diff options
Diffstat (limited to 'compiler/rustc_trait_selection/src/traits/structural_normalize.rs')
-rw-r--r-- | compiler/rustc_trait_selection/src/traits/structural_normalize.rs | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/structural_normalize.rs b/compiler/rustc_trait_selection/src/traits/structural_normalize.rs new file mode 100644 index 000000000..af8dd0da5 --- /dev/null +++ b/compiler/rustc_trait_selection/src/traits/structural_normalize.rs @@ -0,0 +1,55 @@ +use rustc_infer::infer::at::At; +use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; +use rustc_infer::traits::{FulfillmentError, TraitEngine}; +use rustc_middle::ty::{self, Ty}; + +use crate::traits::{query::evaluate_obligation::InferCtxtExt, NormalizeExt, Obligation}; + +pub trait StructurallyNormalizeExt<'tcx> { + fn structurally_normalize( + &self, + ty: Ty<'tcx>, + fulfill_cx: &mut dyn TraitEngine<'tcx>, + ) -> Result<Ty<'tcx>, Vec<FulfillmentError<'tcx>>>; +} + +impl<'tcx> StructurallyNormalizeExt<'tcx> for At<'_, 'tcx> { + fn structurally_normalize( + &self, + mut ty: Ty<'tcx>, + fulfill_cx: &mut dyn TraitEngine<'tcx>, + ) -> Result<Ty<'tcx>, Vec<FulfillmentError<'tcx>>> { + assert!(!ty.is_ty_var(), "should have resolved vars before calling"); + + if self.infcx.tcx.trait_solver_next() { + while let ty::Alias(ty::Projection, projection_ty) = *ty.kind() { + let new_infer_ty = self.infcx.next_ty_var(TypeVariableOrigin { + kind: TypeVariableOriginKind::NormalizeProjectionType, + span: self.cause.span, + }); + let obligation = Obligation::new( + self.infcx.tcx, + self.cause.clone(), + self.param_env, + ty::Binder::dummy(ty::ProjectionPredicate { + projection_ty, + term: new_infer_ty.into(), + }), + ); + if self.infcx.predicate_may_hold(&obligation) { + fulfill_cx.register_predicate_obligation(self.infcx, obligation); + let errors = fulfill_cx.select_where_possible(self.infcx); + if !errors.is_empty() { + return Err(errors); + } + ty = self.infcx.resolve_vars_if_possible(new_infer_ty); + } else { + break; + } + } + Ok(ty) + } else { + Ok(self.normalize(ty).into_value_registering_obligations(self.infcx, fulfill_cx)) + } + } +} |