1 use crate::infer::{InferCtxt, InferOk};
3 use crate::traits::query::Fallible;
5 use crate::infer::canonical::query_response;
6 use crate::infer::canonical::QueryRegionConstraint;
8 use syntax::source_map::DUMMY_SP;
9 use crate::traits::{ObligationCause, TraitEngine, TraitEngineExt};
11 pub struct CustomTypeOp<F, G> {
16 impl<F, G> CustomTypeOp<F, G> {
17 pub fn new<'gcx, 'tcx, R>(closure: F, description: G) -> Self
19 F: FnOnce(&InferCtxt<'_, 'gcx, 'tcx>) -> Fallible<InferOk<'tcx, R>>,
29 impl<'gcx, 'tcx, F, R, G> super::TypeOp<'gcx, 'tcx> for CustomTypeOp<F, G>
31 F: for<'a, 'cx> FnOnce(&'a InferCtxt<'cx, 'gcx, 'tcx>) -> Fallible<InferOk<'tcx, R>>,
36 /// Processes the operation and all resulting obligations,
37 /// returning the final result along with any region constraints
38 /// (they will be given over to the NLL region solver).
41 infcx: &InferCtxt<'_, 'gcx, 'tcx>,
42 ) -> Fallible<(Self::Output, Option<Rc<Vec<QueryRegionConstraint<'tcx>>>>)> {
43 if cfg!(debug_assertions) {
44 info!("fully_perform({:?})", self);
47 scrape_region_constraints(infcx, || Ok((self.closure)(infcx)?))
51 impl<F, G> fmt::Debug for CustomTypeOp<F, G>
55 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
56 write!(f, "{}", (self.description)())
60 /// Executes `op` and then scrapes out all the "old style" region
61 /// constraints that result, creating query-region-constraints.
62 fn scrape_region_constraints<'gcx, 'tcx, R>(
63 infcx: &InferCtxt<'_, 'gcx, 'tcx>,
64 op: impl FnOnce() -> Fallible<InferOk<'tcx, R>>,
65 ) -> Fallible<(R, Option<Rc<Vec<QueryRegionConstraint<'tcx>>>>)> {
66 let mut fulfill_cx = TraitEngine::new(infcx.tcx);
67 let dummy_body_id = ObligationCause::dummy().body_id;
69 // During NLL, we expect that nobody will register region
70 // obligations **except** as part of a custom type op (and, at the
71 // end of each custom type op, we scrape out the region
72 // obligations that resulted). So this vector should be empty on
74 let pre_obligations = infcx.take_registered_region_obligations();
76 pre_obligations.is_empty(),
77 "scrape_region_constraints: incoming region obligations = {:#?}",
81 let InferOk { value, obligations } = infcx.commit_if_ok(|_| op())?;
82 debug_assert!(obligations.iter().all(|o| o.cause.body_id == dummy_body_id));
83 fulfill_cx.register_predicate_obligations(infcx, obligations);
84 if let Err(e) = fulfill_cx.select_all_or_error(infcx) {
85 infcx.tcx.sess.diagnostic().delay_span_bug(
87 &format!("errors selecting obligation during MIR typeck: {:?}", e),
91 let region_obligations = infcx.take_registered_region_obligations();
93 let region_constraint_data = infcx.take_and_reset_region_constraints();
95 let outlives = query_response::make_query_outlives(
99 .map(|(_, r_o)| (r_o.sup_type, r_o.sub_region))
100 .map(|(ty, r)| (infcx.resolve_vars_if_possible(&ty), r)),
101 ®ion_constraint_data,
104 if outlives.is_empty() {
107 Ok((value, Some(Rc::new(outlives))))