rustc_traits/
evaluate_obligation.rs

1use rustc_infer::infer::TyCtxtInferExt;
2use rustc_middle::query::Providers;
3use rustc_middle::ty::{ParamEnvAnd, TyCtxt};
4use rustc_span::DUMMY_SP;
5use rustc_trait_selection::traits::query::CanonicalPredicateGoal;
6use rustc_trait_selection::traits::{
7    EvaluationResult, Obligation, ObligationCause, OverflowError, SelectionContext, TraitQueryMode,
8    sizedness_fast_path,
9};
10use tracing::debug;
11
12pub(crate) fn provide(p: &mut Providers) {
13    *p = Providers { evaluate_obligation, ..*p };
14}
15
16fn evaluate_obligation<'tcx>(
17    tcx: TyCtxt<'tcx>,
18    canonical_goal: CanonicalPredicateGoal<'tcx>,
19) -> Result<EvaluationResult, OverflowError> {
20    assert!(!tcx.next_trait_solver_globally());
21    debug!("evaluate_obligation(canonical_goal={:#?})", canonical_goal);
22    let (ref infcx, goal, _var_values) =
23        tcx.infer_ctxt().build_with_canonical(DUMMY_SP, &canonical_goal);
24    debug!("evaluate_obligation: goal={:#?}", goal);
25    let ParamEnvAnd { param_env, value: predicate } = goal;
26
27    if sizedness_fast_path(tcx, predicate, param_env) {
28        return Ok(EvaluationResult::EvaluatedToOk);
29    }
30
31    let mut selcx = SelectionContext::with_query_mode(infcx, TraitQueryMode::Canonical);
32    let obligation = Obligation::new(tcx, ObligationCause::dummy(), param_env, predicate);
33
34    selcx.evaluate_root_obligation(&obligation)
35}
rustc_traits/evaluate_obligation.rs

rustc_traits/
evaluate_obligation.rs
