diff options
| -rw-r--r-- | compiler/rustc_trait_selection/src/traits/object_safety.rs | 84 | ||||
| -rw-r--r-- | tests/ui/const-generics/generic_const_exprs/object-safety-err-ret.stderr | 7 |
2 files changed, 52 insertions, 39 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/object_safety.rs b/compiler/rustc_trait_selection/src/traits/object_safety.rs index 2d05f934393..dfc4bdf1484 100644 --- a/compiler/rustc_trait_selection/src/traits/object_safety.rs +++ b/compiler/rustc_trait_selection/src/traits/object_safety.rs @@ -97,6 +97,10 @@ fn check_is_object_safe(tcx: TyCtxt<'_>, trait_def_id: DefId) -> bool { /// object. Note that object-safe traits can have some /// non-vtable-safe methods, so long as they require `Self: Sized` or /// otherwise ensure that they cannot be used when `Self = Trait`. +/// +/// [`MethodViolationCode::WhereClauseReferencesSelf`] is considered object safe due to backwards +/// compatibility, see <https://github.com/rust-lang/rust/issues/51443> and +/// [`WHERE_CLAUSES_OBJECT_SAFETY`]. pub fn is_vtable_safe_method(tcx: TyCtxt<'_>, trait_def_id: DefId, method: ty::AssocItem) -> bool { debug_assert!(tcx.generics_of(trait_def_id).has_self); debug!("is_vtable_safe_method({:?}, {:?})", trait_def_id, method); @@ -105,10 +109,9 @@ pub fn is_vtable_safe_method(tcx: TyCtxt<'_>, trait_def_id: DefId, method: ty::A return false; } - match virtual_call_violation_for_method(tcx, trait_def_id, method) { - None | Some(MethodViolationCode::WhereClauseReferencesSelf) => true, - Some(_) => false, - } + virtual_call_violations_for_method(tcx, trait_def_id, method) + .iter() + .all(|v| matches!(v, MethodViolationCode::WhereClauseReferencesSelf)) } fn object_safety_violations_for_trait( @@ -119,7 +122,7 @@ fn object_safety_violations_for_trait( let mut violations: Vec<_> = tcx .associated_items(trait_def_id) .in_definition_order() - .filter_map(|&item| object_safety_violation_for_assoc_item(tcx, trait_def_id, item)) + .flat_map(|&item| object_safety_violations_for_assoc_item(tcx, trait_def_id, item)) .collect(); // Check the trait itself. @@ -357,49 +360,52 @@ fn generics_require_sized_self(tcx: TyCtxt<'_>, def_id: DefId) -> bool { /// Returns `Some(_)` if this item makes the containing trait not object safe. #[instrument(level = "debug", skip(tcx), ret)] -fn object_safety_violation_for_assoc_item( +fn object_safety_violations_for_assoc_item( tcx: TyCtxt<'_>, trait_def_id: DefId, item: ty::AssocItem, -) -> Option<ObjectSafetyViolation> { +) -> Vec<ObjectSafetyViolation> { // Any item that has a `Self : Sized` requisite is otherwise // exempt from the regulations. if tcx.generics_require_sized_self(item.def_id) { - return None; + return Vec::new(); } match item.kind { // Associated consts are never object safe, as they can't have `where` bounds yet at all, // and associated const bounds in trait objects aren't a thing yet either. ty::AssocKind::Const => { - Some(ObjectSafetyViolation::AssocConst(item.name, item.ident(tcx).span)) + vec![ObjectSafetyViolation::AssocConst(item.name, item.ident(tcx).span)] } - ty::AssocKind::Fn => virtual_call_violation_for_method(tcx, trait_def_id, item).map(|v| { - let node = tcx.hir().get_if_local(item.def_id); - // Get an accurate span depending on the violation. - let span = match (&v, node) { - (MethodViolationCode::ReferencesSelfInput(Some(span)), _) => *span, - (MethodViolationCode::UndispatchableReceiver(Some(span)), _) => *span, - (MethodViolationCode::ReferencesImplTraitInTrait(span), _) => *span, - (MethodViolationCode::ReferencesSelfOutput, Some(node)) => { - node.fn_decl().map_or(item.ident(tcx).span, |decl| decl.output.span()) - } - _ => item.ident(tcx).span, - }; + ty::AssocKind::Fn => virtual_call_violations_for_method(tcx, trait_def_id, item) + .into_iter() + .map(|v| { + let node = tcx.hir().get_if_local(item.def_id); + // Get an accurate span depending on the violation. + let span = match (&v, node) { + (MethodViolationCode::ReferencesSelfInput(Some(span)), _) => *span, + (MethodViolationCode::UndispatchableReceiver(Some(span)), _) => *span, + (MethodViolationCode::ReferencesImplTraitInTrait(span), _) => *span, + (MethodViolationCode::ReferencesSelfOutput, Some(node)) => { + node.fn_decl().map_or(item.ident(tcx).span, |decl| decl.output.span()) + } + _ => item.ident(tcx).span, + }; - ObjectSafetyViolation::Method(item.name, v, span) - }), + ObjectSafetyViolation::Method(item.name, v, span) + }) + .collect(), // Associated types can only be object safe if they have `Self: Sized` bounds. ty::AssocKind::Type => { if !tcx.features().generic_associated_types_extended && !tcx.generics_of(item.def_id).params.is_empty() && !item.is_impl_trait_in_trait() { - Some(ObjectSafetyViolation::GAT(item.name, item.ident(tcx).span)) + vec![ObjectSafetyViolation::GAT(item.name, item.ident(tcx).span)] } else { // We will permit associated types if they are explicitly mentioned in the trait object. // We can't check this here, as here we only check if it is guaranteed to not be possible. - None + Vec::new() } } } @@ -409,11 +415,11 @@ fn object_safety_violation_for_assoc_item( /// object; this does not necessarily imply that the enclosing trait /// is not object safe, because the method might have a where clause /// `Self:Sized`. -fn virtual_call_violation_for_method<'tcx>( +fn virtual_call_violations_for_method<'tcx>( tcx: TyCtxt<'tcx>, trait_def_id: DefId, method: ty::AssocItem, -) -> Option<MethodViolationCode> { +) -> Vec<MethodViolationCode> { let sig = tcx.fn_sig(method.def_id).instantiate_identity(); // The method's first parameter must be named `self` @@ -438,9 +444,14 @@ fn virtual_call_violation_for_method<'tcx>( } else { None }; - return Some(MethodViolationCode::StaticMethod(sugg)); + + // Not having `self` parameter messes up the later checks, + // so we need to return instead of pushing + return vec![MethodViolationCode::StaticMethod(sugg)]; } + let mut errors = Vec::new(); + for (i, &input_ty) in sig.skip_binder().inputs().iter().enumerate().skip(1) { if contains_illegal_self_type_reference(tcx, trait_def_id, sig.rebind(input_ty)) { let span = if let Some(hir::Node::TraitItem(hir::TraitItem { @@ -452,20 +463,20 @@ fn virtual_call_violation_for_method<'tcx>( } else { None }; - return Some(MethodViolationCode::ReferencesSelfInput(span)); + errors.push(MethodViolationCode::ReferencesSelfInput(span)); } } if contains_illegal_self_type_reference(tcx, trait_def_id, sig.output()) { - return Some(MethodViolationCode::ReferencesSelfOutput); + errors.push(MethodViolationCode::ReferencesSelfOutput); } if let Some(code) = contains_illegal_impl_trait_in_trait(tcx, method.def_id, sig.output()) { - return Some(code); + errors.push(code); } // We can't monomorphize things like `fn foo<A>(...)`. let own_counts = tcx.generics_of(method.def_id).own_counts(); - if own_counts.types + own_counts.consts != 0 { - return Some(MethodViolationCode::Generic); + if own_counts.types > 0 || own_counts.consts > 0 { + errors.push(MethodViolationCode::Generic); } let receiver_ty = tcx.liberate_late_bound_regions(method.def_id, sig.input(0)); @@ -485,7 +496,7 @@ fn virtual_call_violation_for_method<'tcx>( } else { None }; - return Some(MethodViolationCode::UndispatchableReceiver(span)); + errors.push(MethodViolationCode::UndispatchableReceiver(span)); } else { // Do sanity check to make sure the receiver actually has the layout of a pointer. @@ -593,10 +604,10 @@ fn virtual_call_violation_for_method<'tcx>( contains_illegal_self_type_reference(tcx, trait_def_id, pred) }) { - return Some(MethodViolationCode::WhereClauseReferencesSelf); + errors.push(MethodViolationCode::WhereClauseReferencesSelf); } - None + errors } /// Performs a type substitution to produce the version of `receiver_ty` when `Self = self_ty`. @@ -709,7 +720,6 @@ fn object_ty_for_trait<'tcx>( // FIXME(mikeyhew) when unsized receivers are implemented as part of unsized rvalues, add this // fallback query: `Receiver: Unsize<Receiver[Self => U]>` to support receivers like // `self: Wrapper<Self>`. -#[allow(dead_code)] fn receiver_is_dispatchable<'tcx>( tcx: TyCtxt<'tcx>, method: ty::AssocItem, diff --git a/tests/ui/const-generics/generic_const_exprs/object-safety-err-ret.stderr b/tests/ui/const-generics/generic_const_exprs/object-safety-err-ret.stderr index 4e1d71f1545..7ce2b9ac95a 100644 --- a/tests/ui/const-generics/generic_const_exprs/object-safety-err-ret.stderr +++ b/tests/ui/const-generics/generic_const_exprs/object-safety-err-ret.stderr @@ -5,12 +5,15 @@ LL | fn use_dyn(v: &dyn Foo) { | ^^^^^^^ `Foo` cannot be made into an object | note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety> - --> $DIR/object-safety-err-ret.rs:8:23 + --> $DIR/object-safety-err-ret.rs:8:8 | LL | trait Foo { | --- this trait cannot be made into an object... LL | fn test(&self) -> [u8; bar::<Self>()]; - | ^^^^^^^^^^^^^^^^^^^ ...because method `test` references the `Self` type in its return type + | ^^^^ ^^^^^^^^^^^^^^^^^^^ ...because method `test` references the `Self` type in its return type + | | + | ...because method `test` references the `Self` type in its `where` clause + = help: consider moving `test` to another trait = help: consider moving `test` to another trait error: aborting due to previous error |