rustc_traits/
normalize_projection_ty.rs

1use rustc_infer::infer::TyCtxtInferExt;
2use rustc_infer::infer::canonical::{Canonical, QueryResponse};
3use rustc_infer::traits::PredicateObligations;
4use rustc_middle::query::Providers;
5use rustc_middle::ty::{ParamEnvAnd, TyCtxt};
6use rustc_trait_selection::error_reporting::InferCtxtErrorExt;
7use rustc_trait_selection::infer::InferCtxtBuilderExt;
8use rustc_trait_selection::traits::query::normalize::NormalizationResult;
9use rustc_trait_selection::traits::query::{CanonicalAliasGoal, NoSolution};
10use rustc_trait_selection::traits::{self, ObligationCause, ScrubbedTraitError, SelectionContext};
11use tracing::debug;
12
13pub(crate) fn provide(p: &mut Providers) {
14    *p = Providers {
15        normalize_canonicalized_projection_ty,
16        normalize_canonicalized_free_alias,
17        normalize_canonicalized_inherent_projection_ty,
18        ..*p
19    };
20}
21
22fn normalize_canonicalized_projection_ty<'tcx>(
23    tcx: TyCtxt<'tcx>,
24    goal: CanonicalAliasGoal<'tcx>,
25) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, NormalizationResult<'tcx>>>, NoSolution> {
26    debug!("normalize_canonicalized_projection_ty(goal={:#?})", goal);
27
28    tcx.infer_ctxt().enter_canonical_trait_query(
29        &goal,
30        |ocx, ParamEnvAnd { param_env, value: goal }| {
31            debug_assert!(!ocx.infcx.next_trait_solver());
32            let selcx = &mut SelectionContext::new(ocx.infcx);
33            let cause = ObligationCause::dummy();
34            let mut obligations = PredicateObligations::new();
35            let answer = traits::normalize_projection_term(
36                selcx,
37                param_env,
38                goal.into(),
39                cause,
40                0,
41                &mut obligations,
42            );
43            ocx.register_obligations(obligations);
44            // #112047: With projections and opaques, we are able to create opaques that
45            // are recursive (given some generic parameters of the opaque's type variables).
46            // In that case, we may only realize a cycle error when calling
47            // `normalize_erasing_regions` in mono.
48            let errors = ocx.select_where_possible();
49            if !errors.is_empty() {
50                // Rustdoc may attempt to normalize type alias types which are not
51                // well-formed. Rustdoc also normalizes types that are just not
52                // well-formed, since we don't do as much HIR analysis (checking
53                // that impl vars are constrained by the signature, for example).
54                if !tcx.sess.opts.actually_rustdoc {
55                    for error in &errors {
56                        if let ScrubbedTraitError::Cycle(cycle) = &error {
57                            ocx.infcx.err_ctxt().report_overflow_obligation_cycle(cycle);
58                        }
59                    }
60                }
61                return Err(NoSolution);
62            }
63
64            // FIXME(associated_const_equality): All users of normalize_canonicalized_projection_ty
65            // expected a type, but there is the possibility it could've been a const now.
66            // Maybe change it to a Term later?
67            Ok(NormalizationResult { normalized_ty: answer.expect_type() })
68        },
69    )
70}
71
72fn normalize_canonicalized_free_alias<'tcx>(
73    tcx: TyCtxt<'tcx>,
74    goal: CanonicalAliasGoal<'tcx>,
75) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, NormalizationResult<'tcx>>>, NoSolution> {
76    debug!("normalize_canonicalized_free_alias(goal={:#?})", goal);
77
78    tcx.infer_ctxt().enter_canonical_trait_query(
79        &goal,
80        |ocx, ParamEnvAnd { param_env, value: goal }| {
81            let obligations = tcx.predicates_of(goal.def_id).instantiate_own(tcx, goal.args).map(
82                |(predicate, span)| {
83                    traits::Obligation::new(
84                        tcx,
85                        ObligationCause::dummy_with_span(span),
86                        param_env,
87                        predicate,
88                    )
89                },
90            );
91            ocx.register_obligations(obligations);
92            let normalized_ty = tcx.type_of(goal.def_id).instantiate(tcx, goal.args);
93            Ok(NormalizationResult { normalized_ty })
94        },
95    )
96}
97
98fn normalize_canonicalized_inherent_projection_ty<'tcx>(
99    tcx: TyCtxt<'tcx>,
100    goal: CanonicalAliasGoal<'tcx>,
101) -> Result<&'tcx Canonical<'tcx, QueryResponse<'tcx, NormalizationResult<'tcx>>>, NoSolution> {
102    debug!("normalize_canonicalized_inherent_projection_ty(goal={:#?})", goal);
103
104    tcx.infer_ctxt().enter_canonical_trait_query(
105        &goal,
106        |ocx, ParamEnvAnd { param_env, value: goal }| {
107            let selcx = &mut SelectionContext::new(ocx.infcx);
108            let cause = ObligationCause::dummy();
109            let mut obligations = PredicateObligations::new();
110            let answer = traits::normalize_inherent_projection(
111                selcx,
112                param_env,
113                goal.into(),
114                cause,
115                0,
116                &mut obligations,
117            );
118            ocx.register_obligations(obligations);
119
120            Ok(NormalizationResult { normalized_ty: answer.expect_type() })
121        },
122    )
123}
rustc_traits/normalize_projection_ty.rs

rustc_traits/
normalize_projection_ty.rs
