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https://github.com/rust-lang/rust.git
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Make GATs object safe under generic_associated_types_extended feature
This commit is contained in:
Jack Huey
parent
0677edc86e
commit
52b00db235
@ -131,6 +131,7 @@ fn object_safety_violations_for_trait(
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}),
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);
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if !tcx.features().generic_associated_types_extended {
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violations.extend(
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tcx.associated_items(trait_def_id)
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.in_definition_order()
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@ -141,6 +142,7 @@ fn object_safety_violations_for_trait(
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ObjectSafetyViolation::GAT(ident.name, ident.span)
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}),
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);
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}
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debug!(
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"object_safety_violations_for_trait(trait_def_id={:?}) = {:?}",
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@ -11,8 +11,8 @@ use rustc_hir::lang_items::LangItem;
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use rustc_index::bit_set::GrowableBitSet;
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use rustc_infer::infer::InferOk;
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use rustc_infer::infer::LateBoundRegionConversionTime::HigherRankedType;
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use rustc_middle::ty::subst::{GenericArg, GenericArgKind, Subst, SubstsRef};
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use rustc_middle::ty::{self, Ty};
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use rustc_middle::ty::subst::{GenericArg, GenericArgKind, InternalSubsts, Subst, SubstsRef};
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use rustc_middle::ty::{self, GenericParamDefKind, Ty};
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use rustc_middle::ty::{ToPolyTraitRef, ToPredicate};
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use rustc_span::def_id::DefId;
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@ -487,18 +487,80 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
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.collect();
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for assoc_type in assoc_types {
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if !tcx.generics_of(assoc_type).params.is_empty() {
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let defs: &ty::Generics = tcx.generics_of(assoc_type);
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if !defs.params.is_empty() && !tcx.features().generic_associated_types_extended {
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tcx.sess.delay_span_bug(
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obligation.cause.span,
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"GATs in trait object shouldn't have been considered",
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);
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return Err(SelectionError::Unimplemented);
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}
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// This maybe belongs in wf, but that can't (doesn't) handle
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// higher-ranked things.
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// Prevent, e.g., `dyn Iterator<Item = str>`.
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for bound in self.tcx().item_bounds(assoc_type) {
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let subst_bound = bound.subst(tcx, trait_predicate.trait_ref.substs);
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let subst_bound =
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if defs.count() == 0 {
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bound.subst(tcx, trait_predicate.trait_ref.substs)
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} else {
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let mut substs = smallvec::SmallVec::with_capacity(defs.count());
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substs.extend(trait_predicate.trait_ref.substs.iter());
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let mut bound_vars: smallvec::SmallVec<[ty::BoundVariableKind; 8]> =
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smallvec::SmallVec::with_capacity(
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bound.kind().bound_vars().len() + defs.count(),
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);
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bound_vars.extend(bound.kind().bound_vars().into_iter());
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InternalSubsts::fill_single(&mut substs, defs, &mut |param, _| match param
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.kind
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{
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GenericParamDefKind::Type { .. } => {
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let kind = ty::BoundTyKind::Param(param.name);
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let bound_var = ty::BoundVariableKind::Ty(kind);
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bound_vars.push(bound_var);
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tcx.mk_ty(ty::Bound(
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ty::INNERMOST,
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ty::BoundTy {
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var: ty::BoundVar::from_usize(bound_vars.len() - 1),
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kind,
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},
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))
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.into()
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}
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GenericParamDefKind::Lifetime => {
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let kind = ty::BoundRegionKind::BrNamed(param.def_id, param.name);
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let bound_var = ty::BoundVariableKind::Region(kind);
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bound_vars.push(bound_var);
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tcx.mk_region(ty::ReLateBound(
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ty::INNERMOST,
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ty::BoundRegion {
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var: ty::BoundVar::from_usize(bound_vars.len() - 1),
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kind,
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},
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))
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.into()
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}
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GenericParamDefKind::Const { .. } => {
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let bound_var = ty::BoundVariableKind::Const;
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bound_vars.push(bound_var);
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tcx.mk_const(ty::ConstS {
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ty: tcx.type_of(param.def_id),
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val: ty::ConstKind::Bound(
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ty::INNERMOST,
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ty::BoundVar::from_usize(bound_vars.len() - 1),
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),
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})
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.into()
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}
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});
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let bound_vars = tcx.mk_bound_variable_kinds(bound_vars.into_iter());
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let assoc_ty_substs = tcx.intern_substs(&substs);
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let bound_vars = tcx.mk_bound_variable_kinds(bound_vars.into_iter());
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let bound = bound.kind().skip_binder().subst(tcx, assoc_ty_substs);
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tcx.mk_predicate(ty::Binder::bind_with_vars(bound, bound_vars))
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};
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let normalized_bound = normalize_with_depth_to(
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self,
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obligation.param_env,
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@ -1,11 +1,11 @@
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error[E0038]: the trait `Foo` cannot be made into an object
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--> $DIR/gat-in-trait-path.rs:21:17
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--> $DIR/gat-in-trait-path.rs:27:17
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LL | fn f(_arg : Box<dyn for<'a> Foo<A<'a> = &'a ()>>) {}
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `Foo` cannot be made into an object
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|
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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>
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--> $DIR/gat-in-trait-path.rs:5:10
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--> $DIR/gat-in-trait-path.rs:11:10
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LL | trait Foo {
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| --- this trait cannot be made into an object...
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@ -1,5 +1,11 @@
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// revisions: base extended
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//[base] check-fail
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//[extended] check-pass
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#![feature(generic_associated_types)]
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#![feature(associated_type_defaults)]
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#![cfg_attr(extended, feature(generic_associated_types_extended))]
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#![cfg_attr(extended, allow(incomplete_features))]
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trait Foo {
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type A<'a> where Self: 'a;
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@ -19,7 +25,7 @@ impl<T> Foo for Fooer<T> {
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}
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fn f(_arg : Box<dyn for<'a> Foo<A<'a> = &'a ()>>) {}
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//~^ the trait `Foo` cannot be made into an object
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//[base]~^ the trait `Foo` cannot be made into an object
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fn main() {
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@ -1,11 +1,11 @@
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error[E0038]: the trait `X` cannot be made into an object
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--> $DIR/issue-67510-pass.rs:7:23
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--> $DIR/issue-67510-pass.rs:13:23
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LL | fn _func1<'a>(_x: Box<dyn X<Y<'a>=&'a ()>>) {}
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| ^^^^^^^^^^^^^^^^^^^ `X` cannot be made into an object
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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>
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--> $DIR/issue-67510-pass.rs:4:10
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--> $DIR/issue-67510-pass.rs:10:10
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LL | trait X {
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| - this trait cannot be made into an object...
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@ -1,10 +1,16 @@
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// revisions: base extended
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//[base] check-fail
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//[extended] check-pass
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#![feature(generic_associated_types)]
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#![cfg_attr(extended, feature(generic_associated_types_extended))]
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#![cfg_attr(extended, allow(incomplete_features))]
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trait X {
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type Y<'a>;
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}
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fn _func1<'a>(_x: Box<dyn X<Y<'a>=&'a ()>>) {}
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//~^ ERROR the trait `X` cannot be made into an object
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//[base]~^ ERROR the trait `X` cannot be made into an object
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fn main() {}
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@ -1,11 +1,11 @@
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error[E0107]: missing generics for associated type `SuperTrait::SubType`
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--> $DIR/issue-76535.rs:36:33
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--> $DIR/issue-76535.rs:40:33
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LL | let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
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| ^^^^^^^ expected 1 lifetime argument
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note: associated type defined here, with 1 lifetime parameter: `'a`
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--> $DIR/issue-76535.rs:6:10
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--> $DIR/issue-76535.rs:10:10
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LL | type SubType<'a>: SubTrait where Self: 'a;
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| ^^^^^^^ --
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@ -15,13 +15,13 @@ LL | let sub: Box<dyn SuperTrait<SubType<'a> = SubStruct>> = Box::new(SuperS
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| ~~~~~~~~~~~
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error[E0038]: the trait `SuperTrait` cannot be made into an object
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--> $DIR/issue-76535.rs:36:14
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--> $DIR/issue-76535.rs:40:14
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LL | let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `SuperTrait` cannot be made into an object
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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>
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--> $DIR/issue-76535.rs:6:10
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--> $DIR/issue-76535.rs:10:10
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LL | pub trait SuperTrait {
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| ---------- this trait cannot be made into an object...
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@ -30,13 +30,13 @@ LL | type SubType<'a>: SubTrait where Self: 'a;
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= help: consider moving `SubType` to another trait
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error[E0038]: the trait `SuperTrait` cannot be made into an object
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--> $DIR/issue-76535.rs:36:57
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--> $DIR/issue-76535.rs:40:57
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LL | let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `SuperTrait` cannot be made into an object
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|
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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>
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--> $DIR/issue-76535.rs:6:10
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--> $DIR/issue-76535.rs:10:10
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|
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LL | pub trait SuperTrait {
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| ---------- this trait cannot be made into an object...
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@ -0,0 +1,19 @@
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error[E0107]: missing generics for associated type `SuperTrait::SubType`
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--> $DIR/issue-76535.rs:40:33
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LL | let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
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| ^^^^^^^ expected 1 lifetime argument
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|
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note: associated type defined here, with 1 lifetime parameter: `'a`
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--> $DIR/issue-76535.rs:10:10
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LL | type SubType<'a>: SubTrait where Self: 'a;
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| ^^^^^^^ --
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help: add missing lifetime argument
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|
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LL | let sub: Box<dyn SuperTrait<SubType<'a> = SubStruct>> = Box::new(SuperStruct::new(0));
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| ~~~~~~~~~~~
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error: aborting due to previous error
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For more information about this error, try `rustc --explain E0107`.
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@ -1,4 +1,8 @@
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// revisions: base extended
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#![feature(generic_associated_types)]
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#![cfg_attr(extended, feature(generic_associated_types_extended))]
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#![cfg_attr(extended, allow(incomplete_features))]
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pub trait SubTrait {}
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@ -35,6 +39,6 @@ impl SuperTrait for SuperStruct {
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fn main() {
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let sub: Box<dyn SuperTrait<SubType = SubStruct>> = Box::new(SuperStruct::new(0));
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//~^ ERROR missing generics for associated type
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//~^^ ERROR the trait
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//~| ERROR the trait
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//[base]~^^ ERROR the trait
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//[base]~| ERROR the trait
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}
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@ -1,11 +1,11 @@
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error[E0107]: missing generics for associated type `CollectionFamily::Member`
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--> $DIR/issue-78671.rs:7:47
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--> $DIR/issue-78671.rs:11:47
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|
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LL | Box::new(Family) as &dyn CollectionFamily<Member=usize>
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| ^^^^^^ expected 1 generic argument
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|
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note: associated type defined here, with 1 generic parameter: `T`
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--> $DIR/issue-78671.rs:4:10
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--> $DIR/issue-78671.rs:8:10
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|
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LL | type Member<T>;
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| ^^^^^^ -
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@ -15,13 +15,13 @@ LL | Box::new(Family) as &dyn CollectionFamily<Member<T>=usize>
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| ~~~~~~~~~
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error[E0038]: the trait `CollectionFamily` cannot be made into an object
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--> $DIR/issue-78671.rs:7:25
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--> $DIR/issue-78671.rs:11:25
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|
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LL | Box::new(Family) as &dyn CollectionFamily<Member=usize>
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `CollectionFamily` cannot be made into an object
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|
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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>
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--> $DIR/issue-78671.rs:4:10
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--> $DIR/issue-78671.rs:8:10
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|
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LL | trait CollectionFamily {
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| ---------------- this trait cannot be made into an object...
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@ -0,0 +1,19 @@
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error[E0107]: missing generics for associated type `CollectionFamily::Member`
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--> $DIR/issue-78671.rs:11:47
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|
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LL | Box::new(Family) as &dyn CollectionFamily<Member=usize>
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| ^^^^^^ expected 1 generic argument
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|
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note: associated type defined here, with 1 generic parameter: `T`
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--> $DIR/issue-78671.rs:8:10
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|
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LL | type Member<T>;
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| ^^^^^^ -
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help: add missing generic argument
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|
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LL | Box::new(Family) as &dyn CollectionFamily<Member<T>=usize>
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| ~~~~~~~~~
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error: aborting due to previous error
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For more information about this error, try `rustc --explain E0107`.
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@ -1,4 +1,8 @@
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// revisions: base extended
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#![feature(generic_associated_types)]
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#![cfg_attr(extended, feature(generic_associated_types_extended))]
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#![cfg_attr(extended, allow(incomplete_features))]
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trait CollectionFamily {
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type Member<T>;
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@ -6,7 +10,7 @@ trait CollectionFamily {
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fn floatify() {
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Box::new(Family) as &dyn CollectionFamily<Member=usize>
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//~^ ERROR: missing generics for associated type
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//~| ERROR: the trait `CollectionFamily` cannot be made into an object
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//[base]~^^ ERROR: the trait `CollectionFamily` cannot be made into an object
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}
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struct Family;
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@ -1,11 +1,11 @@
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error[E0107]: missing generics for associated type `MapLike::VRefCont`
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--> $DIR/issue-79422.rs:42:36
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--> $DIR/issue-79422.rs:48:36
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|
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LL | as Box<dyn MapLike<u8, u8, VRefCont = dyn RefCont<'_, u8>>>;
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| ^^^^^^^^ expected 1 lifetime argument
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|
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note: associated type defined here, with 1 lifetime parameter: `'a`
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--> $DIR/issue-79422.rs:20:10
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--> $DIR/issue-79422.rs:24:10
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|
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LL | type VRefCont<'a>: RefCont<'a, V> where Self: 'a;
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| ^^^^^^^^ --
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@ -15,13 +15,13 @@ LL | as Box<dyn MapLike<u8, u8, VRefCont<'a> = dyn RefCont<'_, u8>>>;
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| ~~~~~~~~~~~~
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error[E0038]: the trait `MapLike` cannot be made into an object
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--> $DIR/issue-79422.rs:42:12
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--> $DIR/issue-79422.rs:48:12
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|
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LL | as Box<dyn MapLike<u8, u8, VRefCont = dyn RefCont<'_, u8>>>;
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `MapLike` cannot be made into an object
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|
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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>
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--> $DIR/issue-79422.rs:20:10
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--> $DIR/issue-79422.rs:24:10
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|
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LL | trait MapLike<K, V> {
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| ------- this trait cannot be made into an object...
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@ -30,13 +30,13 @@ LL | type VRefCont<'a>: RefCont<'a, V> where Self: 'a;
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= help: consider moving `VRefCont` to another trait
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error[E0038]: the trait `MapLike` cannot be made into an object
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--> $DIR/issue-79422.rs:41:13
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--> $DIR/issue-79422.rs:45:13
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|
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LL | let m = Box::new(std::collections::BTreeMap::<u8, u8>::new())
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `MapLike` cannot be made into an object
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|
|
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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>
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--> $DIR/issue-79422.rs:20:10
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--> $DIR/issue-79422.rs:24:10
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|
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LL | trait MapLike<K, V> {
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| ------- this trait cannot be made into an object...
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@ -0,0 +1,35 @@
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error[E0107]: missing generics for associated type `MapLike::VRefCont`
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--> $DIR/issue-79422.rs:48:36
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|
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LL | as Box<dyn MapLike<u8, u8, VRefCont = dyn RefCont<'_, u8>>>;
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| ^^^^^^^^ expected 1 lifetime argument
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|
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note: associated type defined here, with 1 lifetime parameter: `'a`
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--> $DIR/issue-79422.rs:24:10
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|
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LL | type VRefCont<'a>: RefCont<'a, V> where Self: 'a;
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| ^^^^^^^^ --
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help: add missing lifetime argument
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|
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LL | as Box<dyn MapLike<u8, u8, VRefCont<'a> = dyn RefCont<'_, u8>>>;
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| ~~~~~~~~~~~~
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|
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error[E0271]: type mismatch resolving `<BTreeMap<u8, u8> as MapLike<u8, u8>>::VRefCont<'_> == (dyn RefCont<'_, u8> + 'static)`
|
||||
--> $DIR/issue-79422.rs:45:13
|
||||
|
|
||||
LL | let m = Box::new(std::collections::BTreeMap::<u8, u8>::new())
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type mismatch resolving `<BTreeMap<u8, u8> as MapLike<u8, u8>>::VRefCont<'_> == (dyn RefCont<'_, u8> + 'static)`
|
||||
|
|
||||
note: expected this to be `(dyn RefCont<'_, u8> + 'static)`
|
||||
--> $DIR/issue-79422.rs:29:25
|
||||
|
|
||||
LL | type VRefCont<'a> = &'a V where Self: 'a;
|
||||
| ^^^^^
|
||||
= note: expected trait object `(dyn RefCont<'_, u8> + 'static)`
|
||||
found reference `&u8`
|
||||
= note: required for the cast to the object type `dyn MapLike<u8, u8, VRefCont = (dyn RefCont<'_, u8> + 'static)>`
|
||||
|
||||
error: aborting due to 2 previous errors
|
||||
|
||||
Some errors have detailed explanations: E0107, E0271.
|
||||
For more information about an error, try `rustc --explain E0107`.
|
||||
@ -1,4 +1,8 @@
|
||||
// revisions: base extended
|
||||
|
||||
#![feature(generic_associated_types)]
|
||||
#![cfg_attr(extended, feature(generic_associated_types_extended))]
|
||||
#![cfg_attr(extended, allow(incomplete_features))]
|
||||
|
||||
trait RefCont<'a, T> {
|
||||
fn t(&'a self) -> &'a T;
|
||||
@ -39,8 +43,9 @@ impl<K, V: Default> MapLike<K, V> for Source {
|
||||
|
||||
fn main() {
|
||||
let m = Box::new(std::collections::BTreeMap::<u8, u8>::new())
|
||||
//[base]~^ ERROR the trait
|
||||
//[extended]~^^ type mismatch
|
||||
as Box<dyn MapLike<u8, u8, VRefCont = dyn RefCont<'_, u8>>>;
|
||||
//~^ ERROR missing generics for associated type
|
||||
//~^^ ERROR the trait
|
||||
//~^^^^ ERROR the trait
|
||||
//[base]~^^ ERROR the trait
|
||||
}
|
||||
|
||||
@ -1,11 +1,11 @@
|
||||
error[E0038]: the trait `StreamingIterator` cannot be made into an object
|
||||
--> $DIR/trait-objects.rs:10:21
|
||||
--> $DIR/trait-objects.rs:14:21
|
||||
|
|
||||
LL | fn min_size(x: &mut dyn for<'a> StreamingIterator<Item<'a> = &'a i32>) -> usize {
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `StreamingIterator` 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/trait-objects.rs:4:10
|
||||
--> $DIR/trait-objects.rs:8:10
|
||||
|
|
||||
LL | trait StreamingIterator {
|
||||
| ----------------- this trait cannot be made into an object...
|
||||
@ -0,0 +1,17 @@
|
||||
error[E0521]: borrowed data escapes outside of function
|
||||
--> $DIR/trait-objects.rs:16:5
|
||||
|
|
||||
LL | fn min_size(x: &mut dyn for<'a> StreamingIterator<Item<'a> = &'a i32>) -> usize {
|
||||
| - - let's call the lifetime of this reference `'1`
|
||||
| |
|
||||
| `x` is a reference that is only valid in the function body
|
||||
LL |
|
||||
LL | x.size_hint().0
|
||||
| ^^^^^^^^^^^^^
|
||||
| |
|
||||
| `x` escapes the function body here
|
||||
| argument requires that `'1` must outlive `'static`
|
||||
|
||||
error: aborting due to previous error
|
||||
|
||||
For more information about this error, try `rustc --explain E0521`.
|
||||
@ -0,0 +1,12 @@
|
||||
error[E0621]: explicit lifetime required in the type of `x`
|
||||
--> $DIR/trait-objects.rs:16:7
|
||||
|
|
||||
LL | fn min_size(x: &mut dyn for<'a> StreamingIterator<Item<'a> = &'a i32>) -> usize {
|
||||
| ------------------------------------------------------ help: add explicit lifetime `'a` to the type of `x`: `&'a mut (dyn StreamingIterator<for<'a> Item = &'a i32> + 'a)`
|
||||
LL |
|
||||
LL | x.size_hint().0
|
||||
| ^^^^^^^^^ lifetime `'a` required
|
||||
|
||||
error: aborting due to previous error
|
||||
|
||||
For more information about this error, try `rustc --explain E0621`.
|
||||
@ -1,4 +1,8 @@
|
||||
// revisions: base extended
|
||||
|
||||
#![feature(generic_associated_types)]
|
||||
#![cfg_attr(extended, feature(generic_associated_types_extended))]
|
||||
#![cfg_attr(extended, allow(incomplete_features))]
|
||||
|
||||
trait StreamingIterator {
|
||||
type Item<'a> where Self: 'a;
|
||||
@ -8,8 +12,9 @@ trait StreamingIterator {
|
||||
}
|
||||
|
||||
fn min_size(x: &mut dyn for<'a> StreamingIterator<Item<'a> = &'a i32>) -> usize {
|
||||
//~^ the trait `StreamingIterator` cannot be made into an object
|
||||
//[base]~^ the trait `StreamingIterator` cannot be made into an object
|
||||
x.size_hint().0
|
||||
//[extended]~^ explicit lifetime required
|
||||
}
|
||||
|
||||
fn main() {}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user