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Auto merge of #116885 - aliemjay:rollup-plbeppt, r=aliemjay
Rollup of 5 pull requests Successful merges: - #116812 (Disable missing_copy_implementations lint on non_exhaustive types) - #116856 (Disable effects in libcore again) - #116865 (Suggest constraining assoc types in more cases) - #116870 (Don't compare host param by name) - #116879 (revert #114586) r? `@ghost` `@rustbot` modify labels: rollup
2 parents e8b8c78 + 8489bce commit e1de04a

21 files changed

+272
-140
lines changed

‎compiler/rustc_borrowck/src/region_infer/opaque_types.rs

+13-20
Original file line numberDiff line numberDiff line change
@@ -328,26 +328,19 @@ fn check_opaque_type_well_formed<'tcx>(
328328

329329
// Require that the hidden type actually fulfills all the bounds of the opaque type, even without
330330
// the bounds that the function supplies.
331-
let mut obligations = vec![];
332-
infcx
333-
.insert_hidden_type(
334-
OpaqueTypeKey { def_id, args: identity_args },
335-
&ObligationCause::misc(definition_span, def_id),
336-
param_env,
337-
definition_ty,
338-
true,
339-
&mut obligations,
340-
)
341-
.unwrap();
342-
infcx.add_item_bounds_for_hidden_type(
343-
def_id.to_def_id(),
344-
identity_args,
345-
ObligationCause::misc(definition_span, def_id),
346-
param_env,
347-
definition_ty,
348-
&mut obligations,
349-
);
350-
ocx.register_obligations(obligations);
331+
let opaque_ty = Ty::new_opaque(tcx, def_id.to_def_id(), identity_args);
332+
ocx.eq(&ObligationCause::misc(definition_span, def_id), param_env, opaque_ty, definition_ty)
333+
.map_err(|err| {
334+
infcx
335+
.err_ctxt()
336+
.report_mismatched_types(
337+
&ObligationCause::misc(definition_span, def_id),
338+
opaque_ty,
339+
definition_ty,
340+
err,
341+
)
342+
.emit()
343+
})?;
351344

352345
// Require the hidden type to be well-formed with only the generics of the opaque type.
353346
// Defining use functions may have more bounds than the opaque type, which is ok, as long as the

‎compiler/rustc_hir_analysis/src/bounds.rs

+5-4
Original file line numberDiff line numberDiff line change
@@ -46,10 +46,11 @@ impl<'tcx> Bounds<'tcx> {
4646
) {
4747
self.push_trait_bound_inner(tcx, trait_ref, span, polarity);
4848

49-
// if we have a host param, we push an unconst trait bound in addition
50-
// to the const one.
51-
// FIXME(effects) we should find a better way than name matching
52-
if tcx.features().effects && trait_ref.skip_binder().args.host_effect_param().is_some() {
49+
// push a non-const (`host = true`) version of the bound if it is `~const`.
50+
if tcx.features().effects
51+
&& let Some(host_effect_idx) = tcx.generics_of(trait_ref.def_id()).host_effect_index
52+
&& trait_ref.skip_binder().args.const_at(host_effect_idx) != tcx.consts.true_
53+
{
5354
let generics = tcx.generics_of(trait_ref.def_id());
5455
let Some(host_index) = generics.host_effect_index else { return };
5556
let trait_ref = trait_ref.map_bound(|mut trait_ref| {

‎compiler/rustc_hir_typeck/src/callee.rs

+5-2
Original file line numberDiff line numberDiff line change
@@ -786,8 +786,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
786786
tcx.consts.false_
787787
}
788788
Some(hir::ConstContext::ConstFn) => {
789-
let args = ty::GenericArgs::identity_for_item(tcx, context);
790-
args.host_effect_param().expect("ConstContext::Maybe must have host effect param")
789+
let host_idx = tcx
790+
.generics_of(context)
791+
.host_effect_index
792+
.expect("ConstContext::Maybe must have host effect param");
793+
ty::GenericArgs::identity_for_item(tcx, context).const_at(host_idx)
791794
}
792795
None => tcx.consts.true_,
793796
};

‎compiler/rustc_infer/src/infer/error_reporting/note_and_explain.rs

+58-44
Original file line numberDiff line numberDiff line change
@@ -341,39 +341,48 @@ impl<T> Trait<T> for X {
341341
let tcx = self.tcx;
342342
let assoc = tcx.associated_item(proj_ty.def_id);
343343
let (trait_ref, assoc_args) = proj_ty.trait_ref_and_own_args(tcx);
344-
if let Some(item) = tcx.hir().get_if_local(body_owner_def_id) {
345-
if let Some(hir_generics) = item.generics() {
346-
// Get the `DefId` for the type parameter corresponding to `A` in `<A as T>::Foo`.
347-
// This will also work for `impl Trait`.
348-
let def_id = if let ty::Param(param_ty) = proj_ty.self_ty().kind() {
349-
let generics = tcx.generics_of(body_owner_def_id);
350-
generics.type_param(param_ty, tcx).def_id
351-
} else {
352-
return false;
353-
};
354-
let Some(def_id) = def_id.as_local() else {
355-
return false;
356-
};
357-
358-
// First look in the `where` clause, as this might be
359-
// `fn foo<T>(x: T) where T: Trait`.
360-
for pred in hir_generics.bounds_for_param(def_id) {
361-
if self.constrain_generic_bound_associated_type_structured_suggestion(
362-
diag,
363-
&trait_ref,
364-
pred.bounds,
365-
assoc,
366-
assoc_args,
367-
ty,
368-
&msg,
369-
false,
370-
) {
371-
return true;
372-
}
373-
}
344+
let Some(item) = tcx.hir().get_if_local(body_owner_def_id) else {
345+
return false;
346+
};
347+
let Some(hir_generics) = item.generics() else {
348+
return false;
349+
};
350+
// Get the `DefId` for the type parameter corresponding to `A` in `<A as T>::Foo`.
351+
// This will also work for `impl Trait`.
352+
let def_id = if let ty::Param(param_ty) = proj_ty.self_ty().kind() {
353+
let generics = tcx.generics_of(body_owner_def_id);
354+
generics.type_param(param_ty, tcx).def_id
355+
} else {
356+
return false;
357+
};
358+
let Some(def_id) = def_id.as_local() else {
359+
return false;
360+
};
361+
362+
// First look in the `where` clause, as this might be
363+
// `fn foo<T>(x: T) where T: Trait`.
364+
for pred in hir_generics.bounds_for_param(def_id) {
365+
if self.constrain_generic_bound_associated_type_structured_suggestion(
366+
diag,
367+
&trait_ref,
368+
pred.bounds,
369+
assoc,
370+
assoc_args,
371+
ty,
372+
&msg,
373+
false,
374+
) {
375+
return true;
374376
}
375377
}
376-
false
378+
// If associated item, look to constrain the params of the trait/impl.
379+
let hir_id = match item {
380+
hir::Node::ImplItem(item) => item.hir_id(),
381+
hir::Node::TraitItem(item) => item.hir_id(),
382+
_ => return false,
383+
};
384+
let parent = tcx.hir().get_parent_item(hir_id).def_id;
385+
self.suggest_constraint(diag, msg, parent.into(), proj_ty, ty)
377386
}
378387

379388
/// An associated type was expected and a different type was found.
@@ -426,21 +435,26 @@ impl<T> Trait<T> for X {
426435
let impl_comparison =
427436
matches!(cause_code, ObligationCauseCode::CompareImplItemObligation { .. });
428437
let assoc = tcx.associated_item(proj_ty.def_id);
429-
if !callable_scope || impl_comparison {
438+
if impl_comparison {
430439
// We do not want to suggest calling functions when the reason of the
431-
// type error is a comparison of an `impl` with its `trait` or when the
432-
// scope is outside of a `Body`.
440+
// type error is a comparison of an `impl` with its `trait`.
433441
} else {
434-
// If we find a suitable associated function that returns the expected type, we don't
435-
// want the more general suggestion later in this method about "consider constraining
436-
// the associated type or calling a method that returns the associated type".
437-
let point_at_assoc_fn = self.point_at_methods_that_satisfy_associated_type(
438-
diag,
439-
assoc.container_id(tcx),
440-
current_method_ident,
441-
proj_ty.def_id,
442-
values.expected,
443-
);
442+
let point_at_assoc_fn = if callable_scope
443+
&& self.point_at_methods_that_satisfy_associated_type(
444+
diag,
445+
assoc.container_id(tcx),
446+
current_method_ident,
447+
proj_ty.def_id,
448+
values.expected,
449+
) {
450+
// If we find a suitable associated function that returns the expected type, we
451+
// don't want the more general suggestion later in this method about "consider
452+
// constraining the associated type or calling a method that returns the associated
453+
// type".
454+
true
455+
} else {
456+
false
457+
};
444458
// Possibly suggest constraining the associated type to conform to the
445459
// found type.
446460
if self.suggest_constraint(diag, &msg, body_owner_def_id, proj_ty, values.found)

‎compiler/rustc_infer/src/infer/opaque_types.rs

+1-19
Original file line numberDiff line numberDiff line change
@@ -145,25 +145,7 @@ impl<'tcx> InferCtxt<'tcx> {
145145
return None;
146146
}
147147
}
148-
DefiningAnchor::Bubble => {
149-
if let ty::Alias(ty::Opaque, _) = b.kind() {
150-
// In bubble mode we don't know which of the two opaque types is supposed to have the other
151-
// as a hidden type (both, none or either one of them could be in its defining scope).
152-
let predicate = ty::PredicateKind::AliasRelate(
153-
a.into(),
154-
b.into(),
155-
ty::AliasRelationDirection::Equate,
156-
);
157-
let obligation = traits::Obligation::new(
158-
self.tcx,
159-
cause.clone(),
160-
param_env,
161-
predicate,
162-
);
163-
let obligations = vec![obligation];
164-
return Some(Ok(InferOk { value: (), obligations }));
165-
}
166-
}
148+
DefiningAnchor::Bubble => {}
167149
DefiningAnchor::Error => return None,
168150
};
169151
if let ty::Alias(ty::Opaque, ty::AliasTy { def_id: b_def_id, .. }) = *b.kind() {

‎compiler/rustc_lint/src/builtin.rs

+5
Original file line numberDiff line numberDiff line change
@@ -677,6 +677,11 @@ impl<'tcx> LateLintPass<'tcx> for MissingCopyImplementations {
677677
if type_implements_negative_copy_modulo_regions(cx.tcx, ty, param_env) {
678678
return;
679679
}
680+
if def.is_variant_list_non_exhaustive()
681+
|| def.variants().iter().any(|variant| variant.is_field_list_non_exhaustive())
682+
{
683+
return;
684+
}
680685

681686
// We shouldn't recommend implementing `Copy` on stateful things,
682687
// such as iterators.

‎compiler/rustc_middle/src/ty/generic_args.rs

-5
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,6 @@ use rustc_errors::{DiagnosticArgValue, IntoDiagnosticArg};
1111
use rustc_hir::def_id::DefId;
1212
use rustc_macros::HashStable;
1313
use rustc_serialize::{self, Decodable, Encodable};
14-
use rustc_span::sym;
1514
use rustc_type_ir::WithCachedTypeInfo;
1615
use smallvec::SmallVec;
1716

@@ -452,10 +451,6 @@ impl<'tcx> GenericArgs<'tcx> {
452451
tcx.mk_args_from_iter(self.iter().take(generics.count()))
453452
}
454453

455-
pub fn host_effect_param(&'tcx self) -> Option<ty::Const<'tcx>> {
456-
self.consts().rfind(|x| matches!(x.kind(), ty::ConstKind::Param(p) if p.name == sym::host))
457-
}
458-
459454
pub fn print_as_list(&self) -> String {
460455
let v = self.iter().map(|arg| arg.to_string()).collect::<Vec<_>>();
461456
format!("[{}]", v.join(", "))

‎compiler/rustc_trait_selection/src/traits/fulfill.rs

+2-21
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,6 @@ use rustc_infer::infer::DefineOpaqueTypes;
66
use rustc_infer::traits::ProjectionCacheKey;
77
use rustc_infer::traits::{PolyTraitObligation, SelectionError, TraitEngine};
88
use rustc_middle::mir::interpret::ErrorHandled;
9-
use rustc_middle::traits::DefiningAnchor;
109
use rustc_middle::ty::abstract_const::NotConstEvaluatable;
1110
use rustc_middle::ty::error::{ExpectedFound, TypeError};
1211
use rustc_middle::ty::GenericArgsRef;
@@ -626,27 +625,9 @@ impl<'a, 'tcx> ObligationProcessor for FulfillProcessor<'a, 'tcx> {
626625
}
627626
}
628627
ty::PredicateKind::Ambiguous => ProcessResult::Unchanged,
629-
ty::PredicateKind::AliasRelate(..)
630-
if matches!(self.selcx.infcx.defining_use_anchor, DefiningAnchor::Bubble) =>
631-
{
632-
ProcessResult::Unchanged
628+
ty::PredicateKind::AliasRelate(..) => {
629+
bug!("AliasRelate is only used for new solver")
633630
}
634-
ty::PredicateKind::AliasRelate(a, b, relate) => match relate {
635-
ty::AliasRelationDirection::Equate => match self
636-
.selcx
637-
.infcx
638-
.at(&obligation.cause, obligation.param_env)
639-
.eq(DefineOpaqueTypes::Yes, a, b)
640-
{
641-
Ok(inf_ok) => ProcessResult::Changed(mk_pending(inf_ok.into_obligations())),
642-
Err(_) => ProcessResult::Error(FulfillmentErrorCode::CodeSelectionError(
643-
SelectionError::Unimplemented,
644-
)),
645-
},
646-
ty::AliasRelationDirection::Subtype => {
647-
bug!("AliasRelate with subtyping is only used for new solver")
648-
}
649-
},
650631
ty::PredicateKind::Clause(ty::ClauseKind::ConstArgHasType(ct, ty)) => {
651632
match self.selcx.infcx.at(&obligation.cause, obligation.param_env).eq(
652633
DefineOpaqueTypes::No,

‎compiler/rustc_trait_selection/src/traits/select/mod.rs

+2-21
Original file line numberDiff line numberDiff line change
@@ -38,7 +38,6 @@ use rustc_infer::traits::TraitObligation;
3838
use rustc_middle::dep_graph::dep_kinds;
3939
use rustc_middle::dep_graph::DepNodeIndex;
4040
use rustc_middle::mir::interpret::ErrorHandled;
41-
use rustc_middle::traits::DefiningAnchor;
4241
use rustc_middle::ty::_match::MatchAgainstFreshVars;
4342
use rustc_middle::ty::abstract_const::NotConstEvaluatable;
4443
use rustc_middle::ty::fold::BottomUpFolder;
@@ -1005,27 +1004,9 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
10051004
}
10061005
}
10071006
}
1008-
ty::PredicateKind::AliasRelate(..)
1009-
if matches!(self.infcx.defining_use_anchor, DefiningAnchor::Bubble) =>
1010-
{
1011-
Ok(EvaluatedToAmbig)
1007+
ty::PredicateKind::AliasRelate(..) => {
1008+
bug!("AliasRelate is only used for new solver")
10121009
}
1013-
ty::PredicateKind::AliasRelate(a, b, relate) => match relate {
1014-
ty::AliasRelationDirection::Equate => match self
1015-
.infcx
1016-
.at(&obligation.cause, obligation.param_env)
1017-
.eq(DefineOpaqueTypes::Yes, a, b)
1018-
{
1019-
Ok(inf_ok) => self.evaluate_predicates_recursively(
1020-
previous_stack,
1021-
inf_ok.into_obligations(),
1022-
),
1023-
Err(_) => Ok(EvaluatedToErr),
1024-
},
1025-
ty::AliasRelationDirection::Subtype => {
1026-
bug!("AliasRelate subtyping is only used for new solver")
1027-
}
1028-
},
10291010
ty::PredicateKind::Ambiguous => Ok(EvaluatedToAmbig),
10301011
ty::PredicateKind::Clause(ty::ClauseKind::ConstArgHasType(ct, ty)) => {
10311012
match self.infcx.at(&obligation.cause, obligation.param_env).eq(

‎library/core/src/lib.rs

-1
Original file line numberDiff line numberDiff line change
@@ -219,7 +219,6 @@
219219
#![feature(doc_cfg)]
220220
#![feature(doc_cfg_hide)]
221221
#![feature(doc_notable_trait)]
222-
#![feature(effects)]
223222
#![feature(exhaustive_patterns)]
224223
#![feature(extern_types)]
225224
#![feature(fundamental)]

‎tests/ui/associated-type-bounds/suggest-contraining-assoc-type-because-of-assoc-const.fixed

+14
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,14 @@
1+
// run-rustfix
2+
trait O {
3+
type M;
4+
}
5+
trait U<A: O> {
6+
const N: A::M;
7+
}
8+
impl<D> O for D {
9+
type M = u8;
10+
}
11+
impl<C: O<M = u8>> U<C> for u16 {
12+
const N: C::M = 4u8; //~ ERROR mismatched types
13+
}
14+
fn main() {}

‎tests/ui/associated-type-bounds/suggest-contraining-assoc-type-because-of-assoc-const.rs

+14
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,14 @@
1+
// run-rustfix
2+
trait O {
3+
type M;
4+
}
5+
trait U<A: O> {
6+
const N: A::M;
7+
}
8+
impl<D> O for D {
9+
type M = u8;
10+
}
11+
impl<C: O> U<C> for u16 {
12+
const N: C::M = 4u8; //~ ERROR mismatched types
13+
}
14+
fn main() {}

‎tests/ui/associated-type-bounds/suggest-contraining-assoc-type-because-of-assoc-const.stderr

+16
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,16 @@
1+
error[E0308]: mismatched types
2+
--> $DIR/suggest-contraining-assoc-type-because-of-assoc-const.rs:12:21
3+
|
4+
LL | const N: C::M = 4u8;
5+
| ^^^ expected associated type, found `u8`
6+
|
7+
= note: expected associated type `<C as O>::M`
8+
found type `u8`
9+
help: consider constraining the associated type `<C as O>::M` to `u8`
10+
|
11+
LL | impl<C: O<M = u8>> U<C> for u16 {
12+
| ++++++++
13+
14+
error: aborting due to previous error
15+
16+
For more information about this error, try `rustc --explain E0308`.

‎tests/ui/consts/effect_param.rs

+11
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,11 @@
1+
//! Ensure we don't allow accessing const effect parameters from stable Rust.
2+
3+
fn main() {
4+
i8::checked_sub::<true>(42, 43);
5+
//~^ ERROR: method takes 0 generic arguments but 1 generic argument was supplied
6+
}
7+
8+
const FOO: () = {
9+
i8::checked_sub::<false>(42, 43);
10+
//~^ ERROR: method takes 0 generic arguments but 1 generic argument was supplied
11+
};

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