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Rollup merge of rust-lang#115429 - compiler-errors:assoc-ct-lt-fallth…
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…rough, r=cjgillot

Fall through when resolving elided assoc const lifetimes

`@QuineDot` makes a good point in rust-lang#115010 (comment) that we probably should not accept *more* code due to rust-lang#115011 even though that code will eventually become a forbid-warning in a few versions (rust-lang#115010 (comment)).

Fall through when walking thru the `AnonymousWarnToStatic` (renamed to `AnonymousWarn`) rib so that we can resolve as a fresh lifetime like we did before.
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@fmease
fmease authored Sep 2, 2023
2 parents b9980f3 + b62eeb2 commit 1f3174e
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Showing 3 changed files with 88 additions and 34 deletions.
63 changes: 29 additions & 34 deletions compiler/rustc_resolve/src/late.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -313,7 +313,7 @@ enum LifetimeRibKind {

/// Resolves elided lifetimes to `'static`, but gives a warning that this behavior
/// is a bug and will be reverted soon.
AnonymousWarnToStatic(NodeId),
AnonymousWarn(NodeId),

/// Signal we cannot find which should be the anonymous lifetime.
ElisionFailure,
Expand Down Expand Up @@ -1154,7 +1154,7 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
}
LifetimeRibKind::AnonymousCreateParameter { .. }
| LifetimeRibKind::AnonymousReportError
| LifetimeRibKind::AnonymousWarnToStatic(_)
| LifetimeRibKind::AnonymousWarn(_)
| LifetimeRibKind::Elided(_)
| LifetimeRibKind::ElisionFailure
| LifetimeRibKind::ConcreteAnonConst(_)
Expand Down Expand Up @@ -1522,7 +1522,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
// lifetime would be illegal.
LifetimeRibKind::Item
| LifetimeRibKind::AnonymousReportError
| LifetimeRibKind::AnonymousWarnToStatic(_)
| LifetimeRibKind::AnonymousWarn(_)
| LifetimeRibKind::ElisionFailure => Some(LifetimeUseSet::Many),
// An anonymous lifetime is legal here, and bound to the right
// place, go ahead.
Expand Down Expand Up @@ -1585,7 +1585,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
| LifetimeRibKind::Generics { .. }
| LifetimeRibKind::ElisionFailure
| LifetimeRibKind::AnonymousReportError
| LifetimeRibKind::AnonymousWarnToStatic(_) => {}
| LifetimeRibKind::AnonymousWarn(_) => {}
}
}

Expand Down Expand Up @@ -1625,8 +1625,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
self.record_lifetime_res(lifetime.id, res, elision_candidate);
return;
}
LifetimeRibKind::AnonymousWarnToStatic(node_id) => {
self.record_lifetime_res(lifetime.id, LifetimeRes::Static, elision_candidate);
LifetimeRibKind::AnonymousWarn(node_id) => {
let msg = if elided {
"`&` without an explicit lifetime name cannot be used here"
} else {
Expand All @@ -1642,7 +1641,6 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
span: lifetime.ident.span,
},
);
return;
}
LifetimeRibKind::AnonymousReportError => {
let (msg, note) = if elided {
Expand Down Expand Up @@ -1840,7 +1838,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
// impl Foo for std::cell::Ref<u32> // note lack of '_
// async fn foo(_: std::cell::Ref<u32>) { ... }
LifetimeRibKind::AnonymousCreateParameter { report_in_path: true, .. }
| LifetimeRibKind::AnonymousWarnToStatic(_) => {
| LifetimeRibKind::AnonymousWarn(_) => {
let sess = self.r.tcx.sess;
let mut err = rustc_errors::struct_span_err!(
sess,
Expand Down Expand Up @@ -2936,33 +2934,30 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
kind: LifetimeBinderKind::ConstItem,
},
|this| {
this.with_lifetime_rib(
LifetimeRibKind::AnonymousWarnToStatic(item.id),
|this| {
// If this is a trait impl, ensure the const
// exists in trait
this.check_trait_item(
item.id,
item.ident,
&item.kind,
ValueNS,
item.span,
seen_trait_items,
|i, s, c| ConstNotMemberOfTrait(i, s, c),
);
this.with_lifetime_rib(LifetimeRibKind::AnonymousWarn(item.id), |this| {
// If this is a trait impl, ensure the const
// exists in trait
this.check_trait_item(
item.id,
item.ident,
&item.kind,
ValueNS,
item.span,
seen_trait_items,
|i, s, c| ConstNotMemberOfTrait(i, s, c),
);

this.visit_generics(generics);
this.visit_ty(ty);
if let Some(expr) = expr {
// We allow arbitrary const expressions inside of associated consts,
// even if they are potentially not const evaluatable.
//
// Type parameters can already be used and as associated consts are
// not used as part of the type system, this is far less surprising.
this.resolve_const_body(expr, None);
}
},
);
this.visit_generics(generics);
this.visit_ty(ty);
if let Some(expr) = expr {
// We allow arbitrary const expressions inside of associated consts,
// even if they are potentially not const evaluatable.
//
// Type parameters can already be used and as associated consts are
// not used as part of the type system, this is far less surprising.
this.resolve_const_body(expr, None);
}
});
},
);
}
Expand Down
12 changes: 12 additions & 0 deletions tests/ui/associated-consts/double-elided.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
struct S;

impl S {
const C: &&str = &"";
//~^ WARN `&` without an explicit lifetime name cannot be used here
//~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
//~| WARN `&` without an explicit lifetime name cannot be used here
//~| WARN this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
//~| ERROR in type `&&str`, reference has a longer lifetime than the data it references
}

fn main() {}
47 changes: 47 additions & 0 deletions tests/ui/associated-consts/double-elided.stderr
View file
Original file line number Diff line number Diff line change
@@ -0,0 +1,47 @@
warning: `&` without an explicit lifetime name cannot be used here
--> $DIR/double-elided.rs:4:14
|
LL | const C: &&str = &"";
| ^
|
= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
= note: for more information, see issue #115010 <https://github.com/rust-lang/rust/issues/115010>
= note: `#[warn(elided_lifetimes_in_associated_constant)]` on by default
help: use the `'static` lifetime
|
LL | const C: &'static &str = &"";
| +++++++

warning: `&` without an explicit lifetime name cannot be used here
--> $DIR/double-elided.rs:4:15
|
LL | const C: &&str = &"";
| ^
|
= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
= note: for more information, see issue #115010 <https://github.com/rust-lang/rust/issues/115010>
help: use the `'static` lifetime
|
LL | const C: &&'static str = &"";
| +++++++

error[E0491]: in type `&&str`, reference has a longer lifetime than the data it references
--> $DIR/double-elided.rs:4:5
|
LL | const C: &&str = &"";
| ^^^^^^^^^^^^^^^^^^^^^
|
note: the pointer is valid for the anonymous lifetime as defined here
--> $DIR/double-elided.rs:4:14
|
LL | const C: &&str = &"";
| ^
note: but the referenced data is only valid for the anonymous lifetime as defined here
--> $DIR/double-elided.rs:4:14
|
LL | const C: &&str = &"";
| ^

error: aborting due to previous error; 2 warnings emitted

For more information about this error, try `rustc --explain E0491`.

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