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-rw-r--r--compiler/rustc_typeck/src/check/check.rs1712
1 files changed, 1712 insertions, 0 deletions
diff --git a/compiler/rustc_typeck/src/check/check.rs b/compiler/rustc_typeck/src/check/check.rs
new file mode 100644
index 000000000..9c1fd9b30
--- /dev/null
+++ b/compiler/rustc_typeck/src/check/check.rs
@@ -0,0 +1,1712 @@
+use crate::check::intrinsicck::InlineAsmCtxt;
+
+use super::coercion::CoerceMany;
+use super::compare_method::check_type_bounds;
+use super::compare_method::{compare_const_impl, compare_impl_method, compare_ty_impl};
+use super::*;
+use rustc_attr as attr;
+use rustc_errors::{Applicability, ErrorGuaranteed, MultiSpan};
+use rustc_hir as hir;
+use rustc_hir::def::{DefKind, Res};
+use rustc_hir::def_id::{DefId, LocalDefId};
+use rustc_hir::intravisit::Visitor;
+use rustc_hir::lang_items::LangItem;
+use rustc_hir::{ItemKind, Node, PathSegment};
+use rustc_infer::infer::outlives::env::OutlivesEnvironment;
+use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
+use rustc_infer::infer::{DefiningAnchor, RegionVariableOrigin, TyCtxtInferExt};
+use rustc_infer::traits::Obligation;
+use rustc_lint::builtin::REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS;
+use rustc_middle::hir::nested_filter;
+use rustc_middle::ty::layout::{LayoutError, MAX_SIMD_LANES};
+use rustc_middle::ty::subst::GenericArgKind;
+use rustc_middle::ty::util::{Discr, IntTypeExt};
+use rustc_middle::ty::{
+ self, ParamEnv, ToPredicate, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable,
+};
+use rustc_session::lint::builtin::{UNINHABITED_STATIC, UNSUPPORTED_CALLING_CONVENTIONS};
+use rustc_span::symbol::sym;
+use rustc_span::{self, Span};
+use rustc_target::spec::abi::Abi;
+use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _;
+use rustc_trait_selection::traits::{self, ObligationCtxt};
+use rustc_ty_utils::representability::{self, Representability};
+
+use std::iter;
+use std::ops::ControlFlow;
+
+pub(super) fn check_abi(tcx: TyCtxt<'_>, hir_id: hir::HirId, span: Span, abi: Abi) {
+ match tcx.sess.target.is_abi_supported(abi) {
+ Some(true) => (),
+ Some(false) => {
+ struct_span_err!(
+ tcx.sess,
+ span,
+ E0570,
+ "`{abi}` is not a supported ABI for the current target",
+ )
+ .emit();
+ }
+ None => {
+ tcx.struct_span_lint_hir(UNSUPPORTED_CALLING_CONVENTIONS, hir_id, span, |lint| {
+ lint.build("use of calling convention not supported on this target").emit();
+ });
+ }
+ }
+
+ // This ABI is only allowed on function pointers
+ if abi == Abi::CCmseNonSecureCall {
+ struct_span_err!(
+ tcx.sess,
+ span,
+ E0781,
+ "the `\"C-cmse-nonsecure-call\"` ABI is only allowed on function pointers"
+ )
+ .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)
+#[instrument(skip(inherited, body), level = "debug")]
+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<hir::Movability>,
+ return_type_pre_known: bool,
+) -> (FnCtxt<'a, 'tcx>, Option<GeneratorTypes<'tcx>>) {
+ // 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.set(UnsafetyState::function(fn_sig.unsafety, fn_id));
+ fcx.return_type_pre_known = return_type_pre_known;
+
+ let tcx = fcx.tcx;
+ let hir = tcx.hir();
+
+ let declared_ret_ty = fn_sig.output();
+
+ let ret_ty =
+ fcx.register_infer_ok_obligations(fcx.infcx.replace_opaque_types_with_inference_vars(
+ declared_ret_ty,
+ body.value.hir_id,
+ decl.output.span(),
+ param_env,
+ ));
+ // If we replaced declared_ret_ty with infer vars, then we must be infering
+ // an opaque type, so set a flag so we can improve diagnostics.
+ fcx.return_type_has_opaque = ret_ty != declared_ret_ty;
+
+ fcx.ret_coercion = Some(RefCell::new(CoerceMany::new(ret_ty)));
+ fcx.ret_type_span = Some(decl.output.span());
+
+ let span = body.value.span;
+
+ fn_maybe_err(tcx, span, fn_sig.abi);
+
+ if fn_sig.abi == Abi::RustCall {
+ let expected_args = if let ImplicitSelfKind::None = decl.implicit_self { 1 } else { 2 };
+
+ let err = || {
+ let item = match tcx.hir().get(fn_id) {
+ Node::Item(hir::Item { kind: ItemKind::Fn(header, ..), .. }) => Some(header),
+ Node::ImplItem(hir::ImplItem {
+ kind: hir::ImplItemKind::Fn(header, ..), ..
+ }) => Some(header),
+ Node::TraitItem(hir::TraitItem {
+ kind: hir::TraitItemKind::Fn(header, ..),
+ ..
+ }) => Some(header),
+ // Closures are RustCall, but they tuple their arguments, so shouldn't be checked
+ Node::Expr(hir::Expr { kind: hir::ExprKind::Closure { .. }, .. }) => None,
+ node => bug!("Item being checked wasn't a function/closure: {:?}", node),
+ };
+
+ if let Some(header) = item {
+ tcx.sess.span_err(header.span, "functions with the \"rust-call\" ABI must take a single non-self argument that is a tuple");
+ }
+ };
+
+ if fn_sig.inputs().len() != expected_args {
+ err()
+ } else {
+ // FIXME(CraftSpider) Add a check on parameter expansion, so we don't just make the ICE happen later on
+ // This will probably require wide-scale changes to support a TupleKind obligation
+ // We can't resolve this without knowing the type of the param
+ if !matches!(fn_sig.inputs()[expected_args - 1].kind(), ty::Tuple(_) | ty::Param(_)) {
+ err()
+ }
+ }
+ }
+
+ 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));
+ }
+
+ GatherLocalsVisitor::new(&fcx).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.bound_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(&param.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_fn_params {
+ 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);
+ } else {
+ fcx.require_type_is_sized(declared_ret_ty, decl.output.span(), traits::SizedReturnType);
+ fcx.check_return_expr(&body.value, false);
+ }
+ 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.
+ let coercion = fcx.ret_coercion.take().unwrap().into_inner();
+ let mut actual_return_ty = coercion.complete(&fcx);
+ debug!("actual_return_ty = {:?}", actual_return_ty);
+ if let ty::Dynamic(..) = declared_ret_ty.kind() {
+ // We have special-cased the case where the function is declared
+ // `-> dyn Foo` and we don't actually relate it to the
+ // `fcx.ret_coercion`, so just substitute a type variable.
+ actual_return_ty =
+ fcx.next_ty_var(TypeVariableOrigin { kind: TypeVariableOriginKind::DynReturnFn, span });
+ debug!("actual_return_ty replaced with {:?}", actual_return_ty);
+ }
+
+ // HACK(oli-obk, compiler-errors): We should be comparing this against
+ // `declared_ret_ty`, but then anything uninferred would be inferred to
+ // the opaque type itself. That again would cause writeback to assume
+ // we have a recursive call site and do the sadly stabilized fallback to `()`.
+ fcx.demand_suptype(span, ret_ty, actual_return_ty);
+
+ // Check that a function marked as `#[panic_handler]` has signature `fn(&PanicInfo) -> !`
+ if let Some(panic_impl_did) = tcx.lang_items().panic_impl()
+ && panic_impl_did == hir.local_def_id(fn_id).to_def_id()
+ {
+ check_panic_info_fn(tcx, panic_impl_did.expect_local(), fn_sig, decl, declared_ret_ty);
+ }
+
+ // Check that a function marked as `#[alloc_error_handler]` has signature `fn(Layout) -> !`
+ if let Some(alloc_error_handler_did) = tcx.lang_items().oom()
+ && alloc_error_handler_did == hir.local_def_id(fn_id).to_def_id()
+ {
+ check_alloc_error_fn(tcx, alloc_error_handler_did.expect_local(), fn_sig, decl, declared_ret_ty);
+ }
+
+ (fcx, gen_ty)
+}
+
+fn check_panic_info_fn(
+ tcx: TyCtxt<'_>,
+ fn_id: LocalDefId,
+ fn_sig: ty::FnSig<'_>,
+ decl: &hir::FnDecl<'_>,
+ declared_ret_ty: Ty<'_>,
+) {
+ let Some(panic_info_did) = tcx.lang_items().panic_info() else {
+ tcx.sess.err("language item required, but not found: `panic_info`");
+ return;
+ };
+
+ if *declared_ret_ty.kind() != ty::Never {
+ tcx.sess.span_err(decl.output.span(), "return type should be `!`");
+ }
+
+ let inputs = fn_sig.inputs();
+ if inputs.len() != 1 {
+ tcx.sess.span_err(tcx.def_span(fn_id), "function should have one argument");
+ return;
+ }
+
+ 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.is_static()
+ }
+ _ => false,
+ },
+ _ => false,
+ };
+
+ if !arg_is_panic_info {
+ tcx.sess.span_err(decl.inputs[0].span, "argument should be `&PanicInfo`");
+ }
+
+ let DefKind::Fn = tcx.def_kind(fn_id) else {
+ let span = tcx.def_span(fn_id);
+ tcx.sess.span_err(span, "should be a function");
+ return;
+ };
+
+ let generic_counts = tcx.generics_of(fn_id).own_counts();
+ if generic_counts.types != 0 {
+ let span = tcx.def_span(fn_id);
+ tcx.sess.span_err(span, "should have no type parameters");
+ }
+ if generic_counts.consts != 0 {
+ let span = tcx.def_span(fn_id);
+ tcx.sess.span_err(span, "should have no const parameters");
+ }
+}
+
+fn check_alloc_error_fn(
+ tcx: TyCtxt<'_>,
+ fn_id: LocalDefId,
+ fn_sig: ty::FnSig<'_>,
+ decl: &hir::FnDecl<'_>,
+ declared_ret_ty: Ty<'_>,
+) {
+ let Some(alloc_layout_did) = tcx.lang_items().alloc_layout() else {
+ tcx.sess.err("language item required, but not found: `alloc_layout`");
+ return;
+ };
+
+ if *declared_ret_ty.kind() != ty::Never {
+ tcx.sess.span_err(decl.output.span(), "return type should be `!`");
+ }
+
+ let inputs = fn_sig.inputs();
+ if inputs.len() != 1 {
+ tcx.sess.span_err(tcx.def_span(fn_id), "function should have one argument");
+ return;
+ }
+
+ let arg_is_alloc_layout = match inputs[0].kind() {
+ ty::Adt(ref adt, _) => adt.did() == alloc_layout_did,
+ _ => false,
+ };
+
+ if !arg_is_alloc_layout {
+ tcx.sess.span_err(decl.inputs[0].span, "argument should be `Layout`");
+ }
+
+ let DefKind::Fn = tcx.def_kind(fn_id) else {
+ let span = tcx.def_span(fn_id);
+ tcx.sess.span_err(span, "`#[alloc_error_handler]` should be a function");
+ return;
+ };
+
+ let generic_counts = tcx.generics_of(fn_id).own_counts();
+ if generic_counts.types != 0 {
+ let span = tcx.def_span(fn_id);
+ tcx.sess.span_err(span, "`#[alloc_error_handler]` function should have no type parameters");
+ }
+ if generic_counts.consts != 0 {
+ let span = tcx.def_span(fn_id);
+ tcx.sess
+ .span_err(span, "`#[alloc_error_handler]` function should have no const parameters");
+ }
+}
+
+fn check_struct(tcx: TyCtxt<'_>, def_id: LocalDefId) {
+ let def = tcx.adt_def(def_id);
+ let span = tcx.def_span(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<'_>, def_id: LocalDefId) {
+ let def = tcx.adt_def(def_id);
+ let span = tcx.def_span(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);
+}
+
+/// Check that the fields of the `union` do not 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());
+
+ fn allowed_union_field<'tcx>(
+ ty: Ty<'tcx>,
+ tcx: TyCtxt<'tcx>,
+ param_env: ty::ParamEnv<'tcx>,
+ span: Span,
+ ) -> bool {
+ // We don't just accept all !needs_drop fields, due to semver concerns.
+ match ty.kind() {
+ ty::Ref(..) => true, // references never drop (even mutable refs, which are non-Copy and hence fail the later check)
+ ty::Tuple(tys) => {
+ // allow tuples of allowed types
+ tys.iter().all(|ty| allowed_union_field(ty, tcx, param_env, span))
+ }
+ ty::Array(elem, _len) => {
+ // Like `Copy`, we do *not* special-case length 0.
+ allowed_union_field(*elem, tcx, param_env, span)
+ }
+ _ => {
+ // Fallback case: allow `ManuallyDrop` and things that are `Copy`.
+ ty.ty_adt_def().is_some_and(|adt_def| adt_def.is_manually_drop())
+ || ty.is_copy_modulo_regions(tcx.at(span), param_env)
+ }
+ }
+ }
+
+ let param_env = tcx.param_env(item_def_id);
+ for field in &def.non_enum_variant().fields {
+ let field_ty = field.ty(tcx, substs);
+
+ if !allowed_union_field(field_ty, tcx, param_env, span) {
+ let (field_span, ty_span) = match tcx.hir().get_if_local(field.did) {
+ // We are currently checking the type this field came from, so it must be local.
+ Some(Node::Field(field)) => (field.span, field.ty.span),
+ _ => unreachable!("mir field has to correspond to hir field"),
+ };
+ struct_span_err!(
+ tcx.sess,
+ field_span,
+ E0740,
+ "unions cannot contain fields that may need dropping"
+ )
+ .note(
+ "a type is guaranteed not to need dropping \
+ when it implements `Copy`, or when it is the special `ManuallyDrop<_>` type",
+ )
+ .multipart_suggestion_verbose(
+ "when the type does not implement `Copy`, \
+ wrap it inside a `ManuallyDrop<_>` and ensure it is manually dropped",
+ vec![
+ (ty_span.shrink_to_lo(), "std::mem::ManuallyDrop<".into()),
+ (ty_span.shrink_to_hi(), ">".into()),
+ ],
+ Applicability::MaybeIncorrect,
+ )
+ .emit();
+ return false;
+ } else if field_ty.needs_drop(tcx, param_env) {
+ // This should never happen. But we can get here e.g. in case of name resolution errors.
+ tcx.sess.delay_span_bug(span, "we should never accept maybe-dropping union fields");
+ }
+ }
+ } else {
+ span_bug!(span, "unions must be ty::Adt, but got {:?}", item_type.kind());
+ }
+ true
+}
+
+/// Check that a `static` is inhabited.
+fn check_static_inhabited<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) {
+ // Make sure statics are inhabited.
+ // Other parts of the compiler assume that there are no uninhabited places. In principle it
+ // would be enough to check this for `extern` statics, as statics with an initializer will
+ // have UB during initialization if they are uninhabited, but there also seems to be no good
+ // reason to allow any statics to be uninhabited.
+ let ty = tcx.type_of(def_id);
+ let span = tcx.def_span(def_id);
+ let layout = match tcx.layout_of(ParamEnv::reveal_all().and(ty)) {
+ Ok(l) => l,
+ // Foreign statics that overflow their allowed size should emit an error
+ Err(LayoutError::SizeOverflow(_))
+ if {
+ let node = tcx.hir().get_by_def_id(def_id);
+ matches!(
+ node,
+ hir::Node::ForeignItem(hir::ForeignItem {
+ kind: hir::ForeignItemKind::Static(..),
+ ..
+ })
+ )
+ } =>
+ {
+ tcx.sess
+ .struct_span_err(span, "extern static is too large for the current architecture")
+ .emit();
+ return;
+ }
+ // Generic statics are rejected, but we still reach this case.
+ Err(e) => {
+ tcx.sess.delay_span_bug(span, &e.to_string());
+ return;
+ }
+ };
+ if layout.abi.is_uninhabited() {
+ tcx.struct_span_lint_hir(
+ UNINHABITED_STATIC,
+ tcx.hir().local_def_id_to_hir_id(def_id),
+ span,
+ |lint| {
+ lint.build("static of uninhabited type")
+ .note("uninhabited statics cannot be initialized, and any access would be an immediate error")
+ .emit();
+ },
+ );
+ }
+}
+
+/// 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>,
+ origin: &hir::OpaqueTyOrigin,
+) {
+ let span = tcx.def_span(def_id);
+ check_opaque_for_inheriting_lifetimes(tcx, def_id, span);
+ if tcx.type_of(def_id).references_error() {
+ return;
+ }
+ if check_opaque_for_cycles(tcx, def_id, substs, span, origin).is_err() {
+ return;
+ }
+ check_opaque_meets_bounds(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".
+#[instrument(level = "debug", skip(tcx, span))]
+pub(super) fn check_opaque_for_inheriting_lifetimes<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ def_id: LocalDefId,
+ span: Span,
+) {
+ let item = tcx.hir().expect_item(def_id);
+ debug!(?item, ?span);
+
+ struct FoundParentLifetime;
+ struct FindParentLifetimeVisitor<'tcx>(&'tcx ty::Generics);
+ impl<'tcx> ty::visit::TypeVisitor<'tcx> for FindParentLifetimeVisitor<'tcx> {
+ type BreakTy = FoundParentLifetime;
+
+ fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
+ debug!("FindParentLifetimeVisitor: r={:?}", r);
+ if let ty::ReEarlyBound(ty::EarlyBoundRegion { index, .. }) = *r {
+ if index < self.0.parent_count as u32 {
+ return ControlFlow::Break(FoundParentLifetime);
+ } else {
+ return ControlFlow::CONTINUE;
+ }
+ }
+
+ r.super_visit_with(self)
+ }
+
+ fn visit_const(&mut self, c: ty::Const<'tcx>) -> ControlFlow<Self::BreakTy> {
+ if let ty::ConstKind::Unevaluated(..) = c.kind() {
+ // FIXME(#72219) We currently 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 ControlFlow::CONTINUE;
+ }
+ c.super_visit_with(self)
+ }
+ }
+
+ struct ProhibitOpaqueVisitor<'tcx> {
+ tcx: TyCtxt<'tcx>,
+ opaque_identity_ty: Ty<'tcx>,
+ generics: &'tcx ty::Generics,
+ selftys: Vec<(Span, Option<String>)>,
+ }
+
+ impl<'tcx> ty::visit::TypeVisitor<'tcx> for ProhibitOpaqueVisitor<'tcx> {
+ type BreakTy = Ty<'tcx>;
+
+ fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
+ debug!("check_opaque_for_inheriting_lifetimes: (visit_ty) t={:?}", t);
+ if t == self.opaque_identity_ty {
+ ControlFlow::CONTINUE
+ } else {
+ t.super_visit_with(&mut FindParentLifetimeVisitor(self.generics))
+ .map_break(|FoundParentLifetime| t)
+ }
+ }
+ }
+
+ impl<'tcx> Visitor<'tcx> for ProhibitOpaqueVisitor<'tcx> {
+ type NestedFilter = nested_filter::OnlyBodies;
+
+ fn nested_visit_map(&mut self) -> Self::Map {
+ self.tcx.hir()
+ }
+
+ fn visit_ty(&mut self, arg: &'tcx hir::Ty<'tcx>) {
+ match arg.kind {
+ hir::TyKind::Path(hir::QPath::Resolved(None, path)) => match &path.segments {
+ [
+ PathSegment {
+ res: Some(Res::SelfTy { trait_: _, alias_to: impl_ref }),
+ ..
+ },
+ ] => {
+ let impl_ty_name =
+ impl_ref.map(|(def_id, _)| self.tcx.def_path_str(def_id));
+ self.selftys.push((path.span, impl_ty_name));
+ }
+ _ => {}
+ },
+ _ => {}
+ }
+ hir::intravisit::walk_ty(self, arg);
+ }
+ }
+
+ 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),
+ tcx,
+ selftys: vec![],
+ };
+ let prohibit_opaque = tcx
+ .explicit_item_bounds(def_id)
+ .iter()
+ .try_for_each(|(predicate, _)| predicate.visit_with(&mut visitor));
+ debug!(
+ "check_opaque_for_inheriting_lifetimes: prohibit_opaque={:?}, visitor.opaque_identity_ty={:?}, visitor.generics={:?}",
+ prohibit_opaque, visitor.opaque_identity_ty, visitor.generics
+ );
+
+ if let Some(ty) = prohibit_opaque.break_value() {
+ visitor.visit_item(&item);
+ let is_async = match item.kind {
+ ItemKind::OpaqueTy(hir::OpaqueTy { origin, .. }) => {
+ matches!(origin, hir::OpaqueTyOrigin::AsyncFn(..))
+ }
+ _ => 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" },
+ );
+
+ for (span, name) in visitor.selftys {
+ err.span_suggestion(
+ span,
+ "consider spelling out the type instead",
+ name.unwrap_or_else(|| 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,
+) -> Result<(), ErrorGuaranteed> {
+ if tcx.try_expand_impl_trait_type(def_id.to_def_id(), substs).is_err() {
+ let reported = match origin {
+ hir::OpaqueTyOrigin::AsyncFn(..) => async_opaque_type_cycle_error(tcx, span),
+ _ => opaque_type_cycle_error(tcx, def_id, span),
+ };
+ Err(reported)
+ } else {
+ Ok(())
+ }
+}
+
+/// Check that the concrete type behind `impl Trait` actually implements `Trait`.
+///
+/// This is mostly checked at the places that specify the opaque type, but we
+/// check those cases in the `param_env` of that function, which may have
+/// bounds not on this opaque type:
+///
+/// type X<T> = impl Clone
+/// fn f<T: Clone>(t: T) -> X<T> {
+/// t
+/// }
+///
+/// Without this check the above code is incorrectly accepted: we would ICE if
+/// some tried, for example, to clone an `Option<X<&mut ()>>`.
+#[instrument(level = "debug", skip(tcx))]
+fn check_opaque_meets_bounds<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ def_id: LocalDefId,
+ substs: SubstsRef<'tcx>,
+ span: Span,
+ origin: &hir::OpaqueTyOrigin,
+) {
+ let hidden_type = tcx.bound_type_of(def_id.to_def_id()).subst(tcx, substs);
+
+ let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
+ let defining_use_anchor = match *origin {
+ hir::OpaqueTyOrigin::FnReturn(did) | hir::OpaqueTyOrigin::AsyncFn(did) => did,
+ hir::OpaqueTyOrigin::TyAlias => def_id,
+ };
+ let param_env = tcx.param_env(defining_use_anchor);
+
+ tcx.infer_ctxt().with_opaque_type_inference(DefiningAnchor::Bind(defining_use_anchor)).enter(
+ move |infcx| {
+ let ocx = ObligationCtxt::new(&infcx);
+ let opaque_ty = tcx.mk_opaque(def_id.to_def_id(), substs);
+
+ let misc_cause = traits::ObligationCause::misc(span, hir_id);
+
+ match infcx.at(&misc_cause, param_env).eq(opaque_ty, hidden_type) {
+ Ok(infer_ok) => ocx.register_infer_ok_obligations(infer_ok),
+ Err(ty_err) => {
+ tcx.sess.delay_span_bug(
+ span,
+ &format!("could not unify `{hidden_type}` with revealed type:\n{ty_err}"),
+ );
+ }
+ }
+
+ // Additionally require the hidden type to be well-formed with only the generics of the opaque type.
+ // Defining use functions may have more bounds than the opaque type, which is ok, as long as the
+ // hidden type is well formed even without those bounds.
+ let predicate = ty::Binder::dummy(ty::PredicateKind::WellFormed(hidden_type.into()))
+ .to_predicate(tcx);
+ ocx.register_obligation(Obligation::new(misc_cause, param_env, predicate));
+
+ // Check that all obligations are satisfied by the implementation's
+ // version.
+ let errors = ocx.select_all_or_error();
+ if !errors.is_empty() {
+ infcx.report_fulfillment_errors(&errors, None, false);
+ }
+ match origin {
+ // Checked when type checking the function containing them.
+ hir::OpaqueTyOrigin::FnReturn(..) | hir::OpaqueTyOrigin::AsyncFn(..) => {}
+ // Can have different predicates to their defining use
+ hir::OpaqueTyOrigin::TyAlias => {
+ let outlives_environment = OutlivesEnvironment::new(param_env);
+ infcx.check_region_obligations_and_report_errors(
+ defining_use_anchor,
+ &outlives_environment,
+ );
+ }
+ }
+ // Clean up after ourselves
+ let _ = infcx.inner.borrow_mut().opaque_type_storage.take_opaque_types();
+ },
+ );
+}
+
+fn check_item_type<'tcx>(tcx: TyCtxt<'tcx>, id: hir::ItemId) {
+ debug!(
+ "check_item_type(it.def_id={:?}, it.name={})",
+ id.def_id,
+ tcx.def_path_str(id.def_id.to_def_id())
+ );
+ let _indenter = indenter();
+ match tcx.def_kind(id.def_id) {
+ DefKind::Static(..) => {
+ tcx.ensure().typeck(id.def_id);
+ maybe_check_static_with_link_section(tcx, id.def_id);
+ check_static_inhabited(tcx, id.def_id);
+ }
+ DefKind::Const => {
+ tcx.ensure().typeck(id.def_id);
+ }
+ DefKind::Enum => {
+ let item = tcx.hir().item(id);
+ let hir::ItemKind::Enum(ref enum_definition, _) = item.kind else {
+ return;
+ };
+ check_enum(tcx, &enum_definition.variants, item.def_id);
+ }
+ DefKind::Fn => {} // entirely within check_item_body
+ DefKind::Impl => {
+ let it = tcx.hir().item(id);
+ let hir::ItemKind::Impl(ref impl_) = it.kind else {
+ return;
+ };
+ debug!("ItemKind::Impl {} with id {:?}", it.ident, it.def_id);
+ if let Some(impl_trait_ref) = tcx.impl_trait_ref(it.def_id) {
+ check_impl_items_against_trait(
+ tcx,
+ it.span,
+ it.def_id,
+ impl_trait_ref,
+ &impl_.items,
+ );
+ check_on_unimplemented(tcx, it);
+ }
+ }
+ DefKind::Trait => {
+ let it = tcx.hir().item(id);
+ let hir::ItemKind::Trait(_, _, _, _, ref items) = it.kind else {
+ return;
+ };
+ check_on_unimplemented(tcx, it);
+
+ for item in items.iter() {
+ let item = tcx.hir().trait_item(item.id);
+ match item.kind {
+ hir::TraitItemKind::Fn(ref sig, _) => {
+ let abi = sig.header.abi;
+ fn_maybe_err(tcx, item.ident.span, abi);
+ }
+ hir::TraitItemKind::Type(.., Some(default)) => {
+ let assoc_item = tcx.associated_item(item.def_id);
+ let trait_substs =
+ InternalSubsts::identity_for_item(tcx, it.def_id.to_def_id());
+ let _: Result<_, rustc_errors::ErrorGuaranteed> = check_type_bounds(
+ tcx,
+ assoc_item,
+ assoc_item,
+ default.span,
+ ty::TraitRef { def_id: it.def_id.to_def_id(), substs: trait_substs },
+ );
+ }
+ _ => {}
+ }
+ }
+ }
+ DefKind::Struct => {
+ check_struct(tcx, id.def_id);
+ }
+ DefKind::Union => {
+ check_union(tcx, id.def_id);
+ }
+ DefKind::OpaqueTy => {
+ let item = tcx.hir().item(id);
+ let hir::ItemKind::OpaqueTy(hir::OpaqueTy { origin, .. }) = item.kind else {
+ return;
+ };
+ // 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 substs = InternalSubsts::identity_for_item(tcx, item.def_id.to_def_id());
+ check_opaque(tcx, item.def_id, substs, &origin);
+ }
+ }
+ DefKind::TyAlias => {
+ let pty_ty = tcx.type_of(id.def_id);
+ let generics = tcx.generics_of(id.def_id);
+ check_type_params_are_used(tcx, &generics, pty_ty);
+ }
+ DefKind::ForeignMod => {
+ let it = tcx.hir().item(id);
+ let hir::ItemKind::ForeignMod { abi, items } = it.kind else {
+ return;
+ };
+ check_abi(tcx, it.hir_id(), it.span, abi);
+
+ if abi == Abi::RustIntrinsic {
+ for item in items {
+ let item = tcx.hir().foreign_item(item.id);
+ intrinsic::check_intrinsic_type(tcx, item);
+ }
+ } else if abi == Abi::PlatformIntrinsic {
+ for item in items {
+ let item = tcx.hir().foreign_item(item.id);
+ intrinsic::check_platform_intrinsic_type(tcx, item);
+ }
+ } else {
+ for item in items {
+ let def_id = item.id.def_id;
+ let generics = tcx.generics_of(def_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 {kinds} parameters",
+ )
+ .span_label(item.span, &format!("can't have {kinds} parameters"))
+ .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();
+ }
+
+ let item = tcx.hir().foreign_item(item.id);
+ match item.kind {
+ hir::ForeignItemKind::Fn(ref fn_decl, _, _) => {
+ require_c_abi_if_c_variadic(tcx, fn_decl, abi, item.span);
+ }
+ hir::ForeignItemKind::Static(..) => {
+ check_static_inhabited(tcx, def_id);
+ }
+ _ => {}
+ }
+ }
+ }
+ }
+ DefKind::GlobalAsm => {
+ let it = tcx.hir().item(id);
+ let hir::ItemKind::GlobalAsm(asm) = it.kind else { span_bug!(it.span, "DefKind::GlobalAsm but got {:#?}", it) };
+ InlineAsmCtxt::new_global_asm(tcx).check_asm(asm, id.hir_id());
+ }
+ _ => {}
+ }
+}
+
+pub(super) fn check_on_unimplemented(tcx: TyCtxt<'_>, item: &hir::Item<'_>) {
+ // an error would be reported if this fails.
+ let _ = traits::OnUnimplementedDirective::of_item(tcx, 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::ImplItemRef,
+) {
+ let Ok(ancestors) = trait_def.ancestors(tcx, impl_id) else { 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.def_id)))
+ }
+ });
+
+ 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],
+) {
+ // 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;
+ }
+ }
+
+ let trait_def = tcx.trait_def(impl_trait_ref.def_id);
+
+ for impl_item in impl_item_refs {
+ let ty_impl_item = tcx.associated_item(impl_item.id.def_id);
+ let ty_trait_item = if let Some(trait_item_id) = ty_impl_item.trait_item_def_id {
+ tcx.associated_item(trait_item_id)
+ } else {
+ // Checked in `associated_item`.
+ tcx.sess.delay_span_bug(impl_item.span, "missing associated item in trait");
+ continue;
+ };
+ let impl_item_full = tcx.hir().impl_item(impl_item.id);
+ match impl_item_full.kind {
+ hir::ImplItemKind::Const(..) => {
+ // Find associated const definition.
+ compare_const_impl(
+ tcx,
+ &ty_impl_item,
+ impl_item.span,
+ &ty_trait_item,
+ impl_trait_ref,
+ );
+ }
+ hir::ImplItemKind::Fn(..) => {
+ let opt_trait_span = tcx.hir().span_if_local(ty_trait_item.def_id);
+ compare_impl_method(
+ tcx,
+ &ty_impl_item,
+ &ty_trait_item,
+ impl_trait_ref,
+ opt_trait_span,
+ );
+ }
+ hir::ImplItemKind::TyAlias(impl_ty) => {
+ let opt_trait_span = tcx.hir().span_if_local(ty_trait_item.def_id);
+ compare_ty_impl(
+ tcx,
+ &ty_impl_item,
+ impl_ty.span,
+ &ty_trait_item,
+ impl_trait_ref,
+ opt_trait_span,
+ );
+ }
+ }
+
+ check_specialization_validity(
+ tcx,
+ trait_def,
+ &ty_trait_item,
+ impl_id.to_def_id(),
+ impl_item,
+ );
+ }
+
+ if let Ok(ancestors) = trait_def.ancestors(tcx, impl_id.to_def_id()) {
+ // Check for missing items from trait
+ let mut missing_items = Vec::new();
+
+ let mut must_implement_one_of: Option<&[Ident]> =
+ trait_def.must_implement_one_of.as_deref();
+
+ for &trait_item_id in tcx.associated_item_def_ids(impl_trait_ref.def_id) {
+ let is_implemented = ancestors
+ .leaf_def(tcx, trait_item_id)
+ .map_or(false, |node_item| node_item.item.defaultness(tcx).has_value());
+
+ if !is_implemented && tcx.impl_defaultness(impl_id).is_final() {
+ missing_items.push(tcx.associated_item(trait_item_id));
+ }
+
+ if let Some(required_items) = &must_implement_one_of {
+ // true if this item is specifically implemented in this impl
+ let is_implemented_here = ancestors
+ .leaf_def(tcx, trait_item_id)
+ .map_or(false, |node_item| !node_item.defining_node.is_from_trait());
+
+ if is_implemented_here {
+ let trait_item = tcx.associated_item(trait_item_id);
+ if required_items.contains(&trait_item.ident(tcx)) {
+ must_implement_one_of = None;
+ }
+ }
+ }
+ }
+
+ if !missing_items.is_empty() {
+ missing_items_err(tcx, tcx.def_span(impl_id), &missing_items, full_impl_span);
+ }
+
+ if let Some(missing_items) = must_implement_one_of {
+ let attr_span = tcx
+ .get_attr(impl_trait_ref.def_id, sym::rustc_must_implement_one_of)
+ .map(|attr| attr.span);
+
+ missing_items_must_implement_one_of_err(
+ tcx,
+ tcx.def_span(impl_id),
+ missing_items,
+ attr_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 representability::ty_is_representable(tcx, rty, sp, None) {
+ 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()
+ && 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;
+ }
+
+ let len = if let ty::Array(_ty, c) = e.kind() {
+ c.try_eval_usize(tcx, tcx.param_env(def.did()))
+ } else {
+ Some(fields.len() as u64)
+ };
+ if let Some(len) = len {
+ if len == 0 {
+ struct_span_err!(tcx.sess, sp, E0075, "SIMD vector cannot be empty").emit();
+ return;
+ } else if len > MAX_SIMD_LANES {
+ struct_span_err!(
+ tcx.sess,
+ sp,
+ E0075,
+ "SIMD vector cannot have more than {MAX_SIMD_LANES} elements",
+ )
+ .emit();
+ return;
+ }
+ }
+
+ // Check that we use types valid for use in the lanes of a SIMD "vector register"
+ // These are scalar types which directly match a "machine" type
+ // Yes: Integers, floats, "thin" pointers
+ // No: char, "fat" pointers, compound types
+ match e.kind() {
+ ty::Param(_) => (), // pass struct<T>(T, T, T, T) through, let monomorphization catch errors
+ ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::RawPtr(_) => (), // struct(u8, u8, u8, u8) is ok
+ ty::Array(t, _) if matches!(t.kind(), ty::Param(_)) => (), // pass struct<T>([T; N]) through, let monomorphization catch errors
+ ty::Array(t, _clen)
+ if matches!(
+ t.kind(),
+ ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::RawPtr(_)
+ ) =>
+ { /* struct([f32; 4]) is ok */ }
+ _ => {
+ struct_span_err!(
+ tcx.sess,
+ sp,
+ E0077,
+ "SIMD vector element type should be a \
+ primitive scalar (integer/float/pointer) 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(), sym::repr) {
+ for r in attr::parse_repr_attr(&tcx.sess, attr) {
+ if let attr::ReprPacked(pack) = r
+ && let Some(repr_pack) = repr.pack
+ && 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<DefId>,
+) -> Option<Vec<(DefId, Span)>> {
+ 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()
+ && !stack.contains(&def.did())
+ && let Some(mut defs) = check_packed_inner(tcx, def.did(), stack)
+ {
+ defs.push((def.did(), field.ident(tcx).span));
+ return Some(defs);
+ }
+ }
+ stack.pop();
+ }
+ }
+
+ None
+}
+
+pub(super) fn check_transparent<'tcx>(tcx: TyCtxt<'tcx>, sp: Span, adt: ty::AdtDef<'tcx>) {
+ if !adt.repr().transparent() {
+ return;
+ }
+
+ 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), with "known"
+ // respecting #[non_exhaustive] attributes.
+ 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_or(false, |layout| layout.is_zst());
+ let align1 = layout.map_or(false, |layout| layout.align.abi.bytes() == 1);
+ if !zst {
+ return (span, zst, align1, None);
+ }
+
+ fn check_non_exhaustive<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ t: Ty<'tcx>,
+ ) -> ControlFlow<(&'static str, DefId, SubstsRef<'tcx>, bool)> {
+ match t.kind() {
+ ty::Tuple(list) => list.iter().try_for_each(|t| check_non_exhaustive(tcx, t)),
+ ty::Array(ty, _) => check_non_exhaustive(tcx, *ty),
+ ty::Adt(def, subst) => {
+ if !def.did().is_local() {
+ let non_exhaustive = def.is_variant_list_non_exhaustive()
+ || def
+ .variants()
+ .iter()
+ .any(ty::VariantDef::is_field_list_non_exhaustive);
+ let has_priv = def.all_fields().any(|f| !f.vis.is_public());
+ if non_exhaustive || has_priv {
+ return ControlFlow::Break((
+ def.descr(),
+ def.did(),
+ subst,
+ non_exhaustive,
+ ));
+ }
+ }
+ def.all_fields()
+ .map(|field| field.ty(tcx, subst))
+ .try_for_each(|t| check_non_exhaustive(tcx, t))
+ }
+ _ => ControlFlow::Continue(()),
+ }
+ }
+
+ (span, zst, align1, check_non_exhaustive(tcx, ty).break_value())
+ });
+
+ let non_zst_fields = field_infos
+ .clone()
+ .filter_map(|(span, zst, _align1, _non_exhaustive)| if !zst { Some(span) } else { None });
+ let non_zst_count = non_zst_fields.clone().count();
+ if non_zst_count >= 2 {
+ bad_non_zero_sized_fields(tcx, adt, non_zst_count, non_zst_fields, sp);
+ }
+ let incompatible_zst_fields =
+ field_infos.clone().filter(|(_, _, _, opt)| opt.is_some()).count();
+ let incompat = incompatible_zst_fields + non_zst_count >= 2 && non_zst_count < 2;
+ for (span, zst, align1, non_exhaustive) 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();
+ }
+ if incompat && let Some((descr, def_id, substs, non_exhaustive)) = non_exhaustive {
+ tcx.struct_span_lint_hir(
+ REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS,
+ tcx.hir().local_def_id_to_hir_id(adt.did().expect_local()),
+ span,
+ |lint| {
+ let note = if non_exhaustive {
+ "is marked with `#[non_exhaustive]`"
+ } else {
+ "contains private fields"
+ };
+ let field_ty = tcx.def_path_str_with_substs(def_id, substs);
+ lint.build("zero-sized fields in repr(transparent) cannot contain external non-exhaustive types")
+ .note(format!("this {descr} contains `{field_ty}`, which {note}, \
+ and makes it not a breaking change to become non-zero-sized in the future."))
+ .emit();
+ },
+ )
+ }
+ }
+}
+
+#[allow(trivial_numeric_casts)]
+fn check_enum<'tcx>(tcx: TyCtxt<'tcx>, vs: &'tcx [hir::Variant<'tcx>], def_id: LocalDefId) {
+ let def = tcx.adt_def(def_id);
+ let sp = tcx.def_span(def_id);
+ def.destructor(tcx); // force the destructor to be evaluated
+
+ if vs.is_empty() {
+ if let Some(attr) = tcx.get_attr(def_id.to_def_id(), 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<'_>| matches!(var.data, hir::VariantData::Unit(..));
+
+ 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<Discr<'tcx>> = Vec::with_capacity(vs.len());
+ // This tracks the previous variant span (in the loop) incase we need it for diagnostics
+ let mut prev_variant_span: Span = DUMMY_SP;
+ for ((_, discr), v) in iter::zip(def.discriminants(tcx), vs) {
+ // Check for duplicate discriminant values
+ if let Some(i) = disr_vals.iter().position(|&x| x.val == discr.val) {
+ let variant_did = def.variant(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.def_span(variant_did),
+ };
+ let span = match v.disr_expr {
+ Some(ref expr) => tcx.hir().span(expr.hir_id),
+ None => v.span,
+ };
+ let display_discr = format_discriminant_overflow(tcx, v, discr);
+ let display_discr_i = format_discriminant_overflow(tcx, variant_i, disr_vals[i]);
+ let no_disr = v.disr_expr.is_none();
+ let mut err = struct_span_err!(
+ tcx.sess,
+ sp,
+ E0081,
+ "discriminant value `{}` assigned more than once",
+ discr,
+ );
+
+ err.span_label(i_span, format!("first assignment of {display_discr_i}"));
+ err.span_label(span, format!("second assignment of {display_discr}"));
+
+ if no_disr {
+ err.span_label(
+ prev_variant_span,
+ format!(
+ "assigned discriminant for `{}` was incremented from this discriminant",
+ v.ident
+ ),
+ );
+ }
+ err.emit();
+ }
+
+ disr_vals.push(discr);
+ prev_variant_span = v.span;
+ }
+
+ check_representable(tcx, sp, def_id);
+ check_transparent(tcx, sp, def);
+}
+
+/// In the case that a discriminant is both a duplicate and an overflowing literal,
+/// we insert both the assigned discriminant and the literal it overflowed from into the formatted
+/// output. Otherwise we format the discriminant normally.
+fn format_discriminant_overflow<'tcx>(
+ tcx: TyCtxt<'tcx>,
+ variant: &hir::Variant<'_>,
+ dis: Discr<'tcx>,
+) -> String {
+ if let Some(expr) = &variant.disr_expr {
+ let body = &tcx.hir().body(expr.body).value;
+ if let hir::ExprKind::Lit(lit) = &body.kind
+ && let rustc_ast::LitKind::Int(lit_value, _int_kind) = &lit.node
+ && dis.val != *lit_value
+ {
+ return format!("`{dis}` (overflowed from `{lit_value}`)");
+ }
+ }
+
+ format!("`{dis}`")
+}
+
+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().is_some());
+ return;
+ }
+
+ for leaf in ty.walk() {
+ if let GenericArgKind::Type(leaf_ty) = leaf.unpack()
+ && 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)
+ && 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) {
+ let module = tcx.hir_module_items(module_def_id);
+ for id in module.items() {
+ check_item_type(tcx, id);
+ }
+}
+
+fn async_opaque_type_cycle_error(tcx: TyCtxt<'_>, span: Span) -> ErrorGuaranteed {
+ 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`")
+ .note(
+ "consider using the `async_recursion` crate: https://crates.io/crates/async_recursion",
+ )
+ .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<'_>, def_id: LocalDefId, span: Span) -> ErrorGuaranteed {
+ let mut err = struct_span_err!(tcx.sess, span, E0720, "cannot resolve opaque type");
+
+ let mut label = false;
+ if let Some((def_id, visitor)) = get_owner_return_paths(tcx, def_id) {
+ let typeck_results = tcx.typeck(def_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::<Vec<Span>>();
+ 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");
+ }
+ 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 OpaqueTypeCollector(Vec<DefId>);
+ impl<'tcx> ty::visit::TypeVisitor<'tcx> for OpaqueTypeCollector {
+ fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
+ match *t.kind() {
+ ty::Opaque(def, _) => {
+ self.0.push(def);
+ ControlFlow::CONTINUE
+ }
+ _ => t.super_visit_with(self),
+ }
+ }
+ }
+ let mut visitor = OpaqueTypeCollector(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()
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-10 11:23:01 +0000