diff options
| -rw-r--r-- | src/librustc_traits/chalk_context/mod.rs | 23 |
1 files changed, 20 insertions, 3 deletions
diff --git a/src/librustc_traits/chalk_context/mod.rs b/src/librustc_traits/chalk_context/mod.rs index 4f6ad83f2e6..41b7e73e553 100644 --- a/src/librustc_traits/chalk_context/mod.rs +++ b/src/librustc_traits/chalk_context/mod.rs @@ -155,12 +155,29 @@ impl context::AggregateOps<ChalkArenas<'gcx>> for ChalkContext<'cx, 'gcx> { } impl context::ContextOps<ChalkArenas<'gcx>> for ChalkContext<'cx, 'gcx> { - /// True if this is a coinductive goal -- e.g., proving an auto trait. + /// True if this is a coinductive goal: basically proving that an auto trait + /// is implemented or proving that a trait reference is well-formed. fn is_coinductive( &self, - _goal: &Canonical<'gcx, InEnvironment<'gcx, Goal<'gcx>>> + goal: &Canonical<'gcx, InEnvironment<'gcx, Goal<'gcx>>> ) -> bool { - unimplemented!() + use rustc::traits::{WellFormed, WhereClause}; + + let mut goal = goal.value.goal; + loop { + match goal { + GoalKind::DomainGoal(domain_goal) => match domain_goal { + DomainGoal::WellFormed(WellFormed::Trait(..)) => return true, + DomainGoal::Holds(WhereClause::Implemented(trait_predicate)) => { + return self.tcx.trait_is_auto(trait_predicate.def_id()); + } + _ => return false, + } + + GoalKind::Quantified(_, bound_goal) => goal = *bound_goal.skip_binder(), + _ => return false, + } + } } /// Create an inference table for processing a new goal and instantiate that goal |