66 lines
2.3 KiB
Rust
66 lines
2.3 KiB
Rust
use rustc_infer::infer::at::At;
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use rustc_infer::traits::TraitEngine;
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use rustc_macros::extension;
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use rustc_middle::ty::{self, Ty};
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use crate::traits::{NormalizeExt, Obligation};
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#[extension(pub trait StructurallyNormalizeExt<'tcx>)]
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impl<'tcx> At<'_, 'tcx> {
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fn structurally_normalize_ty<E: 'tcx>(
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&self,
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ty: Ty<'tcx>,
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fulfill_cx: &mut dyn TraitEngine<'tcx, E>,
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) -> Result<Ty<'tcx>, Vec<E>> {
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self.structurally_normalize_term(ty.into(), fulfill_cx).map(|term| term.expect_type())
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}
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fn structurally_normalize_const<E: 'tcx>(
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&self,
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ct: ty::Const<'tcx>,
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fulfill_cx: &mut dyn TraitEngine<'tcx, E>,
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) -> Result<ty::Const<'tcx>, Vec<E>> {
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if self.infcx.tcx.features().generic_const_exprs() {
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return Ok(super::evaluate_const(&self.infcx, ct, self.param_env));
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}
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self.structurally_normalize_term(ct.into(), fulfill_cx).map(|term| term.expect_const())
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}
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fn structurally_normalize_term<E: 'tcx>(
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&self,
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term: ty::Term<'tcx>,
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fulfill_cx: &mut dyn TraitEngine<'tcx, E>,
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) -> Result<ty::Term<'tcx>, Vec<E>> {
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assert!(!term.is_infer(), "should have resolved vars before calling");
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if self.infcx.next_trait_solver() {
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if let None = term.to_alias_term() {
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return Ok(term);
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}
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let new_infer = self.infcx.next_term_var_of_kind(term, self.cause.span);
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// We simply emit an `alias-eq` goal here, since that will take care of
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// normalizing the LHS of the projection until it is a rigid projection
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// (or a not-yet-defined opaque in scope).
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let obligation = Obligation::new(
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self.infcx.tcx,
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self.cause.clone(),
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self.param_env,
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ty::PredicateKind::AliasRelate(term, new_infer, ty::AliasRelationDirection::Equate),
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);
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fulfill_cx.register_predicate_obligation(self.infcx, obligation);
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let errors = fulfill_cx.select_where_possible(self.infcx);
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if !errors.is_empty() {
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return Err(errors);
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}
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Ok(self.infcx.resolve_vars_if_possible(new_infer))
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} else {
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Ok(self.normalize(term).into_value_registering_obligations(self.infcx, fulfill_cx))
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}
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}
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}
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