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Auto merge of #100676 - lcnr:implied-bounds-yay, r=nikomatsakis

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implied bounds: explicitly state which types are assumed to be wf

Adds a new query which maps each definition to the types which that definition assumes to be well formed. The intent is to make it easier to reason about implied bounds.

This change should not influence the user-facing behavior of rustc. Notably, `borrowck` still only assumes that the function signature of associated functions is well formed while `wfcheck` assumes that the both the function signature and the impl trait ref is well formed. Not sure if that by itself can trigger UB or whether it's just annoying.

As a next step, we can add `WellFormed` predicates to `predicates_of` of these items and can stop adding the wf bounds at each place which uses them. I also intend to move the computation from `assumed_wf_types` to `implied_bounds` into the `param_env` computation. This requires me to take a deeper look at `compare_predicate_entailment` which is currently somewhat weird wrt implied bounds so I am not touching this here.

r? `@nikomatsakis`
This commit is contained in:
bors 2022-08-22 06:10:26 +00:00
commit a9bb589cd6
24 changed files with 321 additions and 237 deletions
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4
src/test/ui/associated-types/associated-types-for-unimpl-trait.stderr
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@ -1,8 +1,8 @@
error[E0277]: the trait bound `Self: Get` is not satisfied
--> $DIR/associated-types-for-unimpl-trait.rs:10:40
--> $DIR/associated-types-for-unimpl-trait.rs:10:5
|
LL | fn uhoh<U:Get>(&self, foo: U, bar: <Self as Get>::Value) {}
| ^^^^^^^^^^^^^^^^^^^^ the trait `Get` is not implemented for `Self`
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Get` is not implemented for `Self`
|
help: consider further restricting `Self`
|

4
src/test/ui/associated-types/associated-types-no-suitable-bound.stderr
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@ -1,8 +1,8 @@
error[E0277]: the trait bound `T: Get` is not satisfied
--> $DIR/associated-types-no-suitable-bound.rs:11:21
--> $DIR/associated-types-no-suitable-bound.rs:11:5
|
LL | fn uhoh<T>(foo: <T as Get>::Value) {}
| ^^^^^^^^^^^^^^^^^ the trait `Get` is not implemented for `T`
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Get` is not implemented for `T`
|
help: consider restricting type parameter `T`
|

4
src/test/ui/associated-types/associated-types-no-suitable-supertrait-2.stderr
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@ -1,8 +1,8 @@
error[E0277]: the trait bound `Self: Get` is not satisfied
--> $DIR/associated-types-no-suitable-supertrait-2.rs:17:40
--> $DIR/associated-types-no-suitable-supertrait-2.rs:17:5
|
LL | fn uhoh<U:Get>(&self, foo: U, bar: <Self as Get>::Value) {}
| ^^^^^^^^^^^^^^^^^^^^ the trait `Get` is not implemented for `Self`
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Get` is not implemented for `Self`
|
help: consider further restricting `Self`
|

8
src/test/ui/associated-types/associated-types-no-suitable-supertrait.stderr
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@ -1,14 +1,14 @@
error[E0277]: the trait bound `(T, U): Get` is not satisfied
--> $DIR/associated-types-no-suitable-supertrait.rs:22:40
--> $DIR/associated-types-no-suitable-supertrait.rs:22:5
|
LL | fn uhoh<U:Get>(&self, foo: U, bar: <(T, U) as Get>::Value) {}
| ^^^^^^^^^^^^^^^^^^^^^^ the trait `Get` is not implemented for `(T, U)`
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Get` is not implemented for `(T, U)`
error[E0277]: the trait bound `Self: Get` is not satisfied
--> $DIR/associated-types-no-suitable-supertrait.rs:17:40
--> $DIR/associated-types-no-suitable-supertrait.rs:17:5
|
LL | fn uhoh<U:Get>(&self, foo: U, bar: <Self as Get>::Value) {}
| ^^^^^^^^^^^^^^^^^^^^ the trait `Get` is not implemented for `Self`
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Get` is not implemented for `Self`
|
help: consider further restricting `Self`
|

4
src/test/ui/associated-types/associated-types-projection-to-unrelated-trait-in-method-without-default.stderr
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@ -1,8 +1,8 @@
error[E0277]: the trait bound `Self: Get` is not satisfied
--> $DIR/associated-types-projection-to-unrelated-trait-in-method-without-default.rs:10:40
--> $DIR/associated-types-projection-to-unrelated-trait-in-method-without-default.rs:10:5
|
LL | fn okay<U:Get>(&self, foo: U, bar: <Self as Get>::Value);
| ^^^^^^^^^^^^^^^^^^^^ the trait `Get` is not implemented for `Self`
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Get` is not implemented for `Self`
|
help: consider further restricting `Self`
|

14
src/test/ui/associated-types/issue-59324.stderr
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@ -45,16 +45,20 @@ LL | pub trait ThriftService<Bug: NotFoo + Foo>:
| +++++
error[E0277]: the trait bound `(): Foo` is not satisfied
--> $DIR/issue-59324.rs:23:29
--> $DIR/issue-59324.rs:23:1
|
LL | fn with_factory<H>(factory: dyn ThriftService<()>) {}
| ^^^^^^^^^^^^^^^^^^^^^ the trait `Foo` is not implemented for `()`
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Foo` is not implemented for `()`
error[E0277]: the trait bound `Bug: Foo` is not satisfied
--> $DIR/issue-59324.rs:16:8
--> $DIR/issue-59324.rs:16:5
|
LL | fn get_service(
| ^^^^^^^^^^^ the trait `Foo` is not implemented for `Bug`
LL | / fn get_service(
LL | |
LL | |
LL | | &self,
LL | | ) -> Self::AssocType;
| |_________________________^ the trait `Foo` is not implemented for `Bug`
|
help: consider further restricting this bound
|

8
src/test/ui/issues/issue-18611.stderr
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@ -1,8 +1,10 @@
error[E0277]: the trait bound `isize: HasState` is not satisfied
--> $DIR/issue-18611.rs:1:18
--> $DIR/issue-18611.rs:1:1
|
LL | fn add_state(op: <isize as HasState>::State) {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `HasState` is not implemented for `isize`
LL | / fn add_state(op: <isize as HasState>::State) {
LL | |
LL | | }
| |_^ the trait `HasState` is not implemented for `isize`
error: aborting due to previous error

24
src/test/ui/issues/issue-20831-debruijn.stderr
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@ -1,8 +1,14 @@
error[E0495]: cannot infer an appropriate lifetime for lifetime parameter `'a` due to conflicting requirements
--> $DIR/issue-20831-debruijn.rs:28:8
--> $DIR/issue-20831-debruijn.rs:28:5
|
LL | fn subscribe(&mut self, t : Box<dyn Subscriber<Input=<Self as Publisher>::Output> + 'a>) {
| ^^^^^^^^^
LL | / fn subscribe(&mut self, t : Box<dyn Subscriber<Input=<Self as Publisher>::Output> + 'a>) {
LL | | // Not obvious, but there is an implicit lifetime here -------^
LL | |
LL | | //
... |
LL | | self.sub = t;
LL | | }
| |_____^
|
note: first, the lifetime cannot outlive the anonymous lifetime defined here...
--> $DIR/issue-20831-debruijn.rs:28:58
@ -15,10 +21,16 @@ note: ...but the lifetime must also be valid for the lifetime `'a` as defined he
LL | impl<'a> Publisher<'a> for MyStruct<'a> {
| ^^
note: ...so that the types are compatible
--> $DIR/issue-20831-debruijn.rs:28:8
--> $DIR/issue-20831-debruijn.rs:28:5
|
LL | fn subscribe(&mut self, t : Box<dyn Subscriber<Input=<Self as Publisher>::Output> + 'a>) {
| ^^^^^^^^^
LL | / fn subscribe(&mut self, t : Box<dyn Subscriber<Input=<Self as Publisher>::Output> + 'a>) {
LL | | // Not obvious, but there is an implicit lifetime here -------^
LL | |
LL | | //
... |
LL | | self.sub = t;
LL | | }
| |_____^
= note: expected `<MyStruct<'a> as Publisher<'_>>`
found `<MyStruct<'_> as Publisher<'_>>`

3
src/test/ui/issues/issue-35570.rs
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@ -6,7 +6,8 @@ trait Trait2<'a> {
}
fn _ice(param: Box<dyn for <'a> Trait1<<() as Trait2<'a>>::Ty>>) {
//~^ the trait bound `for<'a> (): Trait2<'a>` is not satisfied
//~^ ERROR the trait bound `for<'a> (): Trait2<'a>` is not satisfied
//~| ERROR the trait bound `for<'a> (): Trait2<'a>` is not satisfied
let _e: (usize, usize) = unsafe{mem::transmute(param)};
}

12
src/test/ui/issues/issue-35570.stderr
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@ -1,9 +1,19 @@
error[E0277]: the trait bound `for<'a> (): Trait2<'a>` is not satisfied
--> $DIR/issue-35570.rs:8:1
|
LL | / fn _ice(param: Box<dyn for <'a> Trait1<<() as Trait2<'a>>::Ty>>) {
LL | |
LL | |
LL | | let _e: (usize, usize) = unsafe{mem::transmute(param)};
LL | | }
| |_^ the trait `for<'a> Trait2<'a>` is not implemented for `()`
error[E0277]: the trait bound `for<'a> (): Trait2<'a>` is not satisfied
--> $DIR/issue-35570.rs:8:40
|
LL | fn _ice(param: Box<dyn for <'a> Trait1<<() as Trait2<'a>>::Ty>>) {
| ^^^^^^^^^^^^^^^^^^^^^^ the trait `for<'a> Trait2<'a>` is not implemented for `()`
error: aborting due to previous error
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0277`.

8
src/test/ui/nll/normalization-bounds-error.stderr
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@ -1,8 +1,8 @@
error[E0495]: cannot infer an appropriate lifetime for lifetime parameter `'d` due to conflicting requirements
--> $DIR/normalization-bounds-error.rs:12:4
--> $DIR/normalization-bounds-error.rs:12:1
|
LL | fn visit_seq<'d, 'a: 'd>() -> <&'a () as Visitor<'d>>::Value {}
| ^^^^^^^^^
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
note: first, the lifetime cannot outlive the lifetime `'d` as defined here...
--> $DIR/normalization-bounds-error.rs:12:14
@ -15,10 +15,10 @@ note: ...but the lifetime must also be valid for the lifetime `'a` as defined he
LL | fn visit_seq<'d, 'a: 'd>() -> <&'a () as Visitor<'d>>::Value {}
| ^^
note: ...so that the types are compatible
--> $DIR/normalization-bounds-error.rs:12:4
--> $DIR/normalization-bounds-error.rs:12:1
|
LL | fn visit_seq<'d, 'a: 'd>() -> <&'a () as Visitor<'d>>::Value {}
| ^^^^^^^^^
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
= note: expected `Visitor<'d>`
found `Visitor<'_>`

3
src/test/ui/regions/regions-implied-bounds-projection-gap-hr-1.rs
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@ -19,7 +19,8 @@ trait Trait2<'a, 'b> {
// since for it to be WF, we would need to know that `'y: 'x`, but we
// do not infer that.
fn callee<'x, 'y, T>(t: &'x dyn for<'z> Trait1< <T as Trait2<'y, 'z>>::Foo >)
//~^ the trait bound `for<'z> T: Trait2<'y, 'z>` is not satisfied
//~^ ERROR the trait bound `for<'z> T: Trait2<'y, 'z>` is not satisfied
//~| ERROR the trait bound `for<'z> T: Trait2<'y, 'z>` is not satisfied
{
}

17
src/test/ui/regions/regions-implied-bounds-projection-gap-hr-1.stderr
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@ -1,3 +1,18 @@
error[E0277]: the trait bound `for<'z> T: Trait2<'y, 'z>` is not satisfied
--> $DIR/regions-implied-bounds-projection-gap-hr-1.rs:21:1
|
LL | / fn callee<'x, 'y, T>(t: &'x dyn for<'z> Trait1< <T as Trait2<'y, 'z>>::Foo >)
LL | |
LL | |
LL | | {
LL | | }
| |_^ the trait `for<'z> Trait2<'y, 'z>` is not implemented for `T`
|
help: consider restricting type parameter `T`
|
LL | fn callee<'x, 'y, T: for<'z> Trait2<'y, 'z>>(t: &'x dyn for<'z> Trait1< <T as Trait2<'y, 'z>>::Foo >)
| ++++++++++++++++++++++++
error[E0277]: the trait bound `for<'z> T: Trait2<'y, 'z>` is not satisfied
--> $DIR/regions-implied-bounds-projection-gap-hr-1.rs:21:49
|
@ -9,6 +24,6 @@ help: consider restricting type parameter `T`
LL | fn callee<'x, 'y, T: for<'z> Trait2<'y, 'z>>(t: &'x dyn for<'z> Trait1< <T as Trait2<'y, 'z>>::Foo >)
| ++++++++++++++++++++++++
error: aborting due to previous error
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0277`.

18
src/test/ui/specialization/min_specialization/issue-79224.stderr
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@ -1,8 +1,12 @@
error[E0277]: the trait bound `B: Clone` is not satisfied
--> $DIR/issue-79224.rs:18:17
--> $DIR/issue-79224.rs:18:1
|
LL | impl<B: ?Sized> Display for Cow<'_, B> {
| ^^^^^^^ the trait `Clone` is not implemented for `B`
LL | / impl<B: ?Sized> Display for Cow<'_, B> {
LL | | fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
LL | | write!(f, "foo")
LL | | }
LL | | }
| |_^ the trait `Clone` is not implemented for `B`
|
= note: required for `B` to implement `ToOwned`
help: consider further restricting this bound
@ -11,10 +15,12 @@ LL | impl<B: ?Sized + std::clone::Clone> Display for Cow<'_, B> {
| +++++++++++++++++++
error[E0277]: the trait bound `B: Clone` is not satisfied
--> $DIR/issue-79224.rs:19:12
--> $DIR/issue-79224.rs:19:5
|
LL | fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
| ^^^^^ the trait `Clone` is not implemented for `B`
LL | / fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
LL | | write!(f, "foo")
LL | | }
| |_____^ the trait `Clone` is not implemented for `B`
|
= note: required for `B` to implement `ToOwned`
help: consider further restricting this bound

4
src/test/ui/traits/issue-91594.stderr
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@ -1,8 +1,8 @@
error[E0277]: the trait bound `Foo: HasComponent<()>` is not satisfied
--> $DIR/issue-91594.rs:10:6
--> $DIR/issue-91594.rs:10:1
|
LL | impl HasComponent<<Foo as Component<Foo>>::Interface> for Foo {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `HasComponent<()>` is not implemented for `Foo`
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `HasComponent<()>` is not implemented for `Foo`
|
= help: the trait `HasComponent<<Foo as Component<Foo>>::Interface>` is implemented for `Foo`
note: required for `Foo` to implement `Component<Foo>`

4
src/test/ui/wf/wf-foreign-fn-decl-ret.stderr
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@ -1,8 +1,8 @@
error[E0277]: the trait bound `(): Foo` is not satisfied
--> $DIR/wf-foreign-fn-decl-ret.rs:11:25
--> $DIR/wf-foreign-fn-decl-ret.rs:11:5
|
LL | pub fn lint_me() -> <() as Foo>::Assoc;
| ^^^^^^^^^^^^^^^^^^ the trait `Foo` is not implemented for `()`
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Foo` is not implemented for `()`
error[E0277]: the trait bound `u32: Unsatisfied` is not satisfied
--> $DIR/wf-foreign-fn-decl-ret.rs:14:32