Struct rustc_trait_selection::traits::Obligation
source · [−]pub struct Obligation<'tcx, T> {
pub cause: ObligationCause<'tcx>,
pub param_env: ParamEnv<'tcx>,
pub predicate: T,
pub recursion_depth: usize,
}
Expand description
An Obligation
represents some trait reference (e.g., i32: Eq
) for
which the “impl_source” must be found. The process of finding an “impl_source” is
called “resolving” the Obligation
. This process consists of
either identifying an impl
(e.g., impl Eq for i32
) that
satisfies the obligation, or else finding a bound that is in
scope. The eventual result is usually a Selection
(defined below).
Fields
cause: ObligationCause<'tcx>
The reason we have to prove this thing.
param_env: ParamEnv<'tcx>
The environment in which we should prove this thing.
predicate: T
The thing we are trying to prove.
recursion_depth: usize
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.
Auto Trait Implementations
impl<'tcx, T> !RefUnwindSafe for Obligation<'tcx, T>
impl<'tcx, T> !Send for Obligation<'tcx, T>
impl<'tcx, T> !Sync for Obligation<'tcx, T>
impl<'tcx, T> Unpin for Obligation<'tcx, T>where
T: Unpin,
impl<'tcx, T> !UnwindSafe for Obligation<'tcx, T>
Blanket Implementations
sourceimpl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
sourceimpl<'tcx, T> IsSuggestable<'tcx> for Twhere
T: TypeVisitable<'tcx>,
impl<'tcx, T> IsSuggestable<'tcx> for Twhere
T: TypeVisitable<'tcx>,
Layout
Note: Unable to compute type layout, possibly due to this type having generic parameters. Layout can only be computed for concrete, fully-instantiated types.