1 //! Helper functions corresponding to lifetime errors due to
5 use crate::infer::error_reporting::nice_region_error::NiceRegionError;
6 use crate::ty::{self, DefIdTree, Region, Ty};
7 use crate::hir::def_id::DefId;
10 // The struct contains the information about the anonymous region
11 // we are searching for.
13 pub(super) struct AnonymousArgInfo<'tcx> {
14 // the argument corresponding to the anonymous region
15 pub arg: &'tcx hir::Arg,
16 // the type corresponding to the anonymopus region argument
18 // the ty::BoundRegion corresponding to the anonymous region
19 pub bound_region: ty::BoundRegion,
20 // arg_ty_span contains span of argument type
21 pub arg_ty_span : Span,
22 // corresponds to id the argument is the first parameter
27 impl<'a, 'gcx, 'tcx> NiceRegionError<'a, 'gcx, 'tcx> {
28 // This method walks the Type of the function body arguments using
29 // `fold_regions()` function and returns the
30 // &hir::Arg of the function argument corresponding to the anonymous
31 // region and the Ty corresponding to the named region.
32 // Currently only the case where the function declaration consists of
33 // one named region and one anonymous region is handled.
34 // Consider the example `fn foo<'a>(x: &'a i32, y: &i32) -> &'a i32`
35 // Here, we would return the hir::Arg for y, we return the type &'a
36 // i32, which is the type of y but with the anonymous region replaced
37 // with 'a, the corresponding bound region and is_first which is true if
38 // the hir::Arg is the first argument in the function declaration.
39 pub(super) fn find_arg_with_region(
41 anon_region: Region<'tcx>,
42 replace_region: Region<'tcx>,
43 ) -> Option<AnonymousArgInfo<'_>> {
44 let (id, bound_region) = match *anon_region {
45 ty::ReFree(ref free_region) => (free_region.scope, free_region.bound_region),
46 ty::ReEarlyBound(ebr) => (
47 self.tcx().parent(ebr.def_id).unwrap(),
48 ty::BoundRegion::BrNamed(ebr.def_id, ebr.name),
50 _ => return None, // not a free region
53 let hir = &self.tcx().hir();
54 if let Some(node_id) = hir.as_local_node_id(id) {
55 if let Some(body_id) = hir.maybe_body_owned_by(node_id) {
56 let body = hir.body(body_id);
57 let owner_id = hir.body_owner(body_id);
58 let fn_decl = hir.fn_decl(owner_id).unwrap();
59 if let Some(tables) = self.tables {
63 .filter_map(|(index, arg)| {
64 // May return None; sometimes the tables are not yet populated.
65 let ty_hir_id = fn_decl.inputs[index].hir_id;
66 let arg_ty_span = hir.span(hir.hir_to_node_id(ty_hir_id));
67 let ty = tables.node_type_opt(arg.hir_id)?;
68 let mut found_anon_region = false;
69 let new_arg_ty = self.tcx().fold_regions(&ty, &mut false, |r, _| {
70 if *r == *anon_region {
71 found_anon_region = true;
77 if found_anon_region {
78 let is_first = index == 0;
79 Some(AnonymousArgInfo {
82 arg_ty_span : arg_ty_span,
83 bound_region: bound_region,
102 // Here, we check for the case where the anonymous region
103 // is in the return type.
104 // FIXME(#42703) - Need to handle certain cases here.
105 pub(super) fn is_return_type_anon(
111 let ret_ty = self.tcx().type_of(scope_def_id);
112 if let ty::FnDef(_, _) = ret_ty.sty {
113 let sig = ret_ty.fn_sig(self.tcx());
114 let late_bound_regions = self.tcx()
115 .collect_referenced_late_bound_regions(&sig.output());
116 if late_bound_regions.iter().any(|r| *r == br) {
117 return Some(decl.output.span());
123 // Here we check for the case where anonymous region
124 // corresponds to self and if yes, we display E0312.
125 // FIXME(#42700) - Need to format self properly to
126 // enable E0621 for it.
127 pub(super) fn is_self_anon(&self, is_first: bool, scope_def_id: DefId) -> bool {
130 .opt_associated_item(scope_def_id)
131 .map(|i| i.method_has_self_argument) == Some(true)