/// scope. The eventual result is usually a `Selection` (defined below).
#[derive(Clone, PartialEq, Eq, Hash)]
pub struct Obligation<'tcx, T> {
+ /// Why do we have to prove this thing?
pub cause: ObligationCause<'tcx>,
+
+ /// In which environment should we prove this thing?
pub param_env: ty::ParamEnv<'tcx>,
- pub recursion_depth: usize,
+
+ /// What are we trying to prove?
pub predicate: T,
+
+ /// If we started proving this as a result of trying to prove
+ /// something else, track the total depth to ensure termination.
+ /// If this goes over a certain threshold, we abort compilation --
+ /// in such cases, we can not say whether or not the predicate
+ /// holds for certain. Stupid halting problem. Such a drag.
+ pub recursion_depth: usize,
}
pub type PredicateObligation<'tcx> = Obligation<'tcx, ty::Predicate<'tcx>>;