bjoernager/rust
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Allow trait method paths to satisfy const Fn bounds

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This commit is contained in:
Deadbeef 2022-12-28 08:55:01 +00:00
parent 6a4624d73b
commit 983606d367
6 changed files with 100 additions and 13 deletions
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26
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
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@ -12,8 +12,8 @@ use rustc_index::bit_set::GrowableBitSet;
use rustc_infer::infer::InferOk;
use rustc_infer::infer::LateBoundRegionConversionTime::HigherRankedType;
use rustc_middle::ty::{
self, GenericArg, GenericArgKind, GenericParamDefKind, InternalSubsts, SubstsRef,
ToPolyTraitRef, ToPredicate, Ty, TyCtxt,
self, Binder, GenericArg, GenericArgKind, GenericParamDefKind, InternalSubsts, SubstsRef,
ToPolyTraitRef, ToPredicate, TraitRef, Ty, TyCtxt,
};
use rustc_span::def_id::DefId;
@ -98,8 +98,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
ImplSource::Future(vtable_future)
}
FnPointerCandidate { .. } => {
let data = self.confirm_fn_pointer_candidate(obligation)?;
FnPointerCandidate { is_const } => {
let data = self.confirm_fn_pointer_candidate(obligation, is_const)?;
ImplSource::FnPointer(data)
}
@ -597,17 +597,19 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
fn confirm_fn_pointer_candidate(
&mut self,
obligation: &TraitObligation<'tcx>,
is_const: bool,
) -> Result<ImplSourceFnPointerData<'tcx, PredicateObligation<'tcx>>, SelectionError<'tcx>>
{
debug!(?obligation, "confirm_fn_pointer_candidate");
let tcx = self.tcx();
let self_ty = self
.infcx
.shallow_resolve(obligation.self_ty().no_bound_vars())
.expect("fn pointer should not capture bound vars from predicate");
let sig = self_ty.fn_sig(self.tcx());
let sig = self_ty.fn_sig(tcx);
let trait_ref = closure_trait_ref_and_return_type(
self.tcx(),
tcx,
obligation.predicate.def_id(),
self_ty,
sig,
@ -616,9 +618,19 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
.map_bound(|(trait_ref, _)| trait_ref);
let mut nested = self.confirm_poly_trait_refs(obligation, trait_ref)?;
let cause = obligation.derived_cause(BuiltinDerivedObligation);
if obligation.is_const() && !is_const {
// function is a trait method
if let ty::FnDef(def_id, substs) = self_ty.kind() && let Some(trait_id) = tcx.trait_of_item(*def_id) {
let trait_ref = TraitRef::from_method(tcx, trait_id, *substs);
let poly_trait_pred = Binder::dummy(trait_ref).with_constness(ty::BoundConstness::ConstIfConst);
let obligation = Obligation::new(tcx, cause.clone(), obligation.param_env, poly_trait_pred);
nested.push(obligation);
}
}
// Confirm the `type Output: Sized;` bound that is present on `FnOnce`
let cause = obligation.derived_cause(BuiltinDerivedObligation);
let output_ty = self.infcx.replace_bound_vars_with_placeholders(sig.output());
let output_ty = normalize_with_depth_to(
self,