rustc_trait_selection/traits/
structural_normalize.rsuse rustc_infer::infer::at::At;
use rustc_infer::traits::TraitEngine;
use rustc_macros::extension;
use rustc_middle::ty::{self, Ty};
use crate::traits::{NormalizeExt, Obligation};
#[extension(pub trait StructurallyNormalizeExt<'tcx>)]
impl<'tcx> At<'_, 'tcx> {
fn structurally_normalize<E: 'tcx>(
&self,
ty: Ty<'tcx>,
fulfill_cx: &mut dyn TraitEngine<'tcx, E>,
) -> Result<Ty<'tcx>, Vec<E>> {
assert!(!ty.is_ty_var(), "should have resolved vars before calling");
if self.infcx.next_trait_solver() {
let ty::Alias(..) = *ty.kind() else {
return Ok(ty);
};
let new_infer_ty = self.infcx.next_ty_var(self.cause.span);
let obligation = Obligation::new(
self.infcx.tcx,
self.cause.clone(),
self.param_env,
ty::PredicateKind::AliasRelate(
ty.into(),
new_infer_ty.into(),
ty::AliasRelationDirection::Equate,
),
);
fulfill_cx.register_predicate_obligation(self.infcx, obligation);
let errors = fulfill_cx.select_where_possible(self.infcx);
if !errors.is_empty() {
return Err(errors);
}
Ok(self.infcx.resolve_vars_if_possible(new_infer_ty))
} else {
Ok(self.normalize(ty).into_value_registering_obligations(self.infcx, fulfill_cx))
}
}
fn structurally_normalize_const<E: 'tcx>(
&self,
ct: ty::Const<'tcx>,
fulfill_cx: &mut dyn TraitEngine<'tcx, E>,
) -> Result<ty::Const<'tcx>, Vec<E>> {
assert!(!ct.is_ct_infer(), "should have resolved vars before calling");
if self.infcx.next_trait_solver() {
let ty::ConstKind::Unevaluated(..) = ct.kind() else {
return Ok(ct);
};
let new_infer_ct = self.infcx.next_const_var(self.cause.span);
let obligation = Obligation::new(
self.infcx.tcx,
self.cause.clone(),
self.param_env,
ty::PredicateKind::AliasRelate(
ct.into(),
new_infer_ct.into(),
ty::AliasRelationDirection::Equate,
),
);
fulfill_cx.register_predicate_obligation(self.infcx, obligation);
let errors = fulfill_cx.select_where_possible(self.infcx);
if !errors.is_empty() {
return Err(errors);
}
Ok(self.infcx.resolve_vars_if_possible(new_infer_ct))
} else {
Ok(self.normalize(ct).into_value_registering_obligations(self.infcx, fulfill_cx))
}
}
}