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

This commit is contained in:
Esteban Küber 2020-06-09 13:57:33 -07:00
parent a39c7787ba
commit 562f4967b4
12 changed files with 363 additions and 77 deletions
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2
src/librustc_infer/infer/error_reporting/nice_region_error/find_anon_type.rs
View File

@ -26,7 +26,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
&self,
region: Region<'tcx>,
br: &ty::BoundRegion,
) -> Option<(&hir::Ty<'_>, &hir::FnDecl<'_>)> {
) -> Option<(&hir::Ty<'tcx>, &hir::FnDecl<'tcx>)> {
if let Some(anon_reg) = self.tcx().is_suitable_region(region) {
let def_id = anon_reg.def_id;
if let Some(def_id) = def_id.as_local() {

13
src/librustc_infer/infer/error_reporting/nice_region_error/named_anon_conflict.rs
View File

@ -2,7 +2,8 @@
//! where one region is named and the other is anonymous.
use crate::infer::error_reporting::nice_region_error::NiceRegionError;
use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
use rustc_hir::{FnRetTy, TyKind};
use rustc_hir::intravisit::Visitor;
use rustc_hir::FnRetTy;
use rustc_middle::ty;
impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
@ -80,12 +81,16 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
}
if let FnRetTy::Return(ty) = &fndecl.output {
let mut v = ty::TraitObjectVisitor(vec![]);
rustc_hir::intravisit::walk_ty(&mut v, ty);
let mut v = ty::TraitObjectVisitor(vec![], self.tcx().hir());
v.visit_ty(ty);
debug!("try_report_named_anon_conflict: ret ty {:?}", ty);
if sub == &ty::ReStatic
&& (matches!(ty.kind, TyKind::OpaqueDef(_, _)) || v.0.len() == 1)
&& v.0
.into_iter()
.filter(|t| t.span.desugaring_kind().is_none())
.next()
.is_some()
{
debug!("try_report_named_anon_conflict: impl Trait + 'static");
// This is an `impl Trait` or `dyn Trait` return that evaluates de need of

76
src/librustc_infer/infer/error_reporting/nice_region_error/static_impl_trait.rs
View File

@ -26,8 +26,11 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
);
let anon_reg_sup = self.tcx().is_suitable_region(sup_r)?;
debug!("try_report_static_impl_trait: anon_reg_sup={:?}", anon_reg_sup);
let fn_return = self.tcx().return_type_impl_or_dyn_trait(anon_reg_sup.def_id)?;
debug!("try_report_static_impl_trait: fn_return={:?}", fn_return);
let fn_returns = self.tcx().return_type_impl_or_dyn_trait(anon_reg_sup.def_id);
if fn_returns.is_empty() {
return None;
}
debug!("try_report_static_impl_trait: fn_return={:?}", fn_returns);
if **sub_r == RegionKind::ReStatic {
let sp = var_origin.span();
let return_sp = sub_origin.span();
@ -98,25 +101,26 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
);
}
// only apply this suggestion onto functions with
// explicit non-desugar'able return.
if fn_return.span.desugaring_kind().is_none() {
// FIXME: account for the need of parens in `&(dyn Trait + '_)`
let consider = "consider changing the";
let declare = "to declare that the";
let arg = match param_info.param.pat.simple_ident() {
Some(simple_ident) => format!("argument `{}`", simple_ident),
None => "the argument".to_string(),
};
let explicit =
format!("you can add an explicit `{}` lifetime bound", lifetime_name);
let explicit_static =
format!("explicit `'static` bound to the lifetime of {}", arg);
let captures = format!("captures data from {}", arg);
let add_static_bound =
"alternatively, add an explicit `'static` bound to this reference";
let plus_lt = format!(" + {}", lifetime_name);
// FIXME: account for the need of parens in `&(dyn Trait + '_)`
let consider = "consider changing the";
let declare = "to declare that the";
let arg = match param_info.param.pat.simple_ident() {
Some(simple_ident) => format!("argument `{}`", simple_ident),
None => "the argument".to_string(),
};
let explicit =
format!("you can add an explicit `{}` lifetime bound", lifetime_name);
let explicit_static =
format!("explicit `'static` bound to the lifetime of {}", arg);
let captures = format!("captures data from {}", arg);
let add_static_bound =
"alternatively, add an explicit `'static` bound to this reference";
let plus_lt = format!(" + {}", lifetime_name);
for fn_return in fn_returns {
if fn_return.span.desugaring_kind().is_some() {
// Skip `async` desugaring `impl Future`.
continue;
}
match fn_return.kind {
TyKind::OpaqueDef(item_id, _) => {
let item = self.tcx().hir().item(item_id.id);
@ -143,7 +147,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
err.span_suggestion_verbose(
span,
&format!("{} `impl Trait`'s {}", consider, explicit_static),
lifetime_name,
lifetime_name.clone(),
Applicability::MaybeIncorrect,
);
err.span_suggestion_verbose(
@ -152,6 +156,19 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
param_info.param_ty.to_string(),
Applicability::MaybeIncorrect,
);
} else if let Some(_) = opaque
.bounds
.iter()
.filter_map(|arg| match arg {
GenericBound::Outlives(Lifetime { name, span, .. })
if name.ident().to_string() == lifetime_name =>
{
Some(*span)
}
_ => None,
})
.next()
{
} else {
err.span_suggestion_verbose(
fn_return.span.shrink_to_hi(),
@ -161,10 +178,10 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
captures = captures,
explicit = explicit,
),
plus_lt,
plus_lt.clone(),
Applicability::MaybeIncorrect,
);
};
}
}
TyKind::TraitObject(_, lt) => match lt.name {
LifetimeName::ImplicitObjectLifetimeDefault => {
@ -176,15 +193,19 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
captures = captures,
explicit = explicit,
),
plus_lt,
plus_lt.clone(),
Applicability::MaybeIncorrect,
);
}
_ => {
name if name.ident().to_string() != lifetime_name => {
// With this check we avoid suggesting redundant bounds. This
// would happen if there are nested impl/dyn traits and only
// one of them has the bound we'd suggest already there, like
// in `impl Foo<X = dyn Bar> + '_`.
err.span_suggestion_verbose(
lt.span,
&format!("{} trait object's {}", consider, explicit_static),
lifetime_name,
lifetime_name.clone(),
Applicability::MaybeIncorrect,
);
err.span_suggestion_verbose(
@ -194,6 +215,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
Applicability::MaybeIncorrect,
);
}
_ => {}
},
_ => {}
}

32
src/librustc_middle/ty/context.rs
View File

@ -37,6 +37,7 @@ use rustc_hir as hir;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, DefIdSet, LocalDefId, LOCAL_CRATE};
use rustc_hir::definitions::{DefPathHash, Definitions};
use rustc_hir::intravisit::Visitor;
use rustc_hir::lang_items::{self, PanicLocationLangItem};
use rustc_hir::{HirId, ItemKind, ItemLocalId, ItemLocalMap, ItemLocalSet, Node, TraitCandidate};
use rustc_index::vec::{Idx, IndexVec};
@ -1405,10 +1406,7 @@ impl<'tcx> TyCtxt<'tcx> {
})
}
pub fn return_type_impl_or_dyn_trait(
&self,
scope_def_id: DefId,
) -> Option<&'tcx hir::Ty<'tcx>> {
pub fn return_type_impl_or_dyn_trait(&self, scope_def_id: DefId) -> Vec<&'tcx hir::Ty<'tcx>> {
let hir_id = self.hir().as_local_hir_id(scope_def_id.expect_local());
let hir_output = match self.hir().get(hir_id) {
Node::Item(hir::Item {
@ -1444,30 +1442,12 @@ impl<'tcx> TyCtxt<'tcx> {
),
..
}) => ty,
_ => return None,
_ => return vec![],
};
let ret_ty = self.type_of(scope_def_id);
match ret_ty.kind {
ty::FnDef(_, _) => {
let sig = ret_ty.fn_sig(*self);
let output = self.erase_late_bound_regions(&sig.output());
if output.is_impl_trait() {
let fn_decl = self.hir().fn_decl_by_hir_id(hir_id).unwrap();
if let hir::FnRetTy::Return(ty) = fn_decl.output {
return Some(ty);
}
} else {
let mut v = TraitObjectVisitor(vec![]);
rustc_hir::intravisit::walk_ty(&mut v, hir_output);
if v.0.len() == 1 {
return Some(v.0[0]);
}
}
None
}
_ => None,
}
let mut v = TraitObjectVisitor(vec![], self.hir());
v.visit_ty(hir_output);
v.0
}
pub fn return_type_impl_trait(&self, scope_def_id: DefId) -> Option<(Ty<'tcx>, Span)> {

31
src/librustc_middle/ty/diagnostics.rs
View File

@ -236,7 +236,9 @@ pub fn suggest_constraining_type_param(
}
}
pub struct TraitObjectVisitor<'tcx>(pub Vec<&'tcx hir::Ty<'tcx>>);
/// Collect al types that have an implicit `'static` obligation that we could suggest `'_` for.
pub struct TraitObjectVisitor<'tcx>(pub Vec<&'tcx hir::Ty<'tcx>>, pub crate::hir::map::Map<'tcx>);
impl<'v> hir::intravisit::Visitor<'v> for TraitObjectVisitor<'v> {
type Map = rustc_hir::intravisit::ErasedMap<'v>;
@ -245,15 +247,24 @@ impl<'v> hir::intravisit::Visitor<'v> for TraitObjectVisitor<'v> {
}
fn visit_ty(&mut self, ty: &'v hir::Ty<'v>) {
if let hir::TyKind::TraitObject(
_,
hir::Lifetime {
name: hir::LifetimeName::ImplicitObjectLifetimeDefault | hir::LifetimeName::Static,
..
},
) = ty.kind
{
self.0.push(ty);
match ty.kind {
hir::TyKind::TraitObject(
_,
hir::Lifetime {
name:
hir::LifetimeName::ImplicitObjectLifetimeDefault | hir::LifetimeName::Static,
..
},
) => {
self.0.push(ty);
}
hir::TyKind::OpaqueDef(item_id, _) => {
self.0.push(ty);
let item = self.1.expect_item(item_id.id);
hir::intravisit::walk_item(self, item);
}
_ => {}
}
hir::intravisit::walk_ty(self, ty);
}
}

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`.