rustc_trait_selection/
regions.rs

1use rustc_hir::def_id::LocalDefId;
2use rustc_infer::infer::outlives::env::OutlivesEnvironment;
3use rustc_infer::infer::{InferCtxt, RegionResolutionError};
4use rustc_macros::extension;
5use rustc_middle::traits::ObligationCause;
6use rustc_middle::traits::query::NoSolution;
7use rustc_middle::ty::{self, Ty, elaborate};
8
9use crate::traits::ScrubbedTraitError;
10use crate::traits::outlives_bounds::InferCtxtExt;
11
12#[extension(pub trait OutlivesEnvironmentBuildExt<'tcx>)]
13impl<'tcx> OutlivesEnvironment<'tcx> {
14    fn new(
15        infcx: &InferCtxt<'tcx>,
16        body_id: LocalDefId,
17        param_env: ty::ParamEnv<'tcx>,
18        assumed_wf_tys: impl IntoIterator<Item = Ty<'tcx>>,
19    ) -> Self {
20        Self::new_with_implied_bounds_compat(infcx, body_id, param_env, assumed_wf_tys, false)
21    }
22
23    fn new_with_implied_bounds_compat(
24        infcx: &InferCtxt<'tcx>,
25        body_id: LocalDefId,
26        param_env: ty::ParamEnv<'tcx>,
27        assumed_wf_tys: impl IntoIterator<Item = Ty<'tcx>>,
28        disable_implied_bounds_hack: bool,
29    ) -> Self {
30        let mut bounds = vec![];
31
32        for bound in param_env.caller_bounds() {
33            if let Some(mut type_outlives) = bound.as_type_outlives_clause() {
34                if infcx.next_trait_solver() {
35                    match crate::solve::deeply_normalize::<_, ScrubbedTraitError<'tcx>>(
36                        infcx.at(&ObligationCause::dummy(), param_env),
37                        type_outlives,
38                    ) {
39                        Ok(new) => type_outlives = new,
40                        Err(_) => {
41                            infcx.dcx().delayed_bug(format!("could not normalize `{bound}`"));
42                        }
43                    }
44                }
45                bounds.push(type_outlives);
46            }
47        }
48
49        // FIXME(-Znext-trait-solver): Normalize these.
50        let higher_ranked_assumptions = infcx.take_registered_region_assumptions();
51        let higher_ranked_assumptions =
52            elaborate::elaborate_outlives_assumptions(infcx.tcx, higher_ranked_assumptions);
53
54        // FIXME: This needs to be modified so that we normalize the known type
55        // outlives obligations then elaborate them into their region/type components.
56        // Otherwise, `<W<'a> as Mirror>::Assoc: 'b` will not imply `'a: 'b` even
57        // if we can normalize `'a`.
58        OutlivesEnvironment::from_normalized_bounds(
59            param_env,
60            bounds,
61            infcx.implied_bounds_tys(
62                body_id,
63                param_env,
64                assumed_wf_tys,
65                disable_implied_bounds_hack,
66            ),
67            higher_ranked_assumptions,
68        )
69    }
70}
71
72#[extension(pub trait InferCtxtRegionExt<'tcx>)]
73impl<'tcx> InferCtxt<'tcx> {
74    /// Resolve regions, using the deep normalizer to normalize any type-outlives
75    /// obligations in the process. This is in `rustc_trait_selection` because
76    /// we need to normalize.
77    ///
78    /// Prefer this method over `resolve_regions_with_normalize`, unless you are
79    /// doing something specific for normalization.
80    ///
81    /// This function assumes that all infer variables are already constrained.
82    fn resolve_regions(
83        &self,
84        body_id: LocalDefId,
85        param_env: ty::ParamEnv<'tcx>,
86        assumed_wf_tys: impl IntoIterator<Item = Ty<'tcx>>,
87    ) -> Vec<RegionResolutionError<'tcx>> {
88        self.resolve_regions_with_outlives_env(&OutlivesEnvironment::new(
89            self,
90            body_id,
91            param_env,
92            assumed_wf_tys,
93        ))
94    }
95
96    /// Don't call this directly unless you know what you're doing.
97    fn resolve_regions_with_outlives_env(
98        &self,
99        outlives_env: &OutlivesEnvironment<'tcx>,
100    ) -> Vec<RegionResolutionError<'tcx>> {
101        self.resolve_regions_with_normalize(&outlives_env, |ty, origin| {
102            let ty = self.resolve_vars_if_possible(ty);
103
104            if self.next_trait_solver() {
105                crate::solve::deeply_normalize(
106                    self.at(
107                        &ObligationCause::dummy_with_span(origin.span()),
108                        outlives_env.param_env,
109                    ),
110                    ty,
111                )
112                .map_err(|_: Vec<ScrubbedTraitError<'tcx>>| NoSolution)
113            } else {
114                Ok(ty)
115            }
116        })
117    }
118}
rustc_trait_selection/regions.rs

rustc_trait_selection/
regions.rs
