| use std::collections::VecDeque; |
| use std::fmt::Write; |
| use std::ops::ControlFlow; |
| |
| use rustc_data_structures::fx::FxHashSet; |
| use rustc_errors::codes::*; |
| use rustc_errors::{Applicability, MultiSpan, pluralize, struct_span_code_err}; |
| use rustc_hir as hir; |
| use rustc_hir::def::{DefKind, Res}; |
| use rustc_middle::ty::{self, Representability, Ty, TyCtxt}; |
| use rustc_query_system::Value; |
| use rustc_query_system::query::{CycleError, report_cycle}; |
| use rustc_span::def_id::LocalDefId; |
| use rustc_span::{ErrorGuaranteed, Span}; |
| |
| use crate::dep_graph::dep_kinds; |
| use crate::query::plumbing::CyclePlaceholder; |
| |
| impl<'tcx> Value<TyCtxt<'tcx>> for Ty<'_> { |
| fn from_cycle_error(tcx: TyCtxt<'tcx>, _: &CycleError, guar: ErrorGuaranteed) -> Self { |
| // SAFETY: This is never called when `Self` is not `Ty<'tcx>`. |
| // FIXME: Represent the above fact in the trait system somehow. |
| unsafe { std::mem::transmute::<Ty<'tcx>, Ty<'_>>(Ty::new_error(tcx, guar)) } |
| } |
| } |
| |
| impl<'tcx> Value<TyCtxt<'tcx>> for Result<ty::EarlyBinder<'_, Ty<'_>>, CyclePlaceholder> { |
| fn from_cycle_error(_tcx: TyCtxt<'tcx>, _: &CycleError, guar: ErrorGuaranteed) -> Self { |
| Err(CyclePlaceholder(guar)) |
| } |
| } |
| |
| impl<'tcx> Value<TyCtxt<'tcx>> for ty::SymbolName<'_> { |
| fn from_cycle_error(tcx: TyCtxt<'tcx>, _: &CycleError, _guar: ErrorGuaranteed) -> Self { |
| // SAFETY: This is never called when `Self` is not `SymbolName<'tcx>`. |
| // FIXME: Represent the above fact in the trait system somehow. |
| unsafe { |
| std::mem::transmute::<ty::SymbolName<'tcx>, ty::SymbolName<'_>>(ty::SymbolName::new( |
| tcx, "<error>", |
| )) |
| } |
| } |
| } |
| |
| impl<'tcx> Value<TyCtxt<'tcx>> for ty::Binder<'_, ty::FnSig<'_>> { |
| fn from_cycle_error( |
| tcx: TyCtxt<'tcx>, |
| cycle_error: &CycleError, |
| guar: ErrorGuaranteed, |
| ) -> Self { |
| let err = Ty::new_error(tcx, guar); |
| |
| let arity = if let Some(frame) = cycle_error.cycle.get(0) |
| && frame.query.dep_kind == dep_kinds::fn_sig |
| && let Some(def_id) = frame.query.def_id |
| && let Some(node) = tcx.hir().get_if_local(def_id) |
| && let Some(sig) = node.fn_sig() |
| { |
| sig.decl.inputs.len() |
| } else { |
| tcx.dcx().abort_if_errors(); |
| unreachable!() |
| }; |
| |
| let fn_sig = ty::Binder::dummy(tcx.mk_fn_sig( |
| std::iter::repeat(err).take(arity), |
| err, |
| false, |
| rustc_hir::Safety::Safe, |
| rustc_target::spec::abi::Abi::Rust, |
| )); |
| |
| // SAFETY: This is never called when `Self` is not `ty::Binder<'tcx, ty::FnSig<'tcx>>`. |
| // FIXME: Represent the above fact in the trait system somehow. |
| unsafe { std::mem::transmute::<ty::PolyFnSig<'tcx>, ty::Binder<'_, ty::FnSig<'_>>>(fn_sig) } |
| } |
| } |
| |
| impl<'tcx> Value<TyCtxt<'tcx>> for Representability { |
| fn from_cycle_error( |
| tcx: TyCtxt<'tcx>, |
| cycle_error: &CycleError, |
| _guar: ErrorGuaranteed, |
| ) -> Self { |
| let mut item_and_field_ids = Vec::new(); |
| let mut representable_ids = FxHashSet::default(); |
| for info in &cycle_error.cycle { |
| if info.query.dep_kind == dep_kinds::representability |
| && let Some(field_id) = info.query.def_id |
| && let Some(field_id) = field_id.as_local() |
| && let Some(DefKind::Field) = info.query.def_kind |
| { |
| let parent_id = tcx.parent(field_id.to_def_id()); |
| let item_id = match tcx.def_kind(parent_id) { |
| DefKind::Variant => tcx.parent(parent_id), |
| _ => parent_id, |
| }; |
| item_and_field_ids.push((item_id.expect_local(), field_id)); |
| } |
| } |
| for info in &cycle_error.cycle { |
| if info.query.dep_kind == dep_kinds::representability_adt_ty |
| && let Some(def_id) = info.query.ty_def_id |
| && let Some(def_id) = def_id.as_local() |
| && !item_and_field_ids.iter().any(|&(id, _)| id == def_id) |
| { |
| representable_ids.insert(def_id); |
| } |
| } |
| let guar = recursive_type_error(tcx, item_and_field_ids, &representable_ids); |
| Representability::Infinite(guar) |
| } |
| } |
| |
| impl<'tcx> Value<TyCtxt<'tcx>> for ty::EarlyBinder<'_, Ty<'_>> { |
| fn from_cycle_error( |
| tcx: TyCtxt<'tcx>, |
| cycle_error: &CycleError, |
| guar: ErrorGuaranteed, |
| ) -> Self { |
| ty::EarlyBinder::bind(Ty::from_cycle_error(tcx, cycle_error, guar)) |
| } |
| } |
| |
| impl<'tcx> Value<TyCtxt<'tcx>> for ty::EarlyBinder<'_, ty::Binder<'_, ty::FnSig<'_>>> { |
| fn from_cycle_error( |
| tcx: TyCtxt<'tcx>, |
| cycle_error: &CycleError, |
| guar: ErrorGuaranteed, |
| ) -> Self { |
| ty::EarlyBinder::bind(ty::Binder::from_cycle_error(tcx, cycle_error, guar)) |
| } |
| } |
| |
| impl<'tcx> Value<TyCtxt<'tcx>> for &[ty::Variance] { |
| fn from_cycle_error( |
| tcx: TyCtxt<'tcx>, |
| cycle_error: &CycleError, |
| _guar: ErrorGuaranteed, |
| ) -> Self { |
| if let Some(frame) = cycle_error.cycle.get(0) |
| && frame.query.dep_kind == dep_kinds::variances_of |
| && let Some(def_id) = frame.query.def_id |
| { |
| let n = tcx.generics_of(def_id).own_params.len(); |
| vec![ty::Bivariant; n].leak() |
| } else { |
| span_bug!( |
| cycle_error.usage.as_ref().unwrap().0, |
| "only `variances_of` returns `&[ty::Variance]`" |
| ); |
| } |
| } |
| } |
| |
| // Take a cycle of `Q` and try `try_cycle` on every permutation, falling back to `otherwise`. |
| fn search_for_cycle_permutation<Q, T>( |
| cycle: &[Q], |
| try_cycle: impl Fn(&mut VecDeque<&Q>) -> ControlFlow<T, ()>, |
| otherwise: impl FnOnce() -> T, |
| ) -> T { |
| let mut cycle: VecDeque<_> = cycle.iter().collect(); |
| for _ in 0..cycle.len() { |
| match try_cycle(&mut cycle) { |
| ControlFlow::Continue(_) => { |
| cycle.rotate_left(1); |
| } |
| ControlFlow::Break(t) => return t, |
| } |
| } |
| |
| otherwise() |
| } |
| |
| impl<'tcx, T> Value<TyCtxt<'tcx>> for Result<T, &'_ ty::layout::LayoutError<'_>> { |
| fn from_cycle_error( |
| tcx: TyCtxt<'tcx>, |
| cycle_error: &CycleError, |
| _guar: ErrorGuaranteed, |
| ) -> Self { |
| let diag = search_for_cycle_permutation( |
| &cycle_error.cycle, |
| |cycle| { |
| if cycle[0].query.dep_kind == dep_kinds::layout_of |
| && let Some(def_id) = cycle[0].query.ty_def_id |
| && let Some(def_id) = def_id.as_local() |
| && let def_kind = tcx.def_kind(def_id) |
| && matches!(def_kind, DefKind::Closure) |
| && let Some(coroutine_kind) = tcx.coroutine_kind(def_id) |
| { |
| // FIXME: `def_span` for an fn-like coroutine will point to the fn's body |
| // due to interactions between the desugaring into a closure expr and the |
| // def_span code. I'm not motivated to fix it, because I tried and it was |
| // not working, so just hack around it by grabbing the parent fn's span. |
| let span = if coroutine_kind.is_fn_like() { |
| tcx.def_span(tcx.local_parent(def_id)) |
| } else { |
| tcx.def_span(def_id) |
| }; |
| let mut diag = struct_span_code_err!( |
| tcx.sess.dcx(), |
| span, |
| E0733, |
| "recursion in {} {} requires boxing", |
| tcx.def_kind_descr_article(def_kind, def_id.to_def_id()), |
| tcx.def_kind_descr(def_kind, def_id.to_def_id()), |
| ); |
| for (i, frame) in cycle.iter().enumerate() { |
| if frame.query.dep_kind != dep_kinds::layout_of { |
| continue; |
| } |
| let Some(frame_def_id) = frame.query.ty_def_id else { |
| continue; |
| }; |
| let Some(frame_coroutine_kind) = tcx.coroutine_kind(frame_def_id) else { |
| continue; |
| }; |
| let frame_span = |
| frame.query.default_span(cycle[(i + 1) % cycle.len()].span); |
| if frame_span.is_dummy() { |
| continue; |
| } |
| if i == 0 { |
| diag.span_label(frame_span, "recursive call here"); |
| } else { |
| let coroutine_span: Span = if frame_coroutine_kind.is_fn_like() { |
| tcx.def_span(tcx.parent(frame_def_id)) |
| } else { |
| tcx.def_span(frame_def_id) |
| }; |
| let mut multispan = MultiSpan::from_span(coroutine_span); |
| multispan |
| .push_span_label(frame_span, "...leading to this recursive call"); |
| diag.span_note( |
| multispan, |
| format!("which leads to this {}", tcx.def_descr(frame_def_id)), |
| ); |
| } |
| } |
| // FIXME: We could report a structured suggestion if we had |
| // enough info here... Maybe we can use a hacky HIR walker. |
| if matches!( |
| coroutine_kind, |
| hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Async, _) |
| ) { |
| diag.note("a recursive `async fn` call must introduce indirection such as `Box::pin` to avoid an infinitely sized future"); |
| } |
| |
| ControlFlow::Break(diag) |
| } else { |
| ControlFlow::Continue(()) |
| } |
| }, |
| || report_cycle(tcx.sess, cycle_error), |
| ); |
| |
| let guar = diag.emit(); |
| |
| // tcx.arena.alloc cannot be used because we are not allowed to use &'tcx LayoutError under |
| // min_specialization. Since this is an error path anyways, leaking doesn't matter (and really, |
| // tcx.arena.alloc is pretty much equal to leaking). |
| Err(Box::leak(Box::new(ty::layout::LayoutError::Cycle(guar)))) |
| } |
| } |
| |
| // item_and_field_ids should form a cycle where each field contains the |
| // type in the next element in the list |
| pub fn recursive_type_error( |
| tcx: TyCtxt<'_>, |
| mut item_and_field_ids: Vec<(LocalDefId, LocalDefId)>, |
| representable_ids: &FxHashSet<LocalDefId>, |
| ) -> ErrorGuaranteed { |
| const ITEM_LIMIT: usize = 5; |
| |
| // Rotate the cycle so that the item with the lowest span is first |
| let start_index = item_and_field_ids |
| .iter() |
| .enumerate() |
| .min_by_key(|&(_, &(id, _))| tcx.def_span(id)) |
| .unwrap() |
| .0; |
| item_and_field_ids.rotate_left(start_index); |
| |
| let cycle_len = item_and_field_ids.len(); |
| let show_cycle_len = cycle_len.min(ITEM_LIMIT); |
| |
| let mut err_span = MultiSpan::from_spans( |
| item_and_field_ids[..show_cycle_len] |
| .iter() |
| .map(|(id, _)| tcx.def_span(id.to_def_id())) |
| .collect(), |
| ); |
| let mut suggestion = Vec::with_capacity(show_cycle_len * 2); |
| for i in 0..show_cycle_len { |
| let (_, field_id) = item_and_field_ids[i]; |
| let (next_item_id, _) = item_and_field_ids[(i + 1) % cycle_len]; |
| // Find the span(s) that contain the next item in the cycle |
| let hir::Node::Field(field) = tcx.hir_node_by_def_id(field_id) else { |
| bug!("expected field") |
| }; |
| let mut found = Vec::new(); |
| find_item_ty_spans(tcx, field.ty, next_item_id, &mut found, representable_ids); |
| |
| // Couldn't find the type. Maybe it's behind a type alias? |
| // In any case, we'll just suggest boxing the whole field. |
| if found.is_empty() { |
| found.push(field.ty.span); |
| } |
| |
| for span in found { |
| err_span.push_span_label(span, "recursive without indirection"); |
| // FIXME(compiler-errors): This suggestion might be erroneous if Box is shadowed |
| suggestion.push((span.shrink_to_lo(), "Box<".to_string())); |
| suggestion.push((span.shrink_to_hi(), ">".to_string())); |
| } |
| } |
| let items_list = { |
| let mut s = String::new(); |
| for (i, &(item_id, _)) in item_and_field_ids.iter().enumerate() { |
| let path = tcx.def_path_str(item_id); |
| write!(&mut s, "`{path}`").unwrap(); |
| if i == (ITEM_LIMIT - 1) && cycle_len > ITEM_LIMIT { |
| write!(&mut s, " and {} more", cycle_len - 5).unwrap(); |
| break; |
| } |
| if cycle_len > 1 && i < cycle_len - 2 { |
| s.push_str(", "); |
| } else if cycle_len > 1 && i == cycle_len - 2 { |
| s.push_str(" and ") |
| } |
| } |
| s |
| }; |
| struct_span_code_err!( |
| tcx.dcx(), |
| err_span, |
| E0072, |
| "recursive type{} {} {} infinite size", |
| pluralize!(cycle_len), |
| items_list, |
| pluralize!("has", cycle_len), |
| ) |
| .with_multipart_suggestion( |
| "insert some indirection (e.g., a `Box`, `Rc`, or `&`) to break the cycle", |
| suggestion, |
| Applicability::HasPlaceholders, |
| ) |
| .emit() |
| } |
| |
| fn find_item_ty_spans( |
| tcx: TyCtxt<'_>, |
| ty: &hir::Ty<'_>, |
| needle: LocalDefId, |
| spans: &mut Vec<Span>, |
| seen_representable: &FxHashSet<LocalDefId>, |
| ) { |
| match ty.kind { |
| hir::TyKind::Path(hir::QPath::Resolved(_, path)) => { |
| if let Res::Def(kind, def_id) = path.res |
| && matches!(kind, DefKind::Enum | DefKind::Struct | DefKind::Union) |
| { |
| let check_params = def_id.as_local().map_or(true, |def_id| { |
| if def_id == needle { |
| spans.push(ty.span); |
| } |
| seen_representable.contains(&def_id) |
| }); |
| if check_params && let Some(args) = path.segments.last().unwrap().args { |
| let params_in_repr = tcx.params_in_repr(def_id); |
| // the domain size check is needed because the HIR may not be well-formed at this point |
| for (i, arg) in args.args.iter().enumerate().take(params_in_repr.domain_size()) |
| { |
| if let hir::GenericArg::Type(ty) = arg |
| && params_in_repr.contains(i as u32) |
| { |
| find_item_ty_spans(tcx, ty, needle, spans, seen_representable); |
| } |
| } |
| } |
| } |
| } |
| hir::TyKind::Array(ty, _) => find_item_ty_spans(tcx, ty, needle, spans, seen_representable), |
| hir::TyKind::Tup(tys) => { |
| tys.iter().for_each(|ty| find_item_ty_spans(tcx, ty, needle, spans, seen_representable)) |
| } |
| _ => {} |
| } |
| } |
