//! "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_id::{DefId, LocalDefId, LOCAL_CRATE}; use rustc_hir::intravisit::{self, Visitor}; use rustc_hir::weak_lang_items::WEAK_LANG_ITEMS; use rustc_hir::{lang_items, GenericParamKind, LangItem, 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::{self, AdtKind, Const, DefIdTree, IsSuggestable, ToPredicate, 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, is_type_alias_impl_trait, ..*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); 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, 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, additional_spans: Vec, 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);` 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(_: K)` not `fn foo(_: 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(_), .. } => { self.tcx.ensure().type_of(param.def_id); } hir::GenericParamKind::Type { .. } => {} hir::GenericParamKind::Const { default, .. } => { self.tcx.ensure().type_of(param.def_id); if let Some(default) = default { // need to store default and type of default self.tcx.ensure().type_of(default.def_id); self.tcx.ensure().const_param_default(param.def_id); } } } } intravisit::walk_generics(self, generics); } fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) { if let hir::ExprKind::Closure(closure) = expr.kind { self.tcx.ensure().generics_of(closure.def_id); self.tcx.ensure().codegen_fn_attrs(closure.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, 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> { >::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) -> DefId { 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> { 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 = >::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(<_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 `::C`, not `::C`. self.tcx.anonymize_late_bound_regions(poly_trait_ref).skip_binder(), ), Applicability::MaybeIncorrect, ); } _ => {} } self.tcx().ty_error_with_guaranteed(err.emit()) } } 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, _: ErrorGuaranteed) { // 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 { .. } = ¶m.kind { Some(param.name.ident().as_str().to_string()) } else { None } })) .collect::>(); 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().codegen_fn_attrs(item.owner_id); tcx.ensure().fn_sig(item.owner_id) } hir::ForeignItemKind::Static(..) => { tcx.ensure().codegen_fn_attrs(item.owner_id); let mut visitor = HirPlaceholderCollector::default(); visitor.visit_foreign_item(item); placeholder_type_error( tcx, None, visitor.0, false, None, "static variable", ); } _ => (), } } } hir::ItemKind::Enum(..) => { 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()); } 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() { tcx.ensure().generics_of(f.def_id); tcx.ensure().type_of(f.def_id); tcx.ensure().predicates_of(f.def_id); } if let Some(ctor_def_id) = struct_def.ctor_def_id() { convert_variant_ctor(tcx, ctor_def_id); } } // 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); tcx.ensure().item_bounds(def_id); } hir::ItemKind::TyAlias(..) => { tcx.ensure().generics_of(def_id); tcx.ensure().type_of(def_id); tcx.ensure().predicates_of(def_id); } hir::ItemKind::Static(ty, ..) | hir::ItemKind::Const(ty, ..) => { tcx.ensure().generics_of(def_id); tcx.ensure().type_of(def_id); tcx.ensure().predicates_of(def_id); 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()); } } hir::ItemKind::Fn(..) => { tcx.ensure().generics_of(def_id); tcx.ensure().type_of(def_id); tcx.ensure().predicates_of(def_id); tcx.ensure().fn_sig(def_id); tcx.ensure().codegen_fn_attrs(def_id); } } } 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().codegen_fn_attrs(def_id); 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().codegen_fn_attrs(def_id); 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<'_>, def_id: LocalDefId) { 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) { 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::>; // fill the discriminant values and field types for variant in def.variants() { let wrapped_discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx)); prev_discr = Some( if let ty::VariantDiscr::Explicit(const_def_id) = variant.discr { def.eval_explicit_discr(tcx, const_def_id) } else if let Some(discr) = repr_type.disr_incr(tcx, prev_discr) { Some(discr) } else { let span = tcx.def_span(variant.def_id); struct_span_err!(tcx.sess, span, E0370, "enum discriminant overflowed") .span_label(span, format!("overflowed on value after {}", prev_discr.unwrap())) .note(&format!( "explicitly set `{} = {}` if that is desired outcome", tcx.item_name(variant.def_id), wrapped_discr )) .emit(); None } .unwrap_or(wrapped_discr), ); for f in &variant.fields { tcx.ensure().generics_of(f.did); tcx.ensure().type_of(f.did); tcx.ensure().predicates_of(f.did); } // Convert the ctor, if any. This also registers the variant as // an item. if let Some(ctor_def_id) = variant.ctor_def_id() { convert_variant_ctor(tcx, ctor_def_id.expect_local()); } } } fn convert_variant( tcx: TyCtxt<'_>, variant_did: Option, ident: Ident, discr: ty::VariantDiscr, def: &hir::VariantData<'_>, adt_kind: ty::AdtKind, parent_did: LocalDefId, ) -> ty::VariantDef { let mut seen_fields: FxHashMap = Default::default(); let fields = def .fields() .iter() .map(|f| { 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: f.def_id.to_def_id(), name: f.ident.name, vis: tcx.visibility(f.def_id), } }) .collect(); let recovered = match def { hir::VariantData::Struct(_, r) => *r, _ => false, }; ty::VariantDef::new( ident.name, variant_did.map(LocalDefId::to_def_id), def.ctor().map(|(kind, _, def_id)| (kind, def_id.to_def_id())), discr, fields, 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 = tcx.repr_options_of_def(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 discr = if let Some(ref e) = v.disr_expr { distance_from_explicit = 0; ty::VariantDiscr::Explicit(e.def_id.to_def_id()) } else { ty::VariantDiscr::Relative(distance_from_explicit) }; distance_from_explicit += 1; convert_variant( tcx, Some(v.def_id), v.ident, discr, &v.data, AdtKind::Enum, def_id, ) }) .collect(); (AdtKind::Enum, variants) } ItemKind::Struct(ref def, _) | ItemKind::Union(ref def, _) => { let adt_kind = match item.kind { ItemKind::Struct(..) => AdtKind::Struct, _ => AdtKind::Union, }; let variants = std::iter::once(convert_variant( tcx, None, item.ident, ty::VariantDiscr::Relative(0), def, adt_kind, def_id, )) .collect(); (adt_kind, 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::, _>>() .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 = 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() { >::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, .. }) => >::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().is_some() => { let ty = tcx.type_of(tcx.hir().get_parent_item(hir_id)); let inputs = data.fields().iter().map(|f| tcx.type_of(f.def_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 => >::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> { 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); >::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> + 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, ); let inferred_outlives_iter = inferred_outlives.iter().map(|(clause, span)| ((*clause).to_predicate(tcx), *span)); if result.predicates.is_empty() { result.predicates = tcx.arena.alloc_from_iter(inferred_outlives_iter); } else { result.predicates = tcx.arena.alloc_from_iter( result.predicates.into_iter().copied().chain(inferred_outlives_iter), ); } } 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 = >::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 { 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>, target_features: &mut Vec, ) { 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() { let linkage = Some(linkage_by_name(tcx, did, val.as_str())); if tcx.is_foreign_item(did) { codegen_fn_attrs.import_linkage = linkage; } else { codegen_fn_attrs.linkage = linkage; } } } 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::>(); 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"), ) } } } if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NAKED) { codegen_fn_attrs.flags |= CodegenFnAttrFlags::NO_COVERAGE; codegen_fn_attrs.inline = InlineAttr::Never; } // 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 WEAK_LANG_ITEMS.iter().any(|&l| tcx.lang_items().get(l) == Some(did.to_def_id())) { codegen_fn_attrs.flags |= CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL; } if let Some((name, _)) = lang_items::extract(attrs) && let Some(lang_item) = LangItem::from_name(name) && let Some(link_name) = lang_item.link_name() { codegen_fn_attrs.export_name = Some(link_name); codegen_fn_attrs.link_name = Some(link_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 { 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 { use rustc_ast::{LitIntType, LitKind, MetaItemLit}; 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 = meta_item_list.as_deref(); let sole_meta_list = match meta_item_list { Some([item]) => item.lit(), 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(MetaItemLit { 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, ) { 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(); } } } fn is_type_alias_impl_trait<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> bool { match tcx.hir().get_if_local(def_id) { Some(Node::Item(hir::Item { kind: hir::ItemKind::OpaqueTy(opaque), .. })) => { matches!(opaque.origin, hir::OpaqueTyOrigin::TyAlias) } Some(_) => bug!("tried getting opaque_ty_origin for non-opaque: {:?}", def_id), _ => bug!("tried getting opaque_ty_origin for non-local def-id {:?}", def_id), } }