Struct rustc_lint::middle::traits::FulfillmentContextUnstable
[-] [+]
[src]
pub struct FulfillmentContext<'tcx> { // some fields omitted }
The fulfillment context is used to drive trait resolution. It
consists of a list of obligations that must be (eventually)
satisfied. The job is to track which are satisfied, which yielded
errors, and which are still pending. At any point, users can call
select_where_possible
, and the fulfilment context will try to do
selection, retaining only those obligations that remain
ambiguous. This may be helpful in pushing type inference
along. Once all type inference constraints have been generated, the
method select_all_or_error
can be used to report any remaining
ambiguous cases as errors.
Methods
impl<'tcx> FulfillmentContext<'tcx>
fn new() -> FulfillmentContext<'tcx>
fn normalize_projection_type(&mut self, infcx: &InferCtxt<'a, 'tcx>, typer: &ClosureTyper<'tcx>, projection_ty: ProjectionTy<'tcx>, cause: ObligationCause<'tcx>) -> &'tcx TyS<'tcx>
"Normalize" a projection type <SomeType as SomeTrait>::X
by
creating a fresh type variable $0
as well as a projection
predicate <SomeType as SomeTrait>::X == $0
. When the
inference engine runs, it will attempt to find an impl of
SomeTrait
or a where clause that lets us unify $0
with
something concrete. If this fails, we'll unify $0
with
projection_ty
again.
fn register_builtin_bound(&mut self, infcx: &InferCtxt<'a, 'tcx>, ty: &'tcx TyS<'tcx>, builtin_bound: BuiltinBound, cause: ObligationCause<'tcx>)
fn register_region_obligation(&mut self, infcx: &InferCtxt<'a, 'tcx>, t_a: &'tcx TyS<'tcx>, r_b: Region, cause: ObligationCause<'tcx>)
fn register_predicate_obligation(&mut self, infcx: &InferCtxt<'a, 'tcx>, obligation: Obligation<'tcx, Predicate<'tcx>>)
fn region_obligations(&self, body_id: u32) -> &[RegionObligation<'tcx>]
fn select_all_or_error(&mut self, infcx: &InferCtxt<'a, 'tcx>, typer: &ClosureTyper<'tcx>) -> Result<(), Vec<FulfillmentError<'tcx>>>
fn select_new_obligations(&mut self, infcx: &InferCtxt<'a, 'tcx>, typer: &ClosureTyper<'tcx>) -> Result<(), Vec<FulfillmentError<'tcx>>>
Attempts to select obligations that were registered since the call to a selection routine.
This is used by the type checker to eagerly attempt to resolve obligations in hopes of
gaining type information. It'd be equally valid to use select_where_possible
but it
results in O(n^2)
performance (#18208).