rustc_trait_selection/error_reporting/infer/nice_region_error/
util.rs1use rustc_hir as hir;
5use rustc_hir::def_id::{DefId, LocalDefId};
6use rustc_middle::ty::{self, Binder, Region, Ty, TyCtxt, TypeFoldable, fold_regions};
7use rustc_span::Span;
8use tracing::instrument;
9
10use crate::error_reporting::infer::nice_region_error::NiceRegionError;
11
12#[derive(Debug)]
14pub struct AnonymousParamInfo<'tcx> {
15 pub param: &'tcx hir::Param<'tcx>,
17 pub param_ty: Ty<'tcx>,
19 pub kind: ty::LateParamRegionKind,
21 pub param_ty_span: Span,
23 pub is_first: bool,
25}
26
27#[instrument(skip(tcx), level = "debug")]
39pub fn find_param_with_region<'tcx>(
40 tcx: TyCtxt<'tcx>,
41 generic_param_scope: LocalDefId,
42 anon_region: Region<'tcx>,
43 replace_region: Region<'tcx>,
44) -> Option<AnonymousParamInfo<'tcx>> {
45 let (id, kind) = match *anon_region {
46 ty::ReLateParam(late_param) => (late_param.scope, late_param.kind),
47 ty::ReEarlyParam(ebr) => {
48 let region_def = tcx.generics_of(generic_param_scope).region_param(ebr, tcx).def_id;
49 (tcx.parent(region_def), ty::LateParamRegionKind::Named(region_def, ebr.name))
50 }
51 _ => return None, };
53
54 let hir = &tcx.hir();
55 let def_id = id.as_local()?;
56
57 match tcx.hir_node_by_def_id(generic_param_scope) {
60 hir::Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure { .. }, .. }) => {
61 return None;
62 }
63 _ => {}
64 }
65
66 let body = tcx.hir_maybe_body_owned_by(def_id)?;
67
68 let owner_id = tcx.hir_body_owner(body.id());
69 let fn_decl = tcx.hir_fn_decl_by_hir_id(owner_id)?;
70 let poly_fn_sig = tcx.fn_sig(id).instantiate_identity();
71
72 let fn_sig = tcx.liberate_late_bound_regions(id, poly_fn_sig);
73 body.params
74 .iter()
75 .take(if fn_sig.c_variadic {
76 fn_sig.inputs().len()
77 } else {
78 assert_eq!(fn_sig.inputs().len(), body.params.len());
79 body.params.len()
80 })
81 .enumerate()
82 .find_map(|(index, param)| {
83 let ty = fn_sig.inputs()[index];
85 let mut found_anon_region = false;
86 let new_param_ty = fold_regions(tcx, ty, |r, _| {
87 if r == anon_region {
88 found_anon_region = true;
89 replace_region
90 } else {
91 r
92 }
93 });
94 found_anon_region.then(|| {
95 let ty_hir_id = fn_decl.inputs[index].hir_id;
96 let param_ty_span = hir.span(ty_hir_id);
97 let is_first = index == 0;
98 AnonymousParamInfo { param, param_ty: new_param_ty, param_ty_span, kind, is_first }
99 })
100 })
101}
102
103impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
104 pub(super) fn find_param_with_region(
105 &self,
106 anon_region: Region<'tcx>,
107 replace_region: Region<'tcx>,
108 ) -> Option<AnonymousParamInfo<'tcx>> {
109 find_param_with_region(self.tcx(), self.generic_param_scope, anon_region, replace_region)
110 }
111
112 pub(super) fn is_return_type_anon(
116 &self,
117 scope_def_id: LocalDefId,
118 region_def_id: DefId,
119 hir_sig: &hir::FnSig<'_>,
120 ) -> Option<Span> {
121 let fn_ty = self.tcx().type_of(scope_def_id).instantiate_identity();
122 if let ty::FnDef(_, _) = fn_ty.kind() {
123 let ret_ty = fn_ty.fn_sig(self.tcx()).output();
124 let span = hir_sig.decl.output.span();
125 let future_output = if hir_sig.header.is_async() {
126 ret_ty.map_bound(|ty| self.cx.get_impl_future_output_ty(ty)).transpose()
127 } else {
128 None
129 };
130 return match future_output {
131 Some(output) if self.includes_region(output, region_def_id) => Some(span),
132 None if self.includes_region(ret_ty, region_def_id) => Some(span),
133 _ => None,
134 };
135 }
136 None
137 }
138
139 fn includes_region(
140 &self,
141 ty: Binder<'tcx, impl TypeFoldable<TyCtxt<'tcx>>>,
142 region_def_id: DefId,
143 ) -> bool {
144 let late_bound_regions = self.tcx().collect_referenced_late_bound_regions(ty);
145 #[allow(rustc::potential_query_instability)]
147 late_bound_regions.iter().any(|r| match *r {
148 ty::BoundRegionKind::Named(def_id, _) => def_id == region_def_id,
149 _ => false,
150 })
151 }
152
153 pub(super) fn is_self_anon(&self, is_first: bool, scope_def_id: LocalDefId) -> bool {
158 is_first
159 && self
160 .tcx()
161 .opt_associated_item(scope_def_id.to_def_id())
162 .is_some_and(|i| i.fn_has_self_parameter)
163 }
164}