| //! Helper functions corresponding to lifetime errors due to |
| //! anonymous regions. |
| |
| use crate::infer::error_reporting::nice_region_error::NiceRegionError; |
| use crate::ty::{self, DefIdTree, Region, Ty}; |
| use rustc_hir as hir; |
| use rustc_hir::def_id::DefId; |
| use rustc_span::Span; |
| |
| // The struct contains the information about the anonymous region |
| // we are searching for. |
| #[derive(Debug)] |
| pub(super) struct AnonymousParamInfo<'tcx> { |
| // the parameter corresponding to the anonymous region |
| pub param: &'tcx hir::Param<'tcx>, |
| // the type corresponding to the anonymopus region parameter |
| pub param_ty: Ty<'tcx>, |
| // the ty::BoundRegion corresponding to the anonymous region |
| pub bound_region: ty::BoundRegion, |
| // param_ty_span contains span of parameter type |
| pub param_ty_span: Span, |
| // corresponds to id the argument is the first parameter |
| // in the declaration |
| pub is_first: bool, |
| } |
| |
| impl<'a, 'tcx> NiceRegionError<'a, 'tcx> { |
| // This method walks the Type of the function body parameters using |
| // `fold_regions()` function and returns the |
| // &hir::Param of the function parameter corresponding to the anonymous |
| // region and the Ty corresponding to the named region. |
| // Currently only the case where the function declaration consists of |
| // one named region and one anonymous region is handled. |
| // Consider the example `fn foo<'a>(x: &'a i32, y: &i32) -> &'a i32` |
| // Here, we would return the hir::Param for y, we return the type &'a |
| // i32, which is the type of y but with the anonymous region replaced |
| // with 'a, the corresponding bound region and is_first which is true if |
| // the hir::Param is the first parameter in the function declaration. |
| pub(super) fn find_param_with_region( |
| &self, |
| anon_region: Region<'tcx>, |
| replace_region: Region<'tcx>, |
| ) -> Option<AnonymousParamInfo<'_>> { |
| let (id, bound_region) = match *anon_region { |
| ty::ReFree(ref free_region) => (free_region.scope, free_region.bound_region), |
| ty::ReEarlyBound(ebr) => ( |
| self.tcx().parent(ebr.def_id).unwrap(), |
| ty::BoundRegion::BrNamed(ebr.def_id, ebr.name), |
| ), |
| _ => return None, // not a free region |
| }; |
| |
| let hir = &self.tcx().hir(); |
| if let Some(hir_id) = hir.as_local_hir_id(id) { |
| if let Some(body_id) = hir.maybe_body_owned_by(hir_id) { |
| let body = hir.body(body_id); |
| let owner_id = hir.body_owner(body_id); |
| let fn_decl = hir.fn_decl_by_hir_id(owner_id).unwrap(); |
| if let Some(tables) = self.tables { |
| body.params |
| .iter() |
| .enumerate() |
| .filter_map(|(index, param)| { |
| // May return None; sometimes the tables are not yet populated. |
| let ty_hir_id = fn_decl.inputs[index].hir_id; |
| let param_ty_span = hir.span(ty_hir_id); |
| let ty = tables.node_type_opt(param.hir_id)?; |
| let mut found_anon_region = false; |
| let new_param_ty = self.tcx().fold_regions(&ty, &mut false, |r, _| { |
| if *r == *anon_region { |
| found_anon_region = true; |
| replace_region |
| } else { |
| r |
| } |
| }); |
| if found_anon_region { |
| let is_first = index == 0; |
| Some(AnonymousParamInfo { |
| param: param, |
| param_ty: new_param_ty, |
| param_ty_span: param_ty_span, |
| bound_region: bound_region, |
| is_first: is_first, |
| }) |
| } else { |
| None |
| } |
| }) |
| .next() |
| } else { |
| None |
| } |
| } else { |
| None |
| } |
| } else { |
| None |
| } |
| } |
| |
| // Here, we check for the case where the anonymous region |
| // is in the return type. |
| // FIXME(#42703) - Need to handle certain cases here. |
| pub(super) fn is_return_type_anon( |
| &self, |
| scope_def_id: DefId, |
| br: ty::BoundRegion, |
| decl: &hir::FnDecl<'_>, |
| ) -> Option<Span> { |
| let ret_ty = self.tcx().type_of(scope_def_id); |
| if let ty::FnDef(_, _) = ret_ty.kind { |
| let sig = ret_ty.fn_sig(self.tcx()); |
| let late_bound_regions = |
| self.tcx().collect_referenced_late_bound_regions(&sig.output()); |
| if late_bound_regions.iter().any(|r| *r == br) { |
| return Some(decl.output.span()); |
| } |
| } |
| None |
| } |
| |
| // Here we check for the case where anonymous region |
| // corresponds to self and if yes, we display E0312. |
| // FIXME(#42700) - Need to format self properly to |
| // enable E0621 for it. |
| pub(super) fn is_self_anon(&self, is_first: bool, scope_def_id: DefId) -> bool { |
| is_first |
| && self.tcx().opt_associated_item(scope_def_id).map(|i| i.method_has_self_argument) |
| == Some(true) |
| } |
| } |