diff options
| -rw-r--r-- | compiler/rustc_trait_selection/src/traits/select/mod.rs | 75 |
1 files changed, 51 insertions, 24 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs index 6bf46bb9a1c..daa3f2775e0 100644 --- a/compiler/rustc_trait_selection/src/traits/select/mod.rs +++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs @@ -662,32 +662,59 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> { tcx.features().generic_const_exprs, "`ConstEquate` without a feature gate: {c1:?} {c2:?}", ); - debug!(?c1, ?c2, "evaluate_predicate_recursively: equating consts"); - // FIXME: we probably should only try to unify abstract constants - // if the constants depend on generic parameters. - // - // Let's just see where this breaks :shrug: - if let (ty::ConstKind::Unevaluated(_), ty::ConstKind::Unevaluated(_)) = - (c1.kind(), c2.kind()) { - if let Ok(Some(a)) = tcx.expand_abstract_consts(c1) - && let Ok(Some(b)) = tcx.expand_abstract_consts(c2) - && a.ty() == b.ty() - && let Ok(new_obligations) = self - .infcx - .at(&obligation.cause, obligation.param_env) - .eq(a, b) - { - let mut obligations = new_obligations.obligations; - self.add_depth( - obligations.iter_mut(), - obligation.recursion_depth, - ); - return self.evaluate_predicates_recursively( - previous_stack, - obligations.into_iter(), - ); + let c1 = + if let Ok(Some(a)) = tcx.expand_abstract_consts(c1) { a } else { c1 }; + let c2 = + if let Ok(Some(b)) = tcx.expand_abstract_consts(c2) { b } else { c2 }; + debug!( + "evalaute_predicate_recursively: equating consts:\nc1= {:?}\nc2= {:?}", + c1, c2 + ); + + use rustc_hir::def::DefKind; + use ty::ConstKind::Unevaluated; + match (c1.kind(), c2.kind()) { + (Unevaluated(a), Unevaluated(b)) + if a.def.did == b.def.did + && tcx.def_kind(a.def.did) == DefKind::AssocConst => + { + if let Ok(new_obligations) = self + .infcx + .at(&obligation.cause, obligation.param_env) + .trace(c1, c2) + .eq(a.substs, b.substs) + { + let mut obligations = new_obligations.obligations; + self.add_depth( + obligations.iter_mut(), + obligation.recursion_depth, + ); + return self.evaluate_predicates_recursively( + previous_stack, + obligations.into_iter(), + ); + } + } + (_, Unevaluated(_)) | (Unevaluated(_), _) => (), + (_, _) => { + if let Ok(new_obligations) = self + .infcx + .at(&obligation.cause, obligation.param_env) + .eq(c1, c2) + { + let mut obligations = new_obligations.obligations; + self.add_depth( + obligations.iter_mut(), + obligation.recursion_depth, + ); + return self.evaluate_predicates_recursively( + previous_stack, + obligations.into_iter(), + ); + } + } } } |