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Auto merge of #97039 - cjgillot:no-rpit-hrtb, r=jackh726

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Forbid nested opaque types to reference HRTB from opaque types.

Avoids https://github.com/rust-lang/rust/issues/96194
Alternative to https://github.com/rust-lang/rust/pull/96970

r? `@oli-obk`
This commit is contained in:
bors 2022-05-14 15:47:22 +00:00
commit b36be12d97
13 changed files with 235 additions and 98 deletions
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14
compiler/rustc_resolve/src/late/lifetimes.rs
View File

@ -1025,6 +1025,20 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
}
self.uninsert_lifetime_on_error(lifetime, def.unwrap());
}
if let hir::Node::Item(hir::Item {
kind: hir::ItemKind::OpaqueTy { .. }, ..
}) = self.tcx.hir().get(parent_id)
{
if !self.trait_definition_only {
let mut err = self.tcx.sess.struct_span_err(
lifetime.span,
"higher kinded lifetime bounds on nested opaque types are not supported yet",
);
err.span_note(self.tcx.def_span(def_id), "lifetime declared here");
err.emit();
}
self.uninsert_lifetime_on_error(lifetime, def.unwrap());
}
}
// We want to start our early-bound indices at the end of the parent scope,

3
src/test/ui/impl-trait/issues/issue-54895.rs
View File

@ -1,5 +1,3 @@
// check-pass
trait Trait<'a> {
type Out;
fn call(&'a self) -> Self::Out;
@ -15,6 +13,7 @@ impl<'a> Trait<'a> for X {
}
fn f() -> impl for<'a> Trait<'a, Out = impl Sized + 'a> {
//~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
X(())
}

14
src/test/ui/impl-trait/issues/issue-54895.stderr Normal file
View File

@ -0,0 +1,14 @@
error: higher kinded lifetime bounds on nested opaque types are not supported yet
--> $DIR/issue-54895.rs:15:53
|
LL | fn f() -> impl for<'a> Trait<'a, Out = impl Sized + 'a> {
| ^^
|
note: lifetime declared here
--> $DIR/issue-54895.rs:15:20
|
LL | fn f() -> impl for<'a> Trait<'a, Out = impl Sized + 'a> {
| ^^
error: aborting due to previous error

20
src/test/ui/impl-trait/issues/issue-67830.nll.stderr
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@ -1,20 +0,0 @@
error: implementation of `FnOnce` is not general enough
--> $DIR/issue-67830.rs:23:5
|
LL | Wrap(|a| Some(a).into_iter())
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ implementation of `FnOnce` is not general enough
|
= note: closure with signature `fn(&'2 A) -> std::option::IntoIter<&A>` must implement `FnOnce<(&'1 A,)>`, for any lifetime `'1`...
= note: ...but it actually implements `FnOnce<(&'2 A,)>`, for some specific lifetime `'2`
error: implementation of `FnOnce` is not general enough
--> $DIR/issue-67830.rs:23:5
|
LL | Wrap(|a| Some(a).into_iter())
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ implementation of `FnOnce` is not general enough
|
= note: closure with signature `fn(&'2 A) -> std::option::IntoIter<&A>` must implement `FnOnce<(&'1 A,)>`, for any lifetime `'1`...
= note: ...but it actually implements `FnOnce<(&'2 A,)>`, for some specific lifetime `'2`
error: aborting due to 2 previous errors

2
src/test/ui/impl-trait/issues/issue-67830.rs
View File

@ -19,7 +19,7 @@ where
struct A;
fn test() -> impl for<'a> MyFn<&'a A, Output=impl Iterator + 'a> {
//~^ ERROR implementation of `FnOnce` is not general enough
//~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
Wrap(|a| Some(a).into_iter())
}

13
src/test/ui/impl-trait/issues/issue-67830.stderr
View File

@ -1,11 +1,14 @@
error: implementation of `FnOnce` is not general enough
--> $DIR/issue-67830.rs:21:14
error: higher kinded lifetime bounds on nested opaque types are not supported yet
--> $DIR/issue-67830.rs:21:62
|
LL | fn test() -> impl for<'a> MyFn<&'a A, Output=impl Iterator + 'a> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ implementation of `FnOnce` is not general enough
| ^^
|
= note: closure with signature `fn(&'2 A) -> std::option::IntoIter<&A>` must implement `FnOnce<(&'1 A,)>`, for any lifetime `'1`...
= note: ...but it actually implements `FnOnce<(&'2 A,)>`, for some specific lifetime `'2`
note: lifetime declared here
--> $DIR/issue-67830.rs:21:23
|
LL | fn test() -> impl for<'a> MyFn<&'a A, Output=impl Iterator + 'a> {
| ^^
error: aborting due to previous error

55
src/test/ui/impl-trait/issues/issue-88236-2.nll.stderr
View File

@ -1,55 +0,0 @@
error: implementation of `Hrtb` is not general enough
--> $DIR/issue-88236-2.rs:17:5
|
LL | &()
| ^^^ implementation of `Hrtb` is not general enough
|
= note: `Hrtb<'0>` would have to be implemented for the type `&()`, for any lifetime `'0`...
= note: ...but `Hrtb<'1>` is actually implemented for the type `&'1 ()`, for some specific lifetime `'1`
error: implementation of `Hrtb` is not general enough
--> $DIR/issue-88236-2.rs:17:5
|
LL | &()
| ^^^ implementation of `Hrtb` is not general enough
|
= note: `Hrtb<'0>` would have to be implemented for the type `&()`, for any lifetime `'0`...
= note: ...but `Hrtb<'1>` is actually implemented for the type `&'1 ()`, for some specific lifetime `'1`
error: lifetime may not live long enough
--> $DIR/issue-88236-2.rs:20:5
|
LL | fn make_bad_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {
| -- lifetime `'b` defined here
LL | x
| ^ returning this value requires that `'b` must outlive `'static`
|
help: to declare that the `impl Trait` captures data from argument `x`, you can add an explicit `'b` lifetime bound
|
LL | fn make_bad_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> + 'b {
| ++++
help: to declare that the `impl Trait` captures data from argument `x`, you can add an explicit `'b` lifetime bound
|
LL | fn make_bad_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a + 'b> {
| ++++
error: implementation of `Hrtb` is not general enough
--> $DIR/issue-88236-2.rs:20:5
|
LL | x
| ^ implementation of `Hrtb` is not general enough
|
= note: `Hrtb<'0>` would have to be implemented for the type `&()`, for any lifetime `'0`...
= note: ...but `Hrtb<'1>` is actually implemented for the type `&'1 ()`, for some specific lifetime `'1`
error: implementation of `Hrtb` is not general enough
--> $DIR/issue-88236-2.rs:20:5
|
LL | x
| ^ implementation of `Hrtb` is not general enough
|
= note: `Hrtb<'0>` would have to be implemented for the type `&()`, for any lifetime `'0`...
= note: ...but `Hrtb<'1>` is actually implemented for the type `&'1 ()`, for some specific lifetime `'1`
error: aborting due to 5 previous errors

9
src/test/ui/impl-trait/issues/issue-88236-2.rs
View File

@ -13,11 +13,16 @@ impl<'a> Hrtb<'a> for &'a () {
}
fn make_impl() -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {}
//~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
fn make_weird_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {
&() //~^ ERROR implementation of `Hrtb` is not general enough
//~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
&()
}
fn make_bad_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {
x //~^ ERROR implementation of `Hrtb` is not general enough
//~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
x
}
fn main() {}

40
src/test/ui/impl-trait/issues/issue-88236-2.stderr
View File

@ -1,20 +1,38 @@
error: implementation of `Hrtb` is not general enough
--> $DIR/issue-88236-2.rs:16:38
error: higher kinded lifetime bounds on nested opaque types are not supported yet
--> $DIR/issue-88236-2.rs:15:61
|
LL | fn make_impl() -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {}
| ^^
|
note: lifetime declared here
--> $DIR/issue-88236-2.rs:15:28
|
LL | fn make_impl() -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {}
| ^^
error: higher kinded lifetime bounds on nested opaque types are not supported yet
--> $DIR/issue-88236-2.rs:18:80
|
LL | fn make_weird_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ implementation of `Hrtb` is not general enough
| ^^
|
= note: `Hrtb<'0>` would have to be implemented for the type `&()`, for any lifetime `'0`...
= note: ...but `Hrtb<'1>` is actually implemented for the type `&'1 ()`, for some specific lifetime `'1`
note: lifetime declared here
--> $DIR/issue-88236-2.rs:18:47
|
LL | fn make_weird_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {
| ^^
error: implementation of `Hrtb` is not general enough
--> $DIR/issue-88236-2.rs:19:36
error: higher kinded lifetime bounds on nested opaque types are not supported yet
--> $DIR/issue-88236-2.rs:23:78
|
LL | fn make_bad_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ implementation of `Hrtb` is not general enough
| ^^
|
= note: `Hrtb<'1>` would have to be implemented for the type `&()`, for any lifetime `'1`...
= note: ...but `Hrtb<'_>` is actually implemented for the type `&()`
note: lifetime declared here
--> $DIR/issue-88236-2.rs:23:45
|
LL | fn make_bad_impl<'b>(x: &'b ()) -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {
| ^^
error: aborting due to 2 previous errors
error: aborting due to 3 previous errors

3
src/test/ui/impl-trait/issues/issue-88236.rs
View File

@ -1,5 +1,3 @@
// check-pass
// this used to cause stack overflows
trait Hrtb<'a> {
@ -15,5 +13,6 @@ impl<'a> Hrtb<'a> for &'a () {
}
fn make_impl() -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {}
//~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
fn main() {}

14
src/test/ui/impl-trait/issues/issue-88236.stderr Normal file
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@ -0,0 +1,14 @@
error: higher kinded lifetime bounds on nested opaque types are not supported yet
--> $DIR/issue-88236.rs:15:61
|
LL | fn make_impl() -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {}
| ^^
|
note: lifetime declared here
--> $DIR/issue-88236.rs:15:28
|
LL | fn make_impl() -> impl for<'a> Hrtb<'a, Assoc = impl Send + 'a> {}
| ^^
error: aborting due to previous error

64
src/test/ui/impl-trait/nested-rpit-hrtb.rs Normal file
View File

@ -0,0 +1,64 @@
// Test the interaction between rested RPIT and HRTB.
trait Foo<'a> {
type Assoc;
}
impl Foo<'_> for () {
type Assoc = ();
}
// Alternative version of `Foo` whose impl uses `'a`.
trait Bar<'a> {
type Assoc;
}
impl<'a> Bar<'a> for () {
type Assoc = &'a ();
}
trait Qux<'a> {}
impl Qux<'_> for () {}
// This is not supported.
fn one_hrtb_outlives() -> impl for<'a> Foo<'a, Assoc = impl Sized + 'a> {}
//~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
// This is not supported.
fn one_hrtb_trait_param() -> impl for<'a> Foo<'a, Assoc = impl Qux<'a>> {}
//~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
fn one_hrtb_outlives_uses() -> impl for<'a> Bar<'a, Assoc = impl Sized + 'a> {}
//~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
fn one_hrtb_trait_param_uses() -> impl for<'a> Bar<'a, Assoc = impl Qux<'a>> {}
//~^ ERROR higher kinded lifetime bounds on nested opaque types are not supported yet
// This should pass.
fn one_hrtb_mention_fn_trait_param<'b>() -> impl for<'a> Foo<'a, Assoc = impl Qux<'b>> {}
// This should pass.
fn one_hrtb_mention_fn_outlives<'b>() -> impl for<'a> Foo<'a, Assoc = impl Sized + 'b> {}
// This should pass.
fn one_hrtb_mention_fn_trait_param_uses<'b>() -> impl for<'a> Bar<'a, Assoc = impl Qux<'b>> {}
// This should pass.
fn one_hrtb_mention_fn_outlives_uses<'b>() -> impl for<'a> Bar<'a, Assoc = impl Sized + 'b> {}
// This should pass.
fn two_htrb_trait_param() -> impl for<'a> Foo<'a, Assoc = impl for<'b> Qux<'b>> {}
// `'b` is not in scope for the outlives bound.
fn two_htrb_outlives() -> impl for<'a> Foo<'a, Assoc = impl for<'b> Sized + 'b> {}
//~^ ERROR use of undeclared lifetime name `'b` [E0261]
// This should pass.
fn two_htrb_trait_param_uses() -> impl for<'a> Bar<'a, Assoc = impl for<'b> Qux<'b>> {}
// `'b` is not in scope for the outlives bound.
fn two_htrb_outlives_uses() -> impl for<'a> Bar<'a, Assoc = impl for<'b> Sized + 'b> {}
//~^ ERROR use of undeclared lifetime name `'b` [E0261]
fn main() {}

82
src/test/ui/impl-trait/nested-rpit-hrtb.stderr Normal file
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@ -0,0 +1,82 @@
error[E0261]: use of undeclared lifetime name `'b`
--> $DIR/nested-rpit-hrtb.rs:54:77
|
LL | fn two_htrb_outlives() -> impl for<'a> Foo<'a, Assoc = impl for<'b> Sized + 'b> {}
| ^^ undeclared lifetime
|
= note: for more information on higher-ranked polymorphism, visit https://doc.rust-lang.org/nomicon/hrtb.html
help: consider making the bound lifetime-generic with a new `'b` lifetime
|
LL | fn two_htrb_outlives() -> impl for<'b, 'a> Foo<'a, Assoc = impl for<'b> Sized + 'b> {}
| +++
help: consider introducing lifetime `'b` here
|
LL | fn two_htrb_outlives<'b>() -> impl for<'a> Foo<'a, Assoc = impl for<'b> Sized + 'b> {}
| ++++
error[E0261]: use of undeclared lifetime name `'b`
--> $DIR/nested-rpit-hrtb.rs:61:82
|
LL | fn two_htrb_outlives_uses() -> impl for<'a> Bar<'a, Assoc = impl for<'b> Sized + 'b> {}
| ^^ undeclared lifetime
|
help: consider making the bound lifetime-generic with a new `'b` lifetime
|
LL | fn two_htrb_outlives_uses() -> impl for<'b, 'a> Bar<'a, Assoc = impl for<'b> Sized + 'b> {}
| +++
help: consider introducing lifetime `'b` here
|
LL | fn two_htrb_outlives_uses<'b>() -> impl for<'a> Bar<'a, Assoc = impl for<'b> Sized + 'b> {}
| ++++
error: higher kinded lifetime bounds on nested opaque types are not supported yet
--> $DIR/nested-rpit-hrtb.rs:25:69
|
LL | fn one_hrtb_outlives() -> impl for<'a> Foo<'a, Assoc = impl Sized + 'a> {}
| ^^
|
note: lifetime declared here
--> $DIR/nested-rpit-hrtb.rs:25:36
|
LL | fn one_hrtb_outlives() -> impl for<'a> Foo<'a, Assoc = impl Sized + 'a> {}
| ^^
error: higher kinded lifetime bounds on nested opaque types are not supported yet
--> $DIR/nested-rpit-hrtb.rs:29:68
|
LL | fn one_hrtb_trait_param() -> impl for<'a> Foo<'a, Assoc = impl Qux<'a>> {}
| ^^
|
note: lifetime declared here
--> $DIR/nested-rpit-hrtb.rs:29:39
|
LL | fn one_hrtb_trait_param() -> impl for<'a> Foo<'a, Assoc = impl Qux<'a>> {}
| ^^
error: higher kinded lifetime bounds on nested opaque types are not supported yet
--> $DIR/nested-rpit-hrtb.rs:32:74
|
LL | fn one_hrtb_outlives_uses() -> impl for<'a> Bar<'a, Assoc = impl Sized + 'a> {}
| ^^
|
note: lifetime declared here
--> $DIR/nested-rpit-hrtb.rs:32:41
|
LL | fn one_hrtb_outlives_uses() -> impl for<'a> Bar<'a, Assoc = impl Sized + 'a> {}
| ^^
error: higher kinded lifetime bounds on nested opaque types are not supported yet
--> $DIR/nested-rpit-hrtb.rs:35:73
|
LL | fn one_hrtb_trait_param_uses() -> impl for<'a> Bar<'a, Assoc = impl Qux<'a>> {}
| ^^
|
note: lifetime declared here
--> $DIR/nested-rpit-hrtb.rs:35:44
|
LL | fn one_hrtb_trait_param_uses() -> impl for<'a> Bar<'a, Assoc = impl Qux<'a>> {}
| ^^
error: aborting due to 6 previous errors
For more information about this error, try `rustc --explain E0261`.