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3b2f2976 XL |
1 | //! Helper functions corresponding to lifetime errors due to |
2 | //! anonymous regions. | |
b7449926 | 3 | |
9fa01778 | 4 | use crate::infer::error_reporting::nice_region_error::NiceRegionError; |
dfeec247 | 5 | use rustc_hir as hir; |
f035d41b | 6 | use rustc_hir::def_id::LocalDefId; |
ba9703b0 | 7 | use rustc_middle::ty::{self, DefIdTree, Region, Ty}; |
dfeec247 | 8 | use rustc_span::Span; |
3b2f2976 | 9 | |
3dfed10e | 10 | /// Information about the anonymous region we are searching for. |
ea8adc8c | 11 | #[derive(Debug)] |
e1599b0c | 12 | pub(super) struct AnonymousParamInfo<'tcx> { |
3dfed10e | 13 | /// The parameter corresponding to the anonymous region. |
dfeec247 | 14 | pub param: &'tcx hir::Param<'tcx>, |
3dfed10e | 15 | /// The type corresponding to the anonymous region parameter. |
e1599b0c | 16 | pub param_ty: Ty<'tcx>, |
3dfed10e | 17 | /// The ty::BoundRegion corresponding to the anonymous region. |
3b2f2976 | 18 | pub bound_region: ty::BoundRegion, |
3dfed10e | 19 | /// The `Span` of the parameter type. |
dfeec247 | 20 | pub param_ty_span: Span, |
3dfed10e | 21 | /// Signals that the argument is the first parameter in the declaration. |
3b2f2976 XL |
22 | pub is_first: bool, |
23 | } | |
24 | ||
dc9dc135 | 25 | impl<'a, 'tcx> NiceRegionError<'a, 'tcx> { |
e1599b0c | 26 | // This method walks the Type of the function body parameters using |
3b2f2976 | 27 | // `fold_regions()` function and returns the |
e1599b0c | 28 | // &hir::Param of the function parameter corresponding to the anonymous |
3b2f2976 XL |
29 | // region and the Ty corresponding to the named region. |
30 | // Currently only the case where the function declaration consists of | |
31 | // one named region and one anonymous region is handled. | |
32 | // Consider the example `fn foo<'a>(x: &'a i32, y: &i32) -> &'a i32` | |
e1599b0c | 33 | // Here, we would return the hir::Param for y, we return the type &'a |
3b2f2976 XL |
34 | // i32, which is the type of y but with the anonymous region replaced |
35 | // with 'a, the corresponding bound region and is_first which is true if | |
e1599b0c XL |
36 | // the hir::Param is the first parameter in the function declaration. |
37 | pub(super) fn find_param_with_region( | |
ff7c6d11 XL |
38 | &self, |
39 | anon_region: Region<'tcx>, | |
40 | replace_region: Region<'tcx>, | |
e1599b0c | 41 | ) -> Option<AnonymousParamInfo<'_>> { |
ea8adc8c XL |
42 | let (id, bound_region) = match *anon_region { |
43 | ty::ReFree(ref free_region) => (free_region.scope, free_region.bound_region), | |
48663c56 | 44 | ty::ReEarlyBound(ebr) => ( |
532ac7d7 | 45 | self.tcx().parent(ebr.def_id).unwrap(), |
ff7c6d11 XL |
46 | ty::BoundRegion::BrNamed(ebr.def_id, ebr.name), |
47 | ), | |
ea8adc8c XL |
48 | _ => return None, // not a free region |
49 | }; | |
50 | ||
9fa01778 | 51 | let hir = &self.tcx().hir(); |
3dfed10e | 52 | let hir_id = hir.local_def_id_to_hir_id(id.as_local()?); |
ba9703b0 XL |
53 | let body_id = hir.maybe_body_owned_by(hir_id)?; |
54 | let body = hir.body(body_id); | |
55 | let owner_id = hir.body_owner(body_id); | |
56 | let fn_decl = hir.fn_decl_by_hir_id(owner_id).unwrap(); | |
57 | let poly_fn_sig = self.tcx().fn_sig(id); | |
58 | let fn_sig = self.tcx().liberate_late_bound_regions(id, &poly_fn_sig); | |
f9f354fc XL |
59 | body.params.iter().enumerate().find_map(|(index, param)| { |
60 | // May return None; sometimes the tables are not yet populated. | |
61 | let ty = fn_sig.inputs()[index]; | |
62 | let mut found_anon_region = false; | |
63 | let new_param_ty = self.tcx().fold_regions(&ty, &mut false, |r, _| { | |
64 | if *r == *anon_region { | |
65 | found_anon_region = true; | |
66 | replace_region | |
3b2f2976 | 67 | } else { |
f9f354fc | 68 | r |
3b2f2976 | 69 | } |
f9f354fc XL |
70 | }); |
71 | if found_anon_region { | |
72 | let ty_hir_id = fn_decl.inputs[index].hir_id; | |
73 | let param_ty_span = hir.span(ty_hir_id); | |
74 | let is_first = index == 0; | |
75 | Some(AnonymousParamInfo { | |
76 | param, | |
77 | param_ty: new_param_ty, | |
78 | param_ty_span, | |
79 | bound_region, | |
80 | is_first, | |
81 | }) | |
82 | } else { | |
83 | None | |
84 | } | |
85 | }) | |
3b2f2976 XL |
86 | } |
87 | ||
3b2f2976 XL |
88 | // Here, we check for the case where the anonymous region |
89 | // is in the return type. | |
90 | // FIXME(#42703) - Need to handle certain cases here. | |
ff7c6d11 XL |
91 | pub(super) fn is_return_type_anon( |
92 | &self, | |
f035d41b | 93 | scope_def_id: LocalDefId, |
ff7c6d11 | 94 | br: ty::BoundRegion, |
dfeec247 | 95 | decl: &hir::FnDecl<'_>, |
ff7c6d11 | 96 | ) -> Option<Span> { |
9fa01778 | 97 | let ret_ty = self.tcx().type_of(scope_def_id); |
e74abb32 | 98 | if let ty::FnDef(_, _) = ret_ty.kind { |
9fa01778 | 99 | let sig = ret_ty.fn_sig(self.tcx()); |
dfeec247 XL |
100 | let late_bound_regions = |
101 | self.tcx().collect_referenced_late_bound_regions(&sig.output()); | |
0bf4aa26 XL |
102 | if late_bound_regions.iter().any(|r| *r == br) { |
103 | return Some(decl.output.span()); | |
3b2f2976 | 104 | } |
3b2f2976 | 105 | } |
ea8adc8c | 106 | None |
3b2f2976 | 107 | } |
8faf50e0 | 108 | |
3b2f2976 XL |
109 | // Here we check for the case where anonymous region |
110 | // corresponds to self and if yes, we display E0312. | |
111 | // FIXME(#42700) - Need to format self properly to | |
112 | // enable E0621 for it. | |
f035d41b | 113 | pub(super) fn is_self_anon(&self, is_first: bool, scope_def_id: LocalDefId) -> bool { |
ff7c6d11 | 114 | is_first |
f035d41b XL |
115 | && self |
116 | .tcx() | |
117 | .opt_associated_item(scope_def_id.to_def_id()) | |
118 | .map(|i| i.fn_has_self_parameter) | |
dfeec247 | 119 | == Some(true) |
3b2f2976 | 120 | } |
3b2f2976 | 121 | } |