-use rustc_middle::ty::{self, AdtSizedConstraint, Ty, TyCtxt};
+use rustc_data_structures::fx::FxHashSet;
+use rustc_errors::{pluralize, struct_span_err, Applicability, MultiSpan};
+use rustc_hir as hir;
+use rustc_hir::def::DefKind;
+use rustc_middle::ty::Representability;
+use rustc_middle::ty::{self, AdtSizedConstraint, DefIdTree, Ty, TyCtxt};
+use rustc_query_system::query::QueryInfo;
use rustc_query_system::Value;
+use rustc_span::def_id::LocalDefId;
+use rustc_span::Span;
+
+use std::fmt::Write;
impl<'tcx> Value<TyCtxt<'tcx>> for Ty<'_> {
- fn from_cycle_error(tcx: TyCtxt<'tcx>) -> Self {
+ fn from_cycle_error(tcx: TyCtxt<'tcx>, _: &[QueryInfo]) -> 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<'_>>(tcx.ty_error()) }
}
impl<'tcx> Value<TyCtxt<'tcx>> for ty::SymbolName<'_> {
- fn from_cycle_error(tcx: TyCtxt<'tcx>) -> Self {
+ fn from_cycle_error(tcx: TyCtxt<'tcx>, _: &[QueryInfo]) -> Self {
// SAFETY: This is never called when `Self` is not `SymbolName<'tcx>`.
// FIXME: Represent the above fact in the trait system somehow.
unsafe {
}
impl<'tcx> Value<TyCtxt<'tcx>> for AdtSizedConstraint<'_> {
- fn from_cycle_error(tcx: TyCtxt<'tcx>) -> Self {
+ fn from_cycle_error(tcx: TyCtxt<'tcx>, _: &[QueryInfo]) -> Self {
// SAFETY: This is never called when `Self` is not `AdtSizedConstraint<'tcx>`.
// FIXME: Represent the above fact in the trait system somehow.
unsafe {
}
impl<'tcx> Value<TyCtxt<'tcx>> for ty::Binder<'_, ty::FnSig<'_>> {
- fn from_cycle_error(tcx: TyCtxt<'tcx>) -> Self {
+ fn from_cycle_error(tcx: TyCtxt<'tcx>, _: &[QueryInfo]) -> Self {
let err = tcx.ty_error();
// FIXME(compiler-errors): It would be nice if we could get the
// query key, so we could at least generate a fn signature that
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: &[QueryInfo]) -> Self {
+ let mut item_and_field_ids = Vec::new();
+ let mut representable_ids = FxHashSet::default();
+ for info in cycle {
+ if info.query.name == "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 {
+ if info.query.name == "representability_adt_ty"
+ && let Some(def_id) = info.query.ty_adt_id
+ && let Some(def_id) = def_id.as_local()
+ && !item_and_field_ids.iter().any(|&(id, _)| id == def_id)
+ {
+ representable_ids.insert(def_id);
+ }
+ }
+ recursive_type_error(tcx, item_and_field_ids, &representable_ids);
+ Representability::Infinite
+ }
+}
+
+// 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>,
+) {
+ 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_id = tcx.hir().local_def_id_to_hir_id(field_id);
+ let hir::Node::Field(field) = tcx.hir().get(hir_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.to_def_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
+ };
+ let mut err = struct_span_err!(
+ tcx.sess,
+ err_span,
+ E0072,
+ "recursive type{} {} {} infinite size",
+ pluralize!(cycle_len),
+ items_list,
+ pluralize!("has", cycle_len),
+ );
+ err.multipart_suggestion(
+ "insert some indirection (e.g., a `Box`, `Rc`, or `&`) to break the cycle",
+ suggestion,
+ Applicability::HasPlaceholders,
+ );
+ err.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 Some(def_id) = path.res.opt_def_id() {
+ 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);
+ for (i, arg) in args.args.iter().enumerate() {
+ 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))
+ }
+ _ => {}
+ }
+}
projects / rust.git / blobdiff