rustc_trait_selection/error_reporting/infer/nice_region_error/
mod.rs

1use rustc_errors::{Diag, ErrorGuaranteed};
2use rustc_hir::def_id::LocalDefId;
3use rustc_middle::ty::{self, TyCtxt};
4use rustc_span::Span;
5
6use crate::error_reporting::TypeErrCtxt;
7use crate::infer::RegionResolutionError;
8use crate::infer::RegionResolutionError::*;
9
10mod different_lifetimes;
11pub mod find_anon_type;
12mod mismatched_static_lifetime;
13mod named_anon_conflict;
14pub(crate) mod placeholder_error;
15mod placeholder_relation;
16mod static_impl_trait;
17mod trait_impl_difference;
18mod util;
19
20pub use different_lifetimes::suggest_adding_lifetime_params;
21pub use find_anon_type::find_anon_type;
22pub use static_impl_trait::{HirTraitObjectVisitor, TraitObjectVisitor, suggest_new_region_bound};
23pub use util::find_param_with_region;
24
25impl<'cx, 'tcx> TypeErrCtxt<'cx, 'tcx> {
26    pub fn try_report_nice_region_error(
27        &'cx self,
28        generic_param_scope: LocalDefId,
29        error: &RegionResolutionError<'tcx>,
30    ) -> Option<ErrorGuaranteed> {
31        NiceRegionError::new(self, generic_param_scope, error.clone()).try_report()
32    }
33}
34
35pub struct NiceRegionError<'cx, 'tcx> {
36    cx: &'cx TypeErrCtxt<'cx, 'tcx>,
37    /// The innermost definition that introduces generic parameters that may be involved in
38    /// the region errors we are dealing with.
39    generic_param_scope: LocalDefId,
40    error: Option<RegionResolutionError<'tcx>>,
41    regions: Option<(Span, ty::Region<'tcx>, ty::Region<'tcx>)>,
42}
43
44impl<'cx, 'tcx> NiceRegionError<'cx, 'tcx> {
45    pub fn new(
46        cx: &'cx TypeErrCtxt<'cx, 'tcx>,
47        generic_param_scope: LocalDefId,
48        error: RegionResolutionError<'tcx>,
49    ) -> Self {
50        Self { cx, error: Some(error), regions: None, generic_param_scope }
51    }
52
53    pub fn new_from_span(
54        cx: &'cx TypeErrCtxt<'cx, 'tcx>,
55        generic_param_scope: LocalDefId,
56        span: Span,
57        sub: ty::Region<'tcx>,
58        sup: ty::Region<'tcx>,
59    ) -> Self {
60        Self { cx, error: None, regions: Some((span, sub, sup)), generic_param_scope }
61    }
62
63    fn tcx(&self) -> TyCtxt<'tcx> {
64        self.cx.tcx
65    }
66
67    pub fn try_report_from_nll(&self) -> Option<Diag<'tcx>> {
68        // Due to the improved diagnostics returned by the MIR borrow checker, only a subset of
69        // the nice region errors are required when running under the MIR borrow checker.
70        self.try_report_named_anon_conflict()
71            .or_else(|| self.try_report_placeholder_conflict())
72            .or_else(|| self.try_report_placeholder_relation())
73    }
74
75    pub fn try_report(&self) -> Option<ErrorGuaranteed> {
76        self.try_report_from_nll()
77            .map(|diag| diag.emit())
78            .or_else(|| self.try_report_impl_not_conforming_to_trait())
79            .or_else(|| self.try_report_anon_anon_conflict())
80            .or_else(|| self.try_report_static_impl_trait())
81            .or_else(|| self.try_report_mismatched_static_lifetime())
82    }
83
84    pub(super) fn regions(&self) -> Option<(Span, ty::Region<'tcx>, ty::Region<'tcx>)> {
85        match (&self.error, self.regions) {
86            (Some(ConcreteFailure(origin, sub, sup)), None) => Some((origin.span(), *sub, *sup)),
87            (Some(SubSupConflict(_, _, origin, sub, _, sup, _)), None) => {
88                Some((origin.span(), *sub, *sup))
89            }
90            (None, Some((span, sub, sup))) => Some((span, sub, sup)),
91            _ => None,
92        }
93    }
94}