diff --git a/compiler/rustc_typeck/src/check/check.rs b/compiler/rustc_typeck/src/check/check.rs new file mode 100644 index 00000000000..2daa0354acb --- /dev/null +++ b/compiler/rustc_typeck/src/check/check.rs @@ -0,0 +1,1344 @@ +use super::coercion::CoerceMany; +use super::compare_method::{compare_const_impl, compare_impl_method, compare_ty_impl}; +use super::*; + +use rustc_attr as attr; +use rustc_errors::Applicability; +use rustc_hir as hir; +use rustc_hir::def_id::{DefId, LocalDefId, LOCAL_CRATE}; +use rustc_hir::lang_items::LangItem; +use rustc_hir::{ItemKind, Node}; +use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; +use rustc_infer::infer::RegionVariableOrigin; +use rustc_middle::ty::fold::TypeFoldable; +use rustc_middle::ty::subst::GenericArgKind; +use rustc_middle::ty::util::{Discr, IntTypeExt, Representability}; +use rustc_middle::ty::{self, RegionKind, ToPredicate, Ty, TyCtxt}; +use rustc_session::config::EntryFnType; +use rustc_span::symbol::sym; +use rustc_span::{self, MultiSpan, Span}; +use rustc_target::spec::abi::Abi; +use rustc_trait_selection::traits::{self, ObligationCauseCode}; + +pub fn check_wf_new(tcx: TyCtxt<'_>) { + let visit = wfcheck::CheckTypeWellFormedVisitor::new(tcx); + tcx.hir().krate().par_visit_all_item_likes(&visit); +} + +pub(super) fn check_abi(tcx: TyCtxt<'_>, span: Span, abi: Abi) { + if !tcx.sess.target.target.is_abi_supported(abi) { + struct_span_err!( + tcx.sess, + span, + E0570, + "The ABI `{}` is not supported for the current target", + abi + ) + .emit() + } +} + +/// Helper used for fns and closures. Does the grungy work of checking a function +/// body and returns the function context used for that purpose, since in the case of a fn item +/// there is still a bit more to do. +/// +/// * ... +/// * inherited: other fields inherited from the enclosing fn (if any) +pub(super) fn check_fn<'a, 'tcx>( + inherited: &'a Inherited<'a, 'tcx>, + param_env: ty::ParamEnv<'tcx>, + fn_sig: ty::FnSig<'tcx>, + decl: &'tcx hir::FnDecl<'tcx>, + fn_id: hir::HirId, + body: &'tcx hir::Body<'tcx>, + can_be_generator: Option, +) -> (FnCtxt<'a, 'tcx>, Option>) { + let mut fn_sig = fn_sig; + + debug!("check_fn(sig={:?}, fn_id={}, param_env={:?})", fn_sig, fn_id, param_env); + + // Create the function context. This is either derived from scratch or, + // in the case of closures, based on the outer context. + let mut fcx = FnCtxt::new(inherited, param_env, body.value.hir_id); + *fcx.ps.borrow_mut() = UnsafetyState::function(fn_sig.unsafety, fn_id); + + let tcx = fcx.tcx; + let sess = tcx.sess; + let hir = tcx.hir(); + + let declared_ret_ty = fn_sig.output(); + + let revealed_ret_ty = + fcx.instantiate_opaque_types_from_value(fn_id, &declared_ret_ty, decl.output.span()); + debug!("check_fn: declared_ret_ty: {}, revealed_ret_ty: {}", declared_ret_ty, revealed_ret_ty); + fcx.ret_coercion = Some(RefCell::new(CoerceMany::new(revealed_ret_ty))); + fcx.ret_type_span = Some(decl.output.span()); + if let ty::Opaque(..) = declared_ret_ty.kind() { + fcx.ret_coercion_impl_trait = Some(declared_ret_ty); + } + fn_sig = tcx.mk_fn_sig( + fn_sig.inputs().iter().cloned(), + revealed_ret_ty, + fn_sig.c_variadic, + fn_sig.unsafety, + fn_sig.abi, + ); + + let span = body.value.span; + + fn_maybe_err(tcx, span, fn_sig.abi); + + if body.generator_kind.is_some() && can_be_generator.is_some() { + let yield_ty = fcx + .next_ty_var(TypeVariableOrigin { kind: TypeVariableOriginKind::TypeInference, span }); + fcx.require_type_is_sized(yield_ty, span, traits::SizedYieldType); + + // Resume type defaults to `()` if the generator has no argument. + let resume_ty = fn_sig.inputs().get(0).copied().unwrap_or_else(|| tcx.mk_unit()); + + fcx.resume_yield_tys = Some((resume_ty, yield_ty)); + } + + let outer_def_id = tcx.closure_base_def_id(hir.local_def_id(fn_id).to_def_id()).expect_local(); + let outer_hir_id = hir.local_def_id_to_hir_id(outer_def_id); + GatherLocalsVisitor::new(&fcx, outer_hir_id).visit_body(body); + + // C-variadic fns also have a `VaList` input that's not listed in `fn_sig` + // (as it's created inside the body itself, not passed in from outside). + let maybe_va_list = if fn_sig.c_variadic { + let span = body.params.last().unwrap().span; + let va_list_did = tcx.require_lang_item(LangItem::VaList, Some(span)); + let region = fcx.next_region_var(RegionVariableOrigin::MiscVariable(span)); + + Some(tcx.type_of(va_list_did).subst(tcx, &[region.into()])) + } else { + None + }; + + // Add formal parameters. + let inputs_hir = hir.fn_decl_by_hir_id(fn_id).map(|decl| &decl.inputs); + let inputs_fn = fn_sig.inputs().iter().copied(); + for (idx, (param_ty, param)) in inputs_fn.chain(maybe_va_list).zip(body.params).enumerate() { + // Check the pattern. + let ty_span = try { inputs_hir?.get(idx)?.span }; + fcx.check_pat_top(¶m.pat, param_ty, ty_span, false); + + // Check that argument is Sized. + // The check for a non-trivial pattern is a hack to avoid duplicate warnings + // for simple cases like `fn foo(x: Trait)`, + // where we would error once on the parameter as a whole, and once on the binding `x`. + if param.pat.simple_ident().is_none() && !tcx.features().unsized_locals { + fcx.require_type_is_sized(param_ty, param.pat.span, traits::SizedArgumentType(ty_span)); + } + + fcx.write_ty(param.hir_id, param_ty); + } + + inherited.typeck_results.borrow_mut().liberated_fn_sigs_mut().insert(fn_id, fn_sig); + + fcx.in_tail_expr = true; + if let ty::Dynamic(..) = declared_ret_ty.kind() { + // FIXME: We need to verify that the return type is `Sized` after the return expression has + // been evaluated so that we have types available for all the nodes being returned, but that + // requires the coerced evaluated type to be stored. Moving `check_return_expr` before this + // causes unsized errors caused by the `declared_ret_ty` to point at the return expression, + // while keeping the current ordering we will ignore the tail expression's type because we + // don't know it yet. We can't do `check_expr_kind` while keeping `check_return_expr` + // because we will trigger "unreachable expression" lints unconditionally. + // Because of all of this, we perform a crude check to know whether the simplest `!Sized` + // case that a newcomer might make, returning a bare trait, and in that case we populate + // the tail expression's type so that the suggestion will be correct, but ignore all other + // possible cases. + fcx.check_expr(&body.value); + fcx.require_type_is_sized(declared_ret_ty, decl.output.span(), traits::SizedReturnType); + tcx.sess.delay_span_bug(decl.output.span(), "`!Sized` return type"); + } else { + fcx.require_type_is_sized(declared_ret_ty, decl.output.span(), traits::SizedReturnType); + fcx.check_return_expr(&body.value); + } + fcx.in_tail_expr = false; + + // We insert the deferred_generator_interiors entry after visiting the body. + // This ensures that all nested generators appear before the entry of this generator. + // resolve_generator_interiors relies on this property. + let gen_ty = if let (Some(_), Some(gen_kind)) = (can_be_generator, body.generator_kind) { + let interior = fcx + .next_ty_var(TypeVariableOrigin { kind: TypeVariableOriginKind::MiscVariable, span }); + fcx.deferred_generator_interiors.borrow_mut().push((body.id(), interior, gen_kind)); + + let (resume_ty, yield_ty) = fcx.resume_yield_tys.unwrap(); + Some(GeneratorTypes { + resume_ty, + yield_ty, + interior, + movability: can_be_generator.unwrap(), + }) + } else { + None + }; + + // Finalize the return check by taking the LUB of the return types + // we saw and assigning it to the expected return type. This isn't + // really expected to fail, since the coercions would have failed + // earlier when trying to find a LUB. + // + // However, the behavior around `!` is sort of complex. In the + // event that the `actual_return_ty` comes back as `!`, that + // indicates that the fn either does not return or "returns" only + // values of type `!`. In this case, if there is an expected + // return type that is *not* `!`, that should be ok. But if the + // return type is being inferred, we want to "fallback" to `!`: + // + // let x = move || panic!(); + // + // To allow for that, I am creating a type variable with diverging + // fallback. This was deemed ever so slightly better than unifying + // the return value with `!` because it allows for the caller to + // make more assumptions about the return type (e.g., they could do + // + // let y: Option = Some(x()); + // + // which would then cause this return type to become `u32`, not + // `!`). + let coercion = fcx.ret_coercion.take().unwrap().into_inner(); + let mut actual_return_ty = coercion.complete(&fcx); + if actual_return_ty.is_never() { + actual_return_ty = fcx.next_diverging_ty_var(TypeVariableOrigin { + kind: TypeVariableOriginKind::DivergingFn, + span, + }); + } + fcx.demand_suptype(span, revealed_ret_ty, actual_return_ty); + + // Check that the main return type implements the termination trait. + if let Some(term_id) = tcx.lang_items().termination() { + if let Some((def_id, EntryFnType::Main)) = tcx.entry_fn(LOCAL_CRATE) { + let main_id = hir.local_def_id_to_hir_id(def_id); + if main_id == fn_id { + let substs = tcx.mk_substs_trait(declared_ret_ty, &[]); + let trait_ref = ty::TraitRef::new(term_id, substs); + let return_ty_span = decl.output.span(); + let cause = traits::ObligationCause::new( + return_ty_span, + fn_id, + ObligationCauseCode::MainFunctionType, + ); + + inherited.register_predicate(traits::Obligation::new( + cause, + param_env, + trait_ref.without_const().to_predicate(tcx), + )); + } + } + } + + // Check that a function marked as `#[panic_handler]` has signature `fn(&PanicInfo) -> !` + if let Some(panic_impl_did) = tcx.lang_items().panic_impl() { + if panic_impl_did == hir.local_def_id(fn_id).to_def_id() { + if let Some(panic_info_did) = tcx.lang_items().panic_info() { + if *declared_ret_ty.kind() != ty::Never { + sess.span_err(decl.output.span(), "return type should be `!`"); + } + + let inputs = fn_sig.inputs(); + let span = hir.span(fn_id); + if inputs.len() == 1 { + let arg_is_panic_info = match *inputs[0].kind() { + ty::Ref(region, ty, mutbl) => match *ty.kind() { + ty::Adt(ref adt, _) => { + adt.did == panic_info_did + && mutbl == hir::Mutability::Not + && *region != RegionKind::ReStatic + } + _ => false, + }, + _ => false, + }; + + if !arg_is_panic_info { + sess.span_err(decl.inputs[0].span, "argument should be `&PanicInfo`"); + } + + if let Node::Item(item) = hir.get(fn_id) { + if let ItemKind::Fn(_, ref generics, _) = item.kind { + if !generics.params.is_empty() { + sess.span_err(span, "should have no type parameters"); + } + } + } + } else { + let span = sess.source_map().guess_head_span(span); + sess.span_err(span, "function should have one argument"); + } + } else { + sess.err("language item required, but not found: `panic_info`"); + } + } + } + + // Check that a function marked as `#[alloc_error_handler]` has signature `fn(Layout) -> !` + if let Some(alloc_error_handler_did) = tcx.lang_items().oom() { + if alloc_error_handler_did == hir.local_def_id(fn_id).to_def_id() { + if let Some(alloc_layout_did) = tcx.lang_items().alloc_layout() { + if *declared_ret_ty.kind() != ty::Never { + sess.span_err(decl.output.span(), "return type should be `!`"); + } + + let inputs = fn_sig.inputs(); + let span = hir.span(fn_id); + if inputs.len() == 1 { + let arg_is_alloc_layout = match inputs[0].kind() { + ty::Adt(ref adt, _) => adt.did == alloc_layout_did, + _ => false, + }; + + if !arg_is_alloc_layout { + sess.span_err(decl.inputs[0].span, "argument should be `Layout`"); + } + + if let Node::Item(item) = hir.get(fn_id) { + if let ItemKind::Fn(_, ref generics, _) = item.kind { + if !generics.params.is_empty() { + sess.span_err( + span, + "`#[alloc_error_handler]` function should have no type \ + parameters", + ); + } + } + } + } else { + let span = sess.source_map().guess_head_span(span); + sess.span_err(span, "function should have one argument"); + } + } else { + sess.err("language item required, but not found: `alloc_layout`"); + } + } + } + + (fcx, gen_ty) +} + +pub(super) fn check_struct(tcx: TyCtxt<'_>, id: hir::HirId, span: Span) { + let def_id = tcx.hir().local_def_id(id); + let def = tcx.adt_def(def_id); + def.destructor(tcx); // force the destructor to be evaluated + check_representable(tcx, span, def_id); + + if def.repr.simd() { + check_simd(tcx, span, def_id); + } + + check_transparent(tcx, span, def); + check_packed(tcx, span, def); +} + +pub(super) fn check_union(tcx: TyCtxt<'_>, id: hir::HirId, span: Span) { + let def_id = tcx.hir().local_def_id(id); + let def = tcx.adt_def(def_id); + def.destructor(tcx); // force the destructor to be evaluated + check_representable(tcx, span, def_id); + check_transparent(tcx, span, def); + check_union_fields(tcx, span, def_id); + check_packed(tcx, span, def); +} + +/// When the `#![feature(untagged_unions)]` gate is active, +/// check that the fields of the `union` does not contain fields that need dropping. +pub(super) fn check_union_fields(tcx: TyCtxt<'_>, span: Span, item_def_id: LocalDefId) -> bool { + let item_type = tcx.type_of(item_def_id); + if let ty::Adt(def, substs) = item_type.kind() { + assert!(def.is_union()); + let fields = &def.non_enum_variant().fields; + let param_env = tcx.param_env(item_def_id); + for field in fields { + let field_ty = field.ty(tcx, substs); + // We are currently checking the type this field came from, so it must be local. + let field_span = tcx.hir().span_if_local(field.did).unwrap(); + if field_ty.needs_drop(tcx, param_env) { + struct_span_err!( + tcx.sess, + field_span, + E0740, + "unions may not contain fields that need dropping" + ) + .span_note(field_span, "`std::mem::ManuallyDrop` can be used to wrap the type") + .emit(); + return false; + } + } + } else { + span_bug!(span, "unions must be ty::Adt, but got {:?}", item_type.kind()); + } + true +} + +/// Checks that an opaque type does not contain cycles and does not use `Self` or `T::Foo` +/// projections that would result in "inheriting lifetimes". +pub(super) fn check_opaque<'tcx>( + tcx: TyCtxt<'tcx>, + def_id: LocalDefId, + substs: SubstsRef<'tcx>, + span: Span, + origin: &hir::OpaqueTyOrigin, +) { + check_opaque_for_inheriting_lifetimes(tcx, def_id, span); + check_opaque_for_cycles(tcx, def_id, substs, span, origin); +} + +/// Checks that an opaque type does not use `Self` or `T::Foo` projections that would result +/// in "inheriting lifetimes". +pub(super) fn check_opaque_for_inheriting_lifetimes( + tcx: TyCtxt<'tcx>, + def_id: LocalDefId, + span: Span, +) { + let item = tcx.hir().expect_item(tcx.hir().local_def_id_to_hir_id(def_id)); + debug!( + "check_opaque_for_inheriting_lifetimes: def_id={:?} span={:?} item={:?}", + def_id, span, item + ); + + #[derive(Debug)] + struct ProhibitOpaqueVisitor<'tcx> { + opaque_identity_ty: Ty<'tcx>, + generics: &'tcx ty::Generics, + ty: Option>, + }; + + impl<'tcx> ty::fold::TypeVisitor<'tcx> for ProhibitOpaqueVisitor<'tcx> { + fn visit_ty(&mut self, t: Ty<'tcx>) -> bool { + debug!("check_opaque_for_inheriting_lifetimes: (visit_ty) t={:?}", t); + if t != self.opaque_identity_ty && t.super_visit_with(self) { + self.ty = Some(t); + return true; + } + false + } + + fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool { + debug!("check_opaque_for_inheriting_lifetimes: (visit_region) r={:?}", r); + if let RegionKind::ReEarlyBound(ty::EarlyBoundRegion { index, .. }) = r { + return *index < self.generics.parent_count as u32; + } + + r.super_visit_with(self) + } + + fn visit_const(&mut self, c: &'tcx ty::Const<'tcx>) -> bool { + if let ty::ConstKind::Unevaluated(..) = c.val { + // FIXME(#72219) We currenctly don't detect lifetimes within substs + // which would violate this check. Even though the particular substitution is not used + // within the const, this should still be fixed. + return false; + } + c.super_visit_with(self) + } + } + + if let ItemKind::OpaqueTy(hir::OpaqueTy { + origin: hir::OpaqueTyOrigin::AsyncFn | hir::OpaqueTyOrigin::FnReturn, + .. + }) = item.kind + { + let mut visitor = ProhibitOpaqueVisitor { + opaque_identity_ty: tcx.mk_opaque( + def_id.to_def_id(), + InternalSubsts::identity_for_item(tcx, def_id.to_def_id()), + ), + generics: tcx.generics_of(def_id), + ty: None, + }; + let prohibit_opaque = tcx + .predicates_of(def_id) + .predicates + .iter() + .any(|(predicate, _)| predicate.visit_with(&mut visitor)); + debug!( + "check_opaque_for_inheriting_lifetimes: prohibit_opaque={:?}, visitor={:?}", + prohibit_opaque, visitor + ); + + if prohibit_opaque { + let is_async = match item.kind { + ItemKind::OpaqueTy(hir::OpaqueTy { origin, .. }) => match origin { + hir::OpaqueTyOrigin::AsyncFn => true, + _ => false, + }, + _ => unreachable!(), + }; + + let mut err = struct_span_err!( + tcx.sess, + span, + E0760, + "`{}` return type cannot contain a projection or `Self` that references lifetimes from \ + a parent scope", + if is_async { "async fn" } else { "impl Trait" }, + ); + + if let Ok(snippet) = tcx.sess.source_map().span_to_snippet(span) { + if snippet == "Self" { + if let Some(ty) = visitor.ty { + err.span_suggestion( + span, + "consider spelling out the type instead", + format!("{:?}", ty), + Applicability::MaybeIncorrect, + ); + } + } + } + err.emit(); + } + } +} + +/// Checks that an opaque type does not contain cycles. +pub(super) fn check_opaque_for_cycles<'tcx>( + tcx: TyCtxt<'tcx>, + def_id: LocalDefId, + substs: SubstsRef<'tcx>, + span: Span, + origin: &hir::OpaqueTyOrigin, +) { + if let Err(partially_expanded_type) = tcx.try_expand_impl_trait_type(def_id.to_def_id(), substs) + { + match origin { + hir::OpaqueTyOrigin::AsyncFn => async_opaque_type_cycle_error(tcx, span), + hir::OpaqueTyOrigin::Binding => { + binding_opaque_type_cycle_error(tcx, def_id, span, partially_expanded_type) + } + _ => opaque_type_cycle_error(tcx, def_id, span), + } + } +} + +pub fn check_item_type<'tcx>(tcx: TyCtxt<'tcx>, it: &'tcx hir::Item<'tcx>) { + debug!( + "check_item_type(it.hir_id={}, it.name={})", + it.hir_id, + tcx.def_path_str(tcx.hir().local_def_id(it.hir_id).to_def_id()) + ); + let _indenter = indenter(); + match it.kind { + // Consts can play a role in type-checking, so they are included here. + hir::ItemKind::Static(..) => { + let def_id = tcx.hir().local_def_id(it.hir_id); + tcx.ensure().typeck(def_id); + maybe_check_static_with_link_section(tcx, def_id, it.span); + } + hir::ItemKind::Const(..) => { + tcx.ensure().typeck(tcx.hir().local_def_id(it.hir_id)); + } + hir::ItemKind::Enum(ref enum_definition, _) => { + check_enum(tcx, it.span, &enum_definition.variants, it.hir_id); + } + hir::ItemKind::Fn(..) => {} // entirely within check_item_body + hir::ItemKind::Impl { ref items, .. } => { + debug!("ItemKind::Impl {} with id {}", it.ident, it.hir_id); + let impl_def_id = tcx.hir().local_def_id(it.hir_id); + if let Some(impl_trait_ref) = tcx.impl_trait_ref(impl_def_id) { + check_impl_items_against_trait(tcx, it.span, impl_def_id, impl_trait_ref, items); + let trait_def_id = impl_trait_ref.def_id; + check_on_unimplemented(tcx, trait_def_id, it); + } + } + hir::ItemKind::Trait(_, _, _, _, ref items) => { + let def_id = tcx.hir().local_def_id(it.hir_id); + check_on_unimplemented(tcx, def_id.to_def_id(), it); + + for item in items.iter() { + let item = tcx.hir().trait_item(item.id); + if let hir::TraitItemKind::Fn(sig, _) = &item.kind { + let abi = sig.header.abi; + fn_maybe_err(tcx, item.ident.span, abi); + } + } + } + hir::ItemKind::Struct(..) => { + check_struct(tcx, it.hir_id, it.span); + } + hir::ItemKind::Union(..) => { + check_union(tcx, it.hir_id, it.span); + } + hir::ItemKind::OpaqueTy(hir::OpaqueTy { origin, .. }) => { + // HACK(jynelson): trying to infer the type of `impl trait` breaks documenting + // `async-std` (and `pub async fn` in general). + // Since rustdoc doesn't care about the concrete type behind `impl Trait`, just don't look at it! + // See https://github.com/rust-lang/rust/issues/75100 + if !tcx.sess.opts.actually_rustdoc { + let def_id = tcx.hir().local_def_id(it.hir_id); + + let substs = InternalSubsts::identity_for_item(tcx, def_id.to_def_id()); + check_opaque(tcx, def_id, substs, it.span, &origin); + } + } + hir::ItemKind::TyAlias(..) => { + let def_id = tcx.hir().local_def_id(it.hir_id); + let pty_ty = tcx.type_of(def_id); + let generics = tcx.generics_of(def_id); + check_type_params_are_used(tcx, &generics, pty_ty); + } + hir::ItemKind::ForeignMod(ref m) => { + check_abi(tcx, it.span, m.abi); + + if m.abi == Abi::RustIntrinsic { + for item in m.items { + intrinsic::check_intrinsic_type(tcx, item); + } + } else if m.abi == Abi::PlatformIntrinsic { + for item in m.items { + intrinsic::check_platform_intrinsic_type(tcx, item); + } + } else { + for item in m.items { + let generics = tcx.generics_of(tcx.hir().local_def_id(item.hir_id)); + let own_counts = generics.own_counts(); + if generics.params.len() - own_counts.lifetimes != 0 { + let (kinds, kinds_pl, egs) = match (own_counts.types, own_counts.consts) { + (_, 0) => ("type", "types", Some("u32")), + // We don't specify an example value, because we can't generate + // a valid value for any type. + (0, _) => ("const", "consts", None), + _ => ("type or const", "types or consts", None), + }; + struct_span_err!( + tcx.sess, + item.span, + E0044, + "foreign items may not have {} parameters", + kinds, + ) + .span_label(item.span, &format!("can't have {} parameters", kinds)) + .help( + // FIXME: once we start storing spans for type arguments, turn this + // into a suggestion. + &format!( + "replace the {} parameters with concrete {}{}", + kinds, + kinds_pl, + egs.map(|egs| format!(" like `{}`", egs)).unwrap_or_default(), + ), + ) + .emit(); + } + + if let hir::ForeignItemKind::Fn(ref fn_decl, _, _) = item.kind { + require_c_abi_if_c_variadic(tcx, fn_decl, m.abi, item.span); + } + } + } + } + _ => { /* nothing to do */ } + } +} + +pub(super) fn check_on_unimplemented(tcx: TyCtxt<'_>, trait_def_id: DefId, item: &hir::Item<'_>) { + let item_def_id = tcx.hir().local_def_id(item.hir_id); + // an error would be reported if this fails. + let _ = traits::OnUnimplementedDirective::of_item(tcx, trait_def_id, item_def_id.to_def_id()); +} + +pub(super) fn check_specialization_validity<'tcx>( + tcx: TyCtxt<'tcx>, + trait_def: &ty::TraitDef, + trait_item: &ty::AssocItem, + impl_id: DefId, + impl_item: &hir::ImplItem<'_>, +) { + let kind = match impl_item.kind { + hir::ImplItemKind::Const(..) => ty::AssocKind::Const, + hir::ImplItemKind::Fn(..) => ty::AssocKind::Fn, + hir::ImplItemKind::TyAlias(_) => ty::AssocKind::Type, + }; + + let ancestors = match trait_def.ancestors(tcx, impl_id) { + Ok(ancestors) => ancestors, + Err(_) => return, + }; + let mut ancestor_impls = ancestors + .skip(1) + .filter_map(|parent| { + if parent.is_from_trait() { + None + } else { + Some((parent, parent.item(tcx, trait_item.ident, kind, trait_def.def_id))) + } + }) + .peekable(); + + if ancestor_impls.peek().is_none() { + // No parent, nothing to specialize. + return; + } + + let opt_result = ancestor_impls.find_map(|(parent_impl, parent_item)| { + match parent_item { + // Parent impl exists, and contains the parent item we're trying to specialize, but + // doesn't mark it `default`. + Some(parent_item) if traits::impl_item_is_final(tcx, &parent_item) => { + Some(Err(parent_impl.def_id())) + } + + // Parent impl contains item and makes it specializable. + Some(_) => Some(Ok(())), + + // Parent impl doesn't mention the item. This means it's inherited from the + // grandparent. In that case, if parent is a `default impl`, inherited items use the + // "defaultness" from the grandparent, else they are final. + None => { + if tcx.impl_defaultness(parent_impl.def_id()).is_default() { + None + } else { + Some(Err(parent_impl.def_id())) + } + } + } + }); + + // If `opt_result` is `None`, we have only encountered `default impl`s that don't contain the + // item. This is allowed, the item isn't actually getting specialized here. + let result = opt_result.unwrap_or(Ok(())); + + if let Err(parent_impl) = result { + report_forbidden_specialization(tcx, impl_item, parent_impl); + } +} + +pub(super) fn check_impl_items_against_trait<'tcx>( + tcx: TyCtxt<'tcx>, + full_impl_span: Span, + impl_id: LocalDefId, + impl_trait_ref: ty::TraitRef<'tcx>, + impl_item_refs: &[hir::ImplItemRef<'_>], +) { + let impl_span = tcx.sess.source_map().guess_head_span(full_impl_span); + + // If the trait reference itself is erroneous (so the compilation is going + // to fail), skip checking the items here -- the `impl_item` table in `tcx` + // isn't populated for such impls. + if impl_trait_ref.references_error() { + return; + } + + // Negative impls are not expected to have any items + match tcx.impl_polarity(impl_id) { + ty::ImplPolarity::Reservation | ty::ImplPolarity::Positive => {} + ty::ImplPolarity::Negative => { + if let [first_item_ref, ..] = impl_item_refs { + let first_item_span = tcx.hir().impl_item(first_item_ref.id).span; + struct_span_err!( + tcx.sess, + first_item_span, + E0749, + "negative impls cannot have any items" + ) + .emit(); + } + return; + } + } + + // Locate trait definition and items + let trait_def = tcx.trait_def(impl_trait_ref.def_id); + + let impl_items = || impl_item_refs.iter().map(|iiref| tcx.hir().impl_item(iiref.id)); + + // Check existing impl methods to see if they are both present in trait + // and compatible with trait signature + for impl_item in impl_items() { + let namespace = impl_item.kind.namespace(); + let ty_impl_item = tcx.associated_item(tcx.hir().local_def_id(impl_item.hir_id)); + let ty_trait_item = tcx + .associated_items(impl_trait_ref.def_id) + .find_by_name_and_namespace(tcx, ty_impl_item.ident, namespace, impl_trait_ref.def_id) + .or_else(|| { + // Not compatible, but needed for the error message + tcx.associated_items(impl_trait_ref.def_id) + .filter_by_name(tcx, ty_impl_item.ident, impl_trait_ref.def_id) + .next() + }); + + // Check that impl definition matches trait definition + if let Some(ty_trait_item) = ty_trait_item { + match impl_item.kind { + hir::ImplItemKind::Const(..) => { + // Find associated const definition. + if ty_trait_item.kind == ty::AssocKind::Const { + compare_const_impl( + tcx, + &ty_impl_item, + impl_item.span, + &ty_trait_item, + impl_trait_ref, + ); + } else { + let mut err = struct_span_err!( + tcx.sess, + impl_item.span, + E0323, + "item `{}` is an associated const, \ + which doesn't match its trait `{}`", + ty_impl_item.ident, + impl_trait_ref.print_only_trait_path() + ); + err.span_label(impl_item.span, "does not match trait"); + // We can only get the spans from local trait definition + // Same for E0324 and E0325 + if let Some(trait_span) = tcx.hir().span_if_local(ty_trait_item.def_id) { + err.span_label(trait_span, "item in trait"); + } + err.emit() + } + } + hir::ImplItemKind::Fn(..) => { + let opt_trait_span = tcx.hir().span_if_local(ty_trait_item.def_id); + if ty_trait_item.kind == ty::AssocKind::Fn { + compare_impl_method( + tcx, + &ty_impl_item, + impl_item.span, + &ty_trait_item, + impl_trait_ref, + opt_trait_span, + ); + } else { + let mut err = struct_span_err!( + tcx.sess, + impl_item.span, + E0324, + "item `{}` is an associated method, \ + which doesn't match its trait `{}`", + ty_impl_item.ident, + impl_trait_ref.print_only_trait_path() + ); + err.span_label(impl_item.span, "does not match trait"); + if let Some(trait_span) = opt_trait_span { + err.span_label(trait_span, "item in trait"); + } + err.emit() + } + } + hir::ImplItemKind::TyAlias(_) => { + let opt_trait_span = tcx.hir().span_if_local(ty_trait_item.def_id); + if ty_trait_item.kind == ty::AssocKind::Type { + compare_ty_impl( + tcx, + &ty_impl_item, + impl_item.span, + &ty_trait_item, + impl_trait_ref, + opt_trait_span, + ); + } else { + let mut err = struct_span_err!( + tcx.sess, + impl_item.span, + E0325, + "item `{}` is an associated type, \ + which doesn't match its trait `{}`", + ty_impl_item.ident, + impl_trait_ref.print_only_trait_path() + ); + err.span_label(impl_item.span, "does not match trait"); + if let Some(trait_span) = opt_trait_span { + err.span_label(trait_span, "item in trait"); + } + err.emit() + } + } + } + + check_specialization_validity( + tcx, + trait_def, + &ty_trait_item, + impl_id.to_def_id(), + impl_item, + ); + } + } + + // Check for missing items from trait + let mut missing_items = Vec::new(); + if let Ok(ancestors) = trait_def.ancestors(tcx, impl_id.to_def_id()) { + for trait_item in tcx.associated_items(impl_trait_ref.def_id).in_definition_order() { + let is_implemented = ancestors + .leaf_def(tcx, trait_item.ident, trait_item.kind) + .map(|node_item| !node_item.defining_node.is_from_trait()) + .unwrap_or(false); + + if !is_implemented && tcx.impl_defaultness(impl_id).is_final() { + if !trait_item.defaultness.has_value() { + missing_items.push(*trait_item); + } + } + } + } + + if !missing_items.is_empty() { + missing_items_err(tcx, impl_span, &missing_items, full_impl_span); + } +} + +/// Checks whether a type can be represented in memory. In particular, it +/// identifies types that contain themselves without indirection through a +/// pointer, which would mean their size is unbounded. +pub(super) fn check_representable(tcx: TyCtxt<'_>, sp: Span, item_def_id: LocalDefId) -> bool { + let rty = tcx.type_of(item_def_id); + + // Check that it is possible to represent this type. This call identifies + // (1) types that contain themselves and (2) types that contain a different + // recursive type. It is only necessary to throw an error on those that + // contain themselves. For case 2, there must be an inner type that will be + // caught by case 1. + match rty.is_representable(tcx, sp) { + Representability::SelfRecursive(spans) => { + recursive_type_with_infinite_size_error(tcx, item_def_id.to_def_id(), spans); + return false; + } + Representability::Representable | Representability::ContainsRecursive => (), + } + true +} + +pub fn check_simd(tcx: TyCtxt<'_>, sp: Span, def_id: LocalDefId) { + let t = tcx.type_of(def_id); + if let ty::Adt(def, substs) = t.kind() { + if def.is_struct() { + let fields = &def.non_enum_variant().fields; + if fields.is_empty() { + struct_span_err!(tcx.sess, sp, E0075, "SIMD vector cannot be empty").emit(); + return; + } + let e = fields[0].ty(tcx, substs); + if !fields.iter().all(|f| f.ty(tcx, substs) == e) { + struct_span_err!(tcx.sess, sp, E0076, "SIMD vector should be homogeneous") + .span_label(sp, "SIMD elements must have the same type") + .emit(); + return; + } + match e.kind() { + ty::Param(_) => { /* struct(T, T, T, T) is ok */ } + _ if e.is_machine() => { /* struct(u8, u8, u8, u8) is ok */ } + _ => { + struct_span_err!( + tcx.sess, + sp, + E0077, + "SIMD vector element type should be machine type" + ) + .emit(); + return; + } + } + } + } +} + +pub(super) fn check_packed(tcx: TyCtxt<'_>, sp: Span, def: &ty::AdtDef) { + let repr = def.repr; + if repr.packed() { + for attr in tcx.get_attrs(def.did).iter() { + for r in attr::find_repr_attrs(&tcx.sess, attr) { + if let attr::ReprPacked(pack) = r { + if let Some(repr_pack) = repr.pack { + if pack as u64 != repr_pack.bytes() { + struct_span_err!( + tcx.sess, + sp, + E0634, + "type has conflicting packed representation hints" + ) + .emit(); + } + } + } + } + } + if repr.align.is_some() { + struct_span_err!( + tcx.sess, + sp, + E0587, + "type has conflicting packed and align representation hints" + ) + .emit(); + } else { + if let Some(def_spans) = check_packed_inner(tcx, def.did, &mut vec![]) { + let mut err = struct_span_err!( + tcx.sess, + sp, + E0588, + "packed type cannot transitively contain a `#[repr(align)]` type" + ); + + err.span_note( + tcx.def_span(def_spans[0].0), + &format!( + "`{}` has a `#[repr(align)]` attribute", + tcx.item_name(def_spans[0].0) + ), + ); + + if def_spans.len() > 2 { + let mut first = true; + for (adt_def, span) in def_spans.iter().skip(1).rev() { + let ident = tcx.item_name(*adt_def); + err.span_note( + *span, + &if first { + format!( + "`{}` contains a field of type `{}`", + tcx.type_of(def.did), + ident + ) + } else { + format!("...which contains a field of type `{}`", ident) + }, + ); + first = false; + } + } + + err.emit(); + } + } + } +} + +pub(super) fn check_packed_inner( + tcx: TyCtxt<'_>, + def_id: DefId, + stack: &mut Vec, +) -> Option> { + if let ty::Adt(def, substs) = tcx.type_of(def_id).kind() { + if def.is_struct() || def.is_union() { + if def.repr.align.is_some() { + return Some(vec![(def.did, DUMMY_SP)]); + } + + stack.push(def_id); + for field in &def.non_enum_variant().fields { + if let ty::Adt(def, _) = field.ty(tcx, substs).kind() { + if !stack.contains(&def.did) { + if let Some(mut defs) = check_packed_inner(tcx, def.did, stack) { + defs.push((def.did, field.ident.span)); + return Some(defs); + } + } + } + } + stack.pop(); + } + } + + None +} + +pub(super) fn check_transparent<'tcx>(tcx: TyCtxt<'tcx>, sp: Span, adt: &'tcx ty::AdtDef) { + if !adt.repr.transparent() { + return; + } + let sp = tcx.sess.source_map().guess_head_span(sp); + + if adt.is_union() && !tcx.features().transparent_unions { + feature_err( + &tcx.sess.parse_sess, + sym::transparent_unions, + sp, + "transparent unions are unstable", + ) + .emit(); + } + + if adt.variants.len() != 1 { + bad_variant_count(tcx, adt, sp, adt.did); + if adt.variants.is_empty() { + // Don't bother checking the fields. No variants (and thus no fields) exist. + return; + } + } + + // For each field, figure out if it's known to be a ZST and align(1) + let field_infos = adt.all_fields().map(|field| { + let ty = field.ty(tcx, InternalSubsts::identity_for_item(tcx, field.did)); + let param_env = tcx.param_env(field.did); + let layout = tcx.layout_of(param_env.and(ty)); + // We are currently checking the type this field came from, so it must be local + let span = tcx.hir().span_if_local(field.did).unwrap(); + let zst = layout.map(|layout| layout.is_zst()).unwrap_or(false); + let align1 = layout.map(|layout| layout.align.abi.bytes() == 1).unwrap_or(false); + (span, zst, align1) + }); + + let non_zst_fields = + field_infos.clone().filter_map(|(span, zst, _align1)| if !zst { Some(span) } else { None }); + let non_zst_count = non_zst_fields.clone().count(); + if non_zst_count != 1 { + bad_non_zero_sized_fields(tcx, adt, non_zst_count, non_zst_fields, sp); + } + for (span, zst, align1) in field_infos { + if zst && !align1 { + struct_span_err!( + tcx.sess, + span, + E0691, + "zero-sized field in transparent {} has alignment larger than 1", + adt.descr(), + ) + .span_label(span, "has alignment larger than 1") + .emit(); + } + } +} + +#[allow(trivial_numeric_casts)] +pub fn check_enum<'tcx>( + tcx: TyCtxt<'tcx>, + sp: Span, + vs: &'tcx [hir::Variant<'tcx>], + id: hir::HirId, +) { + let def_id = tcx.hir().local_def_id(id); + let def = tcx.adt_def(def_id); + def.destructor(tcx); // force the destructor to be evaluated + + if vs.is_empty() { + let attributes = tcx.get_attrs(def_id.to_def_id()); + if let Some(attr) = tcx.sess.find_by_name(&attributes, sym::repr) { + struct_span_err!( + tcx.sess, + attr.span, + E0084, + "unsupported representation for zero-variant enum" + ) + .span_label(sp, "zero-variant enum") + .emit(); + } + } + + let repr_type_ty = def.repr.discr_type().to_ty(tcx); + if repr_type_ty == tcx.types.i128 || repr_type_ty == tcx.types.u128 { + if !tcx.features().repr128 { + feature_err( + &tcx.sess.parse_sess, + sym::repr128, + sp, + "repr with 128-bit type is unstable", + ) + .emit(); + } + } + + for v in vs { + if let Some(ref e) = v.disr_expr { + tcx.ensure().typeck(tcx.hir().local_def_id(e.hir_id)); + } + } + + if tcx.adt_def(def_id).repr.int.is_none() && tcx.features().arbitrary_enum_discriminant { + let is_unit = |var: &hir::Variant<'_>| match var.data { + hir::VariantData::Unit(..) => true, + _ => false, + }; + + let has_disr = |var: &hir::Variant<'_>| var.disr_expr.is_some(); + let has_non_units = vs.iter().any(|var| !is_unit(var)); + let disr_units = vs.iter().any(|var| is_unit(&var) && has_disr(&var)); + let disr_non_unit = vs.iter().any(|var| !is_unit(&var) && has_disr(&var)); + + if disr_non_unit || (disr_units && has_non_units) { + let mut err = + struct_span_err!(tcx.sess, sp, E0732, "`#[repr(inttype)]` must be specified"); + err.emit(); + } + } + + let mut disr_vals: Vec> = Vec::with_capacity(vs.len()); + for ((_, discr), v) in def.discriminants(tcx).zip(vs) { + // Check for duplicate discriminant values + if let Some(i) = disr_vals.iter().position(|&x| x.val == discr.val) { + let variant_did = def.variants[VariantIdx::new(i)].def_id; + let variant_i_hir_id = tcx.hir().local_def_id_to_hir_id(variant_did.expect_local()); + let variant_i = tcx.hir().expect_variant(variant_i_hir_id); + let i_span = match variant_i.disr_expr { + Some(ref expr) => tcx.hir().span(expr.hir_id), + None => tcx.hir().span(variant_i_hir_id), + }; + let span = match v.disr_expr { + Some(ref expr) => tcx.hir().span(expr.hir_id), + None => v.span, + }; + struct_span_err!( + tcx.sess, + span, + E0081, + "discriminant value `{}` already exists", + disr_vals[i] + ) + .span_label(i_span, format!("first use of `{}`", disr_vals[i])) + .span_label(span, format!("enum already has `{}`", disr_vals[i])) + .emit(); + } + disr_vals.push(discr); + } + + check_representable(tcx, sp, def_id); + check_transparent(tcx, sp, def); +} + +pub(super) fn check_type_params_are_used<'tcx>( + tcx: TyCtxt<'tcx>, + generics: &ty::Generics, + ty: Ty<'tcx>, +) { + debug!("check_type_params_are_used(generics={:?}, ty={:?})", generics, ty); + + assert_eq!(generics.parent, None); + + if generics.own_counts().types == 0 { + return; + } + + let mut params_used = BitSet::new_empty(generics.params.len()); + + if ty.references_error() { + // If there is already another error, do not emit + // an error for not using a type parameter. + assert!(tcx.sess.has_errors()); + return; + } + + for leaf in ty.walk() { + if let GenericArgKind::Type(leaf_ty) = leaf.unpack() { + if let ty::Param(param) = leaf_ty.kind() { + debug!("found use of ty param {:?}", param); + params_used.insert(param.index); + } + } + } + + for param in &generics.params { + if !params_used.contains(param.index) { + if let ty::GenericParamDefKind::Type { .. } = param.kind { + let span = tcx.def_span(param.def_id); + struct_span_err!( + tcx.sess, + span, + E0091, + "type parameter `{}` is unused", + param.name, + ) + .span_label(span, "unused type parameter") + .emit(); + } + } + } +} + +pub(super) fn check_mod_item_types(tcx: TyCtxt<'_>, module_def_id: LocalDefId) { + tcx.hir().visit_item_likes_in_module(module_def_id, &mut CheckItemTypesVisitor { tcx }); +} + +pub(super) fn check_item_well_formed(tcx: TyCtxt<'_>, def_id: LocalDefId) { + wfcheck::check_item_well_formed(tcx, def_id); +} + +pub(super) fn check_trait_item_well_formed(tcx: TyCtxt<'_>, def_id: LocalDefId) { + wfcheck::check_trait_item(tcx, def_id); +} + +pub(super) fn check_impl_item_well_formed(tcx: TyCtxt<'_>, def_id: LocalDefId) { + wfcheck::check_impl_item(tcx, def_id); +} + +fn async_opaque_type_cycle_error(tcx: TyCtxt<'tcx>, span: Span) { + struct_span_err!(tcx.sess, span, E0733, "recursion in an `async fn` requires boxing") + .span_label(span, "recursive `async fn`") + .note("a recursive `async fn` must be rewritten to return a boxed `dyn Future`") + .emit(); +} + +/// Emit an error for recursive opaque types. +/// +/// If this is a return `impl Trait`, find the item's return expressions and point at them. For +/// direct recursion this is enough, but for indirect recursion also point at the last intermediary +/// `impl Trait`. +/// +/// If all the return expressions evaluate to `!`, then we explain that the error will go away +/// after changing it. This can happen when a user uses `panic!()` or similar as a placeholder. +fn opaque_type_cycle_error(tcx: TyCtxt<'tcx>, def_id: LocalDefId, span: Span) { + let mut err = struct_span_err!(tcx.sess, span, E0720, "cannot resolve opaque type"); + + let mut label = false; + if let Some((hir_id, visitor)) = get_owner_return_paths(tcx, def_id) { + let typeck_results = tcx.typeck(tcx.hir().local_def_id(hir_id)); + if visitor + .returns + .iter() + .filter_map(|expr| typeck_results.node_type_opt(expr.hir_id)) + .all(|ty| matches!(ty.kind(), ty::Never)) + { + let spans = visitor + .returns + .iter() + .filter(|expr| typeck_results.node_type_opt(expr.hir_id).is_some()) + .map(|expr| expr.span) + .collect::>(); + let span_len = spans.len(); + if span_len == 1 { + err.span_label(spans[0], "this returned value is of `!` type"); + } else { + let mut multispan: MultiSpan = spans.clone().into(); + for span in spans { + multispan + .push_span_label(span, "this returned value is of `!` type".to_string()); + } + err.span_note(multispan, "these returned values have a concrete \"never\" type"); + } + err.help("this error will resolve once the item's body returns a concrete type"); + } else { + let mut seen = FxHashSet::default(); + seen.insert(span); + err.span_label(span, "recursive opaque type"); + label = true; + for (sp, ty) in visitor + .returns + .iter() + .filter_map(|e| typeck_results.node_type_opt(e.hir_id).map(|t| (e.span, t))) + .filter(|(_, ty)| !matches!(ty.kind(), ty::Never)) + { + struct VisitTypes(Vec); + impl<'tcx> ty::fold::TypeVisitor<'tcx> for VisitTypes { + fn visit_ty(&mut self, t: Ty<'tcx>) -> bool { + match *t.kind() { + ty::Opaque(def, _) => { + self.0.push(def); + false + } + _ => t.super_visit_with(self), + } + } + } + let mut visitor = VisitTypes(vec![]); + ty.visit_with(&mut visitor); + for def_id in visitor.0 { + let ty_span = tcx.def_span(def_id); + if !seen.contains(&ty_span) { + err.span_label(ty_span, &format!("returning this opaque type `{}`", ty)); + seen.insert(ty_span); + } + err.span_label(sp, &format!("returning here with type `{}`", ty)); + } + } + } + } + if !label { + err.span_label(span, "cannot resolve opaque type"); + } + err.emit(); +} diff --git a/compiler/rustc_typeck/src/check/mod.rs b/compiler/rustc_typeck/src/check/mod.rs index d45b51c42ea..04d4d8171d4 100644 --- a/compiler/rustc_typeck/src/check/mod.rs +++ b/compiler/rustc_typeck/src/check/mod.rs @@ -66,6 +66,7 @@ pub mod _match; mod autoderef; mod callee; pub mod cast; +mod check; mod closure; pub mod coercion; mod compare_method; @@ -88,6 +89,11 @@ mod upvar; mod wfcheck; pub mod writeback; +use check::{ + check_abi, check_fn, check_impl_item_well_formed, check_item_well_formed, check_mod_item_types, + check_trait_item_well_formed, +}; +pub use check::{check_item_type, check_wf_new}; pub use diverges::Diverges; pub use expectation::Expectation; pub use fn_ctxt::FnCtxt; @@ -95,7 +101,6 @@ pub use inherited::{Inherited, InheritedBuilder}; use crate::astconv::AstConv; use crate::check::gather_locals::GatherLocalsVisitor; -use rustc_attr as attr; use rustc_data_structures::fx::{FxHashMap, FxHashSet}; use rustc_errors::{pluralize, struct_span_err, Applicability}; use rustc_hir as hir; @@ -103,38 +108,33 @@ use rustc_hir::def::Res; use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LOCAL_CRATE}; use rustc_hir::intravisit::Visitor; use rustc_hir::itemlikevisit::ItemLikeVisitor; -use rustc_hir::lang_items::LangItem; -use rustc_hir::{HirIdMap, ItemKind, Node}; +use rustc_hir::{HirIdMap, Node}; use rustc_index::bit_set::BitSet; use rustc_index::vec::Idx; -use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; -use rustc_infer::infer::RegionVariableOrigin; use rustc_middle::ty::fold::{TypeFoldable, TypeFolder}; use rustc_middle::ty::query::Providers; use rustc_middle::ty::subst::GenericArgKind; use rustc_middle::ty::subst::{InternalSubsts, Subst, SubstsRef}; -use rustc_middle::ty::util::{Discr, IntTypeExt, Representability}; use rustc_middle::ty::WithConstness; -use rustc_middle::ty::{self, RegionKind, ToPredicate, Ty, TyCtxt, UserType}; -use rustc_session::config::{self, EntryFnType}; +use rustc_middle::ty::{self, RegionKind, Ty, TyCtxt, UserType}; +use rustc_session::config; use rustc_session::parse::feature_err; use rustc_session::Session; use rustc_span::source_map::DUMMY_SP; -use rustc_span::symbol::{kw, sym, Ident}; +use rustc_span::symbol::{kw, Ident}; use rustc_span::{self, BytePos, MultiSpan, Span}; use rustc_target::abi::VariantIdx; use rustc_target::spec::abi::Abi; +use rustc_trait_selection::traits; use rustc_trait_selection::traits::error_reporting::recursive_type_with_infinite_size_error; use rustc_trait_selection::traits::error_reporting::suggestions::ReturnsVisitor; -use rustc_trait_selection::traits::{self, ObligationCauseCode}; use std::cell::{Ref, RefCell, RefMut}; use crate::require_c_abi_if_c_variadic; use crate::util::common::indenter; -use self::coercion::{CoerceMany, DynamicCoerceMany}; -use self::compare_method::{compare_const_impl, compare_impl_method, compare_ty_impl}; +use self::coercion::DynamicCoerceMany; pub use self::Expectation::*; #[macro_export] @@ -245,11 +245,6 @@ impl<'tcx> EnclosingBreakables<'tcx> { } } -pub fn check_wf_new(tcx: TyCtxt<'_>) { - let visit = wfcheck::CheckTypeWellFormedVisitor::new(tcx); - tcx.hir().krate().par_visit_all_item_likes(&visit); -} - pub fn provide(providers: &mut Providers) { method::provide(providers); *providers = Providers { @@ -631,19 +626,6 @@ fn typeck_with_fallback<'tcx>( typeck_results } -fn check_abi(tcx: TyCtxt<'_>, span: Span, abi: Abi) { - if !tcx.sess.target.target.is_abi_supported(abi) { - struct_span_err!( - tcx.sess, - span, - E0570, - "The ABI `{}` is not supported for the current target", - abi - ) - .emit() - } -} - /// When `check_fn` is invoked on a generator (i.e., a body that /// includes yield), it returns back some information about the yield /// points. @@ -661,460 +643,6 @@ struct GeneratorTypes<'tcx> { movability: hir::Movability, } -/// Helper used for fns and closures. Does the grungy work of checking a function -/// body and returns the function context used for that purpose, since in the case of a fn item -/// there is still a bit more to do. -/// -/// * ... -/// * inherited: other fields inherited from the enclosing fn (if any) -fn check_fn<'a, 'tcx>( - inherited: &'a Inherited<'a, 'tcx>, - param_env: ty::ParamEnv<'tcx>, - fn_sig: ty::FnSig<'tcx>, - decl: &'tcx hir::FnDecl<'tcx>, - fn_id: hir::HirId, - body: &'tcx hir::Body<'tcx>, - can_be_generator: Option, -) -> (FnCtxt<'a, 'tcx>, Option>) { - let mut fn_sig = fn_sig; - - debug!("check_fn(sig={:?}, fn_id={}, param_env={:?})", fn_sig, fn_id, param_env); - - // Create the function context. This is either derived from scratch or, - // in the case of closures, based on the outer context. - let mut fcx = FnCtxt::new(inherited, param_env, body.value.hir_id); - *fcx.ps.borrow_mut() = UnsafetyState::function(fn_sig.unsafety, fn_id); - - let tcx = fcx.tcx; - let sess = tcx.sess; - let hir = tcx.hir(); - - let declared_ret_ty = fn_sig.output(); - - let revealed_ret_ty = - fcx.instantiate_opaque_types_from_value(fn_id, &declared_ret_ty, decl.output.span()); - debug!("check_fn: declared_ret_ty: {}, revealed_ret_ty: {}", declared_ret_ty, revealed_ret_ty); - fcx.ret_coercion = Some(RefCell::new(CoerceMany::new(revealed_ret_ty))); - fcx.ret_type_span = Some(decl.output.span()); - if let ty::Opaque(..) = declared_ret_ty.kind() { - fcx.ret_coercion_impl_trait = Some(declared_ret_ty); - } - fn_sig = tcx.mk_fn_sig( - fn_sig.inputs().iter().cloned(), - revealed_ret_ty, - fn_sig.c_variadic, - fn_sig.unsafety, - fn_sig.abi, - ); - - let span = body.value.span; - - fn_maybe_err(tcx, span, fn_sig.abi); - - if body.generator_kind.is_some() && can_be_generator.is_some() { - let yield_ty = fcx - .next_ty_var(TypeVariableOrigin { kind: TypeVariableOriginKind::TypeInference, span }); - fcx.require_type_is_sized(yield_ty, span, traits::SizedYieldType); - - // Resume type defaults to `()` if the generator has no argument. - let resume_ty = fn_sig.inputs().get(0).copied().unwrap_or_else(|| tcx.mk_unit()); - - fcx.resume_yield_tys = Some((resume_ty, yield_ty)); - } - - let outer_def_id = tcx.closure_base_def_id(hir.local_def_id(fn_id).to_def_id()).expect_local(); - let outer_hir_id = hir.local_def_id_to_hir_id(outer_def_id); - GatherLocalsVisitor::new(&fcx, outer_hir_id).visit_body(body); - - // C-variadic fns also have a `VaList` input that's not listed in `fn_sig` - // (as it's created inside the body itself, not passed in from outside). - let maybe_va_list = if fn_sig.c_variadic { - let span = body.params.last().unwrap().span; - let va_list_did = tcx.require_lang_item(LangItem::VaList, Some(span)); - let region = fcx.next_region_var(RegionVariableOrigin::MiscVariable(span)); - - Some(tcx.type_of(va_list_did).subst(tcx, &[region.into()])) - } else { - None - }; - - // Add formal parameters. - let inputs_hir = hir.fn_decl_by_hir_id(fn_id).map(|decl| &decl.inputs); - let inputs_fn = fn_sig.inputs().iter().copied(); - for (idx, (param_ty, param)) in inputs_fn.chain(maybe_va_list).zip(body.params).enumerate() { - // Check the pattern. - let ty_span = try { inputs_hir?.get(idx)?.span }; - fcx.check_pat_top(¶m.pat, param_ty, ty_span, false); - - // Check that argument is Sized. - // The check for a non-trivial pattern is a hack to avoid duplicate warnings - // for simple cases like `fn foo(x: Trait)`, - // where we would error once on the parameter as a whole, and once on the binding `x`. - if param.pat.simple_ident().is_none() && !tcx.features().unsized_locals { - fcx.require_type_is_sized(param_ty, param.pat.span, traits::SizedArgumentType(ty_span)); - } - - fcx.write_ty(param.hir_id, param_ty); - } - - inherited.typeck_results.borrow_mut().liberated_fn_sigs_mut().insert(fn_id, fn_sig); - - fcx.in_tail_expr = true; - if let ty::Dynamic(..) = declared_ret_ty.kind() { - // FIXME: We need to verify that the return type is `Sized` after the return expression has - // been evaluated so that we have types available for all the nodes being returned, but that - // requires the coerced evaluated type to be stored. Moving `check_return_expr` before this - // causes unsized errors caused by the `declared_ret_ty` to point at the return expression, - // while keeping the current ordering we will ignore the tail expression's type because we - // don't know it yet. We can't do `check_expr_kind` while keeping `check_return_expr` - // because we will trigger "unreachable expression" lints unconditionally. - // Because of all of this, we perform a crude check to know whether the simplest `!Sized` - // case that a newcomer might make, returning a bare trait, and in that case we populate - // the tail expression's type so that the suggestion will be correct, but ignore all other - // possible cases. - fcx.check_expr(&body.value); - fcx.require_type_is_sized(declared_ret_ty, decl.output.span(), traits::SizedReturnType); - tcx.sess.delay_span_bug(decl.output.span(), "`!Sized` return type"); - } else { - fcx.require_type_is_sized(declared_ret_ty, decl.output.span(), traits::SizedReturnType); - fcx.check_return_expr(&body.value); - } - fcx.in_tail_expr = false; - - // We insert the deferred_generator_interiors entry after visiting the body. - // This ensures that all nested generators appear before the entry of this generator. - // resolve_generator_interiors relies on this property. - let gen_ty = if let (Some(_), Some(gen_kind)) = (can_be_generator, body.generator_kind) { - let interior = fcx - .next_ty_var(TypeVariableOrigin { kind: TypeVariableOriginKind::MiscVariable, span }); - fcx.deferred_generator_interiors.borrow_mut().push((body.id(), interior, gen_kind)); - - let (resume_ty, yield_ty) = fcx.resume_yield_tys.unwrap(); - Some(GeneratorTypes { - resume_ty, - yield_ty, - interior, - movability: can_be_generator.unwrap(), - }) - } else { - None - }; - - // Finalize the return check by taking the LUB of the return types - // we saw and assigning it to the expected return type. This isn't - // really expected to fail, since the coercions would have failed - // earlier when trying to find a LUB. - // - // However, the behavior around `!` is sort of complex. In the - // event that the `actual_return_ty` comes back as `!`, that - // indicates that the fn either does not return or "returns" only - // values of type `!`. In this case, if there is an expected - // return type that is *not* `!`, that should be ok. But if the - // return type is being inferred, we want to "fallback" to `!`: - // - // let x = move || panic!(); - // - // To allow for that, I am creating a type variable with diverging - // fallback. This was deemed ever so slightly better than unifying - // the return value with `!` because it allows for the caller to - // make more assumptions about the return type (e.g., they could do - // - // let y: Option = Some(x()); - // - // which would then cause this return type to become `u32`, not - // `!`). - let coercion = fcx.ret_coercion.take().unwrap().into_inner(); - let mut actual_return_ty = coercion.complete(&fcx); - if actual_return_ty.is_never() { - actual_return_ty = fcx.next_diverging_ty_var(TypeVariableOrigin { - kind: TypeVariableOriginKind::DivergingFn, - span, - }); - } - fcx.demand_suptype(span, revealed_ret_ty, actual_return_ty); - - // Check that the main return type implements the termination trait. - if let Some(term_id) = tcx.lang_items().termination() { - if let Some((def_id, EntryFnType::Main)) = tcx.entry_fn(LOCAL_CRATE) { - let main_id = hir.local_def_id_to_hir_id(def_id); - if main_id == fn_id { - let substs = tcx.mk_substs_trait(declared_ret_ty, &[]); - let trait_ref = ty::TraitRef::new(term_id, substs); - let return_ty_span = decl.output.span(); - let cause = traits::ObligationCause::new( - return_ty_span, - fn_id, - ObligationCauseCode::MainFunctionType, - ); - - inherited.register_predicate(traits::Obligation::new( - cause, - param_env, - trait_ref.without_const().to_predicate(tcx), - )); - } - } - } - - // Check that a function marked as `#[panic_handler]` has signature `fn(&PanicInfo) -> !` - if let Some(panic_impl_did) = tcx.lang_items().panic_impl() { - if panic_impl_did == hir.local_def_id(fn_id).to_def_id() { - if let Some(panic_info_did) = tcx.lang_items().panic_info() { - if *declared_ret_ty.kind() != ty::Never { - sess.span_err(decl.output.span(), "return type should be `!`"); - } - - let inputs = fn_sig.inputs(); - let span = hir.span(fn_id); - if inputs.len() == 1 { - let arg_is_panic_info = match *inputs[0].kind() { - ty::Ref(region, ty, mutbl) => match *ty.kind() { - ty::Adt(ref adt, _) => { - adt.did == panic_info_did - && mutbl == hir::Mutability::Not - && *region != RegionKind::ReStatic - } - _ => false, - }, - _ => false, - }; - - if !arg_is_panic_info { - sess.span_err(decl.inputs[0].span, "argument should be `&PanicInfo`"); - } - - if let Node::Item(item) = hir.get(fn_id) { - if let ItemKind::Fn(_, ref generics, _) = item.kind { - if !generics.params.is_empty() { - sess.span_err(span, "should have no type parameters"); - } - } - } - } else { - let span = sess.source_map().guess_head_span(span); - sess.span_err(span, "function should have one argument"); - } - } else { - sess.err("language item required, but not found: `panic_info`"); - } - } - } - - // Check that a function marked as `#[alloc_error_handler]` has signature `fn(Layout) -> !` - if let Some(alloc_error_handler_did) = tcx.lang_items().oom() { - if alloc_error_handler_did == hir.local_def_id(fn_id).to_def_id() { - if let Some(alloc_layout_did) = tcx.lang_items().alloc_layout() { - if *declared_ret_ty.kind() != ty::Never { - sess.span_err(decl.output.span(), "return type should be `!`"); - } - - let inputs = fn_sig.inputs(); - let span = hir.span(fn_id); - if inputs.len() == 1 { - let arg_is_alloc_layout = match inputs[0].kind() { - ty::Adt(ref adt, _) => adt.did == alloc_layout_did, - _ => false, - }; - - if !arg_is_alloc_layout { - sess.span_err(decl.inputs[0].span, "argument should be `Layout`"); - } - - if let Node::Item(item) = hir.get(fn_id) { - if let ItemKind::Fn(_, ref generics, _) = item.kind { - if !generics.params.is_empty() { - sess.span_err( - span, - "`#[alloc_error_handler]` function should have no type \ - parameters", - ); - } - } - } - } else { - let span = sess.source_map().guess_head_span(span); - sess.span_err(span, "function should have one argument"); - } - } else { - sess.err("language item required, but not found: `alloc_layout`"); - } - } - } - - (fcx, gen_ty) -} - -fn check_struct(tcx: TyCtxt<'_>, id: hir::HirId, span: Span) { - let def_id = tcx.hir().local_def_id(id); - let def = tcx.adt_def(def_id); - def.destructor(tcx); // force the destructor to be evaluated - check_representable(tcx, span, def_id); - - if def.repr.simd() { - check_simd(tcx, span, def_id); - } - - check_transparent(tcx, span, def); - check_packed(tcx, span, def); -} - -fn check_union(tcx: TyCtxt<'_>, id: hir::HirId, span: Span) { - let def_id = tcx.hir().local_def_id(id); - let def = tcx.adt_def(def_id); - def.destructor(tcx); // force the destructor to be evaluated - check_representable(tcx, span, def_id); - check_transparent(tcx, span, def); - check_union_fields(tcx, span, def_id); - check_packed(tcx, span, def); -} - -/// When the `#![feature(untagged_unions)]` gate is active, -/// check that the fields of the `union` does not contain fields that need dropping. -fn check_union_fields(tcx: TyCtxt<'_>, span: Span, item_def_id: LocalDefId) -> bool { - let item_type = tcx.type_of(item_def_id); - if let ty::Adt(def, substs) = item_type.kind() { - assert!(def.is_union()); - let fields = &def.non_enum_variant().fields; - let param_env = tcx.param_env(item_def_id); - for field in fields { - let field_ty = field.ty(tcx, substs); - // We are currently checking the type this field came from, so it must be local. - let field_span = tcx.hir().span_if_local(field.did).unwrap(); - if field_ty.needs_drop(tcx, param_env) { - struct_span_err!( - tcx.sess, - field_span, - E0740, - "unions may not contain fields that need dropping" - ) - .span_note(field_span, "`std::mem::ManuallyDrop` can be used to wrap the type") - .emit(); - return false; - } - } - } else { - span_bug!(span, "unions must be ty::Adt, but got {:?}", item_type.kind()); - } - true -} - -/// Checks that an opaque type does not contain cycles and does not use `Self` or `T::Foo` -/// projections that would result in "inheriting lifetimes". -fn check_opaque<'tcx>( - tcx: TyCtxt<'tcx>, - def_id: LocalDefId, - substs: SubstsRef<'tcx>, - span: Span, - origin: &hir::OpaqueTyOrigin, -) { - check_opaque_for_inheriting_lifetimes(tcx, def_id, span); - check_opaque_for_cycles(tcx, def_id, substs, span, origin); -} - -/// Checks that an opaque type does not use `Self` or `T::Foo` projections that would result -/// in "inheriting lifetimes". -fn check_opaque_for_inheriting_lifetimes(tcx: TyCtxt<'tcx>, def_id: LocalDefId, span: Span) { - let item = tcx.hir().expect_item(tcx.hir().local_def_id_to_hir_id(def_id)); - debug!( - "check_opaque_for_inheriting_lifetimes: def_id={:?} span={:?} item={:?}", - def_id, span, item - ); - - #[derive(Debug)] - struct ProhibitOpaqueVisitor<'tcx> { - opaque_identity_ty: Ty<'tcx>, - generics: &'tcx ty::Generics, - ty: Option>, - }; - - impl<'tcx> ty::fold::TypeVisitor<'tcx> for ProhibitOpaqueVisitor<'tcx> { - fn visit_ty(&mut self, t: Ty<'tcx>) -> bool { - debug!("check_opaque_for_inheriting_lifetimes: (visit_ty) t={:?}", t); - if t != self.opaque_identity_ty && t.super_visit_with(self) { - self.ty = Some(t); - return true; - } - false - } - - fn visit_region(&mut self, r: ty::Region<'tcx>) -> bool { - debug!("check_opaque_for_inheriting_lifetimes: (visit_region) r={:?}", r); - if let RegionKind::ReEarlyBound(ty::EarlyBoundRegion { index, .. }) = r { - return *index < self.generics.parent_count as u32; - } - - r.super_visit_with(self) - } - - fn visit_const(&mut self, c: &'tcx ty::Const<'tcx>) -> bool { - if let ty::ConstKind::Unevaluated(..) = c.val { - // FIXME(#72219) We currenctly don't detect lifetimes within substs - // which would violate this check. Even though the particular substitution is not used - // within the const, this should still be fixed. - return false; - } - c.super_visit_with(self) - } - } - - if let ItemKind::OpaqueTy(hir::OpaqueTy { - origin: hir::OpaqueTyOrigin::AsyncFn | hir::OpaqueTyOrigin::FnReturn, - .. - }) = item.kind - { - let mut visitor = ProhibitOpaqueVisitor { - opaque_identity_ty: tcx.mk_opaque( - def_id.to_def_id(), - InternalSubsts::identity_for_item(tcx, def_id.to_def_id()), - ), - generics: tcx.generics_of(def_id), - ty: None, - }; - let prohibit_opaque = tcx - .predicates_of(def_id) - .predicates - .iter() - .any(|(predicate, _)| predicate.visit_with(&mut visitor)); - debug!( - "check_opaque_for_inheriting_lifetimes: prohibit_opaque={:?}, visitor={:?}", - prohibit_opaque, visitor - ); - - if prohibit_opaque { - let is_async = match item.kind { - ItemKind::OpaqueTy(hir::OpaqueTy { origin, .. }) => match origin { - hir::OpaqueTyOrigin::AsyncFn => true, - _ => false, - }, - _ => unreachable!(), - }; - - let mut err = struct_span_err!( - tcx.sess, - span, - E0760, - "`{}` return type cannot contain a projection or `Self` that references lifetimes from \ - a parent scope", - if is_async { "async fn" } else { "impl Trait" }, - ); - - if let Ok(snippet) = tcx.sess.source_map().span_to_snippet(span) { - if snippet == "Self" { - if let Some(ty) = visitor.ty { - err.span_suggestion( - span, - "consider spelling out the type instead", - format!("{:?}", ty), - Applicability::MaybeIncorrect, - ); - } - } - } - err.emit(); - } - } -} - /// Given a `DefId` for an opaque type in return position, find its parent item's return /// expressions. fn get_owner_return_paths( @@ -1135,86 +663,6 @@ fn get_owner_return_paths( }) } -/// Emit an error for recursive opaque types. -/// -/// If this is a return `impl Trait`, find the item's return expressions and point at them. For -/// direct recursion this is enough, but for indirect recursion also point at the last intermediary -/// `impl Trait`. -/// -/// If all the return expressions evaluate to `!`, then we explain that the error will go away -/// after changing it. This can happen when a user uses `panic!()` or similar as a placeholder. -fn opaque_type_cycle_error(tcx: TyCtxt<'tcx>, def_id: LocalDefId, span: Span) { - let mut err = struct_span_err!(tcx.sess, span, E0720, "cannot resolve opaque type"); - - let mut label = false; - if let Some((hir_id, visitor)) = get_owner_return_paths(tcx, def_id) { - let typeck_results = tcx.typeck(tcx.hir().local_def_id(hir_id)); - if visitor - .returns - .iter() - .filter_map(|expr| typeck_results.node_type_opt(expr.hir_id)) - .all(|ty| matches!(ty.kind(), ty::Never)) - { - let spans = visitor - .returns - .iter() - .filter(|expr| typeck_results.node_type_opt(expr.hir_id).is_some()) - .map(|expr| expr.span) - .collect::>(); - let span_len = spans.len(); - if span_len == 1 { - err.span_label(spans[0], "this returned value is of `!` type"); - } else { - let mut multispan: MultiSpan = spans.clone().into(); - for span in spans { - multispan - .push_span_label(span, "this returned value is of `!` type".to_string()); - } - err.span_note(multispan, "these returned values have a concrete \"never\" type"); - } - err.help("this error will resolve once the item's body returns a concrete type"); - } else { - let mut seen = FxHashSet::default(); - seen.insert(span); - err.span_label(span, "recursive opaque type"); - label = true; - for (sp, ty) in visitor - .returns - .iter() - .filter_map(|e| typeck_results.node_type_opt(e.hir_id).map(|t| (e.span, t))) - .filter(|(_, ty)| !matches!(ty.kind(), ty::Never)) - { - struct VisitTypes(Vec); - impl<'tcx> ty::fold::TypeVisitor<'tcx> for VisitTypes { - fn visit_ty(&mut self, t: Ty<'tcx>) -> bool { - match *t.kind() { - ty::Opaque(def, _) => { - self.0.push(def); - false - } - _ => t.super_visit_with(self), - } - } - } - let mut visitor = VisitTypes(vec![]); - ty.visit_with(&mut visitor); - for def_id in visitor.0 { - let ty_span = tcx.def_span(def_id); - if !seen.contains(&ty_span) { - err.span_label(ty_span, &format!("returning this opaque type `{}`", ty)); - seen.insert(ty_span); - } - err.span_label(sp, &format!("returning here with type `{}`", ty)); - } - } - } - } - if !label { - err.span_label(span, "cannot resolve opaque type"); - } - err.emit(); -} - /// Emit an error for recursive opaque types in a `let` binding. fn binding_opaque_type_cycle_error( tcx: TyCtxt<'tcx>, @@ -1275,33 +723,6 @@ fn binding_opaque_type_cycle_error( err.emit(); } -fn async_opaque_type_cycle_error(tcx: TyCtxt<'tcx>, span: Span) { - struct_span_err!(tcx.sess, span, E0733, "recursion in an `async fn` requires boxing") - .span_label(span, "recursive `async fn`") - .note("a recursive `async fn` must be rewritten to return a boxed `dyn Future`") - .emit(); -} - -/// Checks that an opaque type does not contain cycles. -fn check_opaque_for_cycles<'tcx>( - tcx: TyCtxt<'tcx>, - def_id: LocalDefId, - substs: SubstsRef<'tcx>, - span: Span, - origin: &hir::OpaqueTyOrigin, -) { - if let Err(partially_expanded_type) = tcx.try_expand_impl_trait_type(def_id.to_def_id(), substs) - { - match origin { - hir::OpaqueTyOrigin::AsyncFn => async_opaque_type_cycle_error(tcx, span), - hir::OpaqueTyOrigin::Binding => { - binding_opaque_type_cycle_error(tcx, def_id, span, partially_expanded_type) - } - _ => opaque_type_cycle_error(tcx, def_id, span), - } - } -} - // Forbid defining intrinsics in Rust code, // as they must always be defined by the compiler. fn fn_maybe_err(tcx: TyCtxt<'_>, sp: Span, abi: Abi) { @@ -1310,126 +731,6 @@ fn fn_maybe_err(tcx: TyCtxt<'_>, sp: Span, abi: Abi) { } } -pub fn check_item_type<'tcx>(tcx: TyCtxt<'tcx>, it: &'tcx hir::Item<'tcx>) { - debug!( - "check_item_type(it.hir_id={}, it.name={})", - it.hir_id, - tcx.def_path_str(tcx.hir().local_def_id(it.hir_id).to_def_id()) - ); - let _indenter = indenter(); - match it.kind { - // Consts can play a role in type-checking, so they are included here. - hir::ItemKind::Static(..) => { - let def_id = tcx.hir().local_def_id(it.hir_id); - tcx.ensure().typeck(def_id); - maybe_check_static_with_link_section(tcx, def_id, it.span); - } - hir::ItemKind::Const(..) => { - tcx.ensure().typeck(tcx.hir().local_def_id(it.hir_id)); - } - hir::ItemKind::Enum(ref enum_definition, _) => { - check_enum(tcx, it.span, &enum_definition.variants, it.hir_id); - } - hir::ItemKind::Fn(..) => {} // entirely within check_item_body - hir::ItemKind::Impl { ref items, .. } => { - debug!("ItemKind::Impl {} with id {}", it.ident, it.hir_id); - let impl_def_id = tcx.hir().local_def_id(it.hir_id); - if let Some(impl_trait_ref) = tcx.impl_trait_ref(impl_def_id) { - check_impl_items_against_trait(tcx, it.span, impl_def_id, impl_trait_ref, items); - let trait_def_id = impl_trait_ref.def_id; - check_on_unimplemented(tcx, trait_def_id, it); - } - } - hir::ItemKind::Trait(_, _, _, _, ref items) => { - let def_id = tcx.hir().local_def_id(it.hir_id); - check_on_unimplemented(tcx, def_id.to_def_id(), it); - - for item in items.iter() { - let item = tcx.hir().trait_item(item.id); - if let hir::TraitItemKind::Fn(sig, _) = &item.kind { - let abi = sig.header.abi; - fn_maybe_err(tcx, item.ident.span, abi); - } - } - } - hir::ItemKind::Struct(..) => { - check_struct(tcx, it.hir_id, it.span); - } - hir::ItemKind::Union(..) => { - check_union(tcx, it.hir_id, it.span); - } - hir::ItemKind::OpaqueTy(hir::OpaqueTy { origin, .. }) => { - // HACK(jynelson): trying to infer the type of `impl trait` breaks documenting - // `async-std` (and `pub async fn` in general). - // Since rustdoc doesn't care about the concrete type behind `impl Trait`, just don't look at it! - // See https://github.com/rust-lang/rust/issues/75100 - if !tcx.sess.opts.actually_rustdoc { - let def_id = tcx.hir().local_def_id(it.hir_id); - - let substs = InternalSubsts::identity_for_item(tcx, def_id.to_def_id()); - check_opaque(tcx, def_id, substs, it.span, &origin); - } - } - hir::ItemKind::TyAlias(..) => { - let def_id = tcx.hir().local_def_id(it.hir_id); - let pty_ty = tcx.type_of(def_id); - let generics = tcx.generics_of(def_id); - check_type_params_are_used(tcx, &generics, pty_ty); - } - hir::ItemKind::ForeignMod(ref m) => { - check_abi(tcx, it.span, m.abi); - - if m.abi == Abi::RustIntrinsic { - for item in m.items { - intrinsic::check_intrinsic_type(tcx, item); - } - } else if m.abi == Abi::PlatformIntrinsic { - for item in m.items { - intrinsic::check_platform_intrinsic_type(tcx, item); - } - } else { - for item in m.items { - let generics = tcx.generics_of(tcx.hir().local_def_id(item.hir_id)); - let own_counts = generics.own_counts(); - if generics.params.len() - own_counts.lifetimes != 0 { - let (kinds, kinds_pl, egs) = match (own_counts.types, own_counts.consts) { - (_, 0) => ("type", "types", Some("u32")), - // We don't specify an example value, because we can't generate - // a valid value for any type. - (0, _) => ("const", "consts", None), - _ => ("type or const", "types or consts", None), - }; - struct_span_err!( - tcx.sess, - item.span, - E0044, - "foreign items may not have {} parameters", - kinds, - ) - .span_label(item.span, &format!("can't have {} parameters", kinds)) - .help( - // FIXME: once we start storing spans for type arguments, turn this - // into a suggestion. - &format!( - "replace the {} parameters with concrete {}{}", - kinds, - kinds_pl, - egs.map(|egs| format!(" like `{}`", egs)).unwrap_or_default(), - ), - ) - .emit(); - } - - if let hir::ForeignItemKind::Fn(ref fn_decl, _, _) = item.kind { - require_c_abi_if_c_variadic(tcx, fn_decl, m.abi, item.span); - } - } - } - } - _ => { /* nothing to do */ } - } -} - fn maybe_check_static_with_link_section(tcx: TyCtxt<'_>, id: LocalDefId, span: Span) { // Only restricted on wasm32 target for now if !tcx.sess.opts.target_triple.triple().starts_with("wasm32") { @@ -1463,12 +764,6 @@ fn maybe_check_static_with_link_section(tcx: TyCtxt<'_>, id: LocalDefId, span: S } } -fn check_on_unimplemented(tcx: TyCtxt<'_>, trait_def_id: DefId, item: &hir::Item<'_>) { - let item_def_id = tcx.hir().local_def_id(item.hir_id); - // an error would be reported if this fails. - let _ = traits::OnUnimplementedDirective::of_item(tcx, trait_def_id, item_def_id.to_def_id()); -} - fn report_forbidden_specialization( tcx: TyCtxt<'_>, impl_item: &hir::ImplItem<'_>, @@ -1500,248 +795,6 @@ fn report_forbidden_specialization( err.emit(); } -fn check_specialization_validity<'tcx>( - tcx: TyCtxt<'tcx>, - trait_def: &ty::TraitDef, - trait_item: &ty::AssocItem, - impl_id: DefId, - impl_item: &hir::ImplItem<'_>, -) { - let kind = match impl_item.kind { - hir::ImplItemKind::Const(..) => ty::AssocKind::Const, - hir::ImplItemKind::Fn(..) => ty::AssocKind::Fn, - hir::ImplItemKind::TyAlias(_) => ty::AssocKind::Type, - }; - - let ancestors = match trait_def.ancestors(tcx, impl_id) { - Ok(ancestors) => ancestors, - Err(_) => return, - }; - let mut ancestor_impls = ancestors - .skip(1) - .filter_map(|parent| { - if parent.is_from_trait() { - None - } else { - Some((parent, parent.item(tcx, trait_item.ident, kind, trait_def.def_id))) - } - }) - .peekable(); - - if ancestor_impls.peek().is_none() { - // No parent, nothing to specialize. - return; - } - - let opt_result = ancestor_impls.find_map(|(parent_impl, parent_item)| { - match parent_item { - // Parent impl exists, and contains the parent item we're trying to specialize, but - // doesn't mark it `default`. - Some(parent_item) if traits::impl_item_is_final(tcx, &parent_item) => { - Some(Err(parent_impl.def_id())) - } - - // Parent impl contains item and makes it specializable. - Some(_) => Some(Ok(())), - - // Parent impl doesn't mention the item. This means it's inherited from the - // grandparent. In that case, if parent is a `default impl`, inherited items use the - // "defaultness" from the grandparent, else they are final. - None => { - if tcx.impl_defaultness(parent_impl.def_id()).is_default() { - None - } else { - Some(Err(parent_impl.def_id())) - } - } - } - }); - - // If `opt_result` is `None`, we have only encountered `default impl`s that don't contain the - // item. This is allowed, the item isn't actually getting specialized here. - let result = opt_result.unwrap_or(Ok(())); - - if let Err(parent_impl) = result { - report_forbidden_specialization(tcx, impl_item, parent_impl); - } -} - -fn check_impl_items_against_trait<'tcx>( - tcx: TyCtxt<'tcx>, - full_impl_span: Span, - impl_id: LocalDefId, - impl_trait_ref: ty::TraitRef<'tcx>, - impl_item_refs: &[hir::ImplItemRef<'_>], -) { - let impl_span = tcx.sess.source_map().guess_head_span(full_impl_span); - - // If the trait reference itself is erroneous (so the compilation is going - // to fail), skip checking the items here -- the `impl_item` table in `tcx` - // isn't populated for such impls. - if impl_trait_ref.references_error() { - return; - } - - // Negative impls are not expected to have any items - match tcx.impl_polarity(impl_id) { - ty::ImplPolarity::Reservation | ty::ImplPolarity::Positive => {} - ty::ImplPolarity::Negative => { - if let [first_item_ref, ..] = impl_item_refs { - let first_item_span = tcx.hir().impl_item(first_item_ref.id).span; - struct_span_err!( - tcx.sess, - first_item_span, - E0749, - "negative impls cannot have any items" - ) - .emit(); - } - return; - } - } - - // Locate trait definition and items - let trait_def = tcx.trait_def(impl_trait_ref.def_id); - - let impl_items = || impl_item_refs.iter().map(|iiref| tcx.hir().impl_item(iiref.id)); - - // Check existing impl methods to see if they are both present in trait - // and compatible with trait signature - for impl_item in impl_items() { - let namespace = impl_item.kind.namespace(); - let ty_impl_item = tcx.associated_item(tcx.hir().local_def_id(impl_item.hir_id)); - let ty_trait_item = tcx - .associated_items(impl_trait_ref.def_id) - .find_by_name_and_namespace(tcx, ty_impl_item.ident, namespace, impl_trait_ref.def_id) - .or_else(|| { - // Not compatible, but needed for the error message - tcx.associated_items(impl_trait_ref.def_id) - .filter_by_name(tcx, ty_impl_item.ident, impl_trait_ref.def_id) - .next() - }); - - // Check that impl definition matches trait definition - if let Some(ty_trait_item) = ty_trait_item { - match impl_item.kind { - hir::ImplItemKind::Const(..) => { - // Find associated const definition. - if ty_trait_item.kind == ty::AssocKind::Const { - compare_const_impl( - tcx, - &ty_impl_item, - impl_item.span, - &ty_trait_item, - impl_trait_ref, - ); - } else { - let mut err = struct_span_err!( - tcx.sess, - impl_item.span, - E0323, - "item `{}` is an associated const, \ - which doesn't match its trait `{}`", - ty_impl_item.ident, - impl_trait_ref.print_only_trait_path() - ); - err.span_label(impl_item.span, "does not match trait"); - // We can only get the spans from local trait definition - // Same for E0324 and E0325 - if let Some(trait_span) = tcx.hir().span_if_local(ty_trait_item.def_id) { - err.span_label(trait_span, "item in trait"); - } - err.emit() - } - } - hir::ImplItemKind::Fn(..) => { - let opt_trait_span = tcx.hir().span_if_local(ty_trait_item.def_id); - if ty_trait_item.kind == ty::AssocKind::Fn { - compare_impl_method( - tcx, - &ty_impl_item, - impl_item.span, - &ty_trait_item, - impl_trait_ref, - opt_trait_span, - ); - } else { - let mut err = struct_span_err!( - tcx.sess, - impl_item.span, - E0324, - "item `{}` is an associated method, \ - which doesn't match its trait `{}`", - ty_impl_item.ident, - impl_trait_ref.print_only_trait_path() - ); - err.span_label(impl_item.span, "does not match trait"); - if let Some(trait_span) = opt_trait_span { - err.span_label(trait_span, "item in trait"); - } - err.emit() - } - } - hir::ImplItemKind::TyAlias(_) => { - let opt_trait_span = tcx.hir().span_if_local(ty_trait_item.def_id); - if ty_trait_item.kind == ty::AssocKind::Type { - compare_ty_impl( - tcx, - &ty_impl_item, - impl_item.span, - &ty_trait_item, - impl_trait_ref, - opt_trait_span, - ); - } else { - let mut err = struct_span_err!( - tcx.sess, - impl_item.span, - E0325, - "item `{}` is an associated type, \ - which doesn't match its trait `{}`", - ty_impl_item.ident, - impl_trait_ref.print_only_trait_path() - ); - err.span_label(impl_item.span, "does not match trait"); - if let Some(trait_span) = opt_trait_span { - err.span_label(trait_span, "item in trait"); - } - err.emit() - } - } - } - - check_specialization_validity( - tcx, - trait_def, - &ty_trait_item, - impl_id.to_def_id(), - impl_item, - ); - } - } - - // Check for missing items from trait - let mut missing_items = Vec::new(); - if let Ok(ancestors) = trait_def.ancestors(tcx, impl_id.to_def_id()) { - for trait_item in tcx.associated_items(impl_trait_ref.def_id).in_definition_order() { - let is_implemented = ancestors - .leaf_def(tcx, trait_item.ident, trait_item.kind) - .map(|node_item| !node_item.defining_node.is_from_trait()) - .unwrap_or(false); - - if !is_implemented && tcx.impl_defaultness(impl_id).is_final() { - if !trait_item.defaultness.has_value() { - missing_items.push(*trait_item); - } - } - } - } - - if !missing_items.is_empty() { - missing_items_err(tcx, impl_span, &missing_items, full_impl_span); - } -} - fn missing_items_err( tcx: TyCtxt<'_>, impl_span: Span, @@ -1941,161 +994,6 @@ fn suggestion_signature(assoc: &ty::AssocItem, tcx: TyCtxt<'_>) -> String { } } -/// Checks whether a type can be represented in memory. In particular, it -/// identifies types that contain themselves without indirection through a -/// pointer, which would mean their size is unbounded. -fn check_representable(tcx: TyCtxt<'_>, sp: Span, item_def_id: LocalDefId) -> bool { - let rty = tcx.type_of(item_def_id); - - // Check that it is possible to represent this type. This call identifies - // (1) types that contain themselves and (2) types that contain a different - // recursive type. It is only necessary to throw an error on those that - // contain themselves. For case 2, there must be an inner type that will be - // caught by case 1. - match rty.is_representable(tcx, sp) { - Representability::SelfRecursive(spans) => { - recursive_type_with_infinite_size_error(tcx, item_def_id.to_def_id(), spans); - return false; - } - Representability::Representable | Representability::ContainsRecursive => (), - } - true -} - -pub fn check_simd(tcx: TyCtxt<'_>, sp: Span, def_id: LocalDefId) { - let t = tcx.type_of(def_id); - if let ty::Adt(def, substs) = t.kind() { - if def.is_struct() { - let fields = &def.non_enum_variant().fields; - if fields.is_empty() { - struct_span_err!(tcx.sess, sp, E0075, "SIMD vector cannot be empty").emit(); - return; - } - let e = fields[0].ty(tcx, substs); - if !fields.iter().all(|f| f.ty(tcx, substs) == e) { - struct_span_err!(tcx.sess, sp, E0076, "SIMD vector should be homogeneous") - .span_label(sp, "SIMD elements must have the same type") - .emit(); - return; - } - match e.kind() { - ty::Param(_) => { /* struct(T, T, T, T) is ok */ } - _ if e.is_machine() => { /* struct(u8, u8, u8, u8) is ok */ } - _ => { - struct_span_err!( - tcx.sess, - sp, - E0077, - "SIMD vector element type should be machine type" - ) - .emit(); - return; - } - } - } - } -} - -fn check_packed(tcx: TyCtxt<'_>, sp: Span, def: &ty::AdtDef) { - let repr = def.repr; - if repr.packed() { - for attr in tcx.get_attrs(def.did).iter() { - for r in attr::find_repr_attrs(&tcx.sess, attr) { - if let attr::ReprPacked(pack) = r { - if let Some(repr_pack) = repr.pack { - if pack as u64 != repr_pack.bytes() { - struct_span_err!( - tcx.sess, - sp, - E0634, - "type has conflicting packed representation hints" - ) - .emit(); - } - } - } - } - } - if repr.align.is_some() { - struct_span_err!( - tcx.sess, - sp, - E0587, - "type has conflicting packed and align representation hints" - ) - .emit(); - } else { - if let Some(def_spans) = check_packed_inner(tcx, def.did, &mut vec![]) { - let mut err = struct_span_err!( - tcx.sess, - sp, - E0588, - "packed type cannot transitively contain a `#[repr(align)]` type" - ); - - err.span_note( - tcx.def_span(def_spans[0].0), - &format!( - "`{}` has a `#[repr(align)]` attribute", - tcx.item_name(def_spans[0].0) - ), - ); - - if def_spans.len() > 2 { - let mut first = true; - for (adt_def, span) in def_spans.iter().skip(1).rev() { - let ident = tcx.item_name(*adt_def); - err.span_note( - *span, - &if first { - format!( - "`{}` contains a field of type `{}`", - tcx.type_of(def.did), - ident - ) - } else { - format!("...which contains a field of type `{}`", ident) - }, - ); - first = false; - } - } - - err.emit(); - } - } - } -} - -fn check_packed_inner( - tcx: TyCtxt<'_>, - def_id: DefId, - stack: &mut Vec, -) -> Option> { - if let ty::Adt(def, substs) = tcx.type_of(def_id).kind() { - if def.is_struct() || def.is_union() { - if def.repr.align.is_some() { - return Some(vec![(def.did, DUMMY_SP)]); - } - - stack.push(def_id); - for field in &def.non_enum_variant().fields { - if let ty::Adt(def, _) = field.ty(tcx, substs).kind() { - if !stack.contains(&def.did) { - if let Some(mut defs) = check_packed_inner(tcx, def.did, stack) { - defs.push((def.did, field.ident.span)); - return Some(defs); - } - } - } - } - stack.pop(); - } - } - - None -} - /// Emit an error when encountering more or less than one variant in a transparent enum. fn bad_variant_count<'tcx>(tcx: TyCtxt<'tcx>, adt: &'tcx ty::AdtDef, sp: Span, did: DefId) { let variant_spans: Vec<_> = adt @@ -2141,158 +1039,6 @@ fn bad_non_zero_sized_fields<'tcx>( err.emit(); } -fn check_transparent<'tcx>(tcx: TyCtxt<'tcx>, sp: Span, adt: &'tcx ty::AdtDef) { - if !adt.repr.transparent() { - return; - } - let sp = tcx.sess.source_map().guess_head_span(sp); - - if adt.is_union() && !tcx.features().transparent_unions { - feature_err( - &tcx.sess.parse_sess, - sym::transparent_unions, - sp, - "transparent unions are unstable", - ) - .emit(); - } - - if adt.variants.len() != 1 { - bad_variant_count(tcx, adt, sp, adt.did); - if adt.variants.is_empty() { - // Don't bother checking the fields. No variants (and thus no fields) exist. - return; - } - } - - // For each field, figure out if it's known to be a ZST and align(1) - let field_infos = adt.all_fields().map(|field| { - let ty = field.ty(tcx, InternalSubsts::identity_for_item(tcx, field.did)); - let param_env = tcx.param_env(field.did); - let layout = tcx.layout_of(param_env.and(ty)); - // We are currently checking the type this field came from, so it must be local - let span = tcx.hir().span_if_local(field.did).unwrap(); - let zst = layout.map(|layout| layout.is_zst()).unwrap_or(false); - let align1 = layout.map(|layout| layout.align.abi.bytes() == 1).unwrap_or(false); - (span, zst, align1) - }); - - let non_zst_fields = - field_infos.clone().filter_map(|(span, zst, _align1)| if !zst { Some(span) } else { None }); - let non_zst_count = non_zst_fields.clone().count(); - if non_zst_count != 1 { - bad_non_zero_sized_fields(tcx, adt, non_zst_count, non_zst_fields, sp); - } - for (span, zst, align1) in field_infos { - if zst && !align1 { - struct_span_err!( - tcx.sess, - span, - E0691, - "zero-sized field in transparent {} has alignment larger than 1", - adt.descr(), - ) - .span_label(span, "has alignment larger than 1") - .emit(); - } - } -} - -#[allow(trivial_numeric_casts)] -pub fn check_enum<'tcx>( - tcx: TyCtxt<'tcx>, - sp: Span, - vs: &'tcx [hir::Variant<'tcx>], - id: hir::HirId, -) { - let def_id = tcx.hir().local_def_id(id); - let def = tcx.adt_def(def_id); - def.destructor(tcx); // force the destructor to be evaluated - - if vs.is_empty() { - let attributes = tcx.get_attrs(def_id.to_def_id()); - if let Some(attr) = tcx.sess.find_by_name(&attributes, sym::repr) { - struct_span_err!( - tcx.sess, - attr.span, - E0084, - "unsupported representation for zero-variant enum" - ) - .span_label(sp, "zero-variant enum") - .emit(); - } - } - - let repr_type_ty = def.repr.discr_type().to_ty(tcx); - if repr_type_ty == tcx.types.i128 || repr_type_ty == tcx.types.u128 { - if !tcx.features().repr128 { - feature_err( - &tcx.sess.parse_sess, - sym::repr128, - sp, - "repr with 128-bit type is unstable", - ) - .emit(); - } - } - - for v in vs { - if let Some(ref e) = v.disr_expr { - tcx.ensure().typeck(tcx.hir().local_def_id(e.hir_id)); - } - } - - if tcx.adt_def(def_id).repr.int.is_none() && tcx.features().arbitrary_enum_discriminant { - let is_unit = |var: &hir::Variant<'_>| match var.data { - hir::VariantData::Unit(..) => true, - _ => false, - }; - - let has_disr = |var: &hir::Variant<'_>| var.disr_expr.is_some(); - let has_non_units = vs.iter().any(|var| !is_unit(var)); - let disr_units = vs.iter().any(|var| is_unit(&var) && has_disr(&var)); - let disr_non_unit = vs.iter().any(|var| !is_unit(&var) && has_disr(&var)); - - if disr_non_unit || (disr_units && has_non_units) { - let mut err = - struct_span_err!(tcx.sess, sp, E0732, "`#[repr(inttype)]` must be specified"); - err.emit(); - } - } - - let mut disr_vals: Vec> = Vec::with_capacity(vs.len()); - for ((_, discr), v) in def.discriminants(tcx).zip(vs) { - // Check for duplicate discriminant values - if let Some(i) = disr_vals.iter().position(|&x| x.val == discr.val) { - let variant_did = def.variants[VariantIdx::new(i)].def_id; - let variant_i_hir_id = tcx.hir().local_def_id_to_hir_id(variant_did.expect_local()); - let variant_i = tcx.hir().expect_variant(variant_i_hir_id); - let i_span = match variant_i.disr_expr { - Some(ref expr) => tcx.hir().span(expr.hir_id), - None => tcx.hir().span(variant_i_hir_id), - }; - let span = match v.disr_expr { - Some(ref expr) => tcx.hir().span(expr.hir_id), - None => v.span, - }; - struct_span_err!( - tcx.sess, - span, - E0081, - "discriminant value `{}` already exists", - disr_vals[i] - ) - .span_label(i_span, format!("first use of `{}`", disr_vals[i])) - .span_label(span, format!("enum already has `{}`", disr_vals[i])) - .emit(); - } - disr_vals.push(discr); - } - - check_representable(tcx, sp, def_id); - check_transparent(tcx, sp, def); -} - fn report_unexpected_variant_res(tcx: TyCtxt<'_>, res: Res, span: Span) { struct_span_err!( tcx.sess, @@ -2337,51 +1083,6 @@ enum FallbackMode { All, } -fn check_type_params_are_used<'tcx>(tcx: TyCtxt<'tcx>, generics: &ty::Generics, ty: Ty<'tcx>) { - debug!("check_type_params_are_used(generics={:?}, ty={:?})", generics, ty); - - assert_eq!(generics.parent, None); - - if generics.own_counts().types == 0 { - return; - } - - let mut params_used = BitSet::new_empty(generics.params.len()); - - if ty.references_error() { - // If there is already another error, do not emit - // an error for not using a type parameter. - assert!(tcx.sess.has_errors()); - return; - } - - for leaf in ty.walk() { - if let GenericArgKind::Type(leaf_ty) = leaf.unpack() { - if let ty::Param(param) = leaf_ty.kind() { - debug!("found use of ty param {:?}", param); - params_used.insert(param.index); - } - } - } - - for param in &generics.params { - if !params_used.contains(param.index) { - if let ty::GenericParamDefKind::Type { .. } = param.kind { - let span = tcx.def_span(param.def_id); - struct_span_err!( - tcx.sess, - span, - E0091, - "type parameter `{}` is unused", - param.name, - ) - .span_label(span, "unused type parameter") - .emit(); - } - } - } -} - /// A wrapper for `InferCtxt`'s `in_progress_typeck_results` field. #[derive(Copy, Clone)] struct MaybeInProgressTables<'a, 'tcx> { @@ -2420,22 +1121,6 @@ impl ItemLikeVisitor<'tcx> for CheckItemTypesVisitor<'tcx> { fn visit_impl_item(&mut self, _: &'tcx hir::ImplItem<'tcx>) {} } -fn check_mod_item_types(tcx: TyCtxt<'_>, module_def_id: LocalDefId) { - tcx.hir().visit_item_likes_in_module(module_def_id, &mut CheckItemTypesVisitor { tcx }); -} - -fn check_item_well_formed(tcx: TyCtxt<'_>, def_id: LocalDefId) { - wfcheck::check_item_well_formed(tcx, def_id); -} - -fn check_trait_item_well_formed(tcx: TyCtxt<'_>, def_id: LocalDefId) { - wfcheck::check_trait_item(tcx, def_id); -} - -fn check_impl_item_well_formed(tcx: TyCtxt<'_>, def_id: LocalDefId) { - wfcheck::check_impl_item(tcx, def_id); -} - fn typeck_item_bodies(tcx: TyCtxt<'_>, crate_num: CrateNum) { debug_assert!(crate_num == LOCAL_CRATE); tcx.par_body_owners(|body_owner_def_id| {