diff options
Diffstat (limited to 'compiler/rustc_infer/src/infer/error_reporting/nice_region_error/util.rs')
| -rw-r--r-- | compiler/rustc_infer/src/infer/error_reporting/nice_region_error/util.rs | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/util.rs b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/util.rs new file mode 100644 index 000000000..3e9d491af --- /dev/null +++ b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/util.rs @@ -0,0 +1,167 @@ +//! Helper functions corresponding to lifetime errors due to +//! anonymous regions. + +use crate::infer::error_reporting::nice_region_error::NiceRegionError; +use crate::infer::TyCtxt; +use rustc_hir as hir; +use rustc_hir::def_id::LocalDefId; +use rustc_middle::ty::{self, Binder, DefIdTree, Region, Ty, TypeVisitable}; +use rustc_span::Span; + +/// Information about the anonymous region we are searching for. +#[derive(Debug)] +pub struct AnonymousParamInfo<'tcx> { + /// The parameter corresponding to the anonymous region. + pub param: &'tcx hir::Param<'tcx>, + /// The type corresponding to the anonymous region parameter. + pub param_ty: Ty<'tcx>, + /// The ty::BoundRegionKind corresponding to the anonymous region. + pub bound_region: ty::BoundRegionKind, + /// The `Span` of the parameter type. + pub param_ty_span: Span, + /// Signals that the argument is the first parameter in the declaration. + pub is_first: bool, +} + +// 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. +#[instrument(skip(tcx), level = "debug")] +pub fn find_param_with_region<'tcx>( + tcx: TyCtxt<'tcx>, + anon_region: Region<'tcx>, + replace_region: Region<'tcx>, +) -> Option<AnonymousParamInfo<'tcx>> { + let (id, bound_region) = match *anon_region { + ty::ReFree(ref free_region) => (free_region.scope, free_region.bound_region), + ty::ReEarlyBound(ebr) => { + (tcx.parent(ebr.def_id), ty::BoundRegionKind::BrNamed(ebr.def_id, ebr.name)) + } + _ => return None, // not a free region + }; + + let hir = &tcx.hir(); + let def_id = id.as_local()?; + let hir_id = hir.local_def_id_to_hir_id(def_id); + + // FIXME: use def_kind + // Don't perform this on closures + match hir.get(hir_id) { + hir::Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure { .. }, .. }) => { + return None; + } + _ => {} + } + + let body_id = hir.maybe_body_owned_by(def_id)?; + + let owner_id = hir.body_owner(body_id); + let fn_decl = hir.fn_decl_by_hir_id(owner_id).unwrap(); + let poly_fn_sig = tcx.fn_sig(id); + + let fn_sig = tcx.liberate_late_bound_regions(id, poly_fn_sig); + let body = hir.body(body_id); + body.params + .iter() + .take(if fn_sig.c_variadic { + fn_sig.inputs().len() + } else { + assert_eq!(fn_sig.inputs().len(), body.params.len()); + body.params.len() + }) + .enumerate() + .find_map(|(index, param)| { + // May return None; sometimes the tables are not yet populated. + let ty = fn_sig.inputs()[index]; + let mut found_anon_region = false; + let new_param_ty = tcx.fold_regions(ty, |r, _| { + if r == anon_region { + found_anon_region = true; + replace_region + } else { + r + } + }); + if found_anon_region { + let ty_hir_id = fn_decl.inputs[index].hir_id; + let param_ty_span = hir.span(ty_hir_id); + let is_first = index == 0; + Some(AnonymousParamInfo { + param, + param_ty: new_param_ty, + param_ty_span, + bound_region, + is_first, + }) + } else { + None + } + }) +} + +impl<'a, 'tcx> NiceRegionError<'a, 'tcx> { + pub(super) fn find_param_with_region( + &self, + anon_region: Region<'tcx>, + replace_region: Region<'tcx>, + ) -> Option<AnonymousParamInfo<'tcx>> { + find_param_with_region(self.tcx(), anon_region, replace_region) + } + + // Here, we check for the case where the anonymous region + // is in the return type as written by the user. + // FIXME(#42703) - Need to handle certain cases here. + pub(super) fn is_return_type_anon( + &self, + scope_def_id: LocalDefId, + br: ty::BoundRegionKind, + hir_sig: &hir::FnSig<'_>, + ) -> Option<Span> { + let fn_ty = self.tcx().type_of(scope_def_id); + if let ty::FnDef(_, _) = fn_ty.kind() { + let ret_ty = fn_ty.fn_sig(self.tcx()).output(); + let span = hir_sig.decl.output.span(); + let future_output = if hir_sig.header.is_async() { + ret_ty.map_bound(|ty| self.infcx.get_impl_future_output_ty(ty)).transpose() + } else { + None + }; + return match future_output { + Some(output) if self.includes_region(output, br) => Some(span), + None if self.includes_region(ret_ty, br) => Some(span), + _ => None, + }; + } + None + } + + fn includes_region( + &self, + ty: Binder<'tcx, impl TypeVisitable<'tcx>>, + region: ty::BoundRegionKind, + ) -> bool { + let late_bound_regions = self.tcx().collect_referenced_late_bound_regions(&ty); + late_bound_regions.iter().any(|r| *r == region) + } + + // 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: LocalDefId) -> bool { + is_first + && self + .tcx() + .opt_associated_item(scope_def_id.to_def_id()) + .map(|i| i.fn_has_self_parameter) + == Some(true) + } +} |