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-rw-r--r--compiler/rustc_hir_analysis/src/collect.rs2263
-rw-r--r--compiler/rustc_hir_analysis/src/collect/generics_of.rs481
-rw-r--r--compiler/rustc_hir_analysis/src/collect/item_bounds.rs (renamed from compiler/rustc_typeck/src/collect/item_bounds.rs)16
-rw-r--r--compiler/rustc_hir_analysis/src/collect/lifetimes.rs1888
-rw-r--r--compiler/rustc_hir_analysis/src/collect/predicates_of.rs707
-rw-r--r--compiler/rustc_hir_analysis/src/collect/type_of.rs (renamed from compiler/rustc_typeck/src/collect/type_of.rs)265
6 files changed, 5528 insertions, 92 deletions
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
new file mode 100644
index 000000000..346d2e2fc
--- /dev/null
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -0,0 +1,2263 @@
+//! "Collection" is the process of determining the type and other external
+//! details of each item in Rust. Collection is specifically concerned
+//! with *inter-procedural* things -- for example, for a function
+//! definition, collection will figure out the type and signature of the
+//! function, but it will not visit the *body* of the function in any way,
+//! nor examine type annotations on local variables (that's the job of
+//! type *checking*).
+//!
+//! Collecting is ultimately defined by a bundle of queries that
+//! inquire after various facts about the items in the crate (e.g.,
+//! `type_of`, `generics_of`, `predicates_of`, etc). See the `provide` function
+//! for the full set.
+//!
+//! At present, however, we do run collection across all items in the
+//! crate as a kind of pass. This should eventually be factored away.
+
+use crate::astconv::AstConv;
+use crate::check::intrinsic::intrinsic_operation_unsafety;
+use crate::errors;
+use rustc_ast as ast;
+use rustc_ast::{MetaItemKind, NestedMetaItem};
+use rustc_attr::{list_contains_name, InlineAttr, InstructionSetAttr, OptimizeAttr};
+use rustc_data_structures::captures::Captures;
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder, ErrorGuaranteed, StashKey};
+use rustc_hir as hir;
+use rustc_hir::def::CtorKind;
+use rustc_hir::def_id::{DefId, LocalDefId, LOCAL_CRATE};
+use rustc_hir::intravisit::{self, Visitor};
+use rustc_hir::weak_lang_items;
+use rustc_hir::{GenericParamKind, Node};
+use rustc_middle::hir::nested_filter;
+use rustc_middle::middle::codegen_fn_attrs::{CodegenFnAttrFlags, CodegenFnAttrs};
+use rustc_middle::mir::mono::Linkage;
+use rustc_middle::ty::query::Providers;
+use rustc_middle::ty::util::{Discr, IntTypeExt};
+use rustc_middle::ty::ReprOptions;
+use rustc_middle::ty::{self, AdtKind, Const, DefIdTree, IsSuggestable, Ty, TyCtxt};
+use rustc_session::lint;
+use rustc_session::parse::feature_err;
+use rustc_span::symbol::{kw, sym, Ident, Symbol};
+use rustc_span::Span;
+use rustc_target::spec::{abi, SanitizerSet};
+use rustc_trait_selection::traits::error_reporting::suggestions::NextTypeParamName;
+use std::iter;
+
+mod generics_of;
+mod item_bounds;
+mod lifetimes;
+mod predicates_of;
+mod type_of;
+
+///////////////////////////////////////////////////////////////////////////
+// Main entry point
+
+fn collect_mod_item_types(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
+ tcx.hir().visit_item_likes_in_module(module_def_id, &mut CollectItemTypesVisitor { tcx });
+}
+
+pub fn provide(providers: &mut Providers) {
+ lifetimes::provide(providers);
+ *providers = Providers {
+ opt_const_param_of: type_of::opt_const_param_of,
+ type_of: type_of::type_of,
+ item_bounds: item_bounds::item_bounds,
+ explicit_item_bounds: item_bounds::explicit_item_bounds,
+ generics_of: generics_of::generics_of,
+ predicates_of: predicates_of::predicates_of,
+ predicates_defined_on,
+ explicit_predicates_of: predicates_of::explicit_predicates_of,
+ super_predicates_of: predicates_of::super_predicates_of,
+ super_predicates_that_define_assoc_type:
+ predicates_of::super_predicates_that_define_assoc_type,
+ trait_explicit_predicates_and_bounds: predicates_of::trait_explicit_predicates_and_bounds,
+ type_param_predicates: predicates_of::type_param_predicates,
+ trait_def,
+ adt_def,
+ fn_sig,
+ impl_trait_ref,
+ impl_polarity,
+ is_foreign_item,
+ generator_kind,
+ codegen_fn_attrs,
+ asm_target_features,
+ collect_mod_item_types,
+ should_inherit_track_caller,
+ ..*providers
+ };
+}
+
+///////////////////////////////////////////////////////////////////////////
+
+/// Context specific to some particular item. This is what implements
+/// [`AstConv`].
+///
+/// # `ItemCtxt` vs `FnCtxt`
+///
+/// `ItemCtxt` is primarily used to type-check item signatures and lower them
+/// from HIR to their [`ty::Ty`] representation, which is exposed using [`AstConv`].
+/// It's also used for the bodies of items like structs where the body (the fields)
+/// are just signatures.
+///
+/// This is in contrast to `FnCtxt`, which is used to type-check bodies of
+/// functions, closures, and `const`s -- anywhere that expressions and statements show up.
+///
+/// An important thing to note is that `ItemCtxt` does no inference -- it has no [`InferCtxt`] --
+/// while `FnCtxt` does do inference.
+///
+/// [`InferCtxt`]: rustc_infer::infer::InferCtxt
+///
+/// # Trait predicates
+///
+/// `ItemCtxt` has information about the predicates that are defined
+/// on the trait. Unfortunately, this predicate information is
+/// available in various different forms at various points in the
+/// process. So we can't just store a pointer to e.g., the AST or the
+/// parsed ty form, we have to be more flexible. To this end, the
+/// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
+/// `get_type_parameter_bounds` requests, drawing the information from
+/// the AST (`hir::Generics`), recursively.
+pub struct ItemCtxt<'tcx> {
+ tcx: TyCtxt<'tcx>,
+ item_def_id: DefId,
+}
+
+///////////////////////////////////////////////////////////////////////////
+
+#[derive(Default)]
+pub(crate) struct HirPlaceholderCollector(pub(crate) Vec<Span>);
+
+impl<'v> Visitor<'v> for HirPlaceholderCollector {
+ fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
+ if let hir::TyKind::Infer = t.kind {
+ self.0.push(t.span);
+ }
+ intravisit::walk_ty(self, t)
+ }
+ fn visit_generic_arg(&mut self, generic_arg: &'v hir::GenericArg<'v>) {
+ match generic_arg {
+ hir::GenericArg::Infer(inf) => {
+ self.0.push(inf.span);
+ intravisit::walk_inf(self, inf);
+ }
+ hir::GenericArg::Type(t) => self.visit_ty(t),
+ _ => {}
+ }
+ }
+ fn visit_array_length(&mut self, length: &'v hir::ArrayLen) {
+ if let &hir::ArrayLen::Infer(_, span) = length {
+ self.0.push(span);
+ }
+ intravisit::walk_array_len(self, length)
+ }
+}
+
+struct CollectItemTypesVisitor<'tcx> {
+ tcx: TyCtxt<'tcx>,
+}
+
+/// If there are any placeholder types (`_`), emit an error explaining that this is not allowed
+/// and suggest adding type parameters in the appropriate place, taking into consideration any and
+/// all already existing generic type parameters to avoid suggesting a name that is already in use.
+pub(crate) fn placeholder_type_error<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ generics: Option<&hir::Generics<'_>>,
+ placeholder_types: Vec<Span>,
+ suggest: bool,
+ hir_ty: Option<&hir::Ty<'_>>,
+ kind: &'static str,
+) {
+ if placeholder_types.is_empty() {
+ return;
+ }
+
+ placeholder_type_error_diag(tcx, generics, placeholder_types, vec![], suggest, hir_ty, kind)
+ .emit();
+}
+
+pub(crate) fn placeholder_type_error_diag<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ generics: Option<&hir::Generics<'_>>,
+ placeholder_types: Vec<Span>,
+ additional_spans: Vec<Span>,
+ suggest: bool,
+ hir_ty: Option<&hir::Ty<'_>>,
+ kind: &'static str,
+) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
+ if placeholder_types.is_empty() {
+ return bad_placeholder(tcx, additional_spans, kind);
+ }
+
+ let params = generics.map(|g| g.params).unwrap_or_default();
+ let type_name = params.next_type_param_name(None);
+ let mut sugg: Vec<_> =
+ placeholder_types.iter().map(|sp| (*sp, (*type_name).to_string())).collect();
+
+ if let Some(generics) = generics {
+ if let Some(arg) = params.iter().find(|arg| {
+ matches!(arg.name, hir::ParamName::Plain(Ident { name: kw::Underscore, .. }))
+ }) {
+ // Account for `_` already present in cases like `struct S<_>(_);` and suggest
+ // `struct S<T>(T);` instead of `struct S<_, T>(T);`.
+ sugg.push((arg.span, (*type_name).to_string()));
+ } else if let Some(span) = generics.span_for_param_suggestion() {
+ // Account for bounds, we want `fn foo<T: E, K>(_: K)` not `fn foo<T, K: E>(_: K)`.
+ sugg.push((span, format!(", {}", type_name)));
+ } else {
+ sugg.push((generics.span, format!("<{}>", type_name)));
+ }
+ }
+
+ let mut err =
+ bad_placeholder(tcx, placeholder_types.into_iter().chain(additional_spans).collect(), kind);
+
+ // Suggest, but only if it is not a function in const or static
+ if suggest {
+ let mut is_fn = false;
+ let mut is_const_or_static = false;
+
+ if let Some(hir_ty) = hir_ty && let hir::TyKind::BareFn(_) = hir_ty.kind {
+ is_fn = true;
+
+ // Check if parent is const or static
+ let parent_id = tcx.hir().get_parent_node(hir_ty.hir_id);
+ let parent_node = tcx.hir().get(parent_id);
+
+ is_const_or_static = matches!(
+ parent_node,
+ Node::Item(&hir::Item {
+ kind: hir::ItemKind::Const(..) | hir::ItemKind::Static(..),
+ ..
+ }) | Node::TraitItem(&hir::TraitItem {
+ kind: hir::TraitItemKind::Const(..),
+ ..
+ }) | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. })
+ );
+ }
+
+ // if function is wrapped around a const or static,
+ // then don't show the suggestion
+ if !(is_fn && is_const_or_static) {
+ err.multipart_suggestion(
+ "use type parameters instead",
+ sugg,
+ Applicability::HasPlaceholders,
+ );
+ }
+ }
+
+ err
+}
+
+fn reject_placeholder_type_signatures_in_item<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ item: &'tcx hir::Item<'tcx>,
+) {
+ let (generics, suggest) = match &item.kind {
+ hir::ItemKind::Union(_, generics)
+ | hir::ItemKind::Enum(_, generics)
+ | hir::ItemKind::TraitAlias(generics, _)
+ | hir::ItemKind::Trait(_, _, generics, ..)
+ | hir::ItemKind::Impl(hir::Impl { generics, .. })
+ | hir::ItemKind::Struct(_, generics) => (generics, true),
+ hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. })
+ | hir::ItemKind::TyAlias(_, generics) => (generics, false),
+ // `static`, `fn` and `const` are handled elsewhere to suggest appropriate type.
+ _ => return,
+ };
+
+ let mut visitor = HirPlaceholderCollector::default();
+ visitor.visit_item(item);
+
+ placeholder_type_error(tcx, Some(generics), visitor.0, suggest, None, item.kind.descr());
+}
+
+impl<'tcx> Visitor<'tcx> for CollectItemTypesVisitor<'tcx> {
+ type NestedFilter = nested_filter::OnlyBodies;
+
+ fn nested_visit_map(&mut self) -> Self::Map {
+ self.tcx.hir()
+ }
+
+ fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
+ convert_item(self.tcx, item.item_id());
+ reject_placeholder_type_signatures_in_item(self.tcx, item);
+ intravisit::walk_item(self, item);
+ }
+
+ fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
+ for param in generics.params {
+ match param.kind {
+ hir::GenericParamKind::Lifetime { .. } => {}
+ hir::GenericParamKind::Type { default: Some(_), .. } => {
+ let def_id = self.tcx.hir().local_def_id(param.hir_id);
+ self.tcx.ensure().type_of(def_id);
+ }
+ hir::GenericParamKind::Type { .. } => {}
+ hir::GenericParamKind::Const { default, .. } => {
+ let def_id = self.tcx.hir().local_def_id(param.hir_id);
+ self.tcx.ensure().type_of(def_id);
+ if let Some(default) = default {
+ let default_def_id = self.tcx.hir().local_def_id(default.hir_id);
+ // need to store default and type of default
+ self.tcx.ensure().type_of(default_def_id);
+ self.tcx.ensure().const_param_default(def_id);
+ }
+ }
+ }
+ }
+ intravisit::walk_generics(self, generics);
+ }
+
+ fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
+ if let hir::ExprKind::Closure { .. } = expr.kind {
+ let def_id = self.tcx.hir().local_def_id(expr.hir_id);
+ self.tcx.ensure().generics_of(def_id);
+ // We do not call `type_of` for closures here as that
+ // depends on typecheck and would therefore hide
+ // any further errors in case one typeck fails.
+ }
+ intravisit::walk_expr(self, expr);
+ }
+
+ fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
+ convert_trait_item(self.tcx, trait_item.trait_item_id());
+ intravisit::walk_trait_item(self, trait_item);
+ }
+
+ fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
+ convert_impl_item(self.tcx, impl_item.impl_item_id());
+ intravisit::walk_impl_item(self, impl_item);
+ }
+}
+
+///////////////////////////////////////////////////////////////////////////
+// Utility types and common code for the above passes.
+
+fn bad_placeholder<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ mut spans: Vec<Span>,
+ kind: &'static str,
+) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> {
+ let kind = if kind.ends_with('s') { format!("{}es", kind) } else { format!("{}s", kind) };
+
+ spans.sort();
+ let mut err = struct_span_err!(
+ tcx.sess,
+ spans.clone(),
+ E0121,
+ "the placeholder `_` is not allowed within types on item signatures for {}",
+ kind
+ );
+ for span in spans {
+ err.span_label(span, "not allowed in type signatures");
+ }
+ err
+}
+
+impl<'tcx> ItemCtxt<'tcx> {
+ pub fn new(tcx: TyCtxt<'tcx>, item_def_id: DefId) -> ItemCtxt<'tcx> {
+ ItemCtxt { tcx, item_def_id }
+ }
+
+ pub fn to_ty(&self, ast_ty: &hir::Ty<'_>) -> Ty<'tcx> {
+ <dyn AstConv<'_>>::ast_ty_to_ty(self, ast_ty)
+ }
+
+ pub fn hir_id(&self) -> hir::HirId {
+ self.tcx.hir().local_def_id_to_hir_id(self.item_def_id.expect_local())
+ }
+
+ pub fn node(&self) -> hir::Node<'tcx> {
+ self.tcx.hir().get(self.hir_id())
+ }
+}
+
+impl<'tcx> AstConv<'tcx> for ItemCtxt<'tcx> {
+ fn tcx(&self) -> TyCtxt<'tcx> {
+ self.tcx
+ }
+
+ fn item_def_id(&self) -> Option<DefId> {
+ Some(self.item_def_id)
+ }
+
+ fn get_type_parameter_bounds(
+ &self,
+ span: Span,
+ def_id: DefId,
+ assoc_name: Ident,
+ ) -> ty::GenericPredicates<'tcx> {
+ self.tcx.at(span).type_param_predicates((
+ self.item_def_id,
+ def_id.expect_local(),
+ assoc_name,
+ ))
+ }
+
+ fn re_infer(&self, _: Option<&ty::GenericParamDef>, _: Span) -> Option<ty::Region<'tcx>> {
+ None
+ }
+
+ fn allow_ty_infer(&self) -> bool {
+ false
+ }
+
+ fn ty_infer(&self, _: Option<&ty::GenericParamDef>, span: Span) -> Ty<'tcx> {
+ self.tcx().ty_error_with_message(span, "bad placeholder type")
+ }
+
+ fn ct_infer(&self, ty: Ty<'tcx>, _: Option<&ty::GenericParamDef>, span: Span) -> Const<'tcx> {
+ let ty = self.tcx.fold_regions(ty, |r, _| match *r {
+ ty::ReErased => self.tcx.lifetimes.re_static,
+ _ => r,
+ });
+ self.tcx().const_error_with_message(ty, span, "bad placeholder constant")
+ }
+
+ fn projected_ty_from_poly_trait_ref(
+ &self,
+ span: Span,
+ item_def_id: DefId,
+ item_segment: &hir::PathSegment<'_>,
+ poly_trait_ref: ty::PolyTraitRef<'tcx>,
+ ) -> Ty<'tcx> {
+ if let Some(trait_ref) = poly_trait_ref.no_bound_vars() {
+ let item_substs = <dyn AstConv<'tcx>>::create_substs_for_associated_item(
+ self,
+ span,
+ item_def_id,
+ item_segment,
+ trait_ref.substs,
+ );
+ self.tcx().mk_projection(item_def_id, item_substs)
+ } else {
+ // There are no late-bound regions; we can just ignore the binder.
+ let mut err = struct_span_err!(
+ self.tcx().sess,
+ span,
+ E0212,
+ "cannot use the associated type of a trait \
+ with uninferred generic parameters"
+ );
+
+ match self.node() {
+ hir::Node::Field(_) | hir::Node::Ctor(_) | hir::Node::Variant(_) => {
+ let item = self
+ .tcx
+ .hir()
+ .expect_item(self.tcx.hir().get_parent_item(self.hir_id()).def_id);
+ match &item.kind {
+ hir::ItemKind::Enum(_, generics)
+ | hir::ItemKind::Struct(_, generics)
+ | hir::ItemKind::Union(_, generics) => {
+ let lt_name = get_new_lifetime_name(self.tcx, poly_trait_ref, generics);
+ let (lt_sp, sugg) = match generics.params {
+ [] => (generics.span, format!("<{}>", lt_name)),
+ [bound, ..] => {
+ (bound.span.shrink_to_lo(), format!("{}, ", lt_name))
+ }
+ };
+ let suggestions = vec![
+ (lt_sp, sugg),
+ (
+ span.with_hi(item_segment.ident.span.lo()),
+ format!(
+ "{}::",
+ // Replace the existing lifetimes with a new named lifetime.
+ self.tcx.replace_late_bound_regions_uncached(
+ poly_trait_ref,
+ |_| {
+ self.tcx.mk_region(ty::ReEarlyBound(
+ ty::EarlyBoundRegion {
+ def_id: item_def_id,
+ index: 0,
+ name: Symbol::intern(&lt_name),
+ },
+ ))
+ }
+ ),
+ ),
+ ),
+ ];
+ err.multipart_suggestion(
+ "use a fully qualified path with explicit lifetimes",
+ suggestions,
+ Applicability::MaybeIncorrect,
+ );
+ }
+ _ => {}
+ }
+ }
+ hir::Node::Item(hir::Item {
+ kind:
+ hir::ItemKind::Struct(..) | hir::ItemKind::Enum(..) | hir::ItemKind::Union(..),
+ ..
+ }) => {}
+ hir::Node::Item(_)
+ | hir::Node::ForeignItem(_)
+ | hir::Node::TraitItem(_)
+ | hir::Node::ImplItem(_) => {
+ err.span_suggestion_verbose(
+ span.with_hi(item_segment.ident.span.lo()),
+ "use a fully qualified path with inferred lifetimes",
+ format!(
+ "{}::",
+ // Erase named lt, we want `<A as B<'_>::C`, not `<A as B<'a>::C`.
+ self.tcx.anonymize_late_bound_regions(poly_trait_ref).skip_binder(),
+ ),
+ Applicability::MaybeIncorrect,
+ );
+ }
+ _ => {}
+ }
+ err.emit();
+ self.tcx().ty_error()
+ }
+ }
+
+ fn normalize_ty(&self, _span: Span, ty: Ty<'tcx>) -> Ty<'tcx> {
+ // Types in item signatures are not normalized to avoid undue dependencies.
+ ty
+ }
+
+ fn set_tainted_by_errors(&self) {
+ // There's no obvious place to track this, so just let it go.
+ }
+
+ fn record_ty(&self, _hir_id: hir::HirId, _ty: Ty<'tcx>, _span: Span) {
+ // There's no place to record types from signatures?
+ }
+}
+
+/// Synthesize a new lifetime name that doesn't clash with any of the lifetimes already present.
+fn get_new_lifetime_name<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ poly_trait_ref: ty::PolyTraitRef<'tcx>,
+ generics: &hir::Generics<'tcx>,
+) -> String {
+ let existing_lifetimes = tcx
+ .collect_referenced_late_bound_regions(&poly_trait_ref)
+ .into_iter()
+ .filter_map(|lt| {
+ if let ty::BoundRegionKind::BrNamed(_, name) = lt {
+ Some(name.as_str().to_string())
+ } else {
+ None
+ }
+ })
+ .chain(generics.params.iter().filter_map(|param| {
+ if let hir::GenericParamKind::Lifetime { .. } = &param.kind {
+ Some(param.name.ident().as_str().to_string())
+ } else {
+ None
+ }
+ }))
+ .collect::<FxHashSet<String>>();
+
+ let a_to_z_repeat_n = |n| {
+ (b'a'..=b'z').map(move |c| {
+ let mut s = '\''.to_string();
+ s.extend(std::iter::repeat(char::from(c)).take(n));
+ s
+ })
+ };
+
+ // If all single char lifetime names are present, we wrap around and double the chars.
+ (1..).flat_map(a_to_z_repeat_n).find(|lt| !existing_lifetimes.contains(lt.as_str())).unwrap()
+}
+
+fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
+ let it = tcx.hir().item(item_id);
+ debug!("convert: item {} with id {}", it.ident, it.hir_id());
+ let def_id = item_id.owner_id.def_id;
+
+ match it.kind {
+ // These don't define types.
+ hir::ItemKind::ExternCrate(_)
+ | hir::ItemKind::Use(..)
+ | hir::ItemKind::Macro(..)
+ | hir::ItemKind::Mod(_)
+ | hir::ItemKind::GlobalAsm(_) => {}
+ hir::ItemKind::ForeignMod { items, .. } => {
+ for item in items {
+ let item = tcx.hir().foreign_item(item.id);
+ tcx.ensure().generics_of(item.owner_id);
+ tcx.ensure().type_of(item.owner_id);
+ tcx.ensure().predicates_of(item.owner_id);
+ match item.kind {
+ hir::ForeignItemKind::Fn(..) => tcx.ensure().fn_sig(item.owner_id),
+ hir::ForeignItemKind::Static(..) => {
+ let mut visitor = HirPlaceholderCollector::default();
+ visitor.visit_foreign_item(item);
+ placeholder_type_error(
+ tcx,
+ None,
+ visitor.0,
+ false,
+ None,
+ "static variable",
+ );
+ }
+ _ => (),
+ }
+ }
+ }
+ hir::ItemKind::Enum(ref enum_definition, _) => {
+ tcx.ensure().generics_of(def_id);
+ tcx.ensure().type_of(def_id);
+ tcx.ensure().predicates_of(def_id);
+ convert_enum_variant_types(tcx, def_id.to_def_id(), enum_definition.variants);
+ }
+ hir::ItemKind::Impl { .. } => {
+ tcx.ensure().generics_of(def_id);
+ tcx.ensure().type_of(def_id);
+ tcx.ensure().impl_trait_ref(def_id);
+ tcx.ensure().predicates_of(def_id);
+ }
+ hir::ItemKind::Trait(..) => {
+ tcx.ensure().generics_of(def_id);
+ tcx.ensure().trait_def(def_id);
+ tcx.at(it.span).super_predicates_of(def_id);
+ tcx.ensure().predicates_of(def_id);
+ }
+ hir::ItemKind::TraitAlias(..) => {
+ tcx.ensure().generics_of(def_id);
+ tcx.at(it.span).super_predicates_of(def_id);
+ tcx.ensure().predicates_of(def_id);
+ }
+ hir::ItemKind::Struct(ref struct_def, _) | hir::ItemKind::Union(ref struct_def, _) => {
+ tcx.ensure().generics_of(def_id);
+ tcx.ensure().type_of(def_id);
+ tcx.ensure().predicates_of(def_id);
+
+ for f in struct_def.fields() {
+ let def_id = tcx.hir().local_def_id(f.hir_id);
+ tcx.ensure().generics_of(def_id);
+ tcx.ensure().type_of(def_id);
+ tcx.ensure().predicates_of(def_id);
+ }
+
+ if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
+ convert_variant_ctor(tcx, ctor_hir_id);
+ }
+ }
+
+ // Desugared from `impl Trait`, so visited by the function's return type.
+ hir::ItemKind::OpaqueTy(hir::OpaqueTy {
+ origin: hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..),
+ ..
+ }) => {}
+
+ // Don't call `type_of` on opaque types, since that depends on type
+ // checking function bodies. `check_item_type` ensures that it's called
+ // instead.
+ hir::ItemKind::OpaqueTy(..) => {
+ tcx.ensure().generics_of(def_id);
+ tcx.ensure().predicates_of(def_id);
+ tcx.ensure().explicit_item_bounds(def_id);
+ }
+ hir::ItemKind::TyAlias(..)
+ | hir::ItemKind::Static(..)
+ | hir::ItemKind::Const(..)
+ | hir::ItemKind::Fn(..) => {
+ tcx.ensure().generics_of(def_id);
+ tcx.ensure().type_of(def_id);
+ tcx.ensure().predicates_of(def_id);
+ match it.kind {
+ hir::ItemKind::Fn(..) => tcx.ensure().fn_sig(def_id),
+ hir::ItemKind::OpaqueTy(..) => tcx.ensure().item_bounds(def_id),
+ hir::ItemKind::Const(ty, ..) | hir::ItemKind::Static(ty, ..) => {
+ if !is_suggestable_infer_ty(ty) {
+ let mut visitor = HirPlaceholderCollector::default();
+ visitor.visit_item(it);
+ placeholder_type_error(tcx, None, visitor.0, false, None, it.kind.descr());
+ }
+ }
+ _ => (),
+ }
+ }
+ }
+}
+
+fn convert_trait_item(tcx: TyCtxt<'_>, trait_item_id: hir::TraitItemId) {
+ let trait_item = tcx.hir().trait_item(trait_item_id);
+ let def_id = trait_item_id.owner_id;
+ tcx.ensure().generics_of(def_id);
+
+ match trait_item.kind {
+ hir::TraitItemKind::Fn(..) => {
+ tcx.ensure().type_of(def_id);
+ tcx.ensure().fn_sig(def_id);
+ }
+
+ hir::TraitItemKind::Const(.., Some(_)) => {
+ tcx.ensure().type_of(def_id);
+ }
+
+ hir::TraitItemKind::Const(hir_ty, _) => {
+ tcx.ensure().type_of(def_id);
+ // Account for `const C: _;`.
+ let mut visitor = HirPlaceholderCollector::default();
+ visitor.visit_trait_item(trait_item);
+ if !tcx.sess.diagnostic().has_stashed_diagnostic(hir_ty.span, StashKey::ItemNoType) {
+ placeholder_type_error(tcx, None, visitor.0, false, None, "constant");
+ }
+ }
+
+ hir::TraitItemKind::Type(_, Some(_)) => {
+ tcx.ensure().item_bounds(def_id);
+ tcx.ensure().type_of(def_id);
+ // Account for `type T = _;`.
+ let mut visitor = HirPlaceholderCollector::default();
+ visitor.visit_trait_item(trait_item);
+ placeholder_type_error(tcx, None, visitor.0, false, None, "associated type");
+ }
+
+ hir::TraitItemKind::Type(_, None) => {
+ tcx.ensure().item_bounds(def_id);
+ // #74612: Visit and try to find bad placeholders
+ // even if there is no concrete type.
+ let mut visitor = HirPlaceholderCollector::default();
+ visitor.visit_trait_item(trait_item);
+
+ placeholder_type_error(tcx, None, visitor.0, false, None, "associated type");
+ }
+ };
+
+ tcx.ensure().predicates_of(def_id);
+}
+
+fn convert_impl_item(tcx: TyCtxt<'_>, impl_item_id: hir::ImplItemId) {
+ let def_id = impl_item_id.owner_id;
+ tcx.ensure().generics_of(def_id);
+ tcx.ensure().type_of(def_id);
+ tcx.ensure().predicates_of(def_id);
+ let impl_item = tcx.hir().impl_item(impl_item_id);
+ match impl_item.kind {
+ hir::ImplItemKind::Fn(..) => {
+ tcx.ensure().fn_sig(def_id);
+ }
+ hir::ImplItemKind::Type(_) => {
+ // Account for `type T = _;`
+ let mut visitor = HirPlaceholderCollector::default();
+ visitor.visit_impl_item(impl_item);
+
+ placeholder_type_error(tcx, None, visitor.0, false, None, "associated type");
+ }
+ hir::ImplItemKind::Const(..) => {}
+ }
+}
+
+fn convert_variant_ctor(tcx: TyCtxt<'_>, ctor_id: hir::HirId) {
+ let def_id = tcx.hir().local_def_id(ctor_id);
+ tcx.ensure().generics_of(def_id);
+ tcx.ensure().type_of(def_id);
+ tcx.ensure().predicates_of(def_id);
+}
+
+fn convert_enum_variant_types(tcx: TyCtxt<'_>, def_id: DefId, variants: &[hir::Variant<'_>]) {
+ let def = tcx.adt_def(def_id);
+ let repr_type = def.repr().discr_type();
+ let initial = repr_type.initial_discriminant(tcx);
+ let mut prev_discr = None::<Discr<'_>>;
+
+ // fill the discriminant values and field types
+ for variant in variants {
+ let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
+ prev_discr = Some(
+ if let Some(ref e) = variant.disr_expr {
+ let expr_did = tcx.hir().local_def_id(e.hir_id);
+ def.eval_explicit_discr(tcx, expr_did.to_def_id())
+ } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) {
+ Some(discr)
+ } else {
+ struct_span_err!(tcx.sess, variant.span, E0370, "enum discriminant overflowed")
+ .span_label(
+ variant.span,
+ format!("overflowed on value after {}", prev_discr.unwrap()),
+ )
+ .note(&format!(
+ "explicitly set `{} = {}` if that is desired outcome",
+ variant.ident, wrapped_discr
+ ))
+ .emit();
+ None
+ }
+ .unwrap_or(wrapped_discr),
+ );
+
+ for f in variant.data.fields() {
+ let def_id = tcx.hir().local_def_id(f.hir_id);
+ tcx.ensure().generics_of(def_id);
+ tcx.ensure().type_of(def_id);
+ tcx.ensure().predicates_of(def_id);
+ }
+
+ // Convert the ctor, if any. This also registers the variant as
+ // an item.
+ if let Some(ctor_hir_id) = variant.data.ctor_hir_id() {
+ convert_variant_ctor(tcx, ctor_hir_id);
+ }
+ }
+}
+
+fn convert_variant(
+ tcx: TyCtxt<'_>,
+ variant_did: Option<LocalDefId>,
+ ctor_did: Option<LocalDefId>,
+ ident: Ident,
+ discr: ty::VariantDiscr,
+ def: &hir::VariantData<'_>,
+ adt_kind: ty::AdtKind,
+ parent_did: LocalDefId,
+) -> ty::VariantDef {
+ let mut seen_fields: FxHashMap<Ident, Span> = Default::default();
+ let fields = def
+ .fields()
+ .iter()
+ .map(|f| {
+ let fid = tcx.hir().local_def_id(f.hir_id);
+ let dup_span = seen_fields.get(&f.ident.normalize_to_macros_2_0()).cloned();
+ if let Some(prev_span) = dup_span {
+ tcx.sess.emit_err(errors::FieldAlreadyDeclared {
+ field_name: f.ident,
+ span: f.span,
+ prev_span,
+ });
+ } else {
+ seen_fields.insert(f.ident.normalize_to_macros_2_0(), f.span);
+ }
+
+ ty::FieldDef { did: fid.to_def_id(), name: f.ident.name, vis: tcx.visibility(fid) }
+ })
+ .collect();
+ let recovered = match def {
+ hir::VariantData::Struct(_, r) => *r,
+ _ => false,
+ };
+ ty::VariantDef::new(
+ ident.name,
+ variant_did.map(LocalDefId::to_def_id),
+ ctor_did.map(LocalDefId::to_def_id),
+ discr,
+ fields,
+ CtorKind::from_hir(def),
+ adt_kind,
+ parent_did.to_def_id(),
+ recovered,
+ adt_kind == AdtKind::Struct && tcx.has_attr(parent_did.to_def_id(), sym::non_exhaustive)
+ || variant_did.map_or(false, |variant_did| {
+ tcx.has_attr(variant_did.to_def_id(), sym::non_exhaustive)
+ }),
+ )
+}
+
+fn adt_def<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> ty::AdtDef<'tcx> {
+ use rustc_hir::*;
+
+ let def_id = def_id.expect_local();
+ let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
+ let Node::Item(item) = tcx.hir().get(hir_id) else {
+ bug!();
+ };
+
+ let repr = ReprOptions::new(tcx, def_id.to_def_id());
+ let (kind, variants) = match item.kind {
+ ItemKind::Enum(ref def, _) => {
+ let mut distance_from_explicit = 0;
+ let variants = def
+ .variants
+ .iter()
+ .map(|v| {
+ let variant_did = Some(tcx.hir().local_def_id(v.id));
+ let ctor_did =
+ v.data.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
+
+ let discr = if let Some(ref e) = v.disr_expr {
+ distance_from_explicit = 0;
+ ty::VariantDiscr::Explicit(tcx.hir().local_def_id(e.hir_id).to_def_id())
+ } else {
+ ty::VariantDiscr::Relative(distance_from_explicit)
+ };
+ distance_from_explicit += 1;
+
+ convert_variant(
+ tcx,
+ variant_did,
+ ctor_did,
+ v.ident,
+ discr,
+ &v.data,
+ AdtKind::Enum,
+ def_id,
+ )
+ })
+ .collect();
+
+ (AdtKind::Enum, variants)
+ }
+ ItemKind::Struct(ref def, _) => {
+ let variant_did = None::<LocalDefId>;
+ let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
+
+ let variants = std::iter::once(convert_variant(
+ tcx,
+ variant_did,
+ ctor_did,
+ item.ident,
+ ty::VariantDiscr::Relative(0),
+ def,
+ AdtKind::Struct,
+ def_id,
+ ))
+ .collect();
+
+ (AdtKind::Struct, variants)
+ }
+ ItemKind::Union(ref def, _) => {
+ let variant_did = None;
+ let ctor_did = def.ctor_hir_id().map(|hir_id| tcx.hir().local_def_id(hir_id));
+
+ let variants = std::iter::once(convert_variant(
+ tcx,
+ variant_did,
+ ctor_did,
+ item.ident,
+ ty::VariantDiscr::Relative(0),
+ def,
+ AdtKind::Union,
+ def_id,
+ ))
+ .collect();
+
+ (AdtKind::Union, variants)
+ }
+ _ => bug!(),
+ };
+ tcx.alloc_adt_def(def_id.to_def_id(), kind, variants, repr)
+}
+
+fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
+ let item = tcx.hir().expect_item(def_id.expect_local());
+
+ let (is_auto, unsafety, items) = match item.kind {
+ hir::ItemKind::Trait(is_auto, unsafety, .., items) => {
+ (is_auto == hir::IsAuto::Yes, unsafety, items)
+ }
+ hir::ItemKind::TraitAlias(..) => (false, hir::Unsafety::Normal, &[][..]),
+ _ => span_bug!(item.span, "trait_def_of_item invoked on non-trait"),
+ };
+
+ let paren_sugar = tcx.has_attr(def_id, sym::rustc_paren_sugar);
+ if paren_sugar && !tcx.features().unboxed_closures {
+ tcx.sess
+ .struct_span_err(
+ item.span,
+ "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
+ which traits can use parenthetical notation",
+ )
+ .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
+ .emit();
+ }
+
+ let is_marker = tcx.has_attr(def_id, sym::marker);
+ let skip_array_during_method_dispatch =
+ tcx.has_attr(def_id, sym::rustc_skip_array_during_method_dispatch);
+ let spec_kind = if tcx.has_attr(def_id, sym::rustc_unsafe_specialization_marker) {
+ ty::trait_def::TraitSpecializationKind::Marker
+ } else if tcx.has_attr(def_id, sym::rustc_specialization_trait) {
+ ty::trait_def::TraitSpecializationKind::AlwaysApplicable
+ } else {
+ ty::trait_def::TraitSpecializationKind::None
+ };
+ let must_implement_one_of = tcx
+ .get_attr(def_id, sym::rustc_must_implement_one_of)
+ // Check that there are at least 2 arguments of `#[rustc_must_implement_one_of]`
+ // and that they are all identifiers
+ .and_then(|attr| match attr.meta_item_list() {
+ Some(items) if items.len() < 2 => {
+ tcx.sess
+ .struct_span_err(
+ attr.span,
+ "the `#[rustc_must_implement_one_of]` attribute must be \
+ used with at least 2 args",
+ )
+ .emit();
+
+ None
+ }
+ Some(items) => items
+ .into_iter()
+ .map(|item| item.ident().ok_or(item.span()))
+ .collect::<Result<Box<[_]>, _>>()
+ .map_err(|span| {
+ tcx.sess
+ .struct_span_err(span, "must be a name of an associated function")
+ .emit();
+ })
+ .ok()
+ .zip(Some(attr.span)),
+ // Error is reported by `rustc_attr!`
+ None => None,
+ })
+ // Check that all arguments of `#[rustc_must_implement_one_of]` reference
+ // functions in the trait with default implementations
+ .and_then(|(list, attr_span)| {
+ let errors = list.iter().filter_map(|ident| {
+ let item = items.iter().find(|item| item.ident == *ident);
+
+ match item {
+ Some(item) if matches!(item.kind, hir::AssocItemKind::Fn { .. }) => {
+ if !tcx.impl_defaultness(item.id.owner_id).has_value() {
+ tcx.sess
+ .struct_span_err(
+ item.span,
+ "This function doesn't have a default implementation",
+ )
+ .span_note(attr_span, "required by this annotation")
+ .emit();
+
+ return Some(());
+ }
+
+ return None;
+ }
+ Some(item) => {
+ tcx.sess
+ .struct_span_err(item.span, "Not a function")
+ .span_note(attr_span, "required by this annotation")
+ .note(
+ "All `#[rustc_must_implement_one_of]` arguments \
+ must be associated function names",
+ )
+ .emit();
+ }
+ None => {
+ tcx.sess
+ .struct_span_err(ident.span, "Function not found in this trait")
+ .emit();
+ }
+ }
+
+ Some(())
+ });
+
+ (errors.count() == 0).then_some(list)
+ })
+ // Check for duplicates
+ .and_then(|list| {
+ let mut set: FxHashMap<Symbol, Span> = FxHashMap::default();
+ let mut no_dups = true;
+
+ for ident in &*list {
+ if let Some(dup) = set.insert(ident.name, ident.span) {
+ tcx.sess
+ .struct_span_err(vec![dup, ident.span], "Functions names are duplicated")
+ .note(
+ "All `#[rustc_must_implement_one_of]` arguments \
+ must be unique",
+ )
+ .emit();
+
+ no_dups = false;
+ }
+ }
+
+ no_dups.then_some(list)
+ });
+
+ ty::TraitDef::new(
+ def_id,
+ unsafety,
+ paren_sugar,
+ is_auto,
+ is_marker,
+ skip_array_during_method_dispatch,
+ spec_kind,
+ must_implement_one_of,
+ )
+}
+
+fn are_suggestable_generic_args(generic_args: &[hir::GenericArg<'_>]) -> bool {
+ generic_args.iter().any(|arg| match arg {
+ hir::GenericArg::Type(ty) => is_suggestable_infer_ty(ty),
+ hir::GenericArg::Infer(_) => true,
+ _ => false,
+ })
+}
+
+/// Whether `ty` is a type with `_` placeholders that can be inferred. Used in diagnostics only to
+/// use inference to provide suggestions for the appropriate type if possible.
+fn is_suggestable_infer_ty(ty: &hir::Ty<'_>) -> bool {
+ debug!(?ty);
+ use hir::TyKind::*;
+ match &ty.kind {
+ Infer => true,
+ Slice(ty) => is_suggestable_infer_ty(ty),
+ Array(ty, length) => {
+ is_suggestable_infer_ty(ty) || matches!(length, hir::ArrayLen::Infer(_, _))
+ }
+ Tup(tys) => tys.iter().any(is_suggestable_infer_ty),
+ Ptr(mut_ty) | Rptr(_, mut_ty) => is_suggestable_infer_ty(mut_ty.ty),
+ OpaqueDef(_, generic_args, _) => are_suggestable_generic_args(generic_args),
+ Path(hir::QPath::TypeRelative(ty, segment)) => {
+ is_suggestable_infer_ty(ty) || are_suggestable_generic_args(segment.args().args)
+ }
+ Path(hir::QPath::Resolved(ty_opt, hir::Path { segments, .. })) => {
+ ty_opt.map_or(false, is_suggestable_infer_ty)
+ || segments.iter().any(|segment| are_suggestable_generic_args(segment.args().args))
+ }
+ _ => false,
+ }
+}
+
+pub fn get_infer_ret_ty<'hir>(output: &'hir hir::FnRetTy<'hir>) -> Option<&'hir hir::Ty<'hir>> {
+ if let hir::FnRetTy::Return(ty) = output {
+ if is_suggestable_infer_ty(ty) {
+ return Some(&*ty);
+ }
+ }
+ None
+}
+
+#[instrument(level = "debug", skip(tcx))]
+fn fn_sig(tcx: TyCtxt<'_>, def_id: DefId) -> ty::PolyFnSig<'_> {
+ use rustc_hir::Node::*;
+ use rustc_hir::*;
+
+ let def_id = def_id.expect_local();
+ let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
+
+ let icx = ItemCtxt::new(tcx, def_id.to_def_id());
+
+ match tcx.hir().get(hir_id) {
+ TraitItem(hir::TraitItem {
+ kind: TraitItemKind::Fn(sig, TraitFn::Provided(_)),
+ generics,
+ ..
+ })
+ | Item(hir::Item { kind: ItemKind::Fn(sig, generics, _), .. }) => {
+ infer_return_ty_for_fn_sig(tcx, sig, generics, def_id, &icx)
+ }
+
+ ImplItem(hir::ImplItem { kind: ImplItemKind::Fn(sig, _), generics, .. }) => {
+ // Do not try to infer the return type for a impl method coming from a trait
+ if let Item(hir::Item { kind: ItemKind::Impl(i), .. }) =
+ tcx.hir().get(tcx.hir().get_parent_node(hir_id))
+ && i.of_trait.is_some()
+ {
+ <dyn AstConv<'_>>::ty_of_fn(
+ &icx,
+ hir_id,
+ sig.header.unsafety,
+ sig.header.abi,
+ sig.decl,
+ Some(generics),
+ None,
+ )
+ } else {
+ infer_return_ty_for_fn_sig(tcx, sig, generics, def_id, &icx)
+ }
+ }
+
+ TraitItem(hir::TraitItem {
+ kind: TraitItemKind::Fn(FnSig { header, decl, span: _ }, _),
+ generics,
+ ..
+ }) => <dyn AstConv<'_>>::ty_of_fn(
+ &icx,
+ hir_id,
+ header.unsafety,
+ header.abi,
+ decl,
+ Some(generics),
+ None,
+ ),
+
+ ForeignItem(&hir::ForeignItem { kind: ForeignItemKind::Fn(fn_decl, _, _), .. }) => {
+ let abi = tcx.hir().get_foreign_abi(hir_id);
+ compute_sig_of_foreign_fn_decl(tcx, def_id.to_def_id(), fn_decl, abi)
+ }
+
+ Ctor(data) | Variant(hir::Variant { data, .. }) if data.ctor_hir_id().is_some() => {
+ let ty = tcx.type_of(tcx.hir().get_parent_item(hir_id));
+ let inputs =
+ data.fields().iter().map(|f| tcx.type_of(tcx.hir().local_def_id(f.hir_id)));
+ ty::Binder::dummy(tcx.mk_fn_sig(
+ inputs,
+ ty,
+ false,
+ hir::Unsafety::Normal,
+ abi::Abi::Rust,
+ ))
+ }
+
+ Expr(&hir::Expr { kind: hir::ExprKind::Closure { .. }, .. }) => {
+ // Closure signatures are not like other function
+ // signatures and cannot be accessed through `fn_sig`. For
+ // example, a closure signature excludes the `self`
+ // argument. In any case they are embedded within the
+ // closure type as part of the `ClosureSubsts`.
+ //
+ // To get the signature of a closure, you should use the
+ // `sig` method on the `ClosureSubsts`:
+ //
+ // substs.as_closure().sig(def_id, tcx)
+ bug!(
+ "to get the signature of a closure, use `substs.as_closure().sig()` not `fn_sig()`",
+ );
+ }
+
+ x => {
+ bug!("unexpected sort of node in fn_sig(): {:?}", x);
+ }
+ }
+}
+
+fn infer_return_ty_for_fn_sig<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ sig: &hir::FnSig<'_>,
+ generics: &hir::Generics<'_>,
+ def_id: LocalDefId,
+ icx: &ItemCtxt<'tcx>,
+) -> ty::PolyFnSig<'tcx> {
+ let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
+
+ match get_infer_ret_ty(&sig.decl.output) {
+ Some(ty) => {
+ let fn_sig = tcx.typeck(def_id).liberated_fn_sigs()[hir_id];
+ // Typeck doesn't expect erased regions to be returned from `type_of`.
+ let fn_sig = tcx.fold_regions(fn_sig, |r, _| match *r {
+ ty::ReErased => tcx.lifetimes.re_static,
+ _ => r,
+ });
+ let fn_sig = ty::Binder::dummy(fn_sig);
+
+ let mut visitor = HirPlaceholderCollector::default();
+ visitor.visit_ty(ty);
+ let mut diag = bad_placeholder(tcx, visitor.0, "return type");
+ let ret_ty = fn_sig.skip_binder().output();
+ if ret_ty.is_suggestable(tcx, false) {
+ diag.span_suggestion(
+ ty.span,
+ "replace with the correct return type",
+ ret_ty,
+ Applicability::MachineApplicable,
+ );
+ } else if matches!(ret_ty.kind(), ty::FnDef(..)) {
+ let fn_sig = ret_ty.fn_sig(tcx);
+ if fn_sig
+ .skip_binder()
+ .inputs_and_output
+ .iter()
+ .all(|t| t.is_suggestable(tcx, false))
+ {
+ diag.span_suggestion(
+ ty.span,
+ "replace with the correct return type",
+ fn_sig,
+ Applicability::MachineApplicable,
+ );
+ }
+ } else if ret_ty.is_closure() {
+ // We're dealing with a closure, so we should suggest using `impl Fn` or trait bounds
+ // to prevent the user from getting a papercut while trying to use the unique closure
+ // syntax (e.g. `[closure@src/lib.rs:2:5: 2:9]`).
+ diag.help("consider using an `Fn`, `FnMut`, or `FnOnce` trait bound");
+ diag.note("for more information on `Fn` traits and closure types, see https://doc.rust-lang.org/book/ch13-01-closures.html");
+ }
+ diag.emit();
+
+ fn_sig
+ }
+ None => <dyn AstConv<'_>>::ty_of_fn(
+ icx,
+ hir_id,
+ sig.header.unsafety,
+ sig.header.abi,
+ sig.decl,
+ Some(generics),
+ None,
+ ),
+ }
+}
+
+fn impl_trait_ref(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::TraitRef<'_>> {
+ let icx = ItemCtxt::new(tcx, def_id);
+ let item = tcx.hir().expect_item(def_id.expect_local());
+ match item.kind {
+ hir::ItemKind::Impl(ref impl_) => impl_.of_trait.as_ref().map(|ast_trait_ref| {
+ let selfty = tcx.type_of(def_id);
+ <dyn AstConv<'_>>::instantiate_mono_trait_ref(
+ &icx,
+ ast_trait_ref,
+ selfty,
+ check_impl_constness(tcx, impl_.constness, ast_trait_ref),
+ )
+ }),
+ _ => bug!(),
+ }
+}
+
+fn check_impl_constness(
+ tcx: TyCtxt<'_>,
+ constness: hir::Constness,
+ ast_trait_ref: &hir::TraitRef<'_>,
+) -> ty::BoundConstness {
+ match constness {
+ hir::Constness::Const => {
+ if let Some(trait_def_id) = ast_trait_ref.trait_def_id() && !tcx.has_attr(trait_def_id, sym::const_trait) {
+ let trait_name = tcx.item_name(trait_def_id).to_string();
+ tcx.sess.emit_err(errors::ConstImplForNonConstTrait {
+ trait_ref_span: ast_trait_ref.path.span,
+ trait_name,
+ local_trait_span: trait_def_id.as_local().map(|_| tcx.def_span(trait_def_id).shrink_to_lo()),
+ marking: (),
+ adding: (),
+ });
+ ty::BoundConstness::NotConst
+ } else {
+ ty::BoundConstness::ConstIfConst
+ }
+ },
+ hir::Constness::NotConst => ty::BoundConstness::NotConst,
+ }
+}
+
+fn impl_polarity(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ImplPolarity {
+ let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
+ let item = tcx.hir().expect_item(def_id.expect_local());
+ match &item.kind {
+ hir::ItemKind::Impl(hir::Impl {
+ polarity: hir::ImplPolarity::Negative(span),
+ of_trait,
+ ..
+ }) => {
+ if is_rustc_reservation {
+ let span = span.to(of_trait.as_ref().map_or(*span, |t| t.path.span));
+ tcx.sess.span_err(span, "reservation impls can't be negative");
+ }
+ ty::ImplPolarity::Negative
+ }
+ hir::ItemKind::Impl(hir::Impl {
+ polarity: hir::ImplPolarity::Positive,
+ of_trait: None,
+ ..
+ }) => {
+ if is_rustc_reservation {
+ tcx.sess.span_err(item.span, "reservation impls can't be inherent");
+ }
+ ty::ImplPolarity::Positive
+ }
+ hir::ItemKind::Impl(hir::Impl {
+ polarity: hir::ImplPolarity::Positive,
+ of_trait: Some(_),
+ ..
+ }) => {
+ if is_rustc_reservation {
+ ty::ImplPolarity::Reservation
+ } else {
+ ty::ImplPolarity::Positive
+ }
+ }
+ item => bug!("impl_polarity: {:?} not an impl", item),
+ }
+}
+
+/// Returns the early-bound lifetimes declared in this generics
+/// listing. For anything other than fns/methods, this is just all
+/// the lifetimes that are declared. For fns or methods, we have to
+/// screen out those that do not appear in any where-clauses etc using
+/// `resolve_lifetime::early_bound_lifetimes`.
+fn early_bound_lifetimes_from_generics<'a, 'tcx: 'a>(
+ tcx: TyCtxt<'tcx>,
+ generics: &'a hir::Generics<'a>,
+) -> impl Iterator<Item = &'a hir::GenericParam<'a>> + Captures<'tcx> {
+ generics.params.iter().filter(move |param| match param.kind {
+ GenericParamKind::Lifetime { .. } => !tcx.is_late_bound(param.hir_id),
+ _ => false,
+ })
+}
+
+/// Returns a list of type predicates for the definition with ID `def_id`, including inferred
+/// lifetime constraints. This includes all predicates returned by `explicit_predicates_of`, plus
+/// inferred constraints concerning which regions outlive other regions.
+#[instrument(level = "debug", skip(tcx))]
+fn predicates_defined_on(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
+ let mut result = tcx.explicit_predicates_of(def_id);
+ debug!("predicates_defined_on: explicit_predicates_of({:?}) = {:?}", def_id, result,);
+ let inferred_outlives = tcx.inferred_outlives_of(def_id);
+ if !inferred_outlives.is_empty() {
+ debug!(
+ "predicates_defined_on: inferred_outlives_of({:?}) = {:?}",
+ def_id, inferred_outlives,
+ );
+ if result.predicates.is_empty() {
+ result.predicates = inferred_outlives;
+ } else {
+ result.predicates = tcx
+ .arena
+ .alloc_from_iter(result.predicates.iter().chain(inferred_outlives).copied());
+ }
+ }
+
+ debug!("predicates_defined_on({:?}) = {:?}", def_id, result);
+ result
+}
+
+fn compute_sig_of_foreign_fn_decl<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ def_id: DefId,
+ decl: &'tcx hir::FnDecl<'tcx>,
+ abi: abi::Abi,
+) -> ty::PolyFnSig<'tcx> {
+ let unsafety = if abi == abi::Abi::RustIntrinsic {
+ intrinsic_operation_unsafety(tcx, def_id)
+ } else {
+ hir::Unsafety::Unsafe
+ };
+ let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
+ let fty = <dyn AstConv<'_>>::ty_of_fn(
+ &ItemCtxt::new(tcx, def_id),
+ hir_id,
+ unsafety,
+ abi,
+ decl,
+ None,
+ None,
+ );
+
+ // Feature gate SIMD types in FFI, since I am not sure that the
+ // ABIs are handled at all correctly. -huonw
+ if abi != abi::Abi::RustIntrinsic
+ && abi != abi::Abi::PlatformIntrinsic
+ && !tcx.features().simd_ffi
+ {
+ let check = |ast_ty: &hir::Ty<'_>, ty: Ty<'_>| {
+ if ty.is_simd() {
+ let snip = tcx
+ .sess
+ .source_map()
+ .span_to_snippet(ast_ty.span)
+ .map_or_else(|_| String::new(), |s| format!(" `{}`", s));
+ tcx.sess
+ .struct_span_err(
+ ast_ty.span,
+ &format!(
+ "use of SIMD type{} in FFI is highly experimental and \
+ may result in invalid code",
+ snip
+ ),
+ )
+ .help("add `#![feature(simd_ffi)]` to the crate attributes to enable")
+ .emit();
+ }
+ };
+ for (input, ty) in iter::zip(decl.inputs, fty.inputs().skip_binder()) {
+ check(input, *ty)
+ }
+ if let hir::FnRetTy::Return(ref ty) = decl.output {
+ check(ty, fty.output().skip_binder())
+ }
+ }
+
+ fty
+}
+
+fn is_foreign_item(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
+ match tcx.hir().get_if_local(def_id) {
+ Some(Node::ForeignItem(..)) => true,
+ Some(_) => false,
+ _ => bug!("is_foreign_item applied to non-local def-id {:?}", def_id),
+ }
+}
+
+fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind> {
+ match tcx.hir().get_if_local(def_id) {
+ Some(Node::Expr(&rustc_hir::Expr {
+ kind: rustc_hir::ExprKind::Closure(&rustc_hir::Closure { body, .. }),
+ ..
+ })) => tcx.hir().body(body).generator_kind(),
+ Some(_) => None,
+ _ => bug!("generator_kind applied to non-local def-id {:?}", def_id),
+ }
+}
+
+fn from_target_feature(
+ tcx: TyCtxt<'_>,
+ attr: &ast::Attribute,
+ supported_target_features: &FxHashMap<String, Option<Symbol>>,
+ target_features: &mut Vec<Symbol>,
+) {
+ let Some(list) = attr.meta_item_list() else { return };
+ let bad_item = |span| {
+ let msg = "malformed `target_feature` attribute input";
+ let code = "enable = \"..\"";
+ tcx.sess
+ .struct_span_err(span, msg)
+ .span_suggestion(span, "must be of the form", code, Applicability::HasPlaceholders)
+ .emit();
+ };
+ let rust_features = tcx.features();
+ for item in list {
+ // Only `enable = ...` is accepted in the meta-item list.
+ if !item.has_name(sym::enable) {
+ bad_item(item.span());
+ continue;
+ }
+
+ // Must be of the form `enable = "..."` (a string).
+ let Some(value) = item.value_str() else {
+ bad_item(item.span());
+ continue;
+ };
+
+ // We allow comma separation to enable multiple features.
+ target_features.extend(value.as_str().split(',').filter_map(|feature| {
+ let Some(feature_gate) = supported_target_features.get(feature) else {
+ let msg =
+ format!("the feature named `{}` is not valid for this target", feature);
+ let mut err = tcx.sess.struct_span_err(item.span(), &msg);
+ err.span_label(
+ item.span(),
+ format!("`{}` is not valid for this target", feature),
+ );
+ if let Some(stripped) = feature.strip_prefix('+') {
+ let valid = supported_target_features.contains_key(stripped);
+ if valid {
+ err.help("consider removing the leading `+` in the feature name");
+ }
+ }
+ err.emit();
+ return None;
+ };
+
+ // Only allow features whose feature gates have been enabled.
+ let allowed = match feature_gate.as_ref().copied() {
+ Some(sym::arm_target_feature) => rust_features.arm_target_feature,
+ Some(sym::hexagon_target_feature) => rust_features.hexagon_target_feature,
+ Some(sym::powerpc_target_feature) => rust_features.powerpc_target_feature,
+ Some(sym::mips_target_feature) => rust_features.mips_target_feature,
+ Some(sym::riscv_target_feature) => rust_features.riscv_target_feature,
+ Some(sym::avx512_target_feature) => rust_features.avx512_target_feature,
+ Some(sym::sse4a_target_feature) => rust_features.sse4a_target_feature,
+ Some(sym::tbm_target_feature) => rust_features.tbm_target_feature,
+ Some(sym::wasm_target_feature) => rust_features.wasm_target_feature,
+ Some(sym::cmpxchg16b_target_feature) => rust_features.cmpxchg16b_target_feature,
+ Some(sym::movbe_target_feature) => rust_features.movbe_target_feature,
+ Some(sym::rtm_target_feature) => rust_features.rtm_target_feature,
+ Some(sym::f16c_target_feature) => rust_features.f16c_target_feature,
+ Some(sym::ermsb_target_feature) => rust_features.ermsb_target_feature,
+ Some(sym::bpf_target_feature) => rust_features.bpf_target_feature,
+ Some(sym::aarch64_ver_target_feature) => rust_features.aarch64_ver_target_feature,
+ Some(name) => bug!("unknown target feature gate {}", name),
+ None => true,
+ };
+ if !allowed {
+ feature_err(
+ &tcx.sess.parse_sess,
+ feature_gate.unwrap(),
+ item.span(),
+ &format!("the target feature `{}` is currently unstable", feature),
+ )
+ .emit();
+ }
+ Some(Symbol::intern(feature))
+ }));
+ }
+}
+
+fn linkage_by_name(tcx: TyCtxt<'_>, def_id: LocalDefId, name: &str) -> Linkage {
+ use rustc_middle::mir::mono::Linkage::*;
+
+ // Use the names from src/llvm/docs/LangRef.rst here. Most types are only
+ // applicable to variable declarations and may not really make sense for
+ // Rust code in the first place but allow them anyway and trust that the
+ // user knows what they're doing. Who knows, unanticipated use cases may pop
+ // up in the future.
+ //
+ // ghost, dllimport, dllexport and linkonce_odr_autohide are not supported
+ // and don't have to be, LLVM treats them as no-ops.
+ match name {
+ "appending" => Appending,
+ "available_externally" => AvailableExternally,
+ "common" => Common,
+ "extern_weak" => ExternalWeak,
+ "external" => External,
+ "internal" => Internal,
+ "linkonce" => LinkOnceAny,
+ "linkonce_odr" => LinkOnceODR,
+ "private" => Private,
+ "weak" => WeakAny,
+ "weak_odr" => WeakODR,
+ _ => tcx.sess.span_fatal(tcx.def_span(def_id), "invalid linkage specified"),
+ }
+}
+
+fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: DefId) -> CodegenFnAttrs {
+ if cfg!(debug_assertions) {
+ let def_kind = tcx.def_kind(did);
+ assert!(
+ def_kind.has_codegen_attrs(),
+ "unexpected `def_kind` in `codegen_fn_attrs`: {def_kind:?}",
+ );
+ }
+
+ let did = did.expect_local();
+ let attrs = tcx.hir().attrs(tcx.hir().local_def_id_to_hir_id(did));
+ let mut codegen_fn_attrs = CodegenFnAttrs::new();
+ if tcx.should_inherit_track_caller(did) {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
+ }
+
+ let supported_target_features = tcx.supported_target_features(LOCAL_CRATE);
+
+ let mut inline_span = None;
+ let mut link_ordinal_span = None;
+ let mut no_sanitize_span = None;
+ for attr in attrs.iter() {
+ if attr.has_name(sym::cold) {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::COLD;
+ } else if attr.has_name(sym::rustc_allocator) {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR;
+ } else if attr.has_name(sym::ffi_returns_twice) {
+ if tcx.is_foreign_item(did) {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_RETURNS_TWICE;
+ } else {
+ // `#[ffi_returns_twice]` is only allowed `extern fn`s.
+ struct_span_err!(
+ tcx.sess,
+ attr.span,
+ E0724,
+ "`#[ffi_returns_twice]` may only be used on foreign functions"
+ )
+ .emit();
+ }
+ } else if attr.has_name(sym::ffi_pure) {
+ if tcx.is_foreign_item(did) {
+ if attrs.iter().any(|a| a.has_name(sym::ffi_const)) {
+ // `#[ffi_const]` functions cannot be `#[ffi_pure]`
+ struct_span_err!(
+ tcx.sess,
+ attr.span,
+ E0757,
+ "`#[ffi_const]` function cannot be `#[ffi_pure]`"
+ )
+ .emit();
+ } else {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_PURE;
+ }
+ } else {
+ // `#[ffi_pure]` is only allowed on foreign functions
+ struct_span_err!(
+ tcx.sess,
+ attr.span,
+ E0755,
+ "`#[ffi_pure]` may only be used on foreign functions"
+ )
+ .emit();
+ }
+ } else if attr.has_name(sym::ffi_const) {
+ if tcx.is_foreign_item(did) {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::FFI_CONST;
+ } else {
+ // `#[ffi_const]` is only allowed on foreign functions
+ struct_span_err!(
+ tcx.sess,
+ attr.span,
+ E0756,
+ "`#[ffi_const]` may only be used on foreign functions"
+ )
+ .emit();
+ }
+ } else if attr.has_name(sym::rustc_nounwind) {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
+ } else if attr.has_name(sym::rustc_reallocator) {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::REALLOCATOR;
+ } else if attr.has_name(sym::rustc_deallocator) {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::DEALLOCATOR;
+ } else if attr.has_name(sym::rustc_allocator_zeroed) {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::ALLOCATOR_ZEROED;
+ } else if attr.has_name(sym::naked) {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::NAKED;
+ } else if attr.has_name(sym::no_mangle) {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
+ } else if attr.has_name(sym::no_coverage) {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_COVERAGE;
+ } else if attr.has_name(sym::rustc_std_internal_symbol) {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
+ } else if attr.has_name(sym::used) {
+ let inner = attr.meta_item_list();
+ match inner.as_deref() {
+ Some([item]) if item.has_name(sym::linker) => {
+ if !tcx.features().used_with_arg {
+ feature_err(
+ &tcx.sess.parse_sess,
+ sym::used_with_arg,
+ attr.span,
+ "`#[used(linker)]` is currently unstable",
+ )
+ .emit();
+ }
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED_LINKER;
+ }
+ Some([item]) if item.has_name(sym::compiler) => {
+ if !tcx.features().used_with_arg {
+ feature_err(
+ &tcx.sess.parse_sess,
+ sym::used_with_arg,
+ attr.span,
+ "`#[used(compiler)]` is currently unstable",
+ )
+ .emit();
+ }
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::USED;
+ }
+ Some(_) => {
+ tcx.sess.emit_err(errors::ExpectedUsedSymbol { span: attr.span });
+ }
+ None => {
+ // Unfortunately, unconditionally using `llvm.used` causes
+ // issues in handling `.init_array` with the gold linker,
+ // but using `llvm.compiler.used` caused a nontrival amount
+ // of unintentional ecosystem breakage -- particularly on
+ // Mach-O targets.
+ //
+ // As a result, we emit `llvm.compiler.used` only on ELF
+ // targets. This is somewhat ad-hoc, but actually follows
+ // our pre-LLVM 13 behavior (prior to the ecosystem
+ // breakage), and seems to match `clang`'s behavior as well
+ // (both before and after LLVM 13), possibly because they
+ // have similar compatibility concerns to us. See
+ // https://github.com/rust-lang/rust/issues/47384#issuecomment-1019080146
+ // and following comments for some discussion of this, as
+ // well as the comments in `rustc_codegen_llvm` where these
+ // flags are handled.
+ //
+ // Anyway, to be clear: this is still up in the air
+ // somewhat, and is subject to change in the future (which
+ // is a good thing, because this would ideally be a bit
+ // more firmed up).
+ let is_like_elf = !(tcx.sess.target.is_like_osx
+ || tcx.sess.target.is_like_windows
+ || tcx.sess.target.is_like_wasm);
+ codegen_fn_attrs.flags |= if is_like_elf {
+ CodegenFnAttrFlags::USED
+ } else {
+ CodegenFnAttrFlags::USED_LINKER
+ };
+ }
+ }
+ } else if attr.has_name(sym::cmse_nonsecure_entry) {
+ if !matches!(tcx.fn_sig(did).abi(), abi::Abi::C { .. }) {
+ struct_span_err!(
+ tcx.sess,
+ attr.span,
+ E0776,
+ "`#[cmse_nonsecure_entry]` requires C ABI"
+ )
+ .emit();
+ }
+ if !tcx.sess.target.llvm_target.contains("thumbv8m") {
+ struct_span_err!(tcx.sess, attr.span, E0775, "`#[cmse_nonsecure_entry]` is only valid for targets with the TrustZone-M extension")
+ .emit();
+ }
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::CMSE_NONSECURE_ENTRY;
+ } else if attr.has_name(sym::thread_local) {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::THREAD_LOCAL;
+ } else if attr.has_name(sym::track_caller) {
+ if !tcx.is_closure(did.to_def_id()) && tcx.fn_sig(did).abi() != abi::Abi::Rust {
+ struct_span_err!(tcx.sess, attr.span, E0737, "`#[track_caller]` requires Rust ABI")
+ .emit();
+ }
+ if tcx.is_closure(did.to_def_id()) && !tcx.features().closure_track_caller {
+ feature_err(
+ &tcx.sess.parse_sess,
+ sym::closure_track_caller,
+ attr.span,
+ "`#[track_caller]` on closures is currently unstable",
+ )
+ .emit();
+ }
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::TRACK_CALLER;
+ } else if attr.has_name(sym::export_name) {
+ if let Some(s) = attr.value_str() {
+ if s.as_str().contains('\0') {
+ // `#[export_name = ...]` will be converted to a null-terminated string,
+ // so it may not contain any null characters.
+ struct_span_err!(
+ tcx.sess,
+ attr.span,
+ E0648,
+ "`export_name` may not contain null characters"
+ )
+ .emit();
+ }
+ codegen_fn_attrs.export_name = Some(s);
+ }
+ } else if attr.has_name(sym::target_feature) {
+ if !tcx.is_closure(did.to_def_id())
+ && tcx.fn_sig(did).unsafety() == hir::Unsafety::Normal
+ {
+ if tcx.sess.target.is_like_wasm || tcx.sess.opts.actually_rustdoc {
+ // The `#[target_feature]` attribute is allowed on
+ // WebAssembly targets on all functions, including safe
+ // ones. Other targets require that `#[target_feature]` is
+ // only applied to unsafe functions (pending the
+ // `target_feature_11` feature) because on most targets
+ // execution of instructions that are not supported is
+ // considered undefined behavior. For WebAssembly which is a
+ // 100% safe target at execution time it's not possible to
+ // execute undefined instructions, and even if a future
+ // feature was added in some form for this it would be a
+ // deterministic trap. There is no undefined behavior when
+ // executing WebAssembly so `#[target_feature]` is allowed
+ // on safe functions (but again, only for WebAssembly)
+ //
+ // Note that this is also allowed if `actually_rustdoc` so
+ // if a target is documenting some wasm-specific code then
+ // it's not spuriously denied.
+ } else if !tcx.features().target_feature_11 {
+ let mut err = feature_err(
+ &tcx.sess.parse_sess,
+ sym::target_feature_11,
+ attr.span,
+ "`#[target_feature(..)]` can only be applied to `unsafe` functions",
+ );
+ err.span_label(tcx.def_span(did), "not an `unsafe` function");
+ err.emit();
+ } else {
+ check_target_feature_trait_unsafe(tcx, did, attr.span);
+ }
+ }
+ from_target_feature(
+ tcx,
+ attr,
+ supported_target_features,
+ &mut codegen_fn_attrs.target_features,
+ );
+ } else if attr.has_name(sym::linkage) {
+ if let Some(val) = attr.value_str() {
+ codegen_fn_attrs.linkage = Some(linkage_by_name(tcx, did, val.as_str()));
+ }
+ } else if attr.has_name(sym::link_section) {
+ if let Some(val) = attr.value_str() {
+ if val.as_str().bytes().any(|b| b == 0) {
+ let msg = format!(
+ "illegal null byte in link_section \
+ value: `{}`",
+ &val
+ );
+ tcx.sess.span_err(attr.span, &msg);
+ } else {
+ codegen_fn_attrs.link_section = Some(val);
+ }
+ }
+ } else if attr.has_name(sym::link_name) {
+ codegen_fn_attrs.link_name = attr.value_str();
+ } else if attr.has_name(sym::link_ordinal) {
+ link_ordinal_span = Some(attr.span);
+ if let ordinal @ Some(_) = check_link_ordinal(tcx, attr) {
+ codegen_fn_attrs.link_ordinal = ordinal;
+ }
+ } else if attr.has_name(sym::no_sanitize) {
+ no_sanitize_span = Some(attr.span);
+ if let Some(list) = attr.meta_item_list() {
+ for item in list.iter() {
+ if item.has_name(sym::address) {
+ codegen_fn_attrs.no_sanitize |= SanitizerSet::ADDRESS;
+ } else if item.has_name(sym::cfi) {
+ codegen_fn_attrs.no_sanitize |= SanitizerSet::CFI;
+ } else if item.has_name(sym::memory) {
+ codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMORY;
+ } else if item.has_name(sym::memtag) {
+ codegen_fn_attrs.no_sanitize |= SanitizerSet::MEMTAG;
+ } else if item.has_name(sym::shadow_call_stack) {
+ codegen_fn_attrs.no_sanitize |= SanitizerSet::SHADOWCALLSTACK;
+ } else if item.has_name(sym::thread) {
+ codegen_fn_attrs.no_sanitize |= SanitizerSet::THREAD;
+ } else if item.has_name(sym::hwaddress) {
+ codegen_fn_attrs.no_sanitize |= SanitizerSet::HWADDRESS;
+ } else {
+ tcx.sess
+ .struct_span_err(item.span(), "invalid argument for `no_sanitize`")
+ .note("expected one of: `address`, `cfi`, `hwaddress`, `memory`, `memtag`, `shadow-call-stack`, or `thread`")
+ .emit();
+ }
+ }
+ }
+ } else if attr.has_name(sym::instruction_set) {
+ codegen_fn_attrs.instruction_set = match attr.meta_kind() {
+ Some(MetaItemKind::List(ref items)) => match items.as_slice() {
+ [NestedMetaItem::MetaItem(set)] => {
+ let segments =
+ set.path.segments.iter().map(|x| x.ident.name).collect::<Vec<_>>();
+ match segments.as_slice() {
+ [sym::arm, sym::a32] | [sym::arm, sym::t32] => {
+ if !tcx.sess.target.has_thumb_interworking {
+ struct_span_err!(
+ tcx.sess.diagnostic(),
+ attr.span,
+ E0779,
+ "target does not support `#[instruction_set]`"
+ )
+ .emit();
+ None
+ } else if segments[1] == sym::a32 {
+ Some(InstructionSetAttr::ArmA32)
+ } else if segments[1] == sym::t32 {
+ Some(InstructionSetAttr::ArmT32)
+ } else {
+ unreachable!()
+ }
+ }
+ _ => {
+ struct_span_err!(
+ tcx.sess.diagnostic(),
+ attr.span,
+ E0779,
+ "invalid instruction set specified",
+ )
+ .emit();
+ None
+ }
+ }
+ }
+ [] => {
+ struct_span_err!(
+ tcx.sess.diagnostic(),
+ attr.span,
+ E0778,
+ "`#[instruction_set]` requires an argument"
+ )
+ .emit();
+ None
+ }
+ _ => {
+ struct_span_err!(
+ tcx.sess.diagnostic(),
+ attr.span,
+ E0779,
+ "cannot specify more than one instruction set"
+ )
+ .emit();
+ None
+ }
+ },
+ _ => {
+ struct_span_err!(
+ tcx.sess.diagnostic(),
+ attr.span,
+ E0778,
+ "must specify an instruction set"
+ )
+ .emit();
+ None
+ }
+ };
+ } else if attr.has_name(sym::repr) {
+ codegen_fn_attrs.alignment = match attr.meta_item_list() {
+ Some(items) => match items.as_slice() {
+ [item] => match item.name_value_literal() {
+ Some((sym::align, literal)) => {
+ let alignment = rustc_attr::parse_alignment(&literal.kind);
+
+ match alignment {
+ Ok(align) => Some(align),
+ Err(msg) => {
+ struct_span_err!(
+ tcx.sess.diagnostic(),
+ attr.span,
+ E0589,
+ "invalid `repr(align)` attribute: {}",
+ msg
+ )
+ .emit();
+
+ None
+ }
+ }
+ }
+ _ => None,
+ },
+ [] => None,
+ _ => None,
+ },
+ None => None,
+ };
+ }
+ }
+
+ codegen_fn_attrs.inline = attrs.iter().fold(InlineAttr::None, |ia, attr| {
+ if !attr.has_name(sym::inline) {
+ return ia;
+ }
+ match attr.meta_kind() {
+ Some(MetaItemKind::Word) => InlineAttr::Hint,
+ Some(MetaItemKind::List(ref items)) => {
+ inline_span = Some(attr.span);
+ if items.len() != 1 {
+ struct_span_err!(
+ tcx.sess.diagnostic(),
+ attr.span,
+ E0534,
+ "expected one argument"
+ )
+ .emit();
+ InlineAttr::None
+ } else if list_contains_name(&items, sym::always) {
+ InlineAttr::Always
+ } else if list_contains_name(&items, sym::never) {
+ InlineAttr::Never
+ } else {
+ struct_span_err!(
+ tcx.sess.diagnostic(),
+ items[0].span(),
+ E0535,
+ "invalid argument"
+ )
+ .help("valid inline arguments are `always` and `never`")
+ .emit();
+
+ InlineAttr::None
+ }
+ }
+ Some(MetaItemKind::NameValue(_)) => ia,
+ None => ia,
+ }
+ });
+
+ codegen_fn_attrs.optimize = attrs.iter().fold(OptimizeAttr::None, |ia, attr| {
+ if !attr.has_name(sym::optimize) {
+ return ia;
+ }
+ let err = |sp, s| struct_span_err!(tcx.sess.diagnostic(), sp, E0722, "{}", s).emit();
+ match attr.meta_kind() {
+ Some(MetaItemKind::Word) => {
+ err(attr.span, "expected one argument");
+ ia
+ }
+ Some(MetaItemKind::List(ref items)) => {
+ inline_span = Some(attr.span);
+ if items.len() != 1 {
+ err(attr.span, "expected one argument");
+ OptimizeAttr::None
+ } else if list_contains_name(&items, sym::size) {
+ OptimizeAttr::Size
+ } else if list_contains_name(&items, sym::speed) {
+ OptimizeAttr::Speed
+ } else {
+ err(items[0].span(), "invalid argument");
+ OptimizeAttr::None
+ }
+ }
+ Some(MetaItemKind::NameValue(_)) => ia,
+ None => ia,
+ }
+ });
+
+ // #73631: closures inherit `#[target_feature]` annotations
+ if tcx.features().target_feature_11 && tcx.is_closure(did.to_def_id()) {
+ let owner_id = tcx.parent(did.to_def_id());
+ if tcx.def_kind(owner_id).has_codegen_attrs() {
+ codegen_fn_attrs
+ .target_features
+ .extend(tcx.codegen_fn_attrs(owner_id).target_features.iter().copied());
+ }
+ }
+
+ // If a function uses #[target_feature] it can't be inlined into general
+ // purpose functions as they wouldn't have the right target features
+ // enabled. For that reason we also forbid #[inline(always)] as it can't be
+ // respected.
+ if !codegen_fn_attrs.target_features.is_empty() {
+ if codegen_fn_attrs.inline == InlineAttr::Always {
+ if let Some(span) = inline_span {
+ tcx.sess.span_err(
+ span,
+ "cannot use `#[inline(always)]` with \
+ `#[target_feature]`",
+ );
+ }
+ }
+ }
+
+ if !codegen_fn_attrs.no_sanitize.is_empty() {
+ if codegen_fn_attrs.inline == InlineAttr::Always {
+ if let (Some(no_sanitize_span), Some(inline_span)) = (no_sanitize_span, inline_span) {
+ let hir_id = tcx.hir().local_def_id_to_hir_id(did);
+ tcx.struct_span_lint_hir(
+ lint::builtin::INLINE_NO_SANITIZE,
+ hir_id,
+ no_sanitize_span,
+ "`no_sanitize` will have no effect after inlining",
+ |lint| lint.span_note(inline_span, "inlining requested here"),
+ )
+ }
+ }
+ }
+
+ // Weak lang items have the same semantics as "std internal" symbols in the
+ // sense that they're preserved through all our LTO passes and only
+ // strippable by the linker.
+ //
+ // Additionally weak lang items have predetermined symbol names.
+ if tcx.is_weak_lang_item(did.to_def_id()) {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL;
+ }
+ if let Some(name) = weak_lang_items::link_name(attrs) {
+ codegen_fn_attrs.export_name = Some(name);
+ codegen_fn_attrs.link_name = Some(name);
+ }
+ check_link_name_xor_ordinal(tcx, &codegen_fn_attrs, link_ordinal_span);
+
+ // Internal symbols to the standard library all have no_mangle semantics in
+ // that they have defined symbol names present in the function name. This
+ // also applies to weak symbols where they all have known symbol names.
+ if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_MANGLE;
+ }
+
+ // Any linkage to LLVM intrinsics for now forcibly marks them all as never
+ // unwinds since LLVM sometimes can't handle codegen which `invoke`s
+ // intrinsic functions.
+ if let Some(name) = &codegen_fn_attrs.link_name {
+ if name.as_str().starts_with("llvm.") {
+ codegen_fn_attrs.flags |= CodegenFnAttrFlags::NEVER_UNWIND;
+ }
+ }
+
+ codegen_fn_attrs
+}
+
+/// Computes the set of target features used in a function for the purposes of
+/// inline assembly.
+fn asm_target_features<'tcx>(tcx: TyCtxt<'tcx>, did: DefId) -> &'tcx FxHashSet<Symbol> {
+ let mut target_features = tcx.sess.unstable_target_features.clone();
+ if tcx.def_kind(did).has_codegen_attrs() {
+ let attrs = tcx.codegen_fn_attrs(did);
+ target_features.extend(&attrs.target_features);
+ match attrs.instruction_set {
+ None => {}
+ Some(InstructionSetAttr::ArmA32) => {
+ target_features.remove(&sym::thumb_mode);
+ }
+ Some(InstructionSetAttr::ArmT32) => {
+ target_features.insert(sym::thumb_mode);
+ }
+ }
+ }
+
+ tcx.arena.alloc(target_features)
+}
+
+/// Checks if the provided DefId is a method in a trait impl for a trait which has track_caller
+/// applied to the method prototype.
+fn should_inherit_track_caller(tcx: TyCtxt<'_>, def_id: DefId) -> bool {
+ if let Some(impl_item) = tcx.opt_associated_item(def_id)
+ && let ty::AssocItemContainer::ImplContainer = impl_item.container
+ && let Some(trait_item) = impl_item.trait_item_def_id
+ {
+ return tcx
+ .codegen_fn_attrs(trait_item)
+ .flags
+ .intersects(CodegenFnAttrFlags::TRACK_CALLER);
+ }
+
+ false
+}
+
+fn check_link_ordinal(tcx: TyCtxt<'_>, attr: &ast::Attribute) -> Option<u16> {
+ use rustc_ast::{Lit, LitIntType, LitKind};
+ if !tcx.features().raw_dylib && tcx.sess.target.arch == "x86" {
+ feature_err(
+ &tcx.sess.parse_sess,
+ sym::raw_dylib,
+ attr.span,
+ "`#[link_ordinal]` is unstable on x86",
+ )
+ .emit();
+ }
+ let meta_item_list = attr.meta_item_list();
+ let meta_item_list: Option<&[ast::NestedMetaItem]> = meta_item_list.as_ref().map(Vec::as_ref);
+ let sole_meta_list = match meta_item_list {
+ Some([item]) => item.literal(),
+ Some(_) => {
+ tcx.sess
+ .struct_span_err(attr.span, "incorrect number of arguments to `#[link_ordinal]`")
+ .note("the attribute requires exactly one argument")
+ .emit();
+ return None;
+ }
+ _ => None,
+ };
+ if let Some(Lit { kind: LitKind::Int(ordinal, LitIntType::Unsuffixed), .. }) = sole_meta_list {
+ // According to the table at https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#import-header,
+ // the ordinal must fit into 16 bits. Similarly, the Ordinal field in COFFShortExport (defined
+ // in llvm/include/llvm/Object/COFFImportFile.h), which we use to communicate import information
+ // to LLVM for `#[link(kind = "raw-dylib"_])`, is also defined to be uint16_t.
+ //
+ // FIXME: should we allow an ordinal of 0? The MSVC toolchain has inconsistent support for this:
+ // both LINK.EXE and LIB.EXE signal errors and abort when given a .DEF file that specifies
+ // a zero ordinal. However, llvm-dlltool is perfectly happy to generate an import library
+ // for such a .DEF file, and MSVC's LINK.EXE is also perfectly happy to consume an import
+ // library produced by LLVM with an ordinal of 0, and it generates an .EXE. (I don't know yet
+ // if the resulting EXE runs, as I haven't yet built the necessary DLL -- see earlier comment
+ // about LINK.EXE failing.)
+ if *ordinal <= u16::MAX as u128 {
+ Some(*ordinal as u16)
+ } else {
+ let msg = format!("ordinal value in `link_ordinal` is too large: `{}`", &ordinal);
+ tcx.sess
+ .struct_span_err(attr.span, &msg)
+ .note("the value may not exceed `u16::MAX`")
+ .emit();
+ None
+ }
+ } else {
+ tcx.sess
+ .struct_span_err(attr.span, "illegal ordinal format in `link_ordinal`")
+ .note("an unsuffixed integer value, e.g., `1`, is expected")
+ .emit();
+ None
+ }
+}
+
+fn check_link_name_xor_ordinal(
+ tcx: TyCtxt<'_>,
+ codegen_fn_attrs: &CodegenFnAttrs,
+ inline_span: Option<Span>,
+) {
+ if codegen_fn_attrs.link_name.is_none() || codegen_fn_attrs.link_ordinal.is_none() {
+ return;
+ }
+ let msg = "cannot use `#[link_name]` with `#[link_ordinal]`";
+ if let Some(span) = inline_span {
+ tcx.sess.span_err(span, msg);
+ } else {
+ tcx.sess.err(msg);
+ }
+}
+
+/// Checks the function annotated with `#[target_feature]` is not a safe
+/// trait method implementation, reporting an error if it is.
+fn check_target_feature_trait_unsafe(tcx: TyCtxt<'_>, id: LocalDefId, attr_span: Span) {
+ let hir_id = tcx.hir().local_def_id_to_hir_id(id);
+ let node = tcx.hir().get(hir_id);
+ if let Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) = node {
+ let parent_id = tcx.hir().get_parent_item(hir_id);
+ let parent_item = tcx.hir().expect_item(parent_id.def_id);
+ if let hir::ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) = parent_item.kind {
+ tcx.sess
+ .struct_span_err(
+ attr_span,
+ "`#[target_feature(..)]` cannot be applied to safe trait method",
+ )
+ .span_label(attr_span, "cannot be applied to safe trait method")
+ .span_label(tcx.def_span(id), "not an `unsafe` function")
+ .emit();
+ }
+ }
+}
diff --git a/compiler/rustc_hir_analysis/src/collect/generics_of.rs b/compiler/rustc_hir_analysis/src/collect/generics_of.rs
new file mode 100644
index 000000000..c7777a946
--- /dev/null
+++ b/compiler/rustc_hir_analysis/src/collect/generics_of.rs
@@ -0,0 +1,481 @@
+use crate::middle::resolve_lifetime as rl;
+use hir::{
+ intravisit::{self, Visitor},
+ GenericParamKind, HirId, Node,
+};
+use rustc_hir as hir;
+use rustc_hir::def::DefKind;
+use rustc_hir::def_id::DefId;
+use rustc_middle::ty::{self, TyCtxt};
+use rustc_session::lint;
+use rustc_span::symbol::{kw, Symbol};
+use rustc_span::Span;
+
+pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::Generics {
+ use rustc_hir::*;
+
+ let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
+
+ let node = tcx.hir().get(hir_id);
+ let parent_def_id = match node {
+ Node::ImplItem(_)
+ | Node::TraitItem(_)
+ | Node::Variant(_)
+ | Node::Ctor(..)
+ | Node::Field(_) => {
+ let parent_id = tcx.hir().get_parent_item(hir_id);
+ Some(parent_id.to_def_id())
+ }
+ // FIXME(#43408) always enable this once `lazy_normalization` is
+ // stable enough and does not need a feature gate anymore.
+ Node::AnonConst(_) => {
+ let parent_def_id = tcx.hir().get_parent_item(hir_id);
+
+ let mut in_param_ty = false;
+ for (_parent, node) in tcx.hir().parent_iter(hir_id) {
+ if let Some(generics) = node.generics() {
+ let mut visitor = AnonConstInParamTyDetector {
+ in_param_ty: false,
+ found_anon_const_in_param_ty: false,
+ ct: hir_id,
+ };
+
+ visitor.visit_generics(generics);
+ in_param_ty = visitor.found_anon_const_in_param_ty;
+ break;
+ }
+ }
+
+ if in_param_ty {
+ // We do not allow generic parameters in anon consts if we are inside
+ // of a const parameter type, e.g. `struct Foo<const N: usize, const M: [u8; N]>` is not allowed.
+ None
+ } else if tcx.lazy_normalization() {
+ if let Some(param_id) = tcx.hir().opt_const_param_default_param_hir_id(hir_id) {
+ // If the def_id we are calling generics_of on is an anon ct default i.e:
+ //
+ // struct Foo<const N: usize = { .. }>;
+ // ^^^ ^ ^^^^^^ def id of this anon const
+ // ^ ^ param_id
+ // ^ parent_def_id
+ //
+ // then we only want to return generics for params to the left of `N`. If we don't do that we
+ // end up with that const looking like: `ty::ConstKind::Unevaluated(def_id, substs: [N#0])`.
+ //
+ // This causes ICEs (#86580) when building the substs for Foo in `fn foo() -> Foo { .. }` as
+ // we substitute the defaults with the partially built substs when we build the substs. Subst'ing
+ // the `N#0` on the unevaluated const indexes into the empty substs we're in the process of building.
+ //
+ // We fix this by having this function return the parent's generics ourselves and truncating the
+ // generics to only include non-forward declared params (with the exception of the `Self` ty)
+ //
+ // For the above code example that means we want `substs: []`
+ // For the following struct def we want `substs: [N#0]` when generics_of is called on
+ // the def id of the `{ N + 1 }` anon const
+ // struct Foo<const N: usize, const M: usize = { N + 1 }>;
+ //
+ // This has some implications for how we get the predicates available to the anon const
+ // see `explicit_predicates_of` for more information on this
+ let generics = tcx.generics_of(parent_def_id.to_def_id());
+ let param_def = tcx.hir().local_def_id(param_id).to_def_id();
+ let param_def_idx = generics.param_def_id_to_index[&param_def];
+ // In the above example this would be .params[..N#0]
+ let params = generics.params[..param_def_idx as usize].to_owned();
+ let param_def_id_to_index =
+ params.iter().map(|param| (param.def_id, param.index)).collect();
+
+ return ty::Generics {
+ // we set the parent of these generics to be our parent's parent so that we
+ // dont end up with substs: [N, M, N] for the const default on a struct like this:
+ // struct Foo<const N: usize, const M: usize = { ... }>;
+ parent: generics.parent,
+ parent_count: generics.parent_count,
+ params,
+ param_def_id_to_index,
+ has_self: generics.has_self,
+ has_late_bound_regions: generics.has_late_bound_regions,
+ };
+ }
+
+ // HACK(eddyb) this provides the correct generics when
+ // `feature(generic_const_expressions)` is enabled, so that const expressions
+ // used with const generics, e.g. `Foo<{N+1}>`, can work at all.
+ //
+ // Note that we do not supply the parent generics when using
+ // `min_const_generics`.
+ Some(parent_def_id.to_def_id())
+ } else {
+ let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
+ match parent_node {
+ // HACK(eddyb) this provides the correct generics for repeat
+ // expressions' count (i.e. `N` in `[x; N]`), and explicit
+ // `enum` discriminants (i.e. `D` in `enum Foo { Bar = D }`),
+ // as they shouldn't be able to cause query cycle errors.
+ Node::Expr(&Expr { kind: ExprKind::Repeat(_, ref constant), .. })
+ if constant.hir_id() == hir_id =>
+ {
+ Some(parent_def_id.to_def_id())
+ }
+ Node::Variant(Variant { disr_expr: Some(ref constant), .. })
+ if constant.hir_id == hir_id =>
+ {
+ Some(parent_def_id.to_def_id())
+ }
+ Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) => {
+ Some(tcx.typeck_root_def_id(def_id))
+ }
+ // Exclude `GlobalAsm` here which cannot have generics.
+ Node::Expr(&Expr { kind: ExprKind::InlineAsm(asm), .. })
+ if asm.operands.iter().any(|(op, _op_sp)| match op {
+ hir::InlineAsmOperand::Const { anon_const }
+ | hir::InlineAsmOperand::SymFn { anon_const } => {
+ anon_const.hir_id == hir_id
+ }
+ _ => false,
+ }) =>
+ {
+ Some(parent_def_id.to_def_id())
+ }
+ _ => None,
+ }
+ }
+ }
+ Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure { .. }, .. }) => {
+ Some(tcx.typeck_root_def_id(def_id))
+ }
+ Node::Item(item) => match item.kind {
+ ItemKind::OpaqueTy(hir::OpaqueTy {
+ origin:
+ hir::OpaqueTyOrigin::FnReturn(fn_def_id) | hir::OpaqueTyOrigin::AsyncFn(fn_def_id),
+ in_trait,
+ ..
+ }) => {
+ if in_trait {
+ assert!(matches!(tcx.def_kind(fn_def_id), DefKind::AssocFn))
+ } else {
+ assert!(matches!(tcx.def_kind(fn_def_id), DefKind::AssocFn | DefKind::Fn))
+ }
+ Some(fn_def_id.to_def_id())
+ }
+ ItemKind::OpaqueTy(hir::OpaqueTy { origin: hir::OpaqueTyOrigin::TyAlias, .. }) => {
+ let parent_id = tcx.hir().get_parent_item(hir_id);
+ assert_ne!(parent_id, hir::CRATE_OWNER_ID);
+ debug!("generics_of: parent of opaque ty {:?} is {:?}", def_id, parent_id);
+ // Opaque types are always nested within another item, and
+ // inherit the generics of the item.
+ Some(parent_id.to_def_id())
+ }
+ _ => None,
+ },
+ _ => None,
+ };
+
+ enum Defaults {
+ Allowed,
+ // See #36887
+ FutureCompatDisallowed,
+ Deny,
+ }
+
+ let no_generics = hir::Generics::empty();
+ let ast_generics = node.generics().unwrap_or(&no_generics);
+ let (opt_self, allow_defaults) = match node {
+ Node::Item(item) => {
+ match item.kind {
+ ItemKind::Trait(..) | ItemKind::TraitAlias(..) => {
+ // Add in the self type parameter.
+ //
+ // Something of a hack: use the node id for the trait, also as
+ // the node id for the Self type parameter.
+ let opt_self = Some(ty::GenericParamDef {
+ index: 0,
+ name: kw::SelfUpper,
+ def_id,
+ pure_wrt_drop: false,
+ kind: ty::GenericParamDefKind::Type {
+ has_default: false,
+ synthetic: false,
+ },
+ });
+
+ (opt_self, Defaults::Allowed)
+ }
+ ItemKind::TyAlias(..)
+ | ItemKind::Enum(..)
+ | ItemKind::Struct(..)
+ | ItemKind::OpaqueTy(..)
+ | ItemKind::Union(..) => (None, Defaults::Allowed),
+ _ => (None, Defaults::FutureCompatDisallowed),
+ }
+ }
+
+ // GATs
+ Node::TraitItem(item) if matches!(item.kind, TraitItemKind::Type(..)) => {
+ (None, Defaults::Deny)
+ }
+ Node::ImplItem(item) if matches!(item.kind, ImplItemKind::Type(..)) => {
+ (None, Defaults::Deny)
+ }
+
+ _ => (None, Defaults::FutureCompatDisallowed),
+ };
+
+ let has_self = opt_self.is_some();
+ let mut parent_has_self = false;
+ let mut own_start = has_self as u32;
+ let parent_count = parent_def_id.map_or(0, |def_id| {
+ let generics = tcx.generics_of(def_id);
+ assert!(!has_self);
+ parent_has_self = generics.has_self;
+ own_start = generics.count() as u32;
+ generics.parent_count + generics.params.len()
+ });
+
+ let mut params: Vec<_> = Vec::with_capacity(ast_generics.params.len() + has_self as usize);
+
+ if let Some(opt_self) = opt_self {
+ params.push(opt_self);
+ }
+
+ let early_lifetimes = super::early_bound_lifetimes_from_generics(tcx, ast_generics);
+ params.extend(early_lifetimes.enumerate().map(|(i, param)| ty::GenericParamDef {
+ name: param.name.ident().name,
+ index: own_start + i as u32,
+ def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
+ pure_wrt_drop: param.pure_wrt_drop,
+ kind: ty::GenericParamDefKind::Lifetime,
+ }));
+
+ // Now create the real type and const parameters.
+ let type_start = own_start - has_self as u32 + params.len() as u32;
+ let mut i = 0;
+ let mut next_index = || {
+ let prev = i;
+ i += 1;
+ prev as u32 + type_start
+ };
+
+ const TYPE_DEFAULT_NOT_ALLOWED: &'static str = "defaults for type parameters are only allowed in \
+ `struct`, `enum`, `type`, or `trait` definitions";
+
+ params.extend(ast_generics.params.iter().filter_map(|param| match param.kind {
+ GenericParamKind::Lifetime { .. } => None,
+ GenericParamKind::Type { ref default, synthetic, .. } => {
+ if default.is_some() {
+ match allow_defaults {
+ Defaults::Allowed => {}
+ Defaults::FutureCompatDisallowed
+ if tcx.features().default_type_parameter_fallback => {}
+ Defaults::FutureCompatDisallowed => {
+ tcx.struct_span_lint_hir(
+ lint::builtin::INVALID_TYPE_PARAM_DEFAULT,
+ param.hir_id,
+ param.span,
+ TYPE_DEFAULT_NOT_ALLOWED,
+ |lint| lint,
+ );
+ }
+ Defaults::Deny => {
+ tcx.sess.span_err(param.span, TYPE_DEFAULT_NOT_ALLOWED);
+ }
+ }
+ }
+
+ let kind = ty::GenericParamDefKind::Type { has_default: default.is_some(), synthetic };
+
+ Some(ty::GenericParamDef {
+ index: next_index(),
+ name: param.name.ident().name,
+ def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
+ pure_wrt_drop: param.pure_wrt_drop,
+ kind,
+ })
+ }
+ GenericParamKind::Const { default, .. } => {
+ if !matches!(allow_defaults, Defaults::Allowed) && default.is_some() {
+ tcx.sess.span_err(
+ param.span,
+ "defaults for const parameters are only allowed in \
+ `struct`, `enum`, `type`, or `trait` definitions",
+ );
+ }
+
+ Some(ty::GenericParamDef {
+ index: next_index(),
+ name: param.name.ident().name,
+ def_id: tcx.hir().local_def_id(param.hir_id).to_def_id(),
+ pure_wrt_drop: param.pure_wrt_drop,
+ kind: ty::GenericParamDefKind::Const { has_default: default.is_some() },
+ })
+ }
+ }));
+
+ // provide junk type parameter defs - the only place that
+ // cares about anything but the length is instantiation,
+ // and we don't do that for closures.
+ if let Node::Expr(&hir::Expr {
+ kind: hir::ExprKind::Closure(hir::Closure { movability: gen, .. }),
+ ..
+ }) = node
+ {
+ let dummy_args = if gen.is_some() {
+ &["<resume_ty>", "<yield_ty>", "<return_ty>", "<witness>", "<upvars>"][..]
+ } else {
+ &["<closure_kind>", "<closure_signature>", "<upvars>"][..]
+ };
+
+ params.extend(dummy_args.iter().map(|&arg| ty::GenericParamDef {
+ index: next_index(),
+ name: Symbol::intern(arg),
+ def_id,
+ pure_wrt_drop: false,
+ kind: ty::GenericParamDefKind::Type { has_default: false, synthetic: false },
+ }));
+ }
+
+ // provide junk type parameter defs for const blocks.
+ if let Node::AnonConst(_) = node {
+ let parent_node = tcx.hir().get(tcx.hir().get_parent_node(hir_id));
+ if let Node::Expr(&Expr { kind: ExprKind::ConstBlock(_), .. }) = parent_node {
+ params.push(ty::GenericParamDef {
+ index: next_index(),
+ name: Symbol::intern("<const_ty>"),
+ def_id,
+ pure_wrt_drop: false,
+ kind: ty::GenericParamDefKind::Type { has_default: false, synthetic: false },
+ });
+ }
+ }
+
+ let param_def_id_to_index = params.iter().map(|param| (param.def_id, param.index)).collect();
+
+ ty::Generics {
+ parent: parent_def_id,
+ parent_count,
+ params,
+ param_def_id_to_index,
+ has_self: has_self || parent_has_self,
+ has_late_bound_regions: has_late_bound_regions(tcx, node),
+ }
+}
+
+fn has_late_bound_regions<'tcx>(tcx: TyCtxt<'tcx>, node: Node<'tcx>) -> Option<Span> {
+ struct LateBoundRegionsDetector<'tcx> {
+ tcx: TyCtxt<'tcx>,
+ outer_index: ty::DebruijnIndex,
+ has_late_bound_regions: Option<Span>,
+ }
+
+ impl<'tcx> Visitor<'tcx> for LateBoundRegionsDetector<'tcx> {
+ fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
+ if self.has_late_bound_regions.is_some() {
+ return;
+ }
+ match ty.kind {
+ hir::TyKind::BareFn(..) => {
+ self.outer_index.shift_in(1);
+ intravisit::walk_ty(self, ty);
+ self.outer_index.shift_out(1);
+ }
+ _ => intravisit::walk_ty(self, ty),
+ }
+ }
+
+ fn visit_poly_trait_ref(&mut self, tr: &'tcx hir::PolyTraitRef<'tcx>) {
+ if self.has_late_bound_regions.is_some() {
+ return;
+ }
+ self.outer_index.shift_in(1);
+ intravisit::walk_poly_trait_ref(self, tr);
+ self.outer_index.shift_out(1);
+ }
+
+ fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
+ if self.has_late_bound_regions.is_some() {
+ return;
+ }
+
+ match self.tcx.named_region(lt.hir_id) {
+ Some(rl::Region::Static | rl::Region::EarlyBound(..)) => {}
+ Some(rl::Region::LateBound(debruijn, _, _)) if debruijn < self.outer_index => {}
+ Some(rl::Region::LateBound(..) | rl::Region::Free(..)) | None => {
+ self.has_late_bound_regions = Some(lt.span);
+ }
+ }
+ }
+ }
+
+ fn has_late_bound_regions<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ generics: &'tcx hir::Generics<'tcx>,
+ decl: &'tcx hir::FnDecl<'tcx>,
+ ) -> Option<Span> {
+ let mut visitor = LateBoundRegionsDetector {
+ tcx,
+ outer_index: ty::INNERMOST,
+ has_late_bound_regions: None,
+ };
+ for param in generics.params {
+ if let GenericParamKind::Lifetime { .. } = param.kind {
+ if tcx.is_late_bound(param.hir_id) {
+ return Some(param.span);
+ }
+ }
+ }
+ visitor.visit_fn_decl(decl);
+ visitor.has_late_bound_regions
+ }
+
+ match node {
+ Node::TraitItem(item) => match item.kind {
+ hir::TraitItemKind::Fn(ref sig, _) => {
+ has_late_bound_regions(tcx, &item.generics, sig.decl)
+ }
+ _ => None,
+ },
+ Node::ImplItem(item) => match item.kind {
+ hir::ImplItemKind::Fn(ref sig, _) => {
+ has_late_bound_regions(tcx, &item.generics, sig.decl)
+ }
+ _ => None,
+ },
+ Node::ForeignItem(item) => match item.kind {
+ hir::ForeignItemKind::Fn(fn_decl, _, ref generics) => {
+ has_late_bound_regions(tcx, generics, fn_decl)
+ }
+ _ => None,
+ },
+ Node::Item(item) => match item.kind {
+ hir::ItemKind::Fn(ref sig, .., ref generics, _) => {
+ has_late_bound_regions(tcx, generics, sig.decl)
+ }
+ _ => None,
+ },
+ _ => None,
+ }
+}
+
+struct AnonConstInParamTyDetector {
+ in_param_ty: bool,
+ found_anon_const_in_param_ty: bool,
+ ct: HirId,
+}
+
+impl<'v> Visitor<'v> for AnonConstInParamTyDetector {
+ fn visit_generic_param(&mut self, p: &'v hir::GenericParam<'v>) {
+ if let GenericParamKind::Const { ty, default: _ } = p.kind {
+ let prev = self.in_param_ty;
+ self.in_param_ty = true;
+ self.visit_ty(ty);
+ self.in_param_ty = prev;
+ }
+ }
+
+ fn visit_anon_const(&mut self, c: &'v hir::AnonConst) {
+ if self.in_param_ty && self.ct == c.hir_id {
+ self.found_anon_const_in_param_ty = true;
+ } else {
+ intravisit::walk_anon_const(self, c)
+ }
+ }
+}
diff --git a/compiler/rustc_typeck/src/collect/item_bounds.rs b/compiler/rustc_hir_analysis/src/collect/item_bounds.rs
index 0d2b75d33..0d34a8bfe 100644
--- a/compiler/rustc_typeck/src/collect/item_bounds.rs
+++ b/compiler/rustc_hir_analysis/src/collect/item_bounds.rs
@@ -53,20 +53,28 @@ fn associated_type_bounds<'tcx>(
/// impl trait it isn't possible to write a suitable predicate on the
/// containing function and for type-alias impl trait we don't have a backwards
/// compatibility issue.
+#[instrument(level = "trace", skip(tcx), ret)]
fn opaque_type_bounds<'tcx>(
tcx: TyCtxt<'tcx>,
opaque_def_id: DefId,
ast_bounds: &'tcx [hir::GenericBound<'tcx>],
span: Span,
+ in_trait: bool,
) -> &'tcx [(ty::Predicate<'tcx>, Span)] {
ty::print::with_no_queries!({
- let item_ty =
- tcx.mk_opaque(opaque_def_id, InternalSubsts::identity_for_item(tcx, opaque_def_id));
+ let substs = InternalSubsts::identity_for_item(tcx, opaque_def_id);
+ let item_ty = if in_trait {
+ tcx.mk_projection(opaque_def_id, substs)
+ } else {
+ tcx.mk_opaque(opaque_def_id, substs)
+ };
let icx = ItemCtxt::new(tcx, opaque_def_id);
let mut bounds = <dyn AstConv<'_>>::compute_bounds(&icx, item_ty, ast_bounds);
// Opaque types are implicitly sized unless a `?Sized` bound is found
<dyn AstConv<'_>>::add_implicitly_sized(&icx, &mut bounds, ast_bounds, None, span);
+ debug!(?bounds);
+
tcx.arena.alloc_from_iter(bounds.predicates(tcx, item_ty))
})
}
@@ -83,10 +91,10 @@ pub(super) fn explicit_item_bounds(
..
}) => associated_type_bounds(tcx, def_id, bounds, *span),
hir::Node::Item(hir::Item {
- kind: hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds, .. }),
+ kind: hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds, in_trait, .. }),
span,
..
- }) => opaque_type_bounds(tcx, def_id, bounds, *span),
+ }) => opaque_type_bounds(tcx, def_id, bounds, *span, *in_trait),
_ => bug!("item_bounds called on {:?}", def_id),
}
}
diff --git a/compiler/rustc_hir_analysis/src/collect/lifetimes.rs b/compiler/rustc_hir_analysis/src/collect/lifetimes.rs
new file mode 100644
index 000000000..3f263a6de
--- /dev/null
+++ b/compiler/rustc_hir_analysis/src/collect/lifetimes.rs
@@ -0,0 +1,1888 @@
+//! Resolution of early vs late bound lifetimes.
+//!
+//! Name resolution for lifetimes is performed on the AST and embedded into HIR. From this
+//! information, typechecking needs to transform the lifetime parameters into bound lifetimes.
+//! Lifetimes can be early-bound or late-bound. Construction of typechecking terms needs to visit
+//! the types in HIR to identify late-bound lifetimes and assign their Debruijn indices. This file
+//! is also responsible for assigning their semantics to implicit lifetimes in trait objects.
+
+use rustc_ast::walk_list;
+use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet};
+use rustc_errors::struct_span_err;
+use rustc_hir as hir;
+use rustc_hir::def::{DefKind, Res};
+use rustc_hir::def_id::LocalDefId;
+use rustc_hir::intravisit::{self, Visitor};
+use rustc_hir::{GenericArg, GenericParam, GenericParamKind, HirIdMap, LifetimeName, Node};
+use rustc_middle::bug;
+use rustc_middle::hir::map::Map;
+use rustc_middle::hir::nested_filter;
+use rustc_middle::middle::resolve_lifetime::*;
+use rustc_middle::ty::{self, DefIdTree, TyCtxt};
+use rustc_span::def_id::DefId;
+use rustc_span::symbol::{sym, Ident};
+use rustc_span::Span;
+use std::fmt;
+
+trait RegionExt {
+ fn early(hir_map: Map<'_>, param: &GenericParam<'_>) -> (LocalDefId, Region);
+
+ fn late(index: u32, hir_map: Map<'_>, param: &GenericParam<'_>) -> (LocalDefId, Region);
+
+ fn id(&self) -> Option<DefId>;
+
+ fn shifted(self, amount: u32) -> Region;
+}
+
+impl RegionExt for Region {
+ fn early(hir_map: Map<'_>, param: &GenericParam<'_>) -> (LocalDefId, Region) {
+ let def_id = hir_map.local_def_id(param.hir_id);
+ debug!("Region::early: def_id={:?}", def_id);
+ (def_id, Region::EarlyBound(def_id.to_def_id()))
+ }
+
+ fn late(idx: u32, hir_map: Map<'_>, param: &GenericParam<'_>) -> (LocalDefId, Region) {
+ let depth = ty::INNERMOST;
+ let def_id = hir_map.local_def_id(param.hir_id);
+ debug!(
+ "Region::late: idx={:?}, param={:?} depth={:?} def_id={:?}",
+ idx, param, depth, def_id,
+ );
+ (def_id, Region::LateBound(depth, idx, def_id.to_def_id()))
+ }
+
+ fn id(&self) -> Option<DefId> {
+ match *self {
+ Region::Static => None,
+
+ Region::EarlyBound(id) | Region::LateBound(_, _, id) | Region::Free(_, id) => Some(id),
+ }
+ }
+
+ fn shifted(self, amount: u32) -> Region {
+ match self {
+ Region::LateBound(debruijn, idx, id) => {
+ Region::LateBound(debruijn.shifted_in(amount), idx, id)
+ }
+ _ => self,
+ }
+ }
+}
+
+/// Maps the id of each lifetime reference to the lifetime decl
+/// that it corresponds to.
+///
+/// FIXME. This struct gets converted to a `ResolveLifetimes` for
+/// actual use. It has the same data, but indexed by `LocalDefId`. This
+/// is silly.
+#[derive(Debug, Default)]
+struct NamedRegionMap {
+ // maps from every use of a named (not anonymous) lifetime to a
+ // `Region` describing how that region is bound
+ defs: HirIdMap<Region>,
+
+ // Maps relevant hir items to the bound vars on them. These include:
+ // - function defs
+ // - function pointers
+ // - closures
+ // - trait refs
+ // - bound types (like `T` in `for<'a> T<'a>: Foo`)
+ late_bound_vars: HirIdMap<Vec<ty::BoundVariableKind>>,
+}
+
+struct LifetimeContext<'a, 'tcx> {
+ tcx: TyCtxt<'tcx>,
+ map: &'a mut NamedRegionMap,
+ scope: ScopeRef<'a>,
+
+ /// Indicates that we only care about the definition of a trait. This should
+ /// be false if the `Item` we are resolving lifetimes for is not a trait or
+ /// we eventually need lifetimes resolve for trait items.
+ trait_definition_only: bool,
+}
+
+#[derive(Debug)]
+enum Scope<'a> {
+ /// Declares lifetimes, and each can be early-bound or late-bound.
+ /// The `DebruijnIndex` of late-bound lifetimes starts at `1` and
+ /// it should be shifted by the number of `Binder`s in between the
+ /// declaration `Binder` and the location it's referenced from.
+ Binder {
+ /// We use an IndexMap here because we want these lifetimes in order
+ /// for diagnostics.
+ lifetimes: FxIndexMap<LocalDefId, Region>,
+
+ scope_type: BinderScopeType,
+
+ /// The late bound vars for a given item are stored by `HirId` to be
+ /// queried later. However, if we enter an elision scope, we have to
+ /// later append the elided bound vars to the list and need to know what
+ /// to append to.
+ hir_id: hir::HirId,
+
+ s: ScopeRef<'a>,
+
+ /// If this binder comes from a where clause, specify how it was created.
+ /// This is used to diagnose inaccessible lifetimes in APIT:
+ /// ```ignore (illustrative)
+ /// fn foo(x: impl for<'a> Trait<'a, Assoc = impl Copy + 'a>) {}
+ /// ```
+ where_bound_origin: Option<hir::PredicateOrigin>,
+ },
+
+ /// Lifetimes introduced by a fn are scoped to the call-site for that fn,
+ /// if this is a fn body, otherwise the original definitions are used.
+ /// Unspecified lifetimes are inferred, unless an elision scope is nested,
+ /// e.g., `(&T, fn(&T) -> &T);` becomes `(&'_ T, for<'a> fn(&'a T) -> &'a T)`.
+ Body {
+ id: hir::BodyId,
+ s: ScopeRef<'a>,
+ },
+
+ /// A scope which either determines unspecified lifetimes or errors
+ /// on them (e.g., due to ambiguity).
+ Elision {
+ s: ScopeRef<'a>,
+ },
+
+ /// Use a specific lifetime (if `Some`) or leave it unset (to be
+ /// inferred in a function body or potentially error outside one),
+ /// for the default choice of lifetime in a trait object type.
+ ObjectLifetimeDefault {
+ lifetime: Option<Region>,
+ s: ScopeRef<'a>,
+ },
+
+ /// When we have nested trait refs, we concatenate late bound vars for inner
+ /// trait refs from outer ones. But we also need to include any HRTB
+ /// lifetimes encountered when identifying the trait that an associated type
+ /// is declared on.
+ Supertrait {
+ lifetimes: Vec<ty::BoundVariableKind>,
+ s: ScopeRef<'a>,
+ },
+
+ TraitRefBoundary {
+ s: ScopeRef<'a>,
+ },
+
+ Root,
+}
+
+#[derive(Copy, Clone, Debug)]
+enum BinderScopeType {
+ /// Any non-concatenating binder scopes.
+ Normal,
+ /// Within a syntactic trait ref, there may be multiple poly trait refs that
+ /// are nested (under the `associated_type_bounds` feature). The binders of
+ /// the inner poly trait refs are extended from the outer poly trait refs
+ /// and don't increase the late bound depth. If you had
+ /// `T: for<'a> Foo<Bar: for<'b> Baz<'a, 'b>>`, then the `for<'b>` scope
+ /// would be `Concatenating`. This also used in trait refs in where clauses
+ /// where we have two binders `for<> T: for<> Foo` (I've intentionally left
+ /// out any lifetimes because they aren't needed to show the two scopes).
+ /// The inner `for<>` has a scope of `Concatenating`.
+ Concatenating,
+}
+
+// A helper struct for debugging scopes without printing parent scopes
+struct TruncatedScopeDebug<'a>(&'a Scope<'a>);
+
+impl<'a> fmt::Debug for TruncatedScopeDebug<'a> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ match self.0 {
+ Scope::Binder { lifetimes, scope_type, hir_id, where_bound_origin, s: _ } => f
+ .debug_struct("Binder")
+ .field("lifetimes", lifetimes)
+ .field("scope_type", scope_type)
+ .field("hir_id", hir_id)
+ .field("where_bound_origin", where_bound_origin)
+ .field("s", &"..")
+ .finish(),
+ Scope::Body { id, s: _ } => {
+ f.debug_struct("Body").field("id", id).field("s", &"..").finish()
+ }
+ Scope::Elision { s: _ } => f.debug_struct("Elision").field("s", &"..").finish(),
+ Scope::ObjectLifetimeDefault { lifetime, s: _ } => f
+ .debug_struct("ObjectLifetimeDefault")
+ .field("lifetime", lifetime)
+ .field("s", &"..")
+ .finish(),
+ Scope::Supertrait { lifetimes, s: _ } => f
+ .debug_struct("Supertrait")
+ .field("lifetimes", lifetimes)
+ .field("s", &"..")
+ .finish(),
+ Scope::TraitRefBoundary { s: _ } => f.debug_struct("TraitRefBoundary").finish(),
+ Scope::Root => f.debug_struct("Root").finish(),
+ }
+ }
+}
+
+type ScopeRef<'a> = &'a Scope<'a>;
+
+const ROOT_SCOPE: ScopeRef<'static> = &Scope::Root;
+
+pub(crate) fn provide(providers: &mut ty::query::Providers) {
+ *providers = ty::query::Providers {
+ resolve_lifetimes_trait_definition,
+ resolve_lifetimes,
+
+ named_region_map: |tcx, id| resolve_lifetimes_for(tcx, id).defs.get(&id),
+ is_late_bound_map,
+ object_lifetime_default,
+ late_bound_vars_map: |tcx, id| resolve_lifetimes_for(tcx, id).late_bound_vars.get(&id),
+
+ ..*providers
+ };
+}
+
+/// Like `resolve_lifetimes`, but does not resolve lifetimes for trait items.
+/// Also does not generate any diagnostics.
+///
+/// This is ultimately a subset of the `resolve_lifetimes` work. It effectively
+/// resolves lifetimes only within the trait "header" -- that is, the trait
+/// and supertrait list. In contrast, `resolve_lifetimes` resolves all the
+/// lifetimes within the trait and its items. There is room to refactor this,
+/// for example to resolve lifetimes for each trait item in separate queries,
+/// but it's convenient to do the entire trait at once because the lifetimes
+/// from the trait definition are in scope within the trait items as well.
+///
+/// The reason for this separate call is to resolve what would otherwise
+/// be a cycle. Consider this example:
+///
+/// ```ignore UNSOLVED (maybe @jackh726 knows what lifetime parameter to give Sub)
+/// trait Base<'a> {
+/// type BaseItem;
+/// }
+/// trait Sub<'b>: for<'a> Base<'a> {
+/// type SubItem: Sub<BaseItem = &'b u32>;
+/// }
+/// ```
+///
+/// When we resolve `Sub` and all its items, we also have to resolve `Sub<BaseItem = &'b u32>`.
+/// To figure out the index of `'b`, we have to know about the supertraits
+/// of `Sub` so that we can determine that the `for<'a>` will be in scope.
+/// (This is because we -- currently at least -- flatten all the late-bound
+/// lifetimes into a single binder.) This requires us to resolve the
+/// *trait definition* of `Sub`; basically just enough lifetime information
+/// to look at the supertraits.
+#[instrument(level = "debug", skip(tcx))]
+fn resolve_lifetimes_trait_definition(
+ tcx: TyCtxt<'_>,
+ local_def_id: LocalDefId,
+) -> ResolveLifetimes {
+ convert_named_region_map(do_resolve(tcx, local_def_id, true))
+}
+
+/// Computes the `ResolveLifetimes` map that contains data for an entire `Item`.
+/// You should not read the result of this query directly, but rather use
+/// `named_region_map`, `is_late_bound_map`, etc.
+#[instrument(level = "debug", skip(tcx))]
+fn resolve_lifetimes(tcx: TyCtxt<'_>, local_def_id: LocalDefId) -> ResolveLifetimes {
+ convert_named_region_map(do_resolve(tcx, local_def_id, false))
+}
+
+fn do_resolve(
+ tcx: TyCtxt<'_>,
+ local_def_id: LocalDefId,
+ trait_definition_only: bool,
+) -> NamedRegionMap {
+ let item = tcx.hir().expect_item(local_def_id);
+ let mut named_region_map =
+ NamedRegionMap { defs: Default::default(), late_bound_vars: Default::default() };
+ let mut visitor = LifetimeContext {
+ tcx,
+ map: &mut named_region_map,
+ scope: ROOT_SCOPE,
+ trait_definition_only,
+ };
+ visitor.visit_item(item);
+
+ named_region_map
+}
+
+fn convert_named_region_map(named_region_map: NamedRegionMap) -> ResolveLifetimes {
+ let mut rl = ResolveLifetimes::default();
+
+ for (hir_id, v) in named_region_map.defs {
+ let map = rl.defs.entry(hir_id.owner).or_default();
+ map.insert(hir_id.local_id, v);
+ }
+ for (hir_id, v) in named_region_map.late_bound_vars {
+ let map = rl.late_bound_vars.entry(hir_id.owner).or_default();
+ map.insert(hir_id.local_id, v);
+ }
+
+ debug!(?rl.defs);
+ debug!(?rl.late_bound_vars);
+ rl
+}
+
+/// Given `any` owner (structs, traits, trait methods, etc.), does lifetime resolution.
+/// There are two important things this does.
+/// First, we have to resolve lifetimes for
+/// the entire *`Item`* that contains this owner, because that's the largest "scope"
+/// where we can have relevant lifetimes.
+/// Second, if we are asking for lifetimes in a trait *definition*, we use `resolve_lifetimes_trait_definition`
+/// instead of `resolve_lifetimes`, which does not descend into the trait items and does not emit diagnostics.
+/// This allows us to avoid cycles. Importantly, if we ask for lifetimes for lifetimes that have an owner
+/// other than the trait itself (like the trait methods or associated types), then we just use the regular
+/// `resolve_lifetimes`.
+fn resolve_lifetimes_for<'tcx>(tcx: TyCtxt<'tcx>, def_id: hir::OwnerId) -> &'tcx ResolveLifetimes {
+ let item_id = item_for(tcx, def_id.def_id);
+ let local_def_id = item_id.owner_id.def_id;
+ if item_id.owner_id == def_id {
+ let item = tcx.hir().item(item_id);
+ match item.kind {
+ hir::ItemKind::Trait(..) => tcx.resolve_lifetimes_trait_definition(local_def_id),
+ _ => tcx.resolve_lifetimes(local_def_id),
+ }
+ } else {
+ tcx.resolve_lifetimes(local_def_id)
+ }
+}
+
+/// Finds the `Item` that contains the given `LocalDefId`
+fn item_for(tcx: TyCtxt<'_>, local_def_id: LocalDefId) -> hir::ItemId {
+ match tcx.hir().find_by_def_id(local_def_id) {
+ Some(Node::Item(item)) => {
+ return item.item_id();
+ }
+ _ => {}
+ }
+ let item = {
+ let hir_id = tcx.hir().local_def_id_to_hir_id(local_def_id);
+ let mut parent_iter = tcx.hir().parent_iter(hir_id);
+ loop {
+ let node = parent_iter.next().map(|n| n.1);
+ match node {
+ Some(hir::Node::Item(item)) => break item.item_id(),
+ Some(hir::Node::Crate(_)) | None => bug!("Called `item_for` on an Item."),
+ _ => {}
+ }
+ }
+ };
+ item
+}
+
+fn late_region_as_bound_region<'tcx>(tcx: TyCtxt<'tcx>, region: &Region) -> ty::BoundVariableKind {
+ match region {
+ Region::LateBound(_, _, def_id) => {
+ let name = tcx.hir().name(tcx.hir().local_def_id_to_hir_id(def_id.expect_local()));
+ ty::BoundVariableKind::Region(ty::BrNamed(*def_id, name))
+ }
+ _ => bug!("{:?} is not a late region", region),
+ }
+}
+
+impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
+ /// Returns the binders in scope and the type of `Binder` that should be created for a poly trait ref.
+ fn poly_trait_ref_binder_info(&mut self) -> (Vec<ty::BoundVariableKind>, BinderScopeType) {
+ let mut scope = self.scope;
+ let mut supertrait_lifetimes = vec![];
+ loop {
+ match scope {
+ Scope::Body { .. } | Scope::Root => {
+ break (vec![], BinderScopeType::Normal);
+ }
+
+ Scope::Elision { s, .. } | Scope::ObjectLifetimeDefault { s, .. } => {
+ scope = s;
+ }
+
+ Scope::Supertrait { s, lifetimes } => {
+ supertrait_lifetimes = lifetimes.clone();
+ scope = s;
+ }
+
+ Scope::TraitRefBoundary { .. } => {
+ // We should only see super trait lifetimes if there is a `Binder` above
+ assert!(supertrait_lifetimes.is_empty());
+ break (vec![], BinderScopeType::Normal);
+ }
+
+ Scope::Binder { hir_id, .. } => {
+ // Nested poly trait refs have the binders concatenated
+ let mut full_binders =
+ self.map.late_bound_vars.entry(*hir_id).or_default().clone();
+ full_binders.extend(supertrait_lifetimes.into_iter());
+ break (full_binders, BinderScopeType::Concatenating);
+ }
+ }
+ }
+ }
+}
+impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
+ type NestedFilter = nested_filter::All;
+
+ fn nested_visit_map(&mut self) -> Self::Map {
+ self.tcx.hir()
+ }
+
+ // We want to nest trait/impl items in their parent, but nothing else.
+ fn visit_nested_item(&mut self, _: hir::ItemId) {}
+
+ fn visit_trait_item_ref(&mut self, ii: &'tcx hir::TraitItemRef) {
+ if !self.trait_definition_only {
+ intravisit::walk_trait_item_ref(self, ii)
+ }
+ }
+
+ fn visit_nested_body(&mut self, body: hir::BodyId) {
+ let body = self.tcx.hir().body(body);
+ self.with(Scope::Body { id: body.id(), s: self.scope }, |this| {
+ this.visit_body(body);
+ });
+ }
+
+ fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
+ if let hir::ExprKind::Closure(hir::Closure {
+ binder, bound_generic_params, fn_decl, ..
+ }) = e.kind
+ {
+ if let &hir::ClosureBinder::For { span: for_sp, .. } = binder {
+ fn span_of_infer(ty: &hir::Ty<'_>) -> Option<Span> {
+ struct V(Option<Span>);
+
+ impl<'v> Visitor<'v> for V {
+ fn visit_ty(&mut self, t: &'v hir::Ty<'v>) {
+ match t.kind {
+ _ if self.0.is_some() => (),
+ hir::TyKind::Infer => {
+ self.0 = Some(t.span);
+ }
+ _ => intravisit::walk_ty(self, t),
+ }
+ }
+ }
+
+ let mut v = V(None);
+ v.visit_ty(ty);
+ v.0
+ }
+
+ let infer_in_rt_sp = match fn_decl.output {
+ hir::FnRetTy::DefaultReturn(sp) => Some(sp),
+ hir::FnRetTy::Return(ty) => span_of_infer(ty),
+ };
+
+ let infer_spans = fn_decl
+ .inputs
+ .into_iter()
+ .filter_map(span_of_infer)
+ .chain(infer_in_rt_sp)
+ .collect::<Vec<_>>();
+
+ if !infer_spans.is_empty() {
+ self.tcx.sess
+ .struct_span_err(
+ infer_spans,
+ "implicit types in closure signatures are forbidden when `for<...>` is present",
+ )
+ .span_label(for_sp, "`for<...>` is here")
+ .emit();
+ }
+ }
+
+ let (lifetimes, binders): (FxIndexMap<LocalDefId, Region>, Vec<_>) =
+ bound_generic_params
+ .iter()
+ .filter(|param| matches!(param.kind, GenericParamKind::Lifetime { .. }))
+ .enumerate()
+ .map(|(late_bound_idx, param)| {
+ let pair = Region::late(late_bound_idx as u32, self.tcx.hir(), param);
+ let r = late_region_as_bound_region(self.tcx, &pair.1);
+ (pair, r)
+ })
+ .unzip();
+
+ self.record_late_bound_vars(e.hir_id, binders);
+ let scope = Scope::Binder {
+ hir_id: e.hir_id,
+ lifetimes,
+ s: self.scope,
+ scope_type: BinderScopeType::Normal,
+ where_bound_origin: None,
+ };
+
+ self.with(scope, |this| {
+ // a closure has no bounds, so everything
+ // contained within is scoped within its binder.
+ intravisit::walk_expr(this, e)
+ });
+ } else {
+ intravisit::walk_expr(self, e)
+ }
+ }
+
+ #[instrument(level = "debug", skip(self))]
+ fn visit_item(&mut self, item: &'tcx hir::Item<'tcx>) {
+ match &item.kind {
+ hir::ItemKind::Impl(hir::Impl { of_trait, .. }) => {
+ if let Some(of_trait) = of_trait {
+ self.record_late_bound_vars(of_trait.hir_ref_id, Vec::default());
+ }
+ }
+ _ => {}
+ }
+ match item.kind {
+ hir::ItemKind::Fn(_, ref generics, _) => {
+ self.visit_early_late(item.hir_id(), generics, |this| {
+ intravisit::walk_item(this, item);
+ });
+ }
+
+ hir::ItemKind::ExternCrate(_)
+ | hir::ItemKind::Use(..)
+ | hir::ItemKind::Macro(..)
+ | hir::ItemKind::Mod(..)
+ | hir::ItemKind::ForeignMod { .. }
+ | hir::ItemKind::GlobalAsm(..) => {
+ // These sorts of items have no lifetime parameters at all.
+ intravisit::walk_item(self, item);
+ }
+ hir::ItemKind::Static(..) | hir::ItemKind::Const(..) => {
+ // No lifetime parameters, but implied 'static.
+ self.with(Scope::Elision { s: self.scope }, |this| {
+ intravisit::walk_item(this, item)
+ });
+ }
+ hir::ItemKind::OpaqueTy(hir::OpaqueTy { .. }) => {
+ // Opaque types are visited when we visit the
+ // `TyKind::OpaqueDef`, so that they have the lifetimes from
+ // their parent opaque_ty in scope.
+ //
+ // The core idea here is that since OpaqueTys are generated with the impl Trait as
+ // their owner, we can keep going until we find the Item that owns that. We then
+ // conservatively add all resolved lifetimes. Otherwise we run into problems in
+ // cases like `type Foo<'a> = impl Bar<As = impl Baz + 'a>`.
+ for (_hir_id, node) in self.tcx.hir().parent_iter(item.owner_id.into()) {
+ match node {
+ hir::Node::Item(parent_item) => {
+ let resolved_lifetimes: &ResolveLifetimes = self.tcx.resolve_lifetimes(
+ item_for(self.tcx, parent_item.owner_id.def_id).owner_id.def_id,
+ );
+ // We need to add *all* deps, since opaque tys may want them from *us*
+ for (&owner, defs) in resolved_lifetimes.defs.iter() {
+ defs.iter().for_each(|(&local_id, region)| {
+ self.map.defs.insert(hir::HirId { owner, local_id }, *region);
+ });
+ }
+ for (&owner, late_bound_vars) in
+ resolved_lifetimes.late_bound_vars.iter()
+ {
+ late_bound_vars.iter().for_each(|(&local_id, late_bound_vars)| {
+ self.record_late_bound_vars(
+ hir::HirId { owner, local_id },
+ late_bound_vars.clone(),
+ );
+ });
+ }
+ break;
+ }
+ hir::Node::Crate(_) => bug!("No Item about an OpaqueTy"),
+ _ => {}
+ }
+ }
+ }
+ hir::ItemKind::TyAlias(_, ref generics)
+ | hir::ItemKind::Enum(_, ref generics)
+ | hir::ItemKind::Struct(_, ref generics)
+ | hir::ItemKind::Union(_, ref generics)
+ | hir::ItemKind::Trait(_, _, ref generics, ..)
+ | hir::ItemKind::TraitAlias(ref generics, ..)
+ | hir::ItemKind::Impl(hir::Impl { ref generics, .. }) => {
+ // These kinds of items have only early-bound lifetime parameters.
+ let lifetimes = generics
+ .params
+ .iter()
+ .filter_map(|param| match param.kind {
+ GenericParamKind::Lifetime { .. } => {
+ Some(Region::early(self.tcx.hir(), param))
+ }
+ GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => None,
+ })
+ .collect();
+ self.record_late_bound_vars(item.hir_id(), vec![]);
+ let scope = Scope::Binder {
+ hir_id: item.hir_id(),
+ lifetimes,
+ scope_type: BinderScopeType::Normal,
+ s: ROOT_SCOPE,
+ where_bound_origin: None,
+ };
+ self.with(scope, |this| {
+ let scope = Scope::TraitRefBoundary { s: this.scope };
+ this.with(scope, |this| {
+ intravisit::walk_item(this, item);
+ });
+ });
+ }
+ }
+ }
+
+ fn visit_foreign_item(&mut self, item: &'tcx hir::ForeignItem<'tcx>) {
+ match item.kind {
+ hir::ForeignItemKind::Fn(_, _, ref generics) => {
+ self.visit_early_late(item.hir_id(), generics, |this| {
+ intravisit::walk_foreign_item(this, item);
+ })
+ }
+ hir::ForeignItemKind::Static(..) => {
+ intravisit::walk_foreign_item(self, item);
+ }
+ hir::ForeignItemKind::Type => {
+ intravisit::walk_foreign_item(self, item);
+ }
+ }
+ }
+
+ #[instrument(level = "debug", skip(self))]
+ fn visit_ty(&mut self, ty: &'tcx hir::Ty<'tcx>) {
+ match ty.kind {
+ hir::TyKind::BareFn(ref c) => {
+ let (lifetimes, binders): (FxIndexMap<LocalDefId, Region>, Vec<_>) = c
+ .generic_params
+ .iter()
+ .filter(|param| matches!(param.kind, GenericParamKind::Lifetime { .. }))
+ .enumerate()
+ .map(|(late_bound_idx, param)| {
+ let pair = Region::late(late_bound_idx as u32, self.tcx.hir(), param);
+ let r = late_region_as_bound_region(self.tcx, &pair.1);
+ (pair, r)
+ })
+ .unzip();
+ self.record_late_bound_vars(ty.hir_id, binders);
+ let scope = Scope::Binder {
+ hir_id: ty.hir_id,
+ lifetimes,
+ s: self.scope,
+ scope_type: BinderScopeType::Normal,
+ where_bound_origin: None,
+ };
+ self.with(scope, |this| {
+ // a bare fn has no bounds, so everything
+ // contained within is scoped within its binder.
+ intravisit::walk_ty(this, ty);
+ });
+ }
+ hir::TyKind::TraitObject(bounds, ref lifetime, _) => {
+ debug!(?bounds, ?lifetime, "TraitObject");
+ let scope = Scope::TraitRefBoundary { s: self.scope };
+ self.with(scope, |this| {
+ for bound in bounds {
+ this.visit_poly_trait_ref(bound);
+ }
+ });
+ match lifetime.name {
+ LifetimeName::ImplicitObjectLifetimeDefault => {
+ // If the user does not write *anything*, we
+ // use the object lifetime defaulting
+ // rules. So e.g., `Box<dyn Debug>` becomes
+ // `Box<dyn Debug + 'static>`.
+ self.resolve_object_lifetime_default(lifetime)
+ }
+ LifetimeName::Infer => {
+ // If the user writes `'_`, we use the *ordinary* elision
+ // rules. So the `'_` in e.g., `Box<dyn Debug + '_>` will be
+ // resolved the same as the `'_` in `&'_ Foo`.
+ //
+ // cc #48468
+ }
+ LifetimeName::Param(..) | LifetimeName::Static => {
+ // If the user wrote an explicit name, use that.
+ self.visit_lifetime(lifetime);
+ }
+ LifetimeName::Error => {}
+ }
+ }
+ hir::TyKind::Rptr(ref lifetime_ref, ref mt) => {
+ self.visit_lifetime(lifetime_ref);
+ let scope = Scope::ObjectLifetimeDefault {
+ lifetime: self.map.defs.get(&lifetime_ref.hir_id).cloned(),
+ s: self.scope,
+ };
+ self.with(scope, |this| this.visit_ty(&mt.ty));
+ }
+ hir::TyKind::OpaqueDef(item_id, lifetimes, _in_trait) => {
+ // Resolve the lifetimes in the bounds to the lifetime defs in the generics.
+ // `fn foo<'a>() -> impl MyTrait<'a> { ... }` desugars to
+ // `type MyAnonTy<'b> = impl MyTrait<'b>;`
+ // ^ ^ this gets resolved in the scope of
+ // the opaque_ty generics
+ let opaque_ty = self.tcx.hir().item(item_id);
+ let (generics, bounds) = match opaque_ty.kind {
+ hir::ItemKind::OpaqueTy(hir::OpaqueTy {
+ origin: hir::OpaqueTyOrigin::TyAlias,
+ ..
+ }) => {
+ intravisit::walk_ty(self, ty);
+
+ // Elided lifetimes are not allowed in non-return
+ // position impl Trait
+ let scope = Scope::TraitRefBoundary { s: self.scope };
+ self.with(scope, |this| {
+ let scope = Scope::Elision { s: this.scope };
+ this.with(scope, |this| {
+ intravisit::walk_item(this, opaque_ty);
+ })
+ });
+
+ return;
+ }
+ hir::ItemKind::OpaqueTy(hir::OpaqueTy {
+ origin: hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..),
+ ref generics,
+ bounds,
+ ..
+ }) => (generics, bounds),
+ ref i => bug!("`impl Trait` pointed to non-opaque type?? {:#?}", i),
+ };
+
+ // Resolve the lifetimes that are applied to the opaque type.
+ // These are resolved in the current scope.
+ // `fn foo<'a>() -> impl MyTrait<'a> { ... }` desugars to
+ // `fn foo<'a>() -> MyAnonTy<'a> { ... }`
+ // ^ ^this gets resolved in the current scope
+ for lifetime in lifetimes {
+ let hir::GenericArg::Lifetime(lifetime) = lifetime else {
+ continue
+ };
+ self.visit_lifetime(lifetime);
+
+ // Check for predicates like `impl for<'a> Trait<impl OtherTrait<'a>>`
+ // and ban them. Type variables instantiated inside binders aren't
+ // well-supported at the moment, so this doesn't work.
+ // In the future, this should be fixed and this error should be removed.
+ let def = self.map.defs.get(&lifetime.hir_id).cloned();
+ let Some(Region::LateBound(_, _, def_id)) = def else {
+ continue
+ };
+ let Some(def_id) = def_id.as_local() else {
+ continue
+ };
+ let hir_id = self.tcx.hir().local_def_id_to_hir_id(def_id);
+ // Ensure that the parent of the def is an item, not HRTB
+ let parent_id = self.tcx.hir().get_parent_node(hir_id);
+ if !parent_id.is_owner() {
+ if !self.trait_definition_only {
+ struct_span_err!(
+ self.tcx.sess,
+ lifetime.span,
+ E0657,
+ "`impl Trait` can only capture lifetimes \
+ bound at the fn or impl level"
+ )
+ .emit();
+ }
+ self.uninsert_lifetime_on_error(lifetime, def.unwrap());
+ }
+ if let hir::Node::Item(hir::Item {
+ kind: hir::ItemKind::OpaqueTy { .. }, ..
+ }) = self.tcx.hir().get(parent_id)
+ {
+ if !self.trait_definition_only {
+ let mut err = self.tcx.sess.struct_span_err(
+ lifetime.span,
+ "higher kinded lifetime bounds on nested opaque types are not supported yet",
+ );
+ err.span_note(self.tcx.def_span(def_id), "lifetime declared here");
+ err.emit();
+ }
+ self.uninsert_lifetime_on_error(lifetime, def.unwrap());
+ }
+ }
+
+ // We want to start our early-bound indices at the end of the parent scope,
+ // not including any parent `impl Trait`s.
+ let mut lifetimes = FxIndexMap::default();
+ debug!(?generics.params);
+ for param in generics.params {
+ match param.kind {
+ GenericParamKind::Lifetime { .. } => {
+ let (def_id, reg) = Region::early(self.tcx.hir(), &param);
+ lifetimes.insert(def_id, reg);
+ }
+ GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => {}
+ }
+ }
+ self.record_late_bound_vars(ty.hir_id, vec![]);
+
+ let scope = Scope::Binder {
+ hir_id: ty.hir_id,
+ lifetimes,
+ s: self.scope,
+ scope_type: BinderScopeType::Normal,
+ where_bound_origin: None,
+ };
+ self.with(scope, |this| {
+ let scope = Scope::TraitRefBoundary { s: this.scope };
+ this.with(scope, |this| {
+ this.visit_generics(generics);
+ for bound in bounds {
+ this.visit_param_bound(bound);
+ }
+ })
+ });
+ }
+ _ => intravisit::walk_ty(self, ty),
+ }
+ }
+
+ #[instrument(level = "debug", skip(self))]
+ fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
+ use self::hir::TraitItemKind::*;
+ match trait_item.kind {
+ Fn(_, _) => {
+ self.visit_early_late(trait_item.hir_id(), &trait_item.generics, |this| {
+ intravisit::walk_trait_item(this, trait_item)
+ });
+ }
+ Type(bounds, ref ty) => {
+ let generics = &trait_item.generics;
+ let lifetimes = generics
+ .params
+ .iter()
+ .filter_map(|param| match param.kind {
+ GenericParamKind::Lifetime { .. } => {
+ Some(Region::early(self.tcx.hir(), param))
+ }
+ GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => None,
+ })
+ .collect();
+ self.record_late_bound_vars(trait_item.hir_id(), vec![]);
+ let scope = Scope::Binder {
+ hir_id: trait_item.hir_id(),
+ lifetimes,
+ s: self.scope,
+ scope_type: BinderScopeType::Normal,
+ where_bound_origin: None,
+ };
+ self.with(scope, |this| {
+ let scope = Scope::TraitRefBoundary { s: this.scope };
+ this.with(scope, |this| {
+ this.visit_generics(generics);
+ for bound in bounds {
+ this.visit_param_bound(bound);
+ }
+ if let Some(ty) = ty {
+ this.visit_ty(ty);
+ }
+ })
+ });
+ }
+ Const(_, _) => {
+ // Only methods and types support generics.
+ assert!(trait_item.generics.params.is_empty());
+ intravisit::walk_trait_item(self, trait_item);
+ }
+ }
+ }
+
+ #[instrument(level = "debug", skip(self))]
+ fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
+ use self::hir::ImplItemKind::*;
+ match impl_item.kind {
+ Fn(..) => self.visit_early_late(impl_item.hir_id(), &impl_item.generics, |this| {
+ intravisit::walk_impl_item(this, impl_item)
+ }),
+ Type(ref ty) => {
+ let generics = &impl_item.generics;
+ let lifetimes: FxIndexMap<LocalDefId, Region> = generics
+ .params
+ .iter()
+ .filter_map(|param| match param.kind {
+ GenericParamKind::Lifetime { .. } => {
+ Some(Region::early(self.tcx.hir(), param))
+ }
+ GenericParamKind::Const { .. } | GenericParamKind::Type { .. } => None,
+ })
+ .collect();
+ self.record_late_bound_vars(impl_item.hir_id(), vec![]);
+ let scope = Scope::Binder {
+ hir_id: impl_item.hir_id(),
+ lifetimes,
+ s: self.scope,
+ scope_type: BinderScopeType::Normal,
+ where_bound_origin: None,
+ };
+ self.with(scope, |this| {
+ let scope = Scope::TraitRefBoundary { s: this.scope };
+ this.with(scope, |this| {
+ this.visit_generics(generics);
+ this.visit_ty(ty);
+ })
+ });
+ }
+ Const(_, _) => {
+ // Only methods and types support generics.
+ assert!(impl_item.generics.params.is_empty());
+ intravisit::walk_impl_item(self, impl_item);
+ }
+ }
+ }
+
+ #[instrument(level = "debug", skip(self))]
+ fn visit_lifetime(&mut self, lifetime_ref: &'tcx hir::Lifetime) {
+ match lifetime_ref.name {
+ hir::LifetimeName::Static => self.insert_lifetime(lifetime_ref, Region::Static),
+ hir::LifetimeName::Param(param_def_id, _) => {
+ self.resolve_lifetime_ref(param_def_id, lifetime_ref)
+ }
+ // If we've already reported an error, just ignore `lifetime_ref`.
+ hir::LifetimeName::Error => {}
+ // Those will be resolved by typechecking.
+ hir::LifetimeName::ImplicitObjectLifetimeDefault | hir::LifetimeName::Infer => {}
+ }
+ }
+
+ fn visit_path(&mut self, path: &'tcx hir::Path<'tcx>, _: hir::HirId) {
+ for (i, segment) in path.segments.iter().enumerate() {
+ let depth = path.segments.len() - i - 1;
+ if let Some(ref args) = segment.args {
+ self.visit_segment_args(path.res, depth, args);
+ }
+ }
+ }
+
+ fn visit_fn(
+ &mut self,
+ fk: intravisit::FnKind<'tcx>,
+ fd: &'tcx hir::FnDecl<'tcx>,
+ body_id: hir::BodyId,
+ _: Span,
+ _: hir::HirId,
+ ) {
+ let output = match fd.output {
+ hir::FnRetTy::DefaultReturn(_) => None,
+ hir::FnRetTy::Return(ref ty) => Some(&**ty),
+ };
+ self.visit_fn_like_elision(&fd.inputs, output, matches!(fk, intravisit::FnKind::Closure));
+ intravisit::walk_fn_kind(self, fk);
+ self.visit_nested_body(body_id)
+ }
+
+ fn visit_generics(&mut self, generics: &'tcx hir::Generics<'tcx>) {
+ let scope = Scope::TraitRefBoundary { s: self.scope };
+ self.with(scope, |this| {
+ for param in generics.params {
+ match param.kind {
+ GenericParamKind::Lifetime { .. } => {}
+ GenericParamKind::Type { ref default, .. } => {
+ if let Some(ref ty) = default {
+ this.visit_ty(&ty);
+ }
+ }
+ GenericParamKind::Const { ref ty, default } => {
+ this.visit_ty(&ty);
+ if let Some(default) = default {
+ this.visit_body(this.tcx.hir().body(default.body));
+ }
+ }
+ }
+ }
+ for predicate in generics.predicates {
+ match predicate {
+ &hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
+ hir_id,
+ ref bounded_ty,
+ bounds,
+ ref bound_generic_params,
+ origin,
+ ..
+ }) => {
+ let lifetimes: FxIndexMap<LocalDefId, Region> =
+ bound_generic_params
+ .iter()
+ .filter(|param| {
+ matches!(param.kind, GenericParamKind::Lifetime { .. })
+ })
+ .enumerate()
+ .map(|(late_bound_idx, param)| {
+ Region::late(late_bound_idx as u32, this.tcx.hir(), param)
+ })
+ .collect();
+ let binders: Vec<_> =
+ lifetimes
+ .iter()
+ .map(|(_, region)| {
+ late_region_as_bound_region(this.tcx, region)
+ })
+ .collect();
+ this.record_late_bound_vars(hir_id, binders.clone());
+ // Even if there are no lifetimes defined here, we still wrap it in a binder
+ // scope. If there happens to be a nested poly trait ref (an error), that
+ // will be `Concatenating` anyways, so we don't have to worry about the depth
+ // being wrong.
+ let scope = Scope::Binder {
+ hir_id,
+ lifetimes,
+ s: this.scope,
+ scope_type: BinderScopeType::Normal,
+ where_bound_origin: Some(origin),
+ };
+ this.with(scope, |this| {
+ this.visit_ty(&bounded_ty);
+ walk_list!(this, visit_param_bound, bounds);
+ })
+ }
+ &hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate {
+ ref lifetime,
+ bounds,
+ ..
+ }) => {
+ this.visit_lifetime(lifetime);
+ walk_list!(this, visit_param_bound, bounds);
+
+ if lifetime.name != hir::LifetimeName::Static {
+ for bound in bounds {
+ let hir::GenericBound::Outlives(ref lt) = bound else {
+ continue;
+ };
+ if lt.name != hir::LifetimeName::Static {
+ continue;
+ }
+ this.insert_lifetime(lt, Region::Static);
+ this.tcx
+ .sess
+ .struct_span_warn(
+ lifetime.span,
+ &format!(
+ "unnecessary lifetime parameter `{}`",
+ lifetime.name.ident(),
+ ),
+ )
+ .help(&format!(
+ "you can use the `'static` lifetime directly, in place of `{}`",
+ lifetime.name.ident(),
+ ))
+ .emit();
+ }
+ }
+ }
+ &hir::WherePredicate::EqPredicate(hir::WhereEqPredicate {
+ ref lhs_ty,
+ ref rhs_ty,
+ ..
+ }) => {
+ this.visit_ty(lhs_ty);
+ this.visit_ty(rhs_ty);
+ }
+ }
+ }
+ })
+ }
+
+ fn visit_param_bound(&mut self, bound: &'tcx hir::GenericBound<'tcx>) {
+ match bound {
+ hir::GenericBound::LangItemTrait(_, _, hir_id, _) => {
+ // FIXME(jackh726): This is pretty weird. `LangItemTrait` doesn't go
+ // through the regular poly trait ref code, so we don't get another
+ // chance to introduce a binder. For now, I'm keeping the existing logic
+ // of "if there isn't a Binder scope above us, add one", but I
+ // imagine there's a better way to go about this.
+ let (binders, scope_type) = self.poly_trait_ref_binder_info();
+
+ self.record_late_bound_vars(*hir_id, binders);
+ let scope = Scope::Binder {
+ hir_id: *hir_id,
+ lifetimes: FxIndexMap::default(),
+ s: self.scope,
+ scope_type,
+ where_bound_origin: None,
+ };
+ self.with(scope, |this| {
+ intravisit::walk_param_bound(this, bound);
+ });
+ }
+ _ => intravisit::walk_param_bound(self, bound),
+ }
+ }
+
+ fn visit_poly_trait_ref(&mut self, trait_ref: &'tcx hir::PolyTraitRef<'tcx>) {
+ debug!("visit_poly_trait_ref(trait_ref={:?})", trait_ref);
+
+ let (mut binders, scope_type) = self.poly_trait_ref_binder_info();
+
+ let initial_bound_vars = binders.len() as u32;
+ let mut lifetimes: FxIndexMap<LocalDefId, Region> = FxIndexMap::default();
+ let binders_iter = trait_ref
+ .bound_generic_params
+ .iter()
+ .filter(|param| matches!(param.kind, GenericParamKind::Lifetime { .. }))
+ .enumerate()
+ .map(|(late_bound_idx, param)| {
+ let pair =
+ Region::late(initial_bound_vars + late_bound_idx as u32, self.tcx.hir(), param);
+ let r = late_region_as_bound_region(self.tcx, &pair.1);
+ lifetimes.insert(pair.0, pair.1);
+ r
+ });
+ binders.extend(binders_iter);
+
+ debug!(?binders);
+ self.record_late_bound_vars(trait_ref.trait_ref.hir_ref_id, binders);
+
+ // Always introduce a scope here, even if this is in a where clause and
+ // we introduced the binders around the bounded Ty. In that case, we
+ // just reuse the concatenation functionality also present in nested trait
+ // refs.
+ let scope = Scope::Binder {
+ hir_id: trait_ref.trait_ref.hir_ref_id,
+ lifetimes,
+ s: self.scope,
+ scope_type,
+ where_bound_origin: None,
+ };
+ self.with(scope, |this| {
+ walk_list!(this, visit_generic_param, trait_ref.bound_generic_params);
+ this.visit_trait_ref(&trait_ref.trait_ref);
+ });
+ }
+}
+
+fn object_lifetime_default<'tcx>(tcx: TyCtxt<'tcx>, param_def_id: DefId) -> ObjectLifetimeDefault {
+ debug_assert_eq!(tcx.def_kind(param_def_id), DefKind::TyParam);
+ let param_def_id = param_def_id.expect_local();
+ let parent_def_id = tcx.local_parent(param_def_id);
+ let generics = tcx.hir().get_generics(parent_def_id).unwrap();
+ let param_hir_id = tcx.local_def_id_to_hir_id(param_def_id);
+ let param = generics.params.iter().find(|p| p.hir_id == param_hir_id).unwrap();
+
+ // Scan the bounds and where-clauses on parameters to extract bounds
+ // of the form `T:'a` so as to determine the `ObjectLifetimeDefault`
+ // for each type parameter.
+ match param.kind {
+ GenericParamKind::Type { .. } => {
+ let mut set = Set1::Empty;
+
+ // Look for `type: ...` where clauses.
+ for bound in generics.bounds_for_param(param_def_id) {
+ // Ignore `for<'a> type: ...` as they can change what
+ // lifetimes mean (although we could "just" handle it).
+ if !bound.bound_generic_params.is_empty() {
+ continue;
+ }
+
+ for bound in bound.bounds {
+ if let hir::GenericBound::Outlives(ref lifetime) = *bound {
+ set.insert(lifetime.name.normalize_to_macros_2_0());
+ }
+ }
+ }
+
+ match set {
+ Set1::Empty => ObjectLifetimeDefault::Empty,
+ Set1::One(hir::LifetimeName::Static) => ObjectLifetimeDefault::Static,
+ Set1::One(hir::LifetimeName::Param(param_def_id, _)) => {
+ ObjectLifetimeDefault::Param(param_def_id.to_def_id())
+ }
+ _ => ObjectLifetimeDefault::Ambiguous,
+ }
+ }
+ _ => {
+ bug!("object_lifetime_default_raw must only be called on a type parameter")
+ }
+ }
+}
+
+impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
+ fn with<F>(&mut self, wrap_scope: Scope<'_>, f: F)
+ where
+ F: for<'b> FnOnce(&mut LifetimeContext<'b, 'tcx>),
+ {
+ let LifetimeContext { tcx, map, .. } = self;
+ let mut this = LifetimeContext {
+ tcx: *tcx,
+ map,
+ scope: &wrap_scope,
+ trait_definition_only: self.trait_definition_only,
+ };
+ let span = debug_span!("scope", scope = ?TruncatedScopeDebug(&this.scope));
+ {
+ let _enter = span.enter();
+ f(&mut this);
+ }
+ }
+
+ fn record_late_bound_vars(&mut self, hir_id: hir::HirId, binder: Vec<ty::BoundVariableKind>) {
+ if let Some(old) = self.map.late_bound_vars.insert(hir_id, binder) {
+ bug!(
+ "overwrote bound vars for {hir_id:?}:\nold={old:?}\nnew={:?}",
+ self.map.late_bound_vars[&hir_id]
+ )
+ }
+ }
+
+ /// Visits self by adding a scope and handling recursive walk over the contents with `walk`.
+ ///
+ /// Handles visiting fns and methods. These are a bit complicated because we must distinguish
+ /// early- vs late-bound lifetime parameters. We do this by checking which lifetimes appear
+ /// within type bounds; those are early bound lifetimes, and the rest are late bound.
+ ///
+ /// For example:
+ ///
+ /// fn foo<'a,'b,'c,T:Trait<'b>>(...)
+ ///
+ /// Here `'a` and `'c` are late bound but `'b` is early bound. Note that early- and late-bound
+ /// lifetimes may be interspersed together.
+ ///
+ /// If early bound lifetimes are present, we separate them into their own list (and likewise
+ /// for late bound). They will be numbered sequentially, starting from the lowest index that is
+ /// already in scope (for a fn item, that will be 0, but for a method it might not be). Late
+ /// bound lifetimes are resolved by name and associated with a binder ID (`binder_id`), so the
+ /// ordering is not important there.
+ fn visit_early_late<F>(
+ &mut self,
+ hir_id: hir::HirId,
+ generics: &'tcx hir::Generics<'tcx>,
+ walk: F,
+ ) where
+ F: for<'b, 'c> FnOnce(&'b mut LifetimeContext<'c, 'tcx>),
+ {
+ let mut named_late_bound_vars = 0;
+ let lifetimes: FxIndexMap<LocalDefId, Region> = generics
+ .params
+ .iter()
+ .filter_map(|param| match param.kind {
+ GenericParamKind::Lifetime { .. } => {
+ if self.tcx.is_late_bound(param.hir_id) {
+ let late_bound_idx = named_late_bound_vars;
+ named_late_bound_vars += 1;
+ Some(Region::late(late_bound_idx, self.tcx.hir(), param))
+ } else {
+ Some(Region::early(self.tcx.hir(), param))
+ }
+ }
+ GenericParamKind::Type { .. } | GenericParamKind::Const { .. } => None,
+ })
+ .collect();
+
+ let binders: Vec<_> = generics
+ .params
+ .iter()
+ .filter(|param| {
+ matches!(param.kind, GenericParamKind::Lifetime { .. })
+ && self.tcx.is_late_bound(param.hir_id)
+ })
+ .enumerate()
+ .map(|(late_bound_idx, param)| {
+ let pair = Region::late(late_bound_idx as u32, self.tcx.hir(), param);
+ late_region_as_bound_region(self.tcx, &pair.1)
+ })
+ .collect();
+ self.record_late_bound_vars(hir_id, binders);
+ let scope = Scope::Binder {
+ hir_id,
+ lifetimes,
+ s: self.scope,
+ scope_type: BinderScopeType::Normal,
+ where_bound_origin: None,
+ };
+ self.with(scope, walk);
+ }
+
+ #[instrument(level = "debug", skip(self))]
+ fn resolve_lifetime_ref(
+ &mut self,
+ region_def_id: LocalDefId,
+ lifetime_ref: &'tcx hir::Lifetime,
+ ) {
+ // Walk up the scope chain, tracking the number of fn scopes
+ // that we pass through, until we find a lifetime with the
+ // given name or we run out of scopes.
+ // search.
+ let mut late_depth = 0;
+ let mut scope = self.scope;
+ let mut outermost_body = None;
+ let result = loop {
+ match *scope {
+ Scope::Body { id, s } => {
+ outermost_body = Some(id);
+ scope = s;
+ }
+
+ Scope::Root => {
+ break None;
+ }
+
+ Scope::Binder { ref lifetimes, scope_type, s, where_bound_origin, .. } => {
+ if let Some(&def) = lifetimes.get(&region_def_id) {
+ break Some(def.shifted(late_depth));
+ }
+ match scope_type {
+ BinderScopeType::Normal => late_depth += 1,
+ BinderScopeType::Concatenating => {}
+ }
+ // Fresh lifetimes in APIT used to be allowed in async fns and forbidden in
+ // regular fns.
+ if let Some(hir::PredicateOrigin::ImplTrait) = where_bound_origin
+ && let hir::LifetimeName::Param(_, hir::ParamName::Fresh) = lifetime_ref.name
+ && let hir::IsAsync::NotAsync = self.tcx.asyncness(lifetime_ref.hir_id.owner.def_id)
+ && !self.tcx.features().anonymous_lifetime_in_impl_trait
+ {
+ let mut diag = rustc_session::parse::feature_err(
+ &self.tcx.sess.parse_sess,
+ sym::anonymous_lifetime_in_impl_trait,
+ lifetime_ref.span,
+ "anonymous lifetimes in `impl Trait` are unstable",
+ );
+
+ match self.tcx.hir().get_generics(lifetime_ref.hir_id.owner.def_id) {
+ Some(generics) => {
+
+ let new_param_sugg_tuple;
+
+ new_param_sugg_tuple = match generics.span_for_param_suggestion() {
+ Some(_) => {
+ Some((self.tcx.sess.source_map().span_through_char(generics.span, '<').shrink_to_hi(), "'a, ".to_owned()))
+ },
+ None => Some((generics.span, "<'a>".to_owned()))
+ };
+
+ let mut multi_sugg_vec = vec![(lifetime_ref.span.shrink_to_hi(), "'a ".to_owned())];
+
+ if let Some(new_tuple) = new_param_sugg_tuple{
+ multi_sugg_vec.push(new_tuple);
+ }
+
+ diag.span_label(lifetime_ref.span, "expected named lifetime parameter");
+ diag.multipart_suggestion("consider introducing a named lifetime parameter",
+ multi_sugg_vec,
+ rustc_errors::Applicability::MaybeIncorrect);
+
+ },
+ None => { }
+ }
+
+ diag.emit();
+ return;
+ }
+ scope = s;
+ }
+
+ Scope::Elision { s, .. }
+ | Scope::ObjectLifetimeDefault { s, .. }
+ | Scope::Supertrait { s, .. }
+ | Scope::TraitRefBoundary { s, .. } => {
+ scope = s;
+ }
+ }
+ };
+
+ if let Some(mut def) = result {
+ if let Region::EarlyBound(..) = def {
+ // Do not free early-bound regions, only late-bound ones.
+ } else if let Some(body_id) = outermost_body {
+ let fn_id = self.tcx.hir().body_owner(body_id);
+ match self.tcx.hir().get(fn_id) {
+ Node::Item(&hir::Item { kind: hir::ItemKind::Fn(..), .. })
+ | Node::TraitItem(&hir::TraitItem {
+ kind: hir::TraitItemKind::Fn(..), ..
+ })
+ | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Fn(..), .. }) => {
+ let scope = self.tcx.hir().local_def_id(fn_id);
+ def = Region::Free(scope.to_def_id(), def.id().unwrap());
+ }
+ _ => {}
+ }
+ }
+
+ self.insert_lifetime(lifetime_ref, def);
+ return;
+ }
+
+ // We may fail to resolve higher-ranked lifetimes that are mentioned by APIT.
+ // AST-based resolution does not care for impl-trait desugaring, which are the
+ // responibility of lowering. This may create a mismatch between the resolution
+ // AST found (`region_def_id`) which points to HRTB, and what HIR allows.
+ // ```
+ // fn foo(x: impl for<'a> Trait<'a, Assoc = impl Copy + 'a>) {}
+ // ```
+ //
+ // In such case, walk back the binders to diagnose it properly.
+ let mut scope = self.scope;
+ loop {
+ match *scope {
+ Scope::Binder {
+ where_bound_origin: Some(hir::PredicateOrigin::ImplTrait), ..
+ } => {
+ let mut err = self.tcx.sess.struct_span_err(
+ lifetime_ref.span,
+ "`impl Trait` can only mention lifetimes bound at the fn or impl level",
+ );
+ err.span_note(self.tcx.def_span(region_def_id), "lifetime declared here");
+ err.emit();
+ return;
+ }
+ Scope::Root => break,
+ Scope::Binder { s, .. }
+ | Scope::Body { s, .. }
+ | Scope::Elision { s, .. }
+ | Scope::ObjectLifetimeDefault { s, .. }
+ | Scope::Supertrait { s, .. }
+ | Scope::TraitRefBoundary { s, .. } => {
+ scope = s;
+ }
+ }
+ }
+
+ self.tcx.sess.delay_span_bug(
+ lifetime_ref.span,
+ &format!("Could not resolve {:?} in scope {:#?}", lifetime_ref, self.scope,),
+ );
+ }
+
+ #[instrument(level = "debug", skip(self))]
+ fn visit_segment_args(
+ &mut self,
+ res: Res,
+ depth: usize,
+ generic_args: &'tcx hir::GenericArgs<'tcx>,
+ ) {
+ if generic_args.parenthesized {
+ self.visit_fn_like_elision(
+ generic_args.inputs(),
+ Some(generic_args.bindings[0].ty()),
+ false,
+ );
+ return;
+ }
+
+ for arg in generic_args.args {
+ if let hir::GenericArg::Lifetime(lt) = arg {
+ self.visit_lifetime(lt);
+ }
+ }
+
+ // Figure out if this is a type/trait segment,
+ // which requires object lifetime defaults.
+ let type_def_id = match res {
+ Res::Def(DefKind::AssocTy, def_id) if depth == 1 => Some(self.tcx.parent(def_id)),
+ Res::Def(DefKind::Variant, def_id) if depth == 0 => Some(self.tcx.parent(def_id)),
+ Res::Def(
+ DefKind::Struct
+ | DefKind::Union
+ | DefKind::Enum
+ | DefKind::TyAlias
+ | DefKind::Trait,
+ def_id,
+ ) if depth == 0 => Some(def_id),
+ _ => None,
+ };
+
+ debug!(?type_def_id);
+
+ // Compute a vector of defaults, one for each type parameter,
+ // per the rules given in RFCs 599 and 1156. Example:
+ //
+ // ```rust
+ // struct Foo<'a, T: 'a, U> { }
+ // ```
+ //
+ // If you have `Foo<'x, dyn Bar, dyn Baz>`, we want to default
+ // `dyn Bar` to `dyn Bar + 'x` (because of the `T: 'a` bound)
+ // and `dyn Baz` to `dyn Baz + 'static` (because there is no
+ // such bound).
+ //
+ // Therefore, we would compute `object_lifetime_defaults` to a
+ // vector like `['x, 'static]`. Note that the vector only
+ // includes type parameters.
+ let object_lifetime_defaults = type_def_id.map_or_else(Vec::new, |def_id| {
+ let in_body = {
+ let mut scope = self.scope;
+ loop {
+ match *scope {
+ Scope::Root => break false,
+
+ Scope::Body { .. } => break true,
+
+ Scope::Binder { s, .. }
+ | Scope::Elision { s, .. }
+ | Scope::ObjectLifetimeDefault { s, .. }
+ | Scope::Supertrait { s, .. }
+ | Scope::TraitRefBoundary { s, .. } => {
+ scope = s;
+ }
+ }
+ }
+ };
+
+ let map = &self.map;
+ let generics = self.tcx.generics_of(def_id);
+
+ // `type_def_id` points to an item, so there is nothing to inherit generics from.
+ debug_assert_eq!(generics.parent_count, 0);
+
+ let set_to_region = |set: ObjectLifetimeDefault| match set {
+ ObjectLifetimeDefault::Empty => {
+ if in_body {
+ None
+ } else {
+ Some(Region::Static)
+ }
+ }
+ ObjectLifetimeDefault::Static => Some(Region::Static),
+ ObjectLifetimeDefault::Param(param_def_id) => {
+ // This index can be used with `generic_args` since `parent_count == 0`.
+ let index = generics.param_def_id_to_index[&param_def_id] as usize;
+ generic_args.args.get(index).and_then(|arg| match arg {
+ GenericArg::Lifetime(lt) => map.defs.get(&lt.hir_id).copied(),
+ _ => None,
+ })
+ }
+ ObjectLifetimeDefault::Ambiguous => None,
+ };
+ generics
+ .params
+ .iter()
+ .filter_map(|param| {
+ match self.tcx.def_kind(param.def_id) {
+ // Generic consts don't impose any constraints.
+ //
+ // We still store a dummy value here to allow generic parameters
+ // in an arbitrary order.
+ DefKind::ConstParam => Some(ObjectLifetimeDefault::Empty),
+ DefKind::TyParam => Some(self.tcx.object_lifetime_default(param.def_id)),
+ // We may also get a `Trait` or `TraitAlias` because of how generics `Self` parameter
+ // works. Ignore it because it can't have a meaningful lifetime default.
+ DefKind::LifetimeParam | DefKind::Trait | DefKind::TraitAlias => None,
+ dk => bug!("unexpected def_kind {:?}", dk),
+ }
+ })
+ .map(set_to_region)
+ .collect()
+ });
+
+ debug!(?object_lifetime_defaults);
+
+ let mut i = 0;
+ for arg in generic_args.args {
+ match arg {
+ GenericArg::Lifetime(_) => {}
+ GenericArg::Type(ty) => {
+ if let Some(&lt) = object_lifetime_defaults.get(i) {
+ let scope = Scope::ObjectLifetimeDefault { lifetime: lt, s: self.scope };
+ self.with(scope, |this| this.visit_ty(ty));
+ } else {
+ self.visit_ty(ty);
+ }
+ i += 1;
+ }
+ GenericArg::Const(ct) => {
+ self.visit_anon_const(&ct.value);
+ i += 1;
+ }
+ GenericArg::Infer(inf) => {
+ self.visit_id(inf.hir_id);
+ i += 1;
+ }
+ }
+ }
+
+ // Hack: when resolving the type `XX` in binding like `dyn
+ // Foo<'b, Item = XX>`, the current object-lifetime default
+ // would be to examine the trait `Foo` to check whether it has
+ // a lifetime bound declared on `Item`. e.g., if `Foo` is
+ // declared like so, then the default object lifetime bound in
+ // `XX` should be `'b`:
+ //
+ // ```rust
+ // trait Foo<'a> {
+ // type Item: 'a;
+ // }
+ // ```
+ //
+ // but if we just have `type Item;`, then it would be
+ // `'static`. However, we don't get all of this logic correct.
+ //
+ // Instead, we do something hacky: if there are no lifetime parameters
+ // to the trait, then we simply use a default object lifetime
+ // bound of `'static`, because there is no other possibility. On the other hand,
+ // if there ARE lifetime parameters, then we require the user to give an
+ // explicit bound for now.
+ //
+ // This is intended to leave room for us to implement the
+ // correct behavior in the future.
+ let has_lifetime_parameter =
+ generic_args.args.iter().any(|arg| matches!(arg, GenericArg::Lifetime(_)));
+
+ // Resolve lifetimes found in the bindings, so either in the type `XX` in `Item = XX` or
+ // in the trait ref `YY<...>` in `Item: YY<...>`.
+ for binding in generic_args.bindings {
+ let scope = Scope::ObjectLifetimeDefault {
+ lifetime: if has_lifetime_parameter { None } else { Some(Region::Static) },
+ s: self.scope,
+ };
+ if let Some(type_def_id) = type_def_id {
+ let lifetimes = LifetimeContext::supertrait_hrtb_lifetimes(
+ self.tcx,
+ type_def_id,
+ binding.ident,
+ );
+ self.with(scope, |this| {
+ let scope = Scope::Supertrait {
+ lifetimes: lifetimes.unwrap_or_default(),
+ s: this.scope,
+ };
+ this.with(scope, |this| this.visit_assoc_type_binding(binding));
+ });
+ } else {
+ self.with(scope, |this| this.visit_assoc_type_binding(binding));
+ }
+ }
+ }
+
+ /// Returns all the late-bound vars that come into scope from supertrait HRTBs, based on the
+ /// associated type name and starting trait.
+ /// For example, imagine we have
+ /// ```ignore (illustrative)
+ /// trait Foo<'a, 'b> {
+ /// type As;
+ /// }
+ /// trait Bar<'b>: for<'a> Foo<'a, 'b> {}
+ /// trait Bar: for<'b> Bar<'b> {}
+ /// ```
+ /// In this case, if we wanted to the supertrait HRTB lifetimes for `As` on
+ /// the starting trait `Bar`, we would return `Some(['b, 'a])`.
+ fn supertrait_hrtb_lifetimes(
+ tcx: TyCtxt<'tcx>,
+ def_id: DefId,
+ assoc_name: Ident,
+ ) -> Option<Vec<ty::BoundVariableKind>> {
+ let trait_defines_associated_type_named = |trait_def_id: DefId| {
+ tcx.associated_items(trait_def_id)
+ .find_by_name_and_kind(tcx, assoc_name, ty::AssocKind::Type, trait_def_id)
+ .is_some()
+ };
+
+ use smallvec::{smallvec, SmallVec};
+ let mut stack: SmallVec<[(DefId, SmallVec<[ty::BoundVariableKind; 8]>); 8]> =
+ smallvec![(def_id, smallvec![])];
+ let mut visited: FxHashSet<DefId> = FxHashSet::default();
+ loop {
+ let Some((def_id, bound_vars)) = stack.pop() else {
+ break None;
+ };
+ // See issue #83753. If someone writes an associated type on a non-trait, just treat it as
+ // there being no supertrait HRTBs.
+ match tcx.def_kind(def_id) {
+ DefKind::Trait | DefKind::TraitAlias | DefKind::Impl => {}
+ _ => break None,
+ }
+
+ if trait_defines_associated_type_named(def_id) {
+ break Some(bound_vars.into_iter().collect());
+ }
+ let predicates =
+ tcx.super_predicates_that_define_assoc_type((def_id, Some(assoc_name)));
+ let obligations = predicates.predicates.iter().filter_map(|&(pred, _)| {
+ let bound_predicate = pred.kind();
+ match bound_predicate.skip_binder() {
+ ty::PredicateKind::Trait(data) => {
+ // The order here needs to match what we would get from `subst_supertrait`
+ let pred_bound_vars = bound_predicate.bound_vars();
+ let mut all_bound_vars = bound_vars.clone();
+ all_bound_vars.extend(pred_bound_vars.iter());
+ let super_def_id = data.trait_ref.def_id;
+ Some((super_def_id, all_bound_vars))
+ }
+ _ => None,
+ }
+ });
+
+ let obligations = obligations.filter(|o| visited.insert(o.0));
+ stack.extend(obligations);
+ }
+ }
+
+ #[instrument(level = "debug", skip(self))]
+ fn visit_fn_like_elision(
+ &mut self,
+ inputs: &'tcx [hir::Ty<'tcx>],
+ output: Option<&'tcx hir::Ty<'tcx>>,
+ in_closure: bool,
+ ) {
+ self.with(Scope::Elision { s: self.scope }, |this| {
+ for input in inputs {
+ this.visit_ty(input);
+ }
+ if !in_closure && let Some(output) = output {
+ this.visit_ty(output);
+ }
+ });
+ if in_closure && let Some(output) = output {
+ self.visit_ty(output);
+ }
+ }
+
+ fn resolve_object_lifetime_default(&mut self, lifetime_ref: &'tcx hir::Lifetime) {
+ debug!("resolve_object_lifetime_default(lifetime_ref={:?})", lifetime_ref);
+ let mut late_depth = 0;
+ let mut scope = self.scope;
+ let lifetime = loop {
+ match *scope {
+ Scope::Binder { s, scope_type, .. } => {
+ match scope_type {
+ BinderScopeType::Normal => late_depth += 1,
+ BinderScopeType::Concatenating => {}
+ }
+ scope = s;
+ }
+
+ Scope::Root | Scope::Elision { .. } => break Region::Static,
+
+ Scope::Body { .. } | Scope::ObjectLifetimeDefault { lifetime: None, .. } => return,
+
+ Scope::ObjectLifetimeDefault { lifetime: Some(l), .. } => break l,
+
+ Scope::Supertrait { s, .. } | Scope::TraitRefBoundary { s, .. } => {
+ scope = s;
+ }
+ }
+ };
+ self.insert_lifetime(lifetime_ref, lifetime.shifted(late_depth));
+ }
+
+ #[instrument(level = "debug", skip(self))]
+ fn insert_lifetime(&mut self, lifetime_ref: &'tcx hir::Lifetime, def: Region) {
+ debug!(
+ node = ?self.tcx.hir().node_to_string(lifetime_ref.hir_id),
+ span = ?self.tcx.sess.source_map().span_to_diagnostic_string(lifetime_ref.span)
+ );
+ self.map.defs.insert(lifetime_ref.hir_id, def);
+ }
+
+ /// Sometimes we resolve a lifetime, but later find that it is an
+ /// error (esp. around impl trait). In that case, we remove the
+ /// entry into `map.defs` so as not to confuse later code.
+ fn uninsert_lifetime_on_error(&mut self, lifetime_ref: &'tcx hir::Lifetime, bad_def: Region) {
+ let old_value = self.map.defs.remove(&lifetime_ref.hir_id);
+ assert_eq!(old_value, Some(bad_def));
+ }
+}
+
+/// Detects late-bound lifetimes and inserts them into
+/// `late_bound`.
+///
+/// A region declared on a fn is **late-bound** if:
+/// - it is constrained by an argument type;
+/// - it does not appear in a where-clause.
+///
+/// "Constrained" basically means that it appears in any type but
+/// not amongst the inputs to a projection. In other words, `<&'a
+/// T as Trait<''b>>::Foo` does not constrain `'a` or `'b`.
+fn is_late_bound_map(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<&FxIndexSet<LocalDefId>> {
+ let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
+ let decl = tcx.hir().fn_decl_by_hir_id(hir_id)?;
+ let generics = tcx.hir().get_generics(def_id)?;
+
+ let mut late_bound = FxIndexSet::default();
+
+ let mut constrained_by_input = ConstrainedCollector::default();
+ for arg_ty in decl.inputs {
+ constrained_by_input.visit_ty(arg_ty);
+ }
+
+ let mut appears_in_output = AllCollector::default();
+ intravisit::walk_fn_ret_ty(&mut appears_in_output, &decl.output);
+
+ debug!(?constrained_by_input.regions);
+
+ // Walk the lifetimes that appear in where clauses.
+ //
+ // Subtle point: because we disallow nested bindings, we can just
+ // ignore binders here and scrape up all names we see.
+ let mut appears_in_where_clause = AllCollector::default();
+ appears_in_where_clause.visit_generics(generics);
+ debug!(?appears_in_where_clause.regions);
+
+ // Late bound regions are those that:
+ // - appear in the inputs
+ // - do not appear in the where-clauses
+ // - are not implicitly captured by `impl Trait`
+ for param in generics.params {
+ match param.kind {
+ hir::GenericParamKind::Lifetime { .. } => { /* fall through */ }
+
+ // Neither types nor consts are late-bound.
+ hir::GenericParamKind::Type { .. } | hir::GenericParamKind::Const { .. } => continue,
+ }
+
+ let param_def_id = tcx.hir().local_def_id(param.hir_id);
+
+ // appears in the where clauses? early-bound.
+ if appears_in_where_clause.regions.contains(&param_def_id) {
+ continue;
+ }
+
+ // does not appear in the inputs, but appears in the return type? early-bound.
+ if !constrained_by_input.regions.contains(&param_def_id)
+ && appears_in_output.regions.contains(&param_def_id)
+ {
+ continue;
+ }
+
+ debug!("lifetime {:?} with id {:?} is late-bound", param.name.ident(), param.hir_id);
+
+ let inserted = late_bound.insert(param_def_id);
+ assert!(inserted, "visited lifetime {:?} twice", param.hir_id);
+ }
+
+ debug!(?late_bound);
+ return Some(tcx.arena.alloc(late_bound));
+
+ #[derive(Default)]
+ struct ConstrainedCollector {
+ regions: FxHashSet<LocalDefId>,
+ }
+
+ impl<'v> Visitor<'v> for ConstrainedCollector {
+ fn visit_ty(&mut self, ty: &'v hir::Ty<'v>) {
+ match ty.kind {
+ hir::TyKind::Path(
+ hir::QPath::Resolved(Some(_), _) | hir::QPath::TypeRelative(..),
+ ) => {
+ // ignore lifetimes appearing in associated type
+ // projections, as they are not *constrained*
+ // (defined above)
+ }
+
+ hir::TyKind::Path(hir::QPath::Resolved(None, ref path)) => {
+ // consider only the lifetimes on the final
+ // segment; I am not sure it's even currently
+ // valid to have them elsewhere, but even if it
+ // is, those would be potentially inputs to
+ // projections
+ if let Some(last_segment) = path.segments.last() {
+ self.visit_path_segment(last_segment);
+ }
+ }
+
+ _ => {
+ intravisit::walk_ty(self, ty);
+ }
+ }
+ }
+
+ fn visit_lifetime(&mut self, lifetime_ref: &'v hir::Lifetime) {
+ if let hir::LifetimeName::Param(def_id, _) = lifetime_ref.name {
+ self.regions.insert(def_id);
+ }
+ }
+ }
+
+ #[derive(Default)]
+ struct AllCollector {
+ regions: FxHashSet<LocalDefId>,
+ }
+
+ impl<'v> Visitor<'v> for AllCollector {
+ fn visit_lifetime(&mut self, lifetime_ref: &'v hir::Lifetime) {
+ if let hir::LifetimeName::Param(def_id, _) = lifetime_ref.name {
+ self.regions.insert(def_id);
+ }
+ }
+ }
+}
diff --git a/compiler/rustc_hir_analysis/src/collect/predicates_of.rs b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
new file mode 100644
index 000000000..2e84e1d01
--- /dev/null
+++ b/compiler/rustc_hir_analysis/src/collect/predicates_of.rs
@@ -0,0 +1,707 @@
+use crate::astconv::AstConv;
+use crate::bounds::Bounds;
+use crate::collect::ItemCtxt;
+use crate::constrained_generic_params as cgp;
+use hir::{HirId, Node};
+use rustc_data_structures::fx::FxIndexSet;
+use rustc_hir as hir;
+use rustc_hir::def::DefKind;
+use rustc_hir::def_id::{DefId, LocalDefId};
+use rustc_hir::intravisit::{self, Visitor};
+use rustc_middle::ty::subst::InternalSubsts;
+use rustc_middle::ty::ToPredicate;
+use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_span::symbol::{sym, Ident};
+use rustc_span::{Span, DUMMY_SP};
+
+#[derive(Debug)]
+struct OnlySelfBounds(bool);
+
+/// Returns a list of all type predicates (explicit and implicit) for the definition with
+/// ID `def_id`. This includes all predicates returned by `predicates_defined_on`, plus
+/// `Self: Trait` predicates for traits.
+pub(super) fn predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
+ let mut result = tcx.predicates_defined_on(def_id);
+
+ if tcx.is_trait(def_id) {
+ // For traits, add `Self: Trait` predicate. This is
+ // not part of the predicates that a user writes, but it
+ // is something that one must prove in order to invoke a
+ // method or project an associated type.
+ //
+ // In the chalk setup, this predicate is not part of the
+ // "predicates" for a trait item. But it is useful in
+ // rustc because if you directly (e.g.) invoke a trait
+ // method like `Trait::method(...)`, you must naturally
+ // prove that the trait applies to the types that were
+ // used, and adding the predicate into this list ensures
+ // that this is done.
+ //
+ // We use a DUMMY_SP here as a way to signal trait bounds that come
+ // from the trait itself that *shouldn't* be shown as the source of
+ // an obligation and instead be skipped. Otherwise we'd use
+ // `tcx.def_span(def_id);`
+
+ let constness = if tcx.has_attr(def_id, sym::const_trait) {
+ ty::BoundConstness::ConstIfConst
+ } else {
+ ty::BoundConstness::NotConst
+ };
+
+ let span = rustc_span::DUMMY_SP;
+ result.predicates =
+ tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(std::iter::once((
+ ty::TraitRef::identity(tcx, def_id).with_constness(constness).to_predicate(tcx),
+ span,
+ ))));
+ }
+ debug!("predicates_of(def_id={:?}) = {:?}", def_id, result);
+ result
+}
+
+/// Returns a list of user-specified type predicates for the definition with ID `def_id`.
+/// N.B., this does not include any implied/inferred constraints.
+#[instrument(level = "trace", skip(tcx), ret)]
+fn gather_explicit_predicates_of(tcx: TyCtxt<'_>, def_id: DefId) -> ty::GenericPredicates<'_> {
+ use rustc_hir::*;
+
+ let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
+ let node = tcx.hir().get(hir_id);
+
+ let mut is_trait = None;
+ let mut is_default_impl_trait = None;
+
+ let icx = ItemCtxt::new(tcx, def_id);
+
+ const NO_GENERICS: &hir::Generics<'_> = hir::Generics::empty();
+
+ // We use an `IndexSet` to preserves order of insertion.
+ // Preserving the order of insertion is important here so as not to break UI tests.
+ let mut predicates: FxIndexSet<(ty::Predicate<'_>, Span)> = FxIndexSet::default();
+
+ let ast_generics = match node {
+ Node::TraitItem(item) => item.generics,
+
+ Node::ImplItem(item) => item.generics,
+
+ Node::Item(item) => {
+ match item.kind {
+ ItemKind::Impl(ref impl_) => {
+ if impl_.defaultness.is_default() {
+ is_default_impl_trait = tcx.impl_trait_ref(def_id).map(ty::Binder::dummy);
+ }
+ &impl_.generics
+ }
+ ItemKind::Fn(.., ref generics, _)
+ | ItemKind::TyAlias(_, ref generics)
+ | ItemKind::Enum(_, ref generics)
+ | ItemKind::Struct(_, ref generics)
+ | ItemKind::Union(_, ref generics) => *generics,
+
+ ItemKind::Trait(_, _, ref generics, ..) => {
+ is_trait = Some(ty::TraitRef::identity(tcx, def_id));
+ *generics
+ }
+ ItemKind::TraitAlias(ref generics, _) => {
+ is_trait = Some(ty::TraitRef::identity(tcx, def_id));
+ *generics
+ }
+ ItemKind::OpaqueTy(OpaqueTy {
+ origin: hir::OpaqueTyOrigin::AsyncFn(..) | hir::OpaqueTyOrigin::FnReturn(..),
+ ..
+ }) => {
+ // return-position impl trait
+ //
+ // We don't inherit predicates from the parent here:
+ // If we have, say `fn f<'a, T: 'a>() -> impl Sized {}`
+ // then the return type is `f::<'static, T>::{{opaque}}`.
+ //
+ // If we inherited the predicates of `f` then we would
+ // require that `T: 'static` to show that the return
+ // type is well-formed.
+ //
+ // The only way to have something with this opaque type
+ // is from the return type of the containing function,
+ // which will ensure that the function's predicates
+ // hold.
+ return ty::GenericPredicates { parent: None, predicates: &[] };
+ }
+ ItemKind::OpaqueTy(OpaqueTy {
+ ref generics,
+ origin: hir::OpaqueTyOrigin::TyAlias,
+ ..
+ }) => {
+ // type-alias impl trait
+ generics
+ }
+
+ _ => NO_GENERICS,
+ }
+ }
+
+ Node::ForeignItem(item) => match item.kind {
+ ForeignItemKind::Static(..) => NO_GENERICS,
+ ForeignItemKind::Fn(_, _, ref generics) => *generics,
+ ForeignItemKind::Type => NO_GENERICS,
+ },
+
+ _ => NO_GENERICS,
+ };
+
+ let generics = tcx.generics_of(def_id);
+ let parent_count = generics.parent_count as u32;
+ let has_own_self = generics.has_self && parent_count == 0;
+
+ // Below we'll consider the bounds on the type parameters (including `Self`)
+ // and the explicit where-clauses, but to get the full set of predicates
+ // on a trait we need to add in the supertrait bounds and bounds found on
+ // associated types.
+ if let Some(_trait_ref) = is_trait {
+ predicates.extend(tcx.super_predicates_of(def_id).predicates.iter().cloned());
+ }
+
+ // In default impls, we can assume that the self type implements
+ // the trait. So in:
+ //
+ // default impl Foo for Bar { .. }
+ //
+ // we add a default where clause `Foo: Bar`. We do a similar thing for traits
+ // (see below). Recall that a default impl is not itself an impl, but rather a
+ // set of defaults that can be incorporated into another impl.
+ if let Some(trait_ref) = is_default_impl_trait {
+ predicates.insert((trait_ref.without_const().to_predicate(tcx), tcx.def_span(def_id)));
+ }
+
+ // Collect the region predicates that were declared inline as
+ // well. In the case of parameters declared on a fn or method, we
+ // have to be careful to only iterate over early-bound regions.
+ let mut index = parent_count
+ + has_own_self as u32
+ + super::early_bound_lifetimes_from_generics(tcx, ast_generics).count() as u32;
+
+ trace!(?predicates);
+ trace!(?ast_generics);
+
+ // Collect the predicates that were written inline by the user on each
+ // type parameter (e.g., `<T: Foo>`).
+ for param in ast_generics.params {
+ match param.kind {
+ // We already dealt with early bound lifetimes above.
+ GenericParamKind::Lifetime { .. } => (),
+ GenericParamKind::Type { .. } => {
+ let name = param.name.ident().name;
+ let param_ty = ty::ParamTy::new(index, name).to_ty(tcx);
+ index += 1;
+
+ let mut bounds = Bounds::default();
+ // Params are implicitly sized unless a `?Sized` bound is found
+ <dyn AstConv<'_>>::add_implicitly_sized(
+ &icx,
+ &mut bounds,
+ &[],
+ Some((param.hir_id, ast_generics.predicates)),
+ param.span,
+ );
+ trace!(?bounds);
+ predicates.extend(bounds.predicates(tcx, param_ty));
+ trace!(?predicates);
+ }
+ GenericParamKind::Const { .. } => {
+ // Bounds on const parameters are currently not possible.
+ index += 1;
+ }
+ }
+ }
+
+ trace!(?predicates);
+ // Add in the bounds that appear in the where-clause.
+ for predicate in ast_generics.predicates {
+ match predicate {
+ hir::WherePredicate::BoundPredicate(bound_pred) => {
+ let ty = icx.to_ty(bound_pred.bounded_ty);
+ let bound_vars = icx.tcx.late_bound_vars(bound_pred.hir_id);
+
+ // Keep the type around in a dummy predicate, in case of no bounds.
+ // That way, `where Ty:` is not a complete noop (see #53696) and `Ty`
+ // is still checked for WF.
+ if bound_pred.bounds.is_empty() {
+ if let ty::Param(_) = ty.kind() {
+ // This is a `where T:`, which can be in the HIR from the
+ // transformation that moves `?Sized` to `T`'s declaration.
+ // We can skip the predicate because type parameters are
+ // trivially WF, but also we *should*, to avoid exposing
+ // users who never wrote `where Type:,` themselves, to
+ // compiler/tooling bugs from not handling WF predicates.
+ } else {
+ let span = bound_pred.bounded_ty.span;
+ let predicate = ty::Binder::bind_with_vars(
+ ty::PredicateKind::WellFormed(ty.into()),
+ bound_vars,
+ );
+ predicates.insert((predicate.to_predicate(tcx), span));
+ }
+ }
+
+ let mut bounds = Bounds::default();
+ <dyn AstConv<'_>>::add_bounds(
+ &icx,
+ ty,
+ bound_pred.bounds.iter(),
+ &mut bounds,
+ bound_vars,
+ );
+ predicates.extend(bounds.predicates(tcx, ty));
+ }
+
+ hir::WherePredicate::RegionPredicate(region_pred) => {
+ let r1 = <dyn AstConv<'_>>::ast_region_to_region(&icx, &region_pred.lifetime, None);
+ predicates.extend(region_pred.bounds.iter().map(|bound| {
+ let (r2, span) = match bound {
+ hir::GenericBound::Outlives(lt) => {
+ (<dyn AstConv<'_>>::ast_region_to_region(&icx, lt, None), lt.span)
+ }
+ _ => bug!(),
+ };
+ let pred = ty::Binder::dummy(ty::PredicateKind::RegionOutlives(
+ ty::OutlivesPredicate(r1, r2),
+ ))
+ .to_predicate(icx.tcx);
+
+ (pred, span)
+ }))
+ }
+
+ hir::WherePredicate::EqPredicate(..) => {
+ // FIXME(#20041)
+ }
+ }
+ }
+
+ if tcx.features().generic_const_exprs {
+ predicates.extend(const_evaluatable_predicates_of(tcx, def_id.expect_local()));
+ }
+
+ let mut predicates: Vec<_> = predicates.into_iter().collect();
+
+ // Subtle: before we store the predicates into the tcx, we
+ // sort them so that predicates like `T: Foo<Item=U>` come
+ // before uses of `U`. This avoids false ambiguity errors
+ // in trait checking. See `setup_constraining_predicates`
+ // for details.
+ if let Node::Item(&Item { kind: ItemKind::Impl { .. }, .. }) = node {
+ let self_ty = tcx.type_of(def_id);
+ let trait_ref = tcx.impl_trait_ref(def_id);
+ cgp::setup_constraining_predicates(
+ tcx,
+ &mut predicates,
+ trait_ref,
+ &mut cgp::parameters_for_impl(self_ty, trait_ref),
+ );
+ }
+
+ ty::GenericPredicates {
+ parent: generics.parent,
+ predicates: tcx.arena.alloc_from_iter(predicates),
+ }
+}
+
+fn const_evaluatable_predicates_of<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ def_id: LocalDefId,
+) -> FxIndexSet<(ty::Predicate<'tcx>, Span)> {
+ struct ConstCollector<'tcx> {
+ tcx: TyCtxt<'tcx>,
+ preds: FxIndexSet<(ty::Predicate<'tcx>, Span)>,
+ }
+
+ impl<'tcx> intravisit::Visitor<'tcx> for ConstCollector<'tcx> {
+ fn visit_anon_const(&mut self, c: &'tcx hir::AnonConst) {
+ let def_id = self.tcx.hir().local_def_id(c.hir_id);
+ let ct = ty::Const::from_anon_const(self.tcx, def_id);
+ if let ty::ConstKind::Unevaluated(_) = ct.kind() {
+ let span = self.tcx.hir().span(c.hir_id);
+ self.preds.insert((
+ ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(ct))
+ .to_predicate(self.tcx),
+ span,
+ ));
+ }
+ }
+
+ fn visit_const_param_default(&mut self, _param: HirId, _ct: &'tcx hir::AnonConst) {
+ // Do not look into const param defaults,
+ // these get checked when they are actually instantiated.
+ //
+ // We do not want the following to error:
+ //
+ // struct Foo<const N: usize, const M: usize = { N + 1 }>;
+ // struct Bar<const N: usize>(Foo<N, 3>);
+ }
+ }
+
+ let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
+ let node = tcx.hir().get(hir_id);
+
+ let mut collector = ConstCollector { tcx, preds: FxIndexSet::default() };
+ if let hir::Node::Item(item) = node && let hir::ItemKind::Impl(ref impl_) = item.kind {
+ if let Some(of_trait) = &impl_.of_trait {
+ debug!("const_evaluatable_predicates_of({:?}): visit impl trait_ref", def_id);
+ collector.visit_trait_ref(of_trait);
+ }
+
+ debug!("const_evaluatable_predicates_of({:?}): visit_self_ty", def_id);
+ collector.visit_ty(impl_.self_ty);
+ }
+
+ if let Some(generics) = node.generics() {
+ debug!("const_evaluatable_predicates_of({:?}): visit_generics", def_id);
+ collector.visit_generics(generics);
+ }
+
+ if let Some(fn_sig) = tcx.hir().fn_sig_by_hir_id(hir_id) {
+ debug!("const_evaluatable_predicates_of({:?}): visit_fn_decl", def_id);
+ collector.visit_fn_decl(fn_sig.decl);
+ }
+ debug!("const_evaluatable_predicates_of({:?}) = {:?}", def_id, collector.preds);
+
+ collector.preds
+}
+
+pub(super) fn trait_explicit_predicates_and_bounds(
+ tcx: TyCtxt<'_>,
+ def_id: LocalDefId,
+) -> ty::GenericPredicates<'_> {
+ assert_eq!(tcx.def_kind(def_id), DefKind::Trait);
+ gather_explicit_predicates_of(tcx, def_id.to_def_id())
+}
+
+pub(super) fn explicit_predicates_of<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ def_id: DefId,
+) -> ty::GenericPredicates<'tcx> {
+ let def_kind = tcx.def_kind(def_id);
+ if let DefKind::Trait = def_kind {
+ // Remove bounds on associated types from the predicates, they will be
+ // returned by `explicit_item_bounds`.
+ let predicates_and_bounds = tcx.trait_explicit_predicates_and_bounds(def_id.expect_local());
+ let trait_identity_substs = InternalSubsts::identity_for_item(tcx, def_id);
+
+ let is_assoc_item_ty = |ty: Ty<'tcx>| {
+ // For a predicate from a where clause to become a bound on an
+ // associated type:
+ // * It must use the identity substs of the item.
+ // * Since any generic parameters on the item are not in scope,
+ // this means that the item is not a GAT, and its identity
+ // substs are the same as the trait's.
+ // * It must be an associated type for this trait (*not* a
+ // supertrait).
+ if let ty::Projection(projection) = ty.kind() {
+ projection.substs == trait_identity_substs
+ && tcx.associated_item(projection.item_def_id).container_id(tcx) == def_id
+ } else {
+ false
+ }
+ };
+
+ let predicates: Vec<_> = predicates_and_bounds
+ .predicates
+ .iter()
+ .copied()
+ .filter(|(pred, _)| match pred.kind().skip_binder() {
+ ty::PredicateKind::Trait(tr) => !is_assoc_item_ty(tr.self_ty()),
+ ty::PredicateKind::Projection(proj) => {
+ !is_assoc_item_ty(proj.projection_ty.self_ty())
+ }
+ ty::PredicateKind::TypeOutlives(outlives) => !is_assoc_item_ty(outlives.0),
+ _ => true,
+ })
+ .collect();
+ if predicates.len() == predicates_and_bounds.predicates.len() {
+ predicates_and_bounds
+ } else {
+ ty::GenericPredicates {
+ parent: predicates_and_bounds.parent,
+ predicates: tcx.arena.alloc_slice(&predicates),
+ }
+ }
+ } else {
+ if matches!(def_kind, DefKind::AnonConst) && tcx.lazy_normalization() {
+ let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
+ if tcx.hir().opt_const_param_default_param_hir_id(hir_id).is_some() {
+ // In `generics_of` we set the generics' parent to be our parent's parent which means that
+ // we lose out on the predicates of our actual parent if we dont return those predicates here.
+ // (See comment in `generics_of` for more information on why the parent shenanigans is necessary)
+ //
+ // struct Foo<T, const N: usize = { <T as Trait>::ASSOC }>(T) where T: Trait;
+ // ^^^ ^^^^^^^^^^^^^^^^^^^^^^^ the def id we are calling
+ // ^^^ explicit_predicates_of on
+ // parent item we dont have set as the
+ // parent of generics returned by `generics_of`
+ //
+ // In the above code we want the anon const to have predicates in its param env for `T: Trait`
+ let item_def_id = tcx.hir().get_parent_item(hir_id);
+ // In the above code example we would be calling `explicit_predicates_of(Foo)` here
+ return tcx.explicit_predicates_of(item_def_id);
+ }
+ }
+ gather_explicit_predicates_of(tcx, def_id)
+ }
+}
+
+/// Ensures that the super-predicates of the trait with a `DefId`
+/// of `trait_def_id` are converted and stored. This also ensures that
+/// the transitive super-predicates are converted.
+pub(super) fn super_predicates_of(
+ tcx: TyCtxt<'_>,
+ trait_def_id: DefId,
+) -> ty::GenericPredicates<'_> {
+ tcx.super_predicates_that_define_assoc_type((trait_def_id, None))
+}
+
+/// Ensures that the super-predicates of the trait with a `DefId`
+/// of `trait_def_id` are converted and stored. This also ensures that
+/// the transitive super-predicates are converted.
+pub(super) fn super_predicates_that_define_assoc_type(
+ tcx: TyCtxt<'_>,
+ (trait_def_id, assoc_name): (DefId, Option<Ident>),
+) -> ty::GenericPredicates<'_> {
+ if trait_def_id.is_local() {
+ debug!("local trait");
+ let trait_hir_id = tcx.hir().local_def_id_to_hir_id(trait_def_id.expect_local());
+
+ let Node::Item(item) = tcx.hir().get(trait_hir_id) else {
+ bug!("trait_node_id {} is not an item", trait_hir_id);
+ };
+
+ let (generics, bounds) = match item.kind {
+ hir::ItemKind::Trait(.., ref generics, ref supertraits, _) => (generics, supertraits),
+ hir::ItemKind::TraitAlias(ref generics, ref supertraits) => (generics, supertraits),
+ _ => span_bug!(item.span, "super_predicates invoked on non-trait"),
+ };
+
+ let icx = ItemCtxt::new(tcx, trait_def_id);
+
+ // Convert the bounds that follow the colon, e.g., `Bar + Zed` in `trait Foo: Bar + Zed`.
+ let self_param_ty = tcx.types.self_param;
+ let superbounds1 = if let Some(assoc_name) = assoc_name {
+ <dyn AstConv<'_>>::compute_bounds_that_match_assoc_type(
+ &icx,
+ self_param_ty,
+ bounds,
+ assoc_name,
+ )
+ } else {
+ <dyn AstConv<'_>>::compute_bounds(&icx, self_param_ty, bounds)
+ };
+
+ let superbounds1 = superbounds1.predicates(tcx, self_param_ty);
+
+ // Convert any explicit superbounds in the where-clause,
+ // e.g., `trait Foo where Self: Bar`.
+ // In the case of trait aliases, however, we include all bounds in the where-clause,
+ // so e.g., `trait Foo = where u32: PartialEq<Self>` would include `u32: PartialEq<Self>`
+ // as one of its "superpredicates".
+ let is_trait_alias = tcx.is_trait_alias(trait_def_id);
+ let superbounds2 = icx.type_parameter_bounds_in_generics(
+ generics,
+ item.hir_id(),
+ self_param_ty,
+ OnlySelfBounds(!is_trait_alias),
+ assoc_name,
+ );
+
+ // Combine the two lists to form the complete set of superbounds:
+ let superbounds = &*tcx.arena.alloc_from_iter(superbounds1.into_iter().chain(superbounds2));
+ debug!(?superbounds);
+
+ // Now require that immediate supertraits are converted,
+ // which will, in turn, reach indirect supertraits.
+ if assoc_name.is_none() {
+ // Now require that immediate supertraits are converted,
+ // which will, in turn, reach indirect supertraits.
+ for &(pred, span) in superbounds {
+ debug!("superbound: {:?}", pred);
+ if let ty::PredicateKind::Trait(bound) = pred.kind().skip_binder() {
+ tcx.at(span).super_predicates_of(bound.def_id());
+ }
+ }
+ }
+
+ ty::GenericPredicates { parent: None, predicates: superbounds }
+ } else {
+ // if `assoc_name` is None, then the query should've been redirected to an
+ // external provider
+ assert!(assoc_name.is_some());
+ tcx.super_predicates_of(trait_def_id)
+ }
+}
+
+/// Returns the predicates defined on `item_def_id` of the form
+/// `X: Foo` where `X` is the type parameter `def_id`.
+#[instrument(level = "trace", skip(tcx))]
+pub(super) fn type_param_predicates(
+ tcx: TyCtxt<'_>,
+ (item_def_id, def_id, assoc_name): (DefId, LocalDefId, Ident),
+) -> ty::GenericPredicates<'_> {
+ use rustc_hir::*;
+
+ // In the AST, bounds can derive from two places. Either
+ // written inline like `<T: Foo>` or in a where-clause like
+ // `where T: Foo`.
+
+ let param_id = tcx.hir().local_def_id_to_hir_id(def_id);
+ let param_owner = tcx.hir().ty_param_owner(def_id);
+ let generics = tcx.generics_of(param_owner);
+ let index = generics.param_def_id_to_index[&def_id.to_def_id()];
+ let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(def_id));
+
+ // Don't look for bounds where the type parameter isn't in scope.
+ let parent = if item_def_id == param_owner.to_def_id() {
+ None
+ } else {
+ tcx.generics_of(item_def_id).parent
+ };
+
+ let mut result = parent
+ .map(|parent| {
+ let icx = ItemCtxt::new(tcx, parent);
+ icx.get_type_parameter_bounds(DUMMY_SP, def_id.to_def_id(), assoc_name)
+ })
+ .unwrap_or_default();
+ let mut extend = None;
+
+ let item_hir_id = tcx.hir().local_def_id_to_hir_id(item_def_id.expect_local());
+ let ast_generics = match tcx.hir().get(item_hir_id) {
+ Node::TraitItem(item) => &item.generics,
+
+ Node::ImplItem(item) => &item.generics,
+
+ Node::Item(item) => {
+ match item.kind {
+ ItemKind::Fn(.., ref generics, _)
+ | ItemKind::Impl(hir::Impl { ref generics, .. })
+ | ItemKind::TyAlias(_, ref generics)
+ | ItemKind::OpaqueTy(OpaqueTy {
+ ref generics,
+ origin: hir::OpaqueTyOrigin::TyAlias,
+ ..
+ })
+ | ItemKind::Enum(_, ref generics)
+ | ItemKind::Struct(_, ref generics)
+ | ItemKind::Union(_, ref generics) => generics,
+ ItemKind::Trait(_, _, ref generics, ..) => {
+ // Implied `Self: Trait` and supertrait bounds.
+ if param_id == item_hir_id {
+ let identity_trait_ref = ty::TraitRef::identity(tcx, item_def_id);
+ extend =
+ Some((identity_trait_ref.without_const().to_predicate(tcx), item.span));
+ }
+ generics
+ }
+ _ => return result,
+ }
+ }
+
+ Node::ForeignItem(item) => match item.kind {
+ ForeignItemKind::Fn(_, _, ref generics) => generics,
+ _ => return result,
+ },
+
+ _ => return result,
+ };
+
+ let icx = ItemCtxt::new(tcx, item_def_id);
+ let extra_predicates = extend.into_iter().chain(
+ icx.type_parameter_bounds_in_generics(
+ ast_generics,
+ param_id,
+ ty,
+ OnlySelfBounds(true),
+ Some(assoc_name),
+ )
+ .into_iter()
+ .filter(|(predicate, _)| match predicate.kind().skip_binder() {
+ ty::PredicateKind::Trait(data) => data.self_ty().is_param(index),
+ _ => false,
+ }),
+ );
+ result.predicates =
+ tcx.arena.alloc_from_iter(result.predicates.iter().copied().chain(extra_predicates));
+ result
+}
+
+impl<'tcx> ItemCtxt<'tcx> {
+ /// Finds bounds from `hir::Generics`. This requires scanning through the
+ /// AST. We do this to avoid having to convert *all* the bounds, which
+ /// would create artificial cycles. Instead, we can only convert the
+ /// bounds for a type parameter `X` if `X::Foo` is used.
+ #[instrument(level = "trace", skip(self, ast_generics))]
+ fn type_parameter_bounds_in_generics(
+ &self,
+ ast_generics: &'tcx hir::Generics<'tcx>,
+ param_id: hir::HirId,
+ ty: Ty<'tcx>,
+ only_self_bounds: OnlySelfBounds,
+ assoc_name: Option<Ident>,
+ ) -> Vec<(ty::Predicate<'tcx>, Span)> {
+ let param_def_id = self.tcx.hir().local_def_id(param_id).to_def_id();
+ trace!(?param_def_id);
+ ast_generics
+ .predicates
+ .iter()
+ .filter_map(|wp| match *wp {
+ hir::WherePredicate::BoundPredicate(ref bp) => Some(bp),
+ _ => None,
+ })
+ .flat_map(|bp| {
+ let bt = if bp.is_param_bound(param_def_id) {
+ Some(ty)
+ } else if !only_self_bounds.0 {
+ Some(self.to_ty(bp.bounded_ty))
+ } else {
+ None
+ };
+ let bvars = self.tcx.late_bound_vars(bp.hir_id);
+
+ bp.bounds.iter().filter_map(move |b| bt.map(|bt| (bt, b, bvars))).filter(
+ |(_, b, _)| match assoc_name {
+ Some(assoc_name) => self.bound_defines_assoc_item(b, assoc_name),
+ None => true,
+ },
+ )
+ })
+ .flat_map(|(bt, b, bvars)| predicates_from_bound(self, bt, b, bvars))
+ .collect()
+ }
+
+ #[instrument(level = "trace", skip(self))]
+ fn bound_defines_assoc_item(&self, b: &hir::GenericBound<'_>, assoc_name: Ident) -> bool {
+ match b {
+ hir::GenericBound::Trait(poly_trait_ref, _) => {
+ let trait_ref = &poly_trait_ref.trait_ref;
+ if let Some(trait_did) = trait_ref.trait_def_id() {
+ self.tcx.trait_may_define_assoc_type(trait_did, assoc_name)
+ } else {
+ false
+ }
+ }
+ _ => false,
+ }
+ }
+}
+
+/// Converts a specific `GenericBound` from the AST into a set of
+/// predicates that apply to the self type. A vector is returned
+/// because this can be anywhere from zero predicates (`T: ?Sized` adds no
+/// predicates) to one (`T: Foo`) to many (`T: Bar<X = i32>` adds `T: Bar`
+/// and `<T as Bar>::X == i32`).
+fn predicates_from_bound<'tcx>(
+ astconv: &dyn AstConv<'tcx>,
+ param_ty: Ty<'tcx>,
+ bound: &'tcx hir::GenericBound<'tcx>,
+ bound_vars: &'tcx ty::List<ty::BoundVariableKind>,
+) -> Vec<(ty::Predicate<'tcx>, Span)> {
+ let mut bounds = Bounds::default();
+ astconv.add_bounds(param_ty, [bound].into_iter(), &mut bounds, bound_vars);
+ bounds.predicates(astconv.tcx(), param_ty).collect()
+}
diff --git a/compiler/rustc_typeck/src/collect/type_of.rs b/compiler/rustc_hir_analysis/src/collect/type_of.rs
index 534ddfa95..c29a645eb 100644
--- a/compiler/rustc_typeck/src/collect/type_of.rs
+++ b/compiler/rustc_hir_analysis/src/collect/type_of.rs
@@ -1,6 +1,5 @@
use rustc_errors::{Applicability, StashKey};
use rustc_hir as hir;
-use rustc_hir::def::Res;
use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::intravisit;
use rustc_hir::intravisit::Visitor;
@@ -19,7 +18,6 @@ use crate::errors::UnconstrainedOpaqueType;
/// Computes the relevant generic parameter for a potential generic const argument.
///
/// This should be called using the query `tcx.opt_const_param_of`.
-#[instrument(level = "debug", skip(tcx))]
pub(super) fn opt_const_param_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<DefId> {
use hir::*;
let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
@@ -67,8 +65,8 @@ pub(super) fn opt_const_param_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<
let ty = item_ctxt.ast_ty_to_ty(hir_ty);
// Iterate through the generics of the projection to find the one that corresponds to
- // the def_id that this query was called with. We filter to only const args here as a
- // precaution for if it's ever allowed to elide lifetimes in GAT's. It currently isn't
+ // the def_id that this query was called with. We filter to only type and const args here
+ // as a precaution for if it's ever allowed to elide lifetimes in GAT's. It currently isn't
// but it can't hurt to be safe ^^
if let ty::Projection(projection) = ty.kind() {
let generics = tcx.generics_of(projection.item_def_id);
@@ -79,7 +77,7 @@ pub(super) fn opt_const_param_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<
args.args
.iter()
.filter(|arg| arg.is_ty_or_const())
- .position(|arg| arg.id() == hir_id)
+ .position(|arg| arg.hir_id() == hir_id)
})
.unwrap_or_else(|| {
bug!("no arg matching AnonConst in segment");
@@ -112,7 +110,7 @@ pub(super) fn opt_const_param_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<
args.args
.iter()
.filter(|arg| arg.is_ty_or_const())
- .position(|arg| arg.id() == hir_id)
+ .position(|arg| arg.hir_id() == hir_id)
})
.unwrap_or_else(|| {
bug!("no arg matching AnonConst in segment");
@@ -166,7 +164,7 @@ pub(super) fn opt_const_param_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<
args.args
.iter()
.filter(|arg| arg.is_ty_or_const())
- .position(|arg| arg.id() == hir_id)
+ .position(|arg| arg.hir_id() == hir_id)
.map(|index| (index, seg)).or_else(|| args.bindings
.iter()
.filter_map(TypeBinding::opt_const)
@@ -180,15 +178,12 @@ pub(super) fn opt_const_param_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> Option<
return None;
};
- // Try to use the segment resolution if it is valid, otherwise we
- // default to the path resolution.
- let res = segment.res.filter(|&r| r != Res::Err).unwrap_or(path.res);
- let generics = match tcx.res_generics_def_id(res) {
+ let generics = match tcx.res_generics_def_id(segment.res) {
Some(def_id) => tcx.generics_of(def_id),
None => {
tcx.sess.delay_span_bug(
tcx.def_span(def_id),
- &format!("unexpected anon const res {:?} in path: {:?}", res, path),
+ &format!("unexpected anon const res {:?} in path: {:?}", segment.res, path),
);
return None;
}
@@ -229,7 +224,7 @@ fn get_path_containing_arg_in_pat<'hir>(
.iter()
.filter_map(|seg| seg.args)
.flat_map(|args| args.args)
- .any(|arg| arg.id() == arg_id)
+ .any(|arg| arg.hir_id() == arg_id)
};
let mut arg_path = None;
pat.walk(|pat| match pat.kind {
@@ -289,7 +284,7 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
icx.to_ty(ty)
}
}
- ImplItemKind::TyAlias(ty) => {
+ ImplItemKind::Type(ty) => {
if tcx.impl_trait_ref(tcx.hir().get_parent_item(hir_id)).is_none() {
check_feature_inherent_assoc_ty(tcx, item.span);
}
@@ -324,7 +319,15 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
}
}
ItemKind::TyAlias(self_ty, _) => icx.to_ty(self_ty),
- ItemKind::Impl(hir::Impl { self_ty, .. }) => icx.to_ty(*self_ty),
+ ItemKind::Impl(hir::Impl { self_ty, .. }) => {
+ match self_ty.find_self_aliases() {
+ spans if spans.len() > 0 => {
+ tcx.sess.emit_err(crate::errors::SelfInImplSelf { span: spans.into(), note: (), });
+ tcx.ty_error()
+ },
+ _ => icx.to_ty(*self_ty),
+ }
+ },
ItemKind::Fn(..) => {
let substs = InternalSubsts::identity_for_item(tcx, def_id.to_def_id());
tcx.mk_fn_def(def_id.to_def_id(), substs)
@@ -338,7 +341,15 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
find_opaque_ty_constraints_for_tait(tcx, def_id)
}
// Opaque types desugared from `impl Trait`.
- ItemKind::OpaqueTy(OpaqueTy { origin: hir::OpaqueTyOrigin::FnReturn(owner) | hir::OpaqueTyOrigin::AsyncFn(owner), .. }) => {
+ ItemKind::OpaqueTy(OpaqueTy {
+ origin:
+ hir::OpaqueTyOrigin::FnReturn(owner) | hir::OpaqueTyOrigin::AsyncFn(owner),
+ in_trait,
+ ..
+ }) => {
+ if in_trait {
+ assert!(tcx.impl_defaultness(owner).has_value());
+ }
find_opaque_ty_constraints_for_rpit(tcx, def_id, owner)
}
ItemKind::Trait(..)
@@ -379,7 +390,9 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
Node::Field(field) => icx.to_ty(field.ty),
- Node::Expr(&Expr { kind: ExprKind::Closure{..}, .. }) => tcx.typeck(def_id).node_type(hir_id),
+ Node::Expr(&Expr { kind: ExprKind::Closure { .. }, .. }) => {
+ tcx.typeck(def_id).node_type(hir_id)
+ }
Node::AnonConst(_) if let Some(param) = tcx.opt_const_param_of(def_id) => {
// We defer to `type_of` of the corresponding parameter
@@ -411,40 +424,93 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
| Node::Item(&Item { kind: ItemKind::GlobalAsm(asm), .. })
if asm.operands.iter().any(|(op, _op_sp)| match op {
hir::InlineAsmOperand::Const { anon_const }
- | hir::InlineAsmOperand::SymFn { anon_const } => anon_const.hir_id == hir_id,
+ | hir::InlineAsmOperand::SymFn { anon_const } => {
+ anon_const.hir_id == hir_id
+ }
_ => false,
}) =>
{
tcx.typeck(def_id).node_type(hir_id)
}
- Node::Variant(Variant { disr_expr: Some(ref e), .. }) if e.hir_id == hir_id => tcx
- .adt_def(tcx.hir().get_parent_item(hir_id))
- .repr()
- .discr_type()
- .to_ty(tcx),
+ Node::Variant(Variant { disr_expr: Some(ref e), .. }) if e.hir_id == hir_id => {
+ tcx.adt_def(tcx.hir().get_parent_item(hir_id)).repr().discr_type().to_ty(tcx)
+ }
- Node::TypeBinding(binding @ &TypeBinding { hir_id: binding_id, .. })
- if let Node::TraitRef(trait_ref) = tcx.hir().get(
- tcx.hir().get_parent_node(binding_id)
- ) =>
+ Node::TypeBinding(
+ binding @ &TypeBinding {
+ hir_id: binding_id,
+ kind: TypeBindingKind::Equality { term: Term::Const(ref e) },
+ ..
+ },
+ ) if let Node::TraitRef(trait_ref) =
+ tcx.hir().get(tcx.hir().get_parent_node(binding_id))
+ && e.hir_id == hir_id =>
{
- let Some(trait_def_id) = trait_ref.trait_def_id() else {
- return tcx.ty_error_with_message(DUMMY_SP, "Could not find trait");
- };
- let assoc_items = tcx.associated_items(trait_def_id);
- let assoc_item = assoc_items.find_by_name_and_kind(
- tcx, binding.ident, ty::AssocKind::Const, def_id.to_def_id(),
- );
- if let Some(assoc_item) = assoc_item {
- tcx.type_of(assoc_item.def_id)
- } else {
- // FIXME(associated_const_equality): add a useful error message here.
- tcx.ty_error_with_message(
- DUMMY_SP,
- "Could not find associated const on trait",
- )
- }
+ let Some(trait_def_id) = trait_ref.trait_def_id() else {
+ return tcx.ty_error_with_message(DUMMY_SP, "Could not find trait");
+ };
+ let assoc_items = tcx.associated_items(trait_def_id);
+ let assoc_item = assoc_items.find_by_name_and_kind(
+ tcx,
+ binding.ident,
+ ty::AssocKind::Const,
+ def_id.to_def_id(),
+ );
+ if let Some(assoc_item) = assoc_item {
+ tcx.type_of(assoc_item.def_id)
+ } else {
+ // FIXME(associated_const_equality): add a useful error message here.
+ tcx.ty_error_with_message(
+ DUMMY_SP,
+ "Could not find associated const on trait",
+ )
+ }
+ }
+
+ Node::TypeBinding(
+ binding @ &TypeBinding { hir_id: binding_id, gen_args, ref kind, .. },
+ ) if let Node::TraitRef(trait_ref) =
+ tcx.hir().get(tcx.hir().get_parent_node(binding_id))
+ && let Some((idx, _)) =
+ gen_args.args.iter().enumerate().find(|(_, arg)| {
+ if let GenericArg::Const(ct) = arg {
+ ct.value.hir_id == hir_id
+ } else {
+ false
+ }
+ }) =>
+ {
+ let Some(trait_def_id) = trait_ref.trait_def_id() else {
+ return tcx.ty_error_with_message(DUMMY_SP, "Could not find trait");
+ };
+ let assoc_items = tcx.associated_items(trait_def_id);
+ let assoc_item = assoc_items.find_by_name_and_kind(
+ tcx,
+ binding.ident,
+ match kind {
+ // I think `<A: T>` type bindings requires that `A` is a type
+ TypeBindingKind::Constraint { .. }
+ | TypeBindingKind::Equality { term: Term::Ty(..) } => {
+ ty::AssocKind::Type
+ }
+ TypeBindingKind::Equality { term: Term::Const(..) } => {
+ ty::AssocKind::Const
+ }
+ },
+ def_id.to_def_id(),
+ );
+ if let Some(param)
+ = assoc_item.map(|item| &tcx.generics_of(item.def_id).params[idx]).filter(|param| param.kind.is_ty_or_const())
+ {
+ tcx.type_of(param.def_id)
+ } else {
+ // FIXME(associated_const_equality): add a useful error message here.
+ tcx.ty_error_with_message(
+ DUMMY_SP,
+ "Could not find associated const on trait",
+ )
+ }
}
Node::GenericParam(&GenericParam {
@@ -453,8 +519,7 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
..
}) if ct.hir_id == hir_id => tcx.type_of(tcx.hir().local_def_id(param_hir_id)),
- x =>
- tcx.ty_error_with_message(
+ x => tcx.ty_error_with_message(
DUMMY_SP,
&format!("unexpected const parent in type_of(): {x:?}"),
),
@@ -508,6 +573,11 @@ fn find_opaque_ty_constraints_for_tait(tcx: TyCtxt<'_>, def_id: LocalDefId) -> T
/// checked against it (we also carry the span of that first
/// type).
found: Option<ty::OpaqueHiddenType<'tcx>>,
+
+ /// In the presence of dead code, typeck may figure out a hidden type
+ /// while borrowck will now. We collect these cases here and check at
+ /// the end that we actually found a type that matches (modulo regions).
+ typeck_types: Vec<ty::OpaqueHiddenType<'tcx>>,
}
impl ConstraintLocator<'_> {
@@ -534,18 +604,23 @@ fn find_opaque_ty_constraints_for_tait(tcx: TyCtxt<'_>, def_id: LocalDefId) -> T
self.found = Some(ty::OpaqueHiddenType { span: DUMMY_SP, ty: self.tcx.ty_error() });
return;
}
- if !tables.concrete_opaque_types.contains_key(&self.def_id) {
+ let Some(&typeck_hidden_ty) = tables.concrete_opaque_types.get(&self.def_id) else {
debug!("no constraints in typeck results");
return;
+ };
+ if self.typeck_types.iter().all(|prev| prev.ty != typeck_hidden_ty.ty) {
+ self.typeck_types.push(typeck_hidden_ty);
}
+
// Use borrowck to get the type with unerased regions.
let concrete_opaque_types = &self.tcx.mir_borrowck(item_def_id).concrete_opaque_types;
debug!(?concrete_opaque_types);
if let Some(&concrete_type) = concrete_opaque_types.get(&self.def_id) {
debug!(?concrete_type, "found constraint");
- if let Some(prev) = self.found {
- if concrete_type.ty != prev.ty && !(concrete_type, prev).references_error() {
+ if let Some(prev) = &mut self.found {
+ if concrete_type.ty != prev.ty && !(concrete_type, prev.ty).references_error() {
prev.report_mismatch(&concrete_type, self.tcx);
+ prev.ty = self.tcx.ty_error();
}
} else {
self.found = Some(concrete_type);
@@ -568,31 +643,31 @@ fn find_opaque_ty_constraints_for_tait(tcx: TyCtxt<'_>, def_id: LocalDefId) -> T
intravisit::walk_expr(self, ex);
}
fn visit_item(&mut self, it: &'tcx Item<'tcx>) {
- trace!(?it.def_id);
+ trace!(?it.owner_id);
// The opaque type itself or its children are not within its reveal scope.
- if it.def_id != self.def_id {
- self.check(it.def_id);
+ if it.owner_id.def_id != self.def_id {
+ self.check(it.owner_id.def_id);
intravisit::walk_item(self, it);
}
}
fn visit_impl_item(&mut self, it: &'tcx ImplItem<'tcx>) {
- trace!(?it.def_id);
+ trace!(?it.owner_id);
// The opaque type itself or its children are not within its reveal scope.
- if it.def_id != self.def_id {
- self.check(it.def_id);
+ if it.owner_id.def_id != self.def_id {
+ self.check(it.owner_id.def_id);
intravisit::walk_impl_item(self, it);
}
}
fn visit_trait_item(&mut self, it: &'tcx TraitItem<'tcx>) {
- trace!(?it.def_id);
- self.check(it.def_id);
+ trace!(?it.owner_id);
+ self.check(it.owner_id.def_id);
intravisit::walk_trait_item(self, it);
}
}
let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
let scope = tcx.hir().get_defining_scope(hir_id);
- let mut locator = ConstraintLocator { def_id: def_id, tcx, found: None };
+ let mut locator = ConstraintLocator { def_id: def_id, tcx, found: None, typeck_types: vec![] };
debug!(?scope);
@@ -622,16 +697,32 @@ fn find_opaque_ty_constraints_for_tait(tcx: TyCtxt<'_>, def_id: LocalDefId) -> T
}
}
- match locator.found {
- Some(hidden) => hidden.ty,
- None => {
- tcx.sess.emit_err(UnconstrainedOpaqueType {
- span: tcx.def_span(def_id),
- name: tcx.item_name(tcx.local_parent(def_id).to_def_id()),
- });
- tcx.ty_error()
+ let Some(hidden) = locator.found else {
+ tcx.sess.emit_err(UnconstrainedOpaqueType {
+ span: tcx.def_span(def_id),
+ name: tcx.item_name(tcx.local_parent(def_id).to_def_id()),
+ what: match tcx.hir().get(scope) {
+ _ if scope == hir::CRATE_HIR_ID => "module",
+ Node::Item(hir::Item { kind: hir::ItemKind::Mod(_), .. }) => "module",
+ Node::Item(hir::Item { kind: hir::ItemKind::Impl(_), .. }) => "impl",
+ _ => "item",
+ },
+ });
+ return tcx.ty_error();
+ };
+
+ // Only check against typeck if we didn't already error
+ if !hidden.ty.references_error() {
+ for concrete_type in locator.typeck_types {
+ if tcx.erase_regions(concrete_type.ty) != tcx.erase_regions(hidden.ty)
+ && !(concrete_type, hidden).references_error()
+ {
+ hidden.report_mismatch(&concrete_type, tcx);
+ }
}
}
+
+ hidden.ty
}
fn find_opaque_ty_constraints_for_rpit(
@@ -687,24 +778,24 @@ fn find_opaque_ty_constraints_for_rpit(
intravisit::walk_expr(self, ex);
}
fn visit_item(&mut self, it: &'tcx Item<'tcx>) {
- trace!(?it.def_id);
+ trace!(?it.owner_id);
// The opaque type itself or its children are not within its reveal scope.
- if it.def_id != self.def_id {
- self.check(it.def_id);
+ if it.owner_id.def_id != self.def_id {
+ self.check(it.owner_id.def_id);
intravisit::walk_item(self, it);
}
}
fn visit_impl_item(&mut self, it: &'tcx ImplItem<'tcx>) {
- trace!(?it.def_id);
+ trace!(?it.owner_id);
// The opaque type itself or its children are not within its reveal scope.
- if it.def_id != self.def_id {
- self.check(it.def_id);
+ if it.owner_id.def_id != self.def_id {
+ self.check(it.owner_id.def_id);
intravisit::walk_impl_item(self, it);
}
}
fn visit_trait_item(&mut self, it: &'tcx TraitItem<'tcx>) {
- trace!(?it.def_id);
- self.check(it.def_id);
+ trace!(?it.owner_id);
+ self.check(it.owner_id.def_id);
intravisit::walk_trait_item(self, it);
}
}
@@ -732,20 +823,15 @@ fn find_opaque_ty_constraints_for_rpit(
// the `concrete_opaque_types` table.
tcx.ty_error()
} else {
- table
- .concrete_opaque_types
- .get(&def_id)
- .copied()
- .unwrap_or_else(|| {
- // We failed to resolve the opaque type or it
- // resolves to itself. We interpret this as the
- // no values of the hidden type ever being constructed,
- // so we can just make the hidden type be `!`.
- // For backwards compatibility reasons, we fall back to
- // `()` until we the diverging default is changed.
- Some(tcx.mk_diverging_default())
- })
- .expect("RPIT always have a hidden type from typeck")
+ table.concrete_opaque_types.get(&def_id).map(|ty| ty.ty).unwrap_or_else(|| {
+ // We failed to resolve the opaque type or it
+ // resolves to itself. We interpret this as the
+ // no values of the hidden type ever being constructed,
+ // so we can just make the hidden type be `!`.
+ // For backwards compatibility reasons, we fall back to
+ // `()` until we the diverging default is changed.
+ tcx.mk_diverging_default()
+ })
}
})
}
@@ -801,6 +887,9 @@ fn infer_placeholder_type<'a>(
match tcx.sess.diagnostic().steal_diagnostic(span, StashKey::ItemNoType) {
Some(mut err) => {
if !ty.references_error() {
+ // Only suggest adding `:` if it was missing (and suggested by parsing diagnostic)
+ let colon = if span == item_ident.span.shrink_to_hi() { ":" } else { "" };
+
// The parser provided a sub-optimal `HasPlaceholders` suggestion for the type.
// We are typeck and have the real type, so remove that and suggest the actual type.
// FIXME(eddyb) this looks like it should be functionality on `Diagnostic`.
@@ -816,7 +905,7 @@ fn infer_placeholder_type<'a>(
err.span_suggestion(
span,
&format!("provide a type for the {item}", item = kind),
- format!("{}: {}", item_ident, sugg_ty),
+ format!("{colon} {sugg_ty}"),
Applicability::MachineApplicable,
);
} else {
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-24 08:52:05 +0000