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Rollup merge of #73496 - estebank:opaque-missing-lts-in-fn-3, r=nikomatsakis

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Account for multiple impl/dyn Trait in return type when suggesting `'_`

Make `impl` and `dyn` Trait lifetime suggestions a bit more resilient.

Follow up to #72804.

r? @nikomatsakis
This commit is contained in:
Manish Goregaokar 2020-06-23 00:33:58 -07:00 • committed by GitHub
commit cd18ac1ce8
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GPG key ID: 4AEE18F83AFDEB23
12 changed files with 367 additions and 79 deletions
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16
src/test/ui/impl-trait/must_outlive_least_region_or_bound.nll.stderr
View file

@ -53,7 +53,15 @@ LL | fn foo<'a>(x: &i32) -> impl Copy + 'a { x }
| help: add explicit lifetime `'a` to the type of `x`: `&'a i32`
error: lifetime may not live long enough
--> $DIR/must_outlive_least_region_or_bound.rs:33:69
--> $DIR/must_outlive_least_region_or_bound.rs:30:24
|
LL | fn elided5(x: &i32) -> (Box<dyn Debug>, impl Debug) { (Box::new(x), x) }
| - ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ opaque type requires that `'1` must outlive `'static`
| |
| let's call the lifetime of this reference `'1`
error: lifetime may not live long enough
--> $DIR/must_outlive_least_region_or_bound.rs:37:69
|
LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
| -- lifetime `'a` defined here ^ returning this value requires that `'a` must outlive `'static`
@ -62,7 +70,7 @@ LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
= help: consider replacing `'a` with `'static`
error: lifetime may not live long enough
--> $DIR/must_outlive_least_region_or_bound.rs:38:61
--> $DIR/must_outlive_least_region_or_bound.rs:42:61
|
LL | fn move_lifetime_into_fn<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Fn(&'a u32) {
| -- -- lifetime `'b` defined here ^^^^^^^^^^^^^^^^ opaque type requires that `'b` must outlive `'a`
@ -72,14 +80,14 @@ LL | fn move_lifetime_into_fn<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Fn(&'a u32
= help: consider adding the following bound: `'b: 'a`
error[E0310]: the parameter type `T` may not live long enough
--> $DIR/must_outlive_least_region_or_bound.rs:43:51
--> $DIR/must_outlive_least_region_or_bound.rs:47:51
|
LL | fn ty_param_wont_outlive_static<T:Debug>(x: T) -> impl Debug + 'static {
| ^^^^^^^^^^^^^^^^^^^^
|
= help: consider adding an explicit lifetime bound `T: 'static`...
error: aborting due to 8 previous errors
error: aborting due to 9 previous errors
Some errors have detailed explanations: E0310, E0621.
For more information about an error, try `rustc --explain E0310`.

4
src/test/ui/impl-trait/must_outlive_least_region_or_bound.rs
View file

@ -27,6 +27,10 @@ fn elided4(x: &i32) -> Box<dyn Debug + 'static> { Box::new(x) }
fn explicit4<'a>(x: &'a i32) -> Box<dyn Debug + 'static> { Box::new(x) }
//~^ ERROR cannot infer an appropriate lifetime
fn elided5(x: &i32) -> (Box<dyn Debug>, impl Debug) { (Box::new(x), x) }
//~^ ERROR cannot infer an appropriate lifetime
//~| ERROR cannot infer an appropriate lifetime
trait LifetimeTrait<'a> {}
impl<'a> LifetimeTrait<'a> for &'a i32 {}

45
src/test/ui/impl-trait/must_outlive_least_region_or_bound.stderr
View file

@ -87,13 +87,48 @@ LL | fn foo<'a>(x: &i32) -> impl Copy + 'a { x }
| help: add explicit lifetime `'a` to the type of `x`: `&'a i32`
error[E0759]: cannot infer an appropriate lifetime
--> $DIR/must_outlive_least_region_or_bound.rs:33:69
--> $DIR/must_outlive_least_region_or_bound.rs:30:65
|
LL | fn elided5(x: &i32) -> (Box<dyn Debug>, impl Debug) { (Box::new(x), x) }
| ---- this data with an anonymous lifetime `'_`... ^ ...is captured here, requiring it to live as long as `'static`
|
help: to declare that the trait object captures data from argument `x`, you can add an explicit `'_` lifetime bound
|
LL | fn elided5(x: &i32) -> (Box<dyn Debug + '_>, impl Debug) { (Box::new(x), x) }
| ^^^^
help: to declare that the `impl Trait` captures data from argument `x`, you can add an explicit `'_` lifetime bound
|
LL | fn elided5(x: &i32) -> (Box<dyn Debug>, impl Debug + '_) { (Box::new(x), x) }
| ^^^^
error[E0759]: cannot infer an appropriate lifetime
--> $DIR/must_outlive_least_region_or_bound.rs:30:69
|
LL | fn elided5(x: &i32) -> (Box<dyn Debug>, impl Debug) { (Box::new(x), x) }
| ---- this data with an anonymous lifetime `'_`... ^ ...is captured here...
|
note: ...and is required to live as long as `'static` here
--> $DIR/must_outlive_least_region_or_bound.rs:30:41
|
LL | fn elided5(x: &i32) -> (Box<dyn Debug>, impl Debug) { (Box::new(x), x) }
| ^^^^^^^^^^
help: to declare that the trait object captures data from argument `x`, you can add an explicit `'_` lifetime bound
|
LL | fn elided5(x: &i32) -> (Box<dyn Debug + '_>, impl Debug) { (Box::new(x), x) }
| ^^^^
help: to declare that the `impl Trait` captures data from argument `x`, you can add an explicit `'_` lifetime bound
|
LL | fn elided5(x: &i32) -> (Box<dyn Debug>, impl Debug + '_) { (Box::new(x), x) }
| ^^^^
error[E0759]: cannot infer an appropriate lifetime
--> $DIR/must_outlive_least_region_or_bound.rs:37:69
|
LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
| ------- this data with lifetime `'a`... ^ ...is captured here...
|
note: ...and is required to live as long as `'static` here
--> $DIR/must_outlive_least_region_or_bound.rs:33:34
--> $DIR/must_outlive_least_region_or_bound.rs:37:34
|
LL | fn with_bound<'a>(x: &'a i32) -> impl LifetimeTrait<'a> + 'static { x }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -107,7 +142,7 @@ LL | fn with_bound<'a>(x: &'static i32) -> impl LifetimeTrait<'a> + 'static { x
| ^^^^^^^^^^^^
error[E0623]: lifetime mismatch
--> $DIR/must_outlive_least_region_or_bound.rs:38:61
--> $DIR/must_outlive_least_region_or_bound.rs:42:61
|
LL | fn move_lifetime_into_fn<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Fn(&'a u32) {
| ------- ^^^^^^^^^^^^^^^^
@ -116,7 +151,7 @@ LL | fn move_lifetime_into_fn<'a, 'b>(x: &'a u32, y: &'b u32) -> impl Fn(&'a u32
| this parameter and the return type are declared with different lifetimes...
error[E0310]: the parameter type `T` may not live long enough
--> $DIR/must_outlive_least_region_or_bound.rs:43:51
--> $DIR/must_outlive_least_region_or_bound.rs:47:51
|
LL | fn ty_param_wont_outlive_static<T:Debug>(x: T) -> impl Debug + 'static {
| -- ^^^^^^^^^^^^^^^^^^^^ ...so that the type `T` will meet its required lifetime bounds
@ -181,7 +216,7 @@ help: alternatively, add an explicit `'static` bound to this reference
LL | fn explicit4<'a>(x: &'static i32) -> Box<dyn Debug + 'static> { Box::new(x) }
| ^^^^^^^^^^^^
error: aborting due to 12 previous errors
error: aborting due to 14 previous errors
Some errors have detailed explanations: E0310, E0621, E0623, E0759.
For more information about an error, try `rustc --explain E0310`.

5
src/test/ui/self/arbitrary_self_types_pin_lifetime_impl_trait-async.stderr
View file

@ -6,6 +6,11 @@ LL | async fn f(self: Pin<&Self>) -> impl Clone { self }
| | |
| | this data with an anonymous lifetime `'_`...
| ...is captured here...
|
help: to declare that the `impl Trait` captures data from argument `self`, you can add an explicit `'_` lifetime bound
|
LL | async fn f(self: Pin<&Self>) -> impl Clone + '_ { self }
| ^^^^
error: aborting due to previous error

53
src/test/ui/suggestions/lifetimes/trait-object-nested-in-impl-trait.nll.stderr Normal file
View file

@ -0,0 +1,53 @@
error: lifetime may not live long enough
--> $DIR/trait-object-nested-in-impl-trait.rs:27:23
|
LL | fn iter(&self) -> impl Iterator<Item = Box<dyn Foo>> {
| - ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ opaque type requires that `'1` must outlive `'static`
| |
| let's call the lifetime of this reference `'1`
|
help: to allow this `impl Trait` to capture borrowed data with lifetime `'1`, add `'_` as a bound
|
LL | fn iter(&self) -> impl Iterator<Item = Box<dyn Foo>> + '_ {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: lifetime may not live long enough
--> $DIR/trait-object-nested-in-impl-trait.rs:39:9
|
LL | fn iter(&self) -> impl Iterator<Item = Box<dyn Foo>> + '_ {
| - let's call the lifetime of this reference `'1`
LL | / Iter {
LL | | current: None,
LL | | remaining: self.0.iter(),
LL | | }
| |_________^ returning this value requires that `'1` must outlive `'static`
error: lifetime may not live long enough
--> $DIR/trait-object-nested-in-impl-trait.rs:50:9
|
LL | fn iter<'a>(&'a self) -> impl Iterator<Item = Box<dyn Foo>> + 'a {
| -- lifetime `'a` defined here
LL | / Iter {
LL | | current: None,
LL | | remaining: self.0.iter(),
LL | | }
| |_________^ returning this value requires that `'a` must outlive `'static`
|
= help: consider replacing `'a` with `'static`
error: lifetime may not live long enough
--> $DIR/trait-object-nested-in-impl-trait.rs:60:30
|
LL | fn iter<'a>(&'a self) -> impl Iterator<Item = Box<dyn Foo>> {
| -- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ opaque type requires that `'a` must outlive `'static`
| |
| lifetime `'a` defined here
|
= help: consider replacing `'a` with `'static`
help: to allow this `impl Trait` to capture borrowed data with lifetime `'a`, add `'a` as a bound
|
LL | fn iter<'a>(&'a self) -> impl Iterator<Item = Box<dyn Foo>> + 'a {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 4 previous errors

68
src/test/ui/suggestions/lifetimes/trait-object-nested-in-impl-trait.rs Normal file
View file

@ -0,0 +1,68 @@
trait Foo {}
impl<'a, T: Foo> Foo for &'a T {}
impl<T: Foo + ?Sized> Foo for Box<T> {}
struct Iter<'a, T> {
current: Option<Box<dyn Foo + 'a>>,
remaining: T,
}
impl<'a, T> Iterator for Iter<'a, T>
where
T: Iterator,
T::Item: Foo + 'a,
{
type Item = Box<dyn Foo + 'a>;
fn next(&mut self) -> Option<Self::Item> {
let result = self.current.take();
self.current = Box::new(self.remaining.next()).map(|f| Box::new(f) as _);
result
}
}
struct Bar(Vec<Box<dyn Foo>>);
impl Bar {
fn iter(&self) -> impl Iterator<Item = Box<dyn Foo>> {
Iter {
current: None,
remaining: self.0.iter(), //~ ERROR cannot infer an appropriate lifetime
}
}
}
struct Baz(Vec<Box<dyn Foo>>);
impl Baz {
fn iter(&self) -> impl Iterator<Item = Box<dyn Foo>> + '_ {
Iter {
current: None,
remaining: self.0.iter(), //~ ERROR cannot infer an appropriate lifetime
}
}
}
struct Bat(Vec<Box<dyn Foo>>);
impl Bat {
fn iter<'a>(&'a self) -> impl Iterator<Item = Box<dyn Foo>> + 'a {
Iter {
current: None,
remaining: self.0.iter(), //~ ERROR cannot infer an appropriate lifetime
}
}
}
struct Ban(Vec<Box<dyn Foo>>);
impl Ban {
fn iter<'a>(&'a self) -> impl Iterator<Item = Box<dyn Foo>> {
Iter {
current: None,
remaining: self.0.iter(), //~ ERROR cannot infer an appropriate lifetime
}
}
}
fn main() {}

95
src/test/ui/suggestions/lifetimes/trait-object-nested-in-impl-trait.stderr Normal file
View file

@ -0,0 +1,95 @@
error[E0759]: cannot infer an appropriate lifetime
--> $DIR/trait-object-nested-in-impl-trait.rs:30:31
|
LL | fn iter(&self) -> impl Iterator<Item = Box<dyn Foo>> {
| ----- this data with an anonymous lifetime `'_`...
...
LL | remaining: self.0.iter(),
| ------ ^^^^
| |
| ...is captured here...
|
note: ...and is required to live as long as `'static` here
--> $DIR/trait-object-nested-in-impl-trait.rs:27:23
|
LL | fn iter(&self) -> impl Iterator<Item = Box<dyn Foo>> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: to declare that the `impl Trait` captures data from argument `self`, you can add an explicit `'_` lifetime bound
|
LL | fn iter(&self) -> impl Iterator<Item = Box<dyn Foo>> + '_ {
| ^^^^
help: to declare that the trait object captures data from argument `self`, you can add an explicit `'_` lifetime bound
|
LL | fn iter(&self) -> impl Iterator<Item = Box<dyn Foo + '_>> {
| ^^^^
error[E0759]: cannot infer an appropriate lifetime
--> $DIR/trait-object-nested-in-impl-trait.rs:41:31
|
LL | fn iter(&self) -> impl Iterator<Item = Box<dyn Foo>> + '_ {
| ----- this data with an anonymous lifetime `'_`...
...
LL | remaining: self.0.iter(),
| ------ ^^^^
| |
| ...is captured here...
|
note: ...and is required to live as long as `'static` here
--> $DIR/trait-object-nested-in-impl-trait.rs:38:23
|
LL | fn iter(&self) -> impl Iterator<Item = Box<dyn Foo>> + '_ {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: to declare that the trait object captures data from argument `self`, you can add an explicit `'_` lifetime bound
|
LL | fn iter(&self) -> impl Iterator<Item = Box<dyn Foo + '_>> + '_ {
| ^^^^
error[E0759]: cannot infer an appropriate lifetime
--> $DIR/trait-object-nested-in-impl-trait.rs:52:31
|
LL | fn iter<'a>(&'a self) -> impl Iterator<Item = Box<dyn Foo>> + 'a {
| -------- this data with lifetime `'a`...
...
LL | remaining: self.0.iter(),
| ------ ^^^^
| |
| ...is captured here...
|
note: ...and is required to live as long as `'static` here
--> $DIR/trait-object-nested-in-impl-trait.rs:49:30
|
LL | fn iter<'a>(&'a self) -> impl Iterator<Item = Box<dyn Foo>> + 'a {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: to declare that the trait object captures data from argument `self`, you can add an explicit `'a` lifetime bound
|
LL | fn iter<'a>(&'a self) -> impl Iterator<Item = Box<dyn Foo + 'a>> + 'a {
| ^^^^
error[E0759]: cannot infer an appropriate lifetime
--> $DIR/trait-object-nested-in-impl-trait.rs:63:31
|
LL | fn iter<'a>(&'a self) -> impl Iterator<Item = Box<dyn Foo>> {
| -------- this data with lifetime `'a`...
...
LL | remaining: self.0.iter(),
| ------ ^^^^
| |
| ...is captured here...
|
note: ...and is required to live as long as `'static` here
--> $DIR/trait-object-nested-in-impl-trait.rs:60:30
|
LL | fn iter<'a>(&'a self) -> impl Iterator<Item = Box<dyn Foo>> {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: to declare that the `impl Trait` captures data from argument `self`, you can add an explicit `'a` lifetime bound
|
LL | fn iter<'a>(&'a self) -> impl Iterator<Item = Box<dyn Foo>> + 'a {
| ^^^^
help: to declare that the trait object captures data from argument `self`, you can add an explicit `'a` lifetime bound
|
LL | fn iter<'a>(&'a self) -> impl Iterator<Item = Box<dyn Foo + 'a>> {
| ^^^^
error: aborting due to 4 previous errors
For more information about this error, try `rustc --explain E0759`.