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Implement ~const opaques
1 parent 588c4c4 commit 5eeaf2e

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11 files changed

+127
-11
lines changed

11 files changed

+127
-11
lines changed

‎compiler/rustc_hir_analysis/src/check/check.rs

+2
Original file line numberDiff line numberDiff line change
@@ -339,6 +339,8 @@ fn check_opaque_meets_bounds<'tcx>(
339339

340340
let misc_cause = ObligationCause::misc(span, def_id);
341341
// FIXME: We should just register the item bounds here, rather than equating.
342+
// FIXME(const_trait_impl): When we do that, please make sure to also register
343+
// the `~const` bounds.
342344
match ocx.eq(&misc_cause, param_env, opaque_ty, hidden_ty) {
343345
Ok(()) => {}
344346
Err(ty_err) => {

‎compiler/rustc_hir_analysis/src/collect.rs

+8
Original file line numberDiff line numberDiff line change
@@ -339,6 +339,10 @@ impl<'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
339339
self.tcx.ensure().explicit_item_super_predicates(def_id);
340340
self.tcx.ensure().item_bounds(def_id);
341341
self.tcx.ensure().item_super_predicates(def_id);
342+
if self.tcx.is_conditionally_const(def_id) {
343+
self.tcx.ensure().explicit_implied_const_bounds(def_id);
344+
self.tcx.ensure().const_conditions(def_id);
345+
}
342346
intravisit::walk_opaque_ty(self, opaque);
343347
}
344348

@@ -681,6 +685,10 @@ fn lower_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
681685
tcx.ensure().generics_of(item.owner_id);
682686
tcx.ensure().type_of(item.owner_id);
683687
tcx.ensure().predicates_of(item.owner_id);
688+
if tcx.is_conditionally_const(def_id) {
689+
tcx.ensure().explicit_implied_const_bounds(def_id);
690+
tcx.ensure().const_conditions(def_id);
691+
}
684692
match item.kind {
685693
hir::ForeignItemKind::Fn(..) => {
686694
tcx.ensure().codegen_fn_attrs(item.owner_id);

‎compiler/rustc_hir_analysis/src/collect/predicates_of.rs

+8-1
Original file line numberDiff line numberDiff line change
@@ -958,6 +958,12 @@ pub(super) fn const_conditions<'tcx>(
958958
hir::ForeignItemKind::Fn(_, _, generics) => (generics, None, false),
959959
_ => bug!("const_conditions called on wrong item: {def_id:?}"),
960960
},
961+
Node::OpaqueTy(opaque) => match opaque.origin {
962+
hir::OpaqueTyOrigin::FnReturn { parent, .. } => return tcx.const_conditions(parent),
963+
hir::OpaqueTyOrigin::AsyncFn { .. } | hir::OpaqueTyOrigin::TyAlias { .. } => {
964+
unreachable!()
965+
}
966+
},
961967
// N.B. Tuple ctors are unconditionally constant.
962968
Node::Ctor(hir::VariantData::Tuple { .. }) => return Default::default(),
963969
_ => bug!("const_conditions called on wrong item: {def_id:?}"),
@@ -1033,7 +1039,8 @@ pub(super) fn explicit_implied_const_bounds<'tcx>(
10331039
PredicateFilter::SelfConstIfConst,
10341040
)
10351041
}
1036-
Node::TraitItem(hir::TraitItem { kind: hir::TraitItemKind::Type(..), .. }) => {
1042+
Node::TraitItem(hir::TraitItem { kind: hir::TraitItemKind::Type(..), .. })
1043+
| Node::OpaqueTy(_) => {
10371044
explicit_item_bounds_with_filter(tcx, def_id, PredicateFilter::ConstIfConst)
10381045
}
10391046
_ => bug!("explicit_implied_const_bounds called on wrong item: {def_id:?}"),

‎compiler/rustc_infer/src/infer/opaque_types/mod.rs

+23-4
Original file line numberDiff line numberDiff line change
@@ -574,9 +574,8 @@ impl<'tcx> InferCtxt<'tcx> {
574574
// unexpected region errors.
575575
goals.push(Goal::new(tcx, param_env, ty::ClauseKind::WellFormed(hidden_ty.into())));
576576

577-
let item_bounds = tcx.explicit_item_bounds(def_id);
578-
for (predicate, _) in item_bounds.iter_instantiated_copied(tcx, args) {
579-
let predicate = predicate.fold_with(&mut BottomUpFolder {
577+
let replace_opaques_in = |clause: ty::Clause<'tcx>, goals: &mut Vec<_>| {
578+
clause.fold_with(&mut BottomUpFolder {
580579
tcx,
581580
ty_op: |ty| match *ty.kind() {
582581
// We can't normalize associated types from `rustc_infer`,
@@ -612,11 +611,31 @@ impl<'tcx> InferCtxt<'tcx> {
612611
},
613612
lt_op: |lt| lt,
614613
ct_op: |ct| ct,
615-
});
614+
})
615+
};
616+
617+
let item_bounds = tcx.explicit_item_bounds(def_id);
618+
for (predicate, _) in item_bounds.iter_instantiated_copied(tcx, args) {
619+
let predicate = replace_opaques_in(predicate, goals);
616620

617621
// Require that the predicate holds for the concrete type.
618622
debug!(?predicate);
619623
goals.push(Goal::new(self.tcx, param_env, predicate));
620624
}
625+
626+
// If this opaque is being defined and it's conditionally const,
627+
if self.tcx.is_conditionally_const(def_id) {
628+
let item_bounds = tcx.explicit_implied_const_bounds(def_id);
629+
for (predicate, _) in item_bounds.iter_instantiated_copied(tcx, args) {
630+
let predicate = replace_opaques_in(
631+
predicate.to_host_effect_clause(self.tcx, ty::BoundConstness::Maybe),
632+
goals,
633+
);
634+
635+
// Require that the predicate holds for the concrete type.
636+
debug!(?predicate);
637+
goals.push(Goal::new(self.tcx, param_env, predicate));
638+
}
639+
}
621640
}
622641
}

‎compiler/rustc_metadata/src/rmeta/encoder.rs

+4
Original file line numberDiff line numberDiff line change
@@ -1532,6 +1532,10 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
15321532
self.encode_explicit_item_super_predicates(def_id);
15331533
record!(self.tables.opaque_ty_origin[def_id] <- self.tcx.opaque_ty_origin(def_id));
15341534
self.encode_precise_capturing_args(def_id);
1535+
if tcx.is_conditionally_const(def_id) {
1536+
record_defaulted_array!(self.tables.explicit_implied_const_bounds[def_id]
1537+
<- tcx.explicit_implied_const_bounds(def_id).skip_binder());
1538+
}
15351539
}
15361540
if tcx.impl_method_has_trait_impl_trait_tys(def_id)
15371541
&& let Ok(table) = self.tcx.collect_return_position_impl_trait_in_trait_tys(def_id)

‎compiler/rustc_middle/src/ty/mod.rs

+7-1
Original file line numberDiff line numberDiff line change
@@ -2117,7 +2117,13 @@ impl<'tcx> TyCtxt<'tcx> {
21172117
_ => bug!("unexpected parent item of associated item: {parent_def_id:?}"),
21182118
}
21192119
}
2120-
DefKind::Closure | DefKind::OpaqueTy => {
2120+
DefKind::OpaqueTy => match self.opaque_ty_origin(def_id) {
2121+
hir::OpaqueTyOrigin::FnReturn { parent, .. } => self.is_conditionally_const(parent),
2122+
hir::OpaqueTyOrigin::AsyncFn { .. } => false,
2123+
// FIXME(const_trait_impl): ATPITs could be conditionally const?
2124+
hir::OpaqueTyOrigin::TyAlias { .. } => false,
2125+
},
2126+
DefKind::Closure => {
21212127
// Closures and RPITs will eventually have const conditions
21222128
// for `~const` bounds.
21232129
false

‎tests/ui/traits/const-traits/const-closure-parse-not-item.stderr

+9-1
Original file line numberDiff line numberDiff line change
@@ -12,5 +12,13 @@ LL | const fn test() -> impl ~const Fn() {
1212
|
1313
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
1414

15-
error: aborting due to 2 previous errors
15+
error: `~const` can only be applied to `#[const_trait]` traits
16+
--> $DIR/const-closure-parse-not-item.rs:7:25
17+
|
18+
LL | const fn test() -> impl ~const Fn() {
19+
| ^^^^^^
20+
|
21+
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
22+
23+
error: aborting due to 3 previous errors
1624

‎tests/ui/traits/const-traits/const-opaque.no.stderr

+15
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,15 @@
1+
error[E0277]: the trait bound `(): const Foo` is not satisfied
2+
--> $DIR/const-opaque.rs:31:18
3+
|
4+
LL | let opaque = bar(());
5+
| ^^^^^^^
6+
7+
error[E0277]: the trait bound `(): const Foo` is not satisfied
8+
--> $DIR/const-opaque.rs:33:5
9+
|
10+
LL | opaque.method();
11+
| ^^^^^^^^^^^^^^^
12+
13+
error: aborting due to 2 previous errors
14+
15+
For more information about this error, try `rustc --explain E0277`.

‎tests/ui/traits/const-traits/const-opaque.rs

+38
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,38 @@
1+
//@ revisions: yes no
2+
//@ compile-flags: -Znext-solver
3+
//@[yes] check-pass
4+
5+
#![feature(const_trait_impl)]
6+
7+
#[const_trait]
8+
trait Foo {
9+
fn method(&self);
10+
}
11+
12+
impl<T: ~const Foo> const Foo for (T,) {
13+
fn method(&self) {}
14+
}
15+
16+
#[cfg(yes)]
17+
impl const Foo for () {
18+
fn method(&self) {}
19+
}
20+
21+
#[cfg(no)]
22+
impl Foo for () {
23+
fn method(&self) {}
24+
}
25+
26+
const fn bar<T: ~const Foo>(t: T) -> impl ~const Foo {
27+
(t,)
28+
}
29+
30+
const _: () = {
31+
let opaque = bar(());
32+
//[no]~^ ERROR the trait bound `(): const Foo` is not satisfied
33+
opaque.method();
34+
//[no]~^ ERROR the trait bound `(): const Foo` is not satisfied
35+
std::mem::forget(opaque);
36+
};
37+
38+
fn main() {}

‎tests/ui/traits/const-traits/effects/ice-112822-expected-type-for-param.rs

+1
Original file line numberDiff line numberDiff line change
@@ -3,6 +3,7 @@
33
const fn test() -> impl ~const Fn() {
44
//~^ ERROR `~const` can only be applied to `#[const_trait]` traits
55
//~| ERROR `~const` can only be applied to `#[const_trait]` traits
6+
//~| ERROR `~const` can only be applied to `#[const_trait]` traits
67
const move || { //~ ERROR const closures are experimental
78
let sl: &[u8] = b"foo";
89

‎tests/ui/traits/const-traits/effects/ice-112822-expected-type-for-param.stderr

+12-4
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
error[E0658]: const closures are experimental
2-
--> $DIR/ice-112822-expected-type-for-param.rs:6:5
2+
--> $DIR/ice-112822-expected-type-for-param.rs:7:5
33
|
44
LL | const move || {
55
| ^^^^^
@@ -22,8 +22,16 @@ LL | const fn test() -> impl ~const Fn() {
2222
|
2323
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
2424

25+
error: `~const` can only be applied to `#[const_trait]` traits
26+
--> $DIR/ice-112822-expected-type-for-param.rs:3:25
27+
|
28+
LL | const fn test() -> impl ~const Fn() {
29+
| ^^^^^^
30+
|
31+
= note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
32+
2533
error[E0015]: cannot call non-const operator in constant functions
26-
--> $DIR/ice-112822-expected-type-for-param.rs:11:17
34+
--> $DIR/ice-112822-expected-type-for-param.rs:12:17
2735
|
2836
LL | assert_eq!(first, &b'f');
2937
| ^^^^^^^^^^^^^^^^^^^^^^^^
@@ -32,15 +40,15 @@ LL | assert_eq!(first, &b'f');
3240
= note: this error originates in the macro `assert_eq` (in Nightly builds, run with -Z macro-backtrace for more info)
3341

3442
error[E0015]: cannot call non-const fn `core::panicking::assert_failed::<&u8, &u8>` in constant functions
35-
--> $DIR/ice-112822-expected-type-for-param.rs:11:17
43+
--> $DIR/ice-112822-expected-type-for-param.rs:12:17
3644
|
3745
LL | assert_eq!(first, &b'f');
3846
| ^^^^^^^^^^^^^^^^^^^^^^^^
3947
|
4048
= note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
4149
= note: this error originates in the macro `assert_eq` (in Nightly builds, run with -Z macro-backtrace for more info)
4250

43-
error: aborting due to 5 previous errors
51+
error: aborting due to 6 previous errors
4452

4553
Some errors have detailed explanations: E0015, E0658.
4654
For more information about an error, try `rustc --explain E0015`.

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