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matthiaskrgrmatthiaskrgr
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Rollup merge of #129519 - compiler-errors:lowering-flags, r=fmease
Remove redundant flags from `lower_ty_common` that can be inferred from the HIR ...and then get rid of `lower_ty_common`. r? ``@fmease`` or re-roll if you're busy!
2 parents 5a07308 + ecd2d11 commit ae21236

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7 files changed

+74
-44
lines changed

7 files changed

+74
-44
lines changed

‎compiler/rustc_hir_analysis/src/collect.rs

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -392,7 +392,7 @@ impl<'tcx> HirTyLowerer<'tcx> for ItemCtxt<'tcx> {
392392
}
393393

394394
fn re_infer(&self, span: Span, reason: RegionInferReason<'_>) -> ty::Region<'tcx> {
395-
if let RegionInferReason::BorrowedObjectLifetimeDefault = reason {
395+
if let RegionInferReason::ObjectLifetimeDefault = reason {
396396
let e = struct_span_code_err!(
397397
self.dcx(),
398398
span,

‎compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs

Lines changed: 16 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -15,11 +15,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
1515
///
1616
/// *Bare* trait object types are ones that aren't preceded by the keyword `dyn`.
1717
/// In edition 2021 and onward we emit a hard error for them.
18-
pub(super) fn prohibit_or_lint_bare_trait_object_ty(
19-
&self,
20-
self_ty: &hir::Ty<'_>,
21-
in_path: bool,
22-
) {
18+
pub(super) fn prohibit_or_lint_bare_trait_object_ty(&self, self_ty: &hir::Ty<'_>) {
2319
let tcx = self.tcx();
2420

2521
let hir::TyKind::TraitObject([poly_trait_ref, ..], _, TraitObjectSyntax::None) =
@@ -28,6 +24,21 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
2824
return;
2925
};
3026

27+
let in_path = match tcx.parent_hir_node(self_ty.hir_id) {
28+
hir::Node::Ty(hir::Ty {
29+
kind: hir::TyKind::Path(hir::QPath::TypeRelative(qself, _)),
30+
..
31+
})
32+
| hir::Node::Expr(hir::Expr {
33+
kind: hir::ExprKind::Path(hir::QPath::TypeRelative(qself, _)),
34+
..
35+
})
36+
| hir::Node::Pat(hir::Pat {
37+
kind: hir::PatKind::Path(hir::QPath::TypeRelative(qself, _)),
38+
..
39+
}) if qself.hir_id == self_ty.hir_id => true,
40+
_ => false,
41+
};
3142
let needs_bracket = in_path
3243
&& !tcx
3344
.sess

‎compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

Lines changed: 8 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -85,10 +85,9 @@ pub enum PredicateFilter {
8585

8686
#[derive(Debug)]
8787
pub enum RegionInferReason<'a> {
88-
/// Lifetime on a trait object behind a reference.
89-
/// This allows inferring information from the reference.
90-
BorrowedObjectLifetimeDefault,
91-
/// A trait object's lifetime.
88+
/// Lifetime on a trait object that is spelled explicitly, e.g. `+ 'a` or `+ '_`.
89+
ExplicitObjectLifetime,
90+
/// A trait object's lifetime when it is elided, e.g. `dyn Any`.
9291
ObjectLifetimeDefault,
9392
/// Generic lifetime parameter
9493
Param(&'a ty::GenericParamDef),
@@ -1999,16 +1998,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
19991998
}
20001999
}
20012000

2002-
/// Lower a type from the HIR to our internal notion of a type.
2003-
pub fn lower_ty(&self, hir_ty: &hir::Ty<'tcx>) -> Ty<'tcx> {
2004-
self.lower_ty_common(hir_ty, false, false)
2005-
}
2006-
2007-
/// Lower a type inside of a path from the HIR to our internal notion of a type.
2008-
pub fn lower_ty_in_path(&self, hir_ty: &hir::Ty<'tcx>) -> Ty<'tcx> {
2009-
self.lower_ty_common(hir_ty, false, true)
2010-
}
2011-
20122001
fn lower_delegation_ty(&self, idx: hir::InferDelegationKind) -> Ty<'tcx> {
20132002
let delegation_sig = self.tcx().inherit_sig_for_delegation_item(self.item_def_id());
20142003
match idx {
@@ -2026,7 +2015,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
20262015
/// 2. `in_path`: Whether the type appears inside of a path.
20272016
/// Used to provide correct diagnostics for bare trait object types.
20282017
#[instrument(level = "debug", skip(self), ret)]
2029-
fn lower_ty_common(&self, hir_ty: &hir::Ty<'tcx>, borrowed: bool, in_path: bool) -> Ty<'tcx> {
2018+
pub fn lower_ty(&self, hir_ty: &hir::Ty<'tcx>) -> Ty<'tcx> {
20302019
let tcx = self.tcx();
20312020

20322021
let result_ty = match &hir_ty.kind {
@@ -2036,7 +2025,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
20362025
hir::TyKind::Ref(region, mt) => {
20372026
let r = self.lower_lifetime(region, RegionInferReason::Reference);
20382027
debug!(?r);
2039-
let t = self.lower_ty_common(mt.ty, true, false);
2028+
let t = self.lower_ty(mt.ty);
20402029
Ty::new_ref(tcx, r, t, mt.mutbl)
20412030
}
20422031
hir::TyKind::Never => tcx.types.never,
@@ -2065,20 +2054,13 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
20652054
)
20662055
}
20672056
hir::TyKind::TraitObject(bounds, lifetime, repr) => {
2068-
self.prohibit_or_lint_bare_trait_object_ty(hir_ty, in_path);
2057+
self.prohibit_or_lint_bare_trait_object_ty(hir_ty);
20692058

20702059
let repr = match repr {
20712060
TraitObjectSyntax::Dyn | TraitObjectSyntax::None => ty::Dyn,
20722061
TraitObjectSyntax::DynStar => ty::DynStar,
20732062
};
2074-
self.lower_trait_object_ty(
2075-
hir_ty.span,
2076-
hir_ty.hir_id,
2077-
bounds,
2078-
lifetime,
2079-
borrowed,
2080-
repr,
2081-
)
2063+
self.lower_trait_object_ty(hir_ty.span, hir_ty.hir_id, bounds, lifetime, repr)
20822064
}
20832065
hir::TyKind::Path(hir::QPath::Resolved(maybe_qself, path)) => {
20842066
debug!(?maybe_qself, ?path);
@@ -2106,7 +2088,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
21062088
}
21072089
hir::TyKind::Path(hir::QPath::TypeRelative(qself, segment)) => {
21082090
debug!(?qself, ?segment);
2109-
let ty = self.lower_ty_common(qself, false, true);
2091+
let ty = self.lower_ty(qself);
21102092
self.lower_assoc_path(hir_ty.hir_id, hir_ty.span, ty, qself, segment, false)
21112093
.map(|(ty, _, _)| ty)
21122094
.unwrap_or_else(|guar| Ty::new_error(tcx, guar))

‎compiler/rustc_hir_analysis/src/hir_ty_lowering/object_safety.rs

Lines changed: 20 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -30,7 +30,6 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
3030
hir_id: hir::HirId,
3131
hir_trait_bounds: &[(hir::PolyTraitRef<'tcx>, hir::TraitBoundModifier)],
3232
lifetime: &hir::Lifetime,
33-
borrowed: bool,
3433
representation: DynKind,
3534
) -> Ty<'tcx> {
3635
let tcx = self.tcx();
@@ -325,22 +324,32 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
325324
v.dedup();
326325
let existential_predicates = tcx.mk_poly_existential_predicates(&v);
327326

328-
// Use explicitly-specified region bound.
327+
// Use explicitly-specified region bound, unless the bound is missing.
329328
let region_bound = if !lifetime.is_elided() {
330-
self.lower_lifetime(lifetime, RegionInferReason::ObjectLifetimeDefault)
329+
self.lower_lifetime(lifetime, RegionInferReason::ExplicitObjectLifetime)
331330
} else {
332331
self.compute_object_lifetime_bound(span, existential_predicates).unwrap_or_else(|| {
332+
// Curiously, we prefer object lifetime default for `+ '_`...
333333
if tcx.named_bound_var(lifetime.hir_id).is_some() {
334-
self.lower_lifetime(lifetime, RegionInferReason::ObjectLifetimeDefault)
334+
self.lower_lifetime(lifetime, RegionInferReason::ExplicitObjectLifetime)
335335
} else {
336-
self.re_infer(
337-
span,
338-
if borrowed {
339-
RegionInferReason::ObjectLifetimeDefault
336+
let reason =
337+
if let hir::LifetimeName::ImplicitObjectLifetimeDefault = lifetime.res {
338+
if let hir::Node::Ty(hir::Ty {
339+
kind: hir::TyKind::Ref(parent_lifetime, _),
340+
..
341+
}) = tcx.parent_hir_node(hir_id)
342+
&& tcx.named_bound_var(parent_lifetime.hir_id).is_none()
343+
{
344+
// Parent lifetime must have failed to resolve. Don't emit a redundant error.
345+
RegionInferReason::ExplicitObjectLifetime
346+
} else {
347+
RegionInferReason::ObjectLifetimeDefault
348+
}
340349
} else {
341-
RegionInferReason::BorrowedObjectLifetimeDefault
342-
},
343-
)
350+
RegionInferReason::ExplicitObjectLifetime
351+
};
352+
self.re_infer(span, reason)
344353
}
345354
})
346355
};

‎compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -798,7 +798,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
798798
// to be object-safe.
799799
// We manually call `register_wf_obligation` in the success path
800800
// below.
801-
let ty = self.lowerer().lower_ty_in_path(qself);
801+
let ty = self.lowerer().lower_ty(qself);
802802
(LoweredTy::from_raw(self, span, ty), qself, segment)
803803
}
804804
QPath::LangItem(..) => {

‎tests/ui/dyn-keyword/suggest-dyn-on-bare-trait-in-pat.rs

Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,14 @@
1+
//@ edition: 2021
2+
3+
trait Trait {}
4+
5+
impl dyn Trait {
6+
const CONST: () = ();
7+
}
8+
9+
fn main() {
10+
match () {
11+
Trait::CONST => {}
12+
//~^ ERROR trait objects must include the `dyn` keyword
13+
}
14+
}

‎tests/ui/dyn-keyword/suggest-dyn-on-bare-trait-in-pat.stderr

Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,14 @@
1+
error[E0782]: trait objects must include the `dyn` keyword
2+
--> $DIR/suggest-dyn-on-bare-trait-in-pat.rs:11:9
3+
|
4+
LL | Trait::CONST => {}
5+
| ^^^^^
6+
|
7+
help: add `dyn` keyword before this trait
8+
|
9+
LL | <dyn Trait>::CONST => {}
10+
| ++++ +
11+
12+
error: aborting due to 1 previous error
13+
14+
For more information about this error, try `rustc --explain E0782`.

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