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https://github.com/rust-lang/rust.git
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Suggest setting lifetime in borrowck error involving types with elided lifetimes
```
error: lifetime may not live long enough
--> $DIR/ex3-both-anon-regions-both-are-structs-2.rs:7:5
|
LL | fn foo(mut x: Ref, y: Ref) {
| ----- - has type `Ref<'_, '1>`
| |
| has type `Ref<'_, '2>`
LL | x.b = y.b;
| ^^^^^^^^^ assignment requires that `'1` must outlive `'2`
|
help: consider introducing a named lifetime parameter
|
LL | fn foo<'a>(mut x: Ref<'a, 'a>, y: Ref<'a, 'a>) {
| ++++ ++++++++ ++++++++
```
As can be seen above, it currently doesn't try to compare the `ty::Ty` lifetimes that diverged vs the `hir::Ty` to correctly suggest the following
```
help: consider introducing a named lifetime parameter
|
LL | fn foo<'a>(mut x: Ref<'_, 'a>, y: Ref<'_, 'a>) {
| ++++ ++++++++ ++++++++
```
but I believe this to still be an improvement over the status quo.
CC #40990.
This commit is contained in:
Esteban Küber
parent
1a73979886
commit
9f730e92f2
@ -4,6 +4,7 @@ use rustc_errors::{
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MultiSpan, SubdiagMessageOp, Subdiagnostic,
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};
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use rustc_hir as hir;
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use rustc_hir::intravisit::{walk_ty, Visitor};
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use rustc_hir::FnRetTy;
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use rustc_macros::{Diagnostic, Subdiagnostic};
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use rustc_middle::ty::print::TraitRefPrintOnlyTraitPath;
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@ -355,18 +356,6 @@ impl Subdiagnostic for AddLifetimeParamsSuggestion<'_> {
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_f: &F,
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) {
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let mut mk_suggestion = || {
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let (
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hir::Ty { kind: hir::TyKind::Ref(lifetime_sub, _), .. },
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hir::Ty { kind: hir::TyKind::Ref(lifetime_sup, _), .. },
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) = (self.ty_sub, self.ty_sup)
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else {
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return false;
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};
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if !lifetime_sub.is_anonymous() || !lifetime_sup.is_anonymous() {
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return false;
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};
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let Some(anon_reg) = self.tcx.is_suitable_region(self.sub) else {
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return false;
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};
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@ -393,21 +382,77 @@ impl Subdiagnostic for AddLifetimeParamsSuggestion<'_> {
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let suggestion_param_name =
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suggestion_param_name.map(|n| n.to_string()).unwrap_or_else(|| "'a".to_owned());
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debug!(?lifetime_sup.ident.span);
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debug!(?lifetime_sub.ident.span);
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let make_suggestion = |ident: Ident| {
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let sugg = if ident.name == kw::Empty {
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format!("{suggestion_param_name}, ")
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} else if ident.name == kw::UnderscoreLifetime && ident.span.is_empty() {
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format!("{suggestion_param_name} ")
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} else {
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suggestion_param_name.clone()
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};
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(ident.span, sugg)
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};
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let mut suggestions =
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vec![make_suggestion(lifetime_sub.ident), make_suggestion(lifetime_sup.ident)];
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struct ImplicitLifetimeFinder {
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suggestions: Vec<(Span, String)>,
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suggestion_param_name: String,
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}
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impl<'v> Visitor<'v> for ImplicitLifetimeFinder {
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fn visit_ty(&mut self, ty: &'v hir::Ty<'v>) {
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let make_suggestion = |ident: Ident| {
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if ident.name == kw::Empty && ident.span.is_empty() {
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format!("{}, ", self.suggestion_param_name)
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} else if ident.name == kw::UnderscoreLifetime && ident.span.is_empty() {
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format!("{} ", self.suggestion_param_name)
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} else {
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self.suggestion_param_name.clone()
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}
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};
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match ty.kind {
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hir::TyKind::Path(hir::QPath::Resolved(_, path)) => {
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for segment in path.segments {
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if let Some(args) = segment.args {
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if args.args.iter().all(|arg| {
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matches!(
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arg,
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hir::GenericArg::Lifetime(lifetime)
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if lifetime.ident.name == kw::Empty
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)
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}) {
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self.suggestions.push((
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segment.ident.span.shrink_to_hi(),
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format!(
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"<{}>",
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args.args
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.iter()
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.map(|_| self.suggestion_param_name.clone())
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.collect::<Vec<_>>()
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.join(", ")
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),
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));
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} else {
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for arg in args.args {
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if let hir::GenericArg::Lifetime(lifetime) = arg
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&& lifetime.is_anonymous()
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{
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self.suggestions.push((
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lifetime.ident.span,
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make_suggestion(lifetime.ident),
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));
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}
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}
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}
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}
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}
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}
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hir::TyKind::Ref(lifetime, ..) if lifetime.is_anonymous() => {
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self.suggestions
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.push((lifetime.ident.span, make_suggestion(lifetime.ident)));
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}
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_ => {}
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}
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walk_ty(self, ty);
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}
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}
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let mut visitor = ImplicitLifetimeFinder {
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suggestions: vec![],
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suggestion_param_name: suggestion_param_name.clone(),
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};
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visitor.visit_ty(self.ty_sub);
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visitor.visit_ty(self.ty_sup);
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if visitor.suggestions.is_empty() {
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return false;
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}
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if introduce_new {
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let new_param_suggestion = if let Some(first) =
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generics.params.iter().find(|p| !p.name.ident().span.is_empty())
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@ -417,15 +462,15 @@ impl Subdiagnostic for AddLifetimeParamsSuggestion<'_> {
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(generics.span, format!("<{suggestion_param_name}>"))
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};
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suggestions.push(new_param_suggestion);
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visitor.suggestions.push(new_param_suggestion);
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}
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diag.multipart_suggestion(
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diag.multipart_suggestion_verbose(
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fluent::infer_lifetime_param_suggestion,
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suggestions,
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visitor.suggestions,
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Applicability::MaybeIncorrect,
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);
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diag.arg("is_impl", is_impl);
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true
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};
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if mk_suggestion() && self.add_note {
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@ -8,6 +8,11 @@ LL | fn foo<'a>(x: &i32, y: &'a i32) -> &'a i32 {
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LL |
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LL | if x > y { x } else { y }
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| ^ associated function was supposed to return data with lifetime `'a` but it is returning data with lifetime `'1`
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help: consider introducing a named lifetime parameter and update trait if needed
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LL | fn foo<'a>(x: &'a i32, y: &'a i32) -> &'a i32 {
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| ++
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error: aborting due to 1 previous error
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@ -8,6 +8,11 @@ LL | fn foo<'a>(&self, x: &'a i32) -> &i32 {
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LL |
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LL | x
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| ^ method was supposed to return data with lifetime `'1` but it is returning data with lifetime `'a`
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help: consider introducing a named lifetime parameter and update trait if needed
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LL | fn foo<'a>(&'a self, x: &'a i32) -> &i32 {
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| ++
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error: aborting due to 1 previous error
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@ -8,6 +8,11 @@ LL | fn foo<'a>(&self, x: &'a Foo) -> &'a Foo {
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LL |
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LL | if true { x } else { self }
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| ^^^^ method was supposed to return data with lifetime `'a` but it is returning data with lifetime `'1`
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help: consider introducing a named lifetime parameter and update trait if needed
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LL | fn foo<'a>(&'a self, x: &'a Foo) -> &'a Foo {
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| ++
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error: aborting due to 1 previous error
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@ -7,6 +7,11 @@ LL | fn foo(x: &mut Vec<Ref<i32>>, y: Ref<i32>) {
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| has type `&mut Vec<Ref<'2, i32>>`
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LL | x.push(y);
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| ^^^^^^^^^ argument requires that `'1` must outlive `'2`
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help: consider introducing a named lifetime parameter
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LL | fn foo<'a>(x: &mut Vec<Ref<'a, i32>>, y: Ref<'a, i32>) {
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| ++++ +++ +++
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error: aborting due to 1 previous error
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@ -7,6 +7,11 @@ LL | fn foo(mut x: Ref, y: Ref) {
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| has type `Ref<'_, '2>`
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LL | x.b = y.b;
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| ^^^^^^^^^ assignment requires that `'1` must outlive `'2`
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|
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help: consider introducing a named lifetime parameter
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LL | fn foo<'a>(mut x: Ref<'a, 'a>, y: Ref<'a, 'a>) {
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| ++++ ++++++++ ++++++++
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error: aborting due to 1 previous error
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@ -8,6 +8,11 @@ LL | fn foo(mut x: Ref) {
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| has type `Ref<'2, '_>`
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LL | x.a = x.b;
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| ^^^^^^^^^ assignment requires that `'1` must outlive `'2`
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help: consider introducing a named lifetime parameter
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LL | fn foo<'a>(mut x: Ref<'a, 'a>) {
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| ++++ ++++++++
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error: aborting due to 1 previous error
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@ -7,6 +7,11 @@ LL | fn foo(mut x: Vec<Ref>, y: Ref) {
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| has type `Vec<Ref<'2>>`
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LL | x.push(y);
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| ^^^^^^^^^ argument requires that `'1` must outlive `'2`
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|
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help: consider introducing a named lifetime parameter
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LL | fn foo<'a>(mut x: Vec<Ref<'a>>, y: Ref<'a>) {
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| ++++ ++++ ++++
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error: aborting due to 1 previous error
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@ -7,6 +7,11 @@ LL | fn foo(mut x: Ref, y: &u32) {
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| has type `Ref<'_, '1>`
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LL | y = x.b;
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| ^^^^^^^ assignment requires that `'1` must outlive `'2`
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help: consider introducing a named lifetime parameter
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LL | fn foo<'a>(mut x: Ref<'a, 'a>, y: &'a u32) {
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| ++++ ++++++++ ++
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error[E0384]: cannot assign to immutable argument `y`
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--> $DIR/ex3-both-anon-regions-one-is-struct-2.rs:4:5
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@ -7,6 +7,11 @@ LL | fn foo(mut y: Ref, x: &u32) {
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| has type `Ref<'_, '2>`
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LL | y.b = x;
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| ^^^^^^^ assignment requires that `'1` must outlive `'2`
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|
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help: consider introducing a named lifetime parameter
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|
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LL | fn foo<'a>(mut y: Ref<'a, 'a>, x: &'a u32) {
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| ++++ ++++++++ ++
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error: aborting due to 1 previous error
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@ -7,6 +7,11 @@ LL | fn foo(mut y: Ref, x: &u32) {
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| has type `Ref<'_, '2>`
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LL | y.b = x;
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| ^^^^^^^ assignment requires that `'1` must outlive `'2`
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|
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help: consider introducing a named lifetime parameter
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|
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LL | fn foo<'a>(mut y: Ref<'a, 'a>, x: &'a u32) {
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| ++++ ++++++++ ++
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error: aborting due to 1 previous error
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@ -7,6 +7,11 @@ LL | fn foo(mut x: Ref, y: &u32) {
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| has type `Ref<'_, '2>`
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LL | x.b = y;
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| ^^^^^^^ assignment requires that `'1` must outlive `'2`
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|
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help: consider introducing a named lifetime parameter
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|
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LL | fn foo<'a>(mut x: Ref<'a, 'a>, y: &'a u32) {
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| ++++ ++++++++ ++
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error: aborting due to 1 previous error
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@ -34,6 +34,11 @@ LL | async fn bar<'a>(self: Alias<&Self>, arg: &'a ()) -> &() { arg }
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| | |
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| | let's call the lifetime of this reference `'1`
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| lifetime `'a` defined here
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|
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help: consider introducing a named lifetime parameter and update trait if needed
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|
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LL | async fn bar<'a>(self: Alias<&'a Self>, arg: &'a ()) -> &() { arg }
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| ++
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error: aborting due to 3 previous errors
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@ -33,6 +33,11 @@ LL | fn bar<'a>(self: Alias<&Self>, arg: &'a ()) -> &() { arg }
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| -- ---- has type `Pin<&'1 Foo>` ^^^ method was supposed to return data with lifetime `'1` but it is returning data with lifetime `'a`
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| |
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| lifetime `'a` defined here
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|
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help: consider introducing a named lifetime parameter and update trait if needed
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|
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LL | fn bar<'a>(self: Alias<&'a Self>, arg: &'a ()) -> &() { arg }
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| ++
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error: aborting due to 3 previous errors
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