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matthiaskrgrmatthiaskrgr
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Rollup merge of #108553 - compiler-errors:non-lt-late-bound-in-anon-ct, r=petrochenkov
Deny capturing late-bound non-lifetime param in anon const Introduce a new AnonConstBoundary so we can detect when we capture a late-bound non-lifetime param with `non_lifetime_binders` enabled. In the future, we could technically do something like introduce an early-bound parameter on the anon const, and stick the late-bound param in its substs (kinda like how we turn late-bound lifetimes in opaques into early-bound ones). But for now, just deny it so we don't ICE. Fixes #108191
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‎compiler/rustc_hir_analysis/locales/en-US.ftl‎

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Original file line numberDiff line numberDiff line change
@@ -147,3 +147,11 @@ hir_analysis_main_function_generic_parameters = `main` function is not allowed t
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hir_analysis_variadic_function_compatible_convention = C-variadic function must have a compatible calling convention, like {$conventions}
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.label = C-variadic function must have a compatible calling convention
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hir_analysis_cannot_capture_late_bound_ty_in_anon_const =
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cannot capture late-bound type parameter in a constant
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.label = parameter defined here
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hir_analysis_cannot_capture_late_bound_const_in_anon_const =
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cannot capture late-bound const parameter in a constant
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.label = parameter defined here

‎compiler/rustc_hir_analysis/src/collect/resolve_bound_vars.rs‎

Lines changed: 57 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -24,6 +24,8 @@ use rustc_span::symbol::{sym, Ident};
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use rustc_span::Span;
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use std::fmt;
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use crate::errors;
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trait RegionExt {
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fn early(param: &GenericParam<'_>) -> (LocalDefId, ResolvedArg);
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@@ -161,6 +163,15 @@ enum Scope<'a> {
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s: ScopeRef<'a>,
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},
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/// Disallows capturing non-lifetime binders from parent scopes.
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///
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/// This is necessary for something like `for<T> [(); { /* references T */ }]:`,
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/// since we don't do something more correct like replacing any captured
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/// late-bound vars with early-bound params in the const's own generics.
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AnonConstBoundary {
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s: ScopeRef<'a>,
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},
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Root {
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opt_parent_item: Option<LocalDefId>,
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},
@@ -211,6 +222,7 @@ impl<'a> fmt::Debug for TruncatedScopeDebug<'a> {
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.field("s", &"..")
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.finish(),
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Scope::TraitRefBoundary { s: _ } => f.debug_struct("TraitRefBoundary").finish(),
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Scope::AnonConstBoundary { s: _ } => f.debug_struct("AnonConstBoundary").finish(),
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Scope::Root { opt_parent_item } => {
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f.debug_struct("Root").field("opt_parent_item", &opt_parent_item).finish()
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}
@@ -312,7 +324,9 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
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break (vec![], BinderScopeType::Normal);
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}
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315-
Scope::Elision { s, .. } | Scope::ObjectLifetimeDefault { s, .. } => {
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Scope::Elision { s, .. }
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| Scope::ObjectLifetimeDefault { s, .. }
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| Scope::AnonConstBoundary { s } => {
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scope = s;
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}
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@@ -1029,6 +1043,12 @@ impl<'a, 'tcx> Visitor<'tcx> for BoundVarContext<'a, 'tcx> {
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fn visit_poly_trait_ref(&mut self, trait_ref: &'tcx hir::PolyTraitRef<'tcx>) {
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self.visit_poly_trait_ref_inner(trait_ref, NonLifetimeBinderAllowed::Allow);
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}
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fn visit_anon_const(&mut self, c: &'tcx hir::AnonConst) {
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self.with(Scope::AnonConstBoundary { s: self.scope }, |this| {
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intravisit::walk_anon_const(this, c);
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});
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}
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}
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fn object_lifetime_default(tcx: TyCtxt<'_>, param_def_id: DefId) -> ObjectLifetimeDefault {
@@ -1275,7 +1295,8 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
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Scope::Elision { s, .. }
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| Scope::ObjectLifetimeDefault { s, .. }
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| Scope::Supertrait { s, .. }
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| Scope::TraitRefBoundary { s, .. } => {
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| Scope::TraitRefBoundary { s, .. }
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| Scope::AnonConstBoundary { s } => {
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scope = s;
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}
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}
@@ -1340,7 +1361,8 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
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| Scope::Elision { s, .. }
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| Scope::ObjectLifetimeDefault { s, .. }
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| Scope::Supertrait { s, .. }
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| Scope::TraitRefBoundary { s, .. } => {
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| Scope::TraitRefBoundary { s, .. }
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| Scope::AnonConstBoundary { s } => {
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scope = s;
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}
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}
@@ -1359,6 +1381,7 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
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// search.
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let mut late_depth = 0;
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let mut scope = self.scope;
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let mut crossed_anon_const = false;
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let result = loop {
13631386
match *scope {
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Scope::Body { s, .. } => {
@@ -1392,10 +1415,36 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
13921415
| Scope::TraitRefBoundary { s, .. } => {
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scope = s;
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}
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Scope::AnonConstBoundary { s } => {
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crossed_anon_const = true;
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scope = s;
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}
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}
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};
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if let Some(def) = result {
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if let ResolvedArg::LateBound(..) = def && crossed_anon_const {
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let use_span = self.tcx.hir().span(hir_id);
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let def_span = self.tcx.def_span(param_def_id);
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match self.tcx.def_kind(param_def_id) {
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DefKind::ConstParam => {
1432+
self.tcx.sess.emit_err(errors::CannotCaptureLateBoundInAnonConst::Const {
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use_span,
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def_span,
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});
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}
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DefKind::TyParam => {
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self.tcx.sess.emit_err(errors::CannotCaptureLateBoundInAnonConst::Type {
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use_span,
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def_span,
1441+
});
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}
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_ => unreachable!(),
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}
1445+
return;
1446+
}
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self.map.defs.insert(hir_id, def);
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return;
14011450
}
@@ -1474,7 +1523,8 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
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| Scope::Elision { s, .. }
14751524
| Scope::ObjectLifetimeDefault { s, .. }
14761525
| Scope::Supertrait { s, .. }
1477-
| Scope::TraitRefBoundary { s, .. } => {
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| Scope::TraitRefBoundary { s, .. }
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| Scope::AnonConstBoundary { s } => {
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scope = s;
14791529
}
14801530
}
@@ -1710,7 +1760,9 @@ impl<'a, 'tcx> BoundVarContext<'a, 'tcx> {
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17111761
Scope::ObjectLifetimeDefault { lifetime: Some(l), .. } => break l,
17121762

1713-
Scope::Supertrait { s, .. } | Scope::TraitRefBoundary { s, .. } => {
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Scope::Supertrait { s, .. }
1764+
| Scope::TraitRefBoundary { s, .. }
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| Scope::AnonConstBoundary { s } => {
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scope = s;
17151767
}
17161768
}

‎compiler/rustc_hir_analysis/src/errors.rs‎

Lines changed: 18 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -381,3 +381,21 @@ pub(crate) struct VariadicFunctionCompatibleConvention<'a> {
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pub span: Span,
382382
pub conventions: &'a str,
383383
}
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385+
#[derive(Diagnostic)]
386+
pub(crate) enum CannotCaptureLateBoundInAnonConst {
387+
#[diag(hir_analysis_cannot_capture_late_bound_ty_in_anon_const)]
388+
Type {
389+
#[primary_span]
390+
use_span: Span,
391+
#[label]
392+
def_span: Span,
393+
},
394+
#[diag(hir_analysis_cannot_capture_late_bound_const_in_anon_const)]
395+
Const {
396+
#[primary_span]
397+
use_span: Span,
398+
#[label]
399+
def_span: Span,
400+
},
401+
}

‎tests/ui/traits/non_lifetime_binders/late-bound-in-anon-ct.rs‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,11 @@
1+
#![feature(non_lifetime_binders, generic_const_exprs)]
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//~^ WARN the feature `non_lifetime_binders` is incomplete
3+
//~| WARN the feature `generic_const_exprs` is incomplete
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5+
fn foo() -> usize
6+
where
7+
for<T> [i32; { let _: T = todo!(); 0 }]:,
8+
//~^ ERROR cannot capture late-bound type parameter in a constant
9+
{}
10+
11+
fn main() {}

‎tests/ui/traits/non_lifetime_binders/late-bound-in-anon-ct.stderr‎

Lines changed: 27 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,27 @@
1+
warning: the feature `non_lifetime_binders` is incomplete and may not be safe to use and/or cause compiler crashes
2+
--> $DIR/late-bound-in-anon-ct.rs:1:12
3+
|
4+
LL | #![feature(non_lifetime_binders, generic_const_exprs)]
5+
| ^^^^^^^^^^^^^^^^^^^^
6+
|
7+
= note: see issue #108185 <https://github.com/rust-lang/rust/issues/108185> for more information
8+
= note: `#[warn(incomplete_features)]` on by default
9+
10+
warning: the feature `generic_const_exprs` is incomplete and may not be safe to use and/or cause compiler crashes
11+
--> $DIR/late-bound-in-anon-ct.rs:1:34
12+
|
13+
LL | #![feature(non_lifetime_binders, generic_const_exprs)]
14+
| ^^^^^^^^^^^^^^^^^^^
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|
16+
= note: see issue #76560 <https://github.com/rust-lang/rust/issues/76560> for more information
17+
18+
error: cannot capture late-bound type parameter in a constant
19+
--> $DIR/late-bound-in-anon-ct.rs:7:27
20+
|
21+
LL | for<T> [i32; { let _: T = todo!(); 0 }]:,
22+
| - ^
23+
| |
24+
| parameter defined here
25+
26+
error: aborting due to previous error; 2 warnings emitted
27+

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