pass
 
 #![feature(type_alias_impl_trait)]
 
@@ -22,7 +22,6 @@ impl Trait<()> for Foo {
 
 fn bop(_: Bar) {
     let x = <Foo as Trait<Bar>>::Assoc::default();
-    //[current]~^ `Foo: Trait<Bar>` is not satisfied
 }
 
 fn main() {}
diff --git a/tests/ui/type-alias-impl-trait/constrain_in_projection2.current.stderr b/tests/ui/type-alias-impl-trait/constrain_in_projection2.current.stderr
@@ -1,13 +1,19 @@
-error[E0277]: the trait bound `Foo: Trait<Bar>` is not satisfied
+error[E0283]: type annotations needed: cannot satisfy `Foo: Trait<Bar>`
   --> $DIR/constrain_in_projection2.rs:27:14
    |
 LL |     let x = <Foo as Trait<Bar>>::Assoc::default();
-   |              ^^^ the trait `Trait<Bar>` is not implemented for `Foo`
+   |              ^^^ help: use the fully qualified path to an implementation: `<Type as Trait>::Assoc`
    |
-   = help: the following other types implement trait `Trait<T>`:
-             `Foo` implements `Trait<()>`
-             `Foo` implements `Trait<u32>`
+note: multiple `impl`s satisfying `Foo: Trait<Bar>` found
+  --> $DIR/constrain_in_projection2.rs:18:1
+   |
+LL | impl Trait<()> for Foo {
+   | ^^^^^^^^^^^^^^^^^^^^^^
+...
+LL | impl Trait<u32> for Foo {
+   | ^^^^^^^^^^^^^^^^^^^^^^^
+   = note: associated types cannot be accessed directly on a `trait`, they can only be accessed through a specific `impl`
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0277`.
+For more information about this error, try `rustc --explain E0283`.
diff --git a/tests/ui/type-alias-impl-trait/constrain_in_projection2.rs b/tests/ui/type-alias-impl-trait/constrain_in_projection2.rs
@@ -25,8 +25,7 @@ impl Trait<u32> for Foo {
 
 fn bop(_: Bar) {
     let x = <Foo as Trait<Bar>>::Assoc::default();
-    //[next]~^ ERROR: cannot satisfy `Foo: Trait<Bar>`
-    //[current]~^^ ERROR: `Foo: Trait<Bar>` is not satisfied
+    //~^ ERROR: cannot satisfy `Foo: Trait<Bar>`
 }
 
 fn main() {}
diff --git a/tests/ui/type-alias-impl-trait/issue-84660-unsoundness.current.stderr b/tests/ui/type-alias-impl-trait/issue-84660-unsoundness.current.stderr
@@ -1,25 +1,12 @@
 error[E0119]: conflicting implementations of trait `Trait<Bar, _>`
-  --> $DIR/issue-84660-unsoundness.rs:29:1
+  --> $DIR/issue-84660-unsoundness.rs:28:1
    |
 LL | impl<In, Out> Trait<Bar, In> for Out {
    | ------------------------------------ first implementation here
 ...
 LL | impl<In, Out> Trait<(), In> for Out {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation
 
-error: item does not constrain `Bar::{opaque#0}`, but has it in its signature
-  --> $DIR/issue-84660-unsoundness.rs:22:8
-   |
-LL |     fn convert(_i: In) -> Self::Out {
-   |        ^^^^^^^
-   |
-   = note: consider moving the opaque type's declaration and defining uses into a separate module
-note: this opaque type is in the signature
-  --> $DIR/issue-84660-unsoundness.rs:12:12
-   |
-LL | type Bar = impl Foo;
-   |            ^^^^^^^^
-
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0119`.
diff --git a/tests/ui/type-alias-impl-trait/issue-84660-unsoundness.next.stderr b/tests/ui/type-alias-impl-trait/issue-84660-unsoundness.next.stderr
@@ -1,5 +1,5 @@
 error[E0119]: conflicting implementations of trait `Trait<Bar, _>`
-  --> $DIR/issue-84660-unsoundness.rs:29:1
+  --> $DIR/issue-84660-unsoundness.rs:28:1
    |
 LL | impl<In, Out> Trait<Bar, In> for Out {
    | ------------------------------------ first implementation here
@@ -13,7 +13,6 @@ error[E0284]: type annotations needed: cannot satisfy `Bar == _`
 LL |       fn convert(_i: In) -> Self::Out {
    |  _____________________________________^
 LL | |
-LL | |
 LL | |         unreachable!();
 LL | |     }
    | |_____^ cannot satisfy `Bar == _`
diff --git a/tests/ui/type-alias-impl-trait/issue-84660-unsoundness.rs b/tests/ui/type-alias-impl-trait/issue-84660-unsoundness.rs
@@ -21,7 +21,6 @@ impl<In, Out> Trait<Bar, In> for Out {
     type Out = Out;
     fn convert(_i: In) -> Self::Out {
         //[next]~^  ERROR: cannot satisfy `Bar == _`
-        //[current]~^^ ERROR: item does not constrain `Bar::{opaque#0}`, but has it in its signature
         unreachable!();
     }
 }
diff --git a/tests/ui/type-alias-impl-trait/nested-tait-inference.current.stderr b/tests/ui/type-alias-impl-trait/nested-tait-inference.current.stderr
diff --git a/tests/ui/type-alias-impl-trait/nested-tait-inference.rs b/tests/ui/type-alias-impl-trait/nested-tait-inference.rs
@@ -4,7 +4,7 @@
 //@ revisions: current next
 //@ ignore-compare-mode-next-solver (explicit revisions)
 //@[next] compile-flags: -Znext-solver
-//@[next] check-pass
+//@check-pass
 
 use std::fmt::Debug;
 
@@ -15,8 +15,6 @@ trait Foo<A> {}
 impl Foo<()> for () {}
 
 fn foo() -> impl Foo<FooX> {
-    //[current]~^ ERROR: the trait bound `(): Foo<FooX>` is not satisfied
-    // FIXME(type-alias-impl-trait): We could probably make this work.
     ()
 }
 
diff --git a/tests/ui/type-alias-impl-trait/nested-tait-inference2.current.stderr b/tests/ui/type-alias-impl-trait/nested-tait-inference2.current.stderr
diff --git a/tests/ui/type-alias-impl-trait/nested-tait-inference2.rs b/tests/ui/type-alias-impl-trait/nested-tait-inference2.rs
diff --git a/tests/ui/type-alias-impl-trait/normalize-hidden-types.current.stderr b/tests/ui/type-alias-impl-trait/normalize-hidden-types.current.stderr
diff --git a/tests/ui/type-alias-impl-trait/self-referential-2.current.stderr b/tests/ui/type-alias-impl-trait/self-referential-2.current.stderr
diff --git a/tests/ui/type-alias-impl-trait/self-referential-2.rs b/tests/ui/type-alias-impl-trait/self-referential-2.rs
diff --git a/tests/ui/type-alias-impl-trait/self-referential-3.rs b/tests/ui/type-alias-impl-trait/self-referential-3.rs
diff --git a/tests/ui/type-alias-impl-trait/self-referential-3.stderr b/tests/ui/type-alias-impl-trait/self-referential-3.stderr

Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,5 @@`
`1`	`1`	error[E0282]: type annotations needed for `&_`
`2`		`- --> $DIR/call_method_on_inherent_impl_on_rigid_type.rs:14:13`
	`2`	`+ --> $DIR/call_method_on_inherent_impl_on_rigid_type.rs:15:13`
`3`	`3`	`\|`
`4`	`4`	`LL \| let x = &my_foo();`
`5`	`5`	`\| ^`
Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,6 @@`
`1`	`1`	`//@ revisions: current next`
`2`	`2`	`//@[next] compile-flags: -Znext-solver`
	`3`	`+//@[current] check-pass`
`3`	`4`
`4`	`5`	`trait MyDebug {`
`5`	`6`	`fn my_debug(&self);`
`@@ -14,7 +15,6 @@ fn my_foo() -> impl std::fmt::Debug {`
`14`	`15`	`let x = &my_foo();`
`15`	`16`	`//[next]~^ ERROR: type annotations needed`
`16`	`17`	`x.my_debug();`
`17`		- //[current]~^ ERROR: no method named `my_debug`
`18`	`18`	`}`
`19`	`19`	`()`
`20`	`20`	`}`
Original file line number	Diff line number	Diff line change
`@@ -22,7 +22,7 @@ fn sum_to(n: u32) -> impl Foo {`
`22`	`22`	`0`
`23`	`23`	`} else {`
`24`	`24`	`n + sum_to(n - 1)`
`25`		- //~^ ERROR cannot add `impl Foo` to `u32`
	`25`	+ //~^ ERROR cannot satisfy `<u32 as Add<impl Foo>>::Output == i32`
`26`	`26`	`}`
`27`	`27`	`}`
`28`	`28`