Rollup merge of #134367 - WaffleLapkin:trait_upcasting_as_a_treat, r=compiler-errors

Stabilize `feature(trait_upcasting)`

This feature was "done" for a while now, I think it's finally time to stabilize it! Stabilization report: https://github.com/rust-lang/rust/pull/134367#issuecomment-2545839841.
cc reference PR: https://github.com/rust-lang/reference/pull/1622.

Closes #65991 (tracking issue), closes #89460 (the lint is no longer future incompat).

r? compiler-errors

compiler/rustc_feature/src/accepted.rs

@@ -400,6 +400,9 @@ declare_features! (
     /// Allows `#[track_caller]` to be used which provides
     /// accurate caller location reporting during panic (RFC 2091).
     (accepted, track_caller, "1.46.0", Some(47809)),
+    /// Allows dyn upcasting trait objects via supertraits.
+    /// Dyn upcasting is casting, e.g., `dyn Foo -> dyn Bar` where `Foo: Bar`.
+    (accepted, trait_upcasting, "CURRENT_RUSTC_VERSION", Some(65991)),
     /// Allows #[repr(transparent)] on univariant enums (RFC 2645).
     (accepted, transparent_enums, "1.42.0", Some(60405)),
     /// Allows indexing tuples.

compiler/rustc_feature/src/unstable.rs

@@ -634,9 +634,6 @@ declare_features! (
     (unstable, thread_local, "1.0.0", Some(29594)),
     /// Allows defining `trait X = A + B;` alias items.
     (unstable, trait_alias, "1.24.0", Some(41517)),
-    /// Allows dyn upcasting trait objects via supertraits.
-    /// Dyn upcasting is casting, e.g., `dyn Foo -> dyn Bar` where `Foo: Bar`.
-    (unstable, trait_upcasting, "1.56.0", Some(65991)),
     /// Allows for transmuting between arrays with sizes that contain generic consts.
     (unstable, transmute_generic_consts, "1.70.0", Some(109929)),
     /// Allows #[repr(transparent)] on unions (RFC 2645).

compiler/rustc_hir_typeck/src/coercion.rs

@@ -605,7 +605,6 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
         )];
 
         let mut has_unsized_tuple_coercion = false;
-        let mut has_trait_upcasting_coercion = None;
 
         // Keep resolving `CoerceUnsized` and `Unsize` predicates to avoid
         // emitting a coercion in cases like `Foo<$1>` -> `Foo<$2>`, where
@@ -690,13 +689,6 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
                     // these here and emit a feature error if coercion doesn't fail
                     // due to another reason.
                     match impl_source {
-                        traits::ImplSource::Builtin(
-                            BuiltinImplSource::TraitUpcasting { .. },
-                            _,
-                        ) => {
-                            has_trait_upcasting_coercion =
-                                Some((trait_pred.self_ty(), trait_pred.trait_ref.args.type_at(1)));
-                        }
                         traits::ImplSource::Builtin(BuiltinImplSource::TupleUnsizing, _) => {
                             has_unsized_tuple_coercion = true;
                         }
@@ -707,21 +699,6 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> {
             }
         }
 
-        if let Some((sub, sup)) = has_trait_upcasting_coercion
-            && !self.tcx().features().trait_upcasting()
-        {
-            // Renders better when we erase regions, since they're not really the point here.
-            let (sub, sup) = self.tcx.erase_regions((sub, sup));
-            let mut err = feature_err(
-                &self.tcx.sess,
-                sym::trait_upcasting,
-                self.cause.span,
-                format!("cannot cast `{sub}` to `{sup}`, trait upcasting coercion is experimental"),
-            );
-            err.note(format!("required when coercing `{source}` into `{target}`"));
-            err.emit();
-        }
-
         if has_unsized_tuple_coercion && !self.tcx.features().unsized_tuple_coercion() {
             feature_err(
                 &self.tcx.sess,

compiler/rustc_lint/src/deref_into_dyn_supertrait.rs

@@ -1,6 +1,5 @@
 use rustc_hir::{self as hir, LangItem};
 use rustc_middle::ty;
-use rustc_session::lint::FutureIncompatibilityReason;
 use rustc_session::{declare_lint, declare_lint_pass};
 use rustc_span::sym;
 use rustc_trait_selection::traits::supertraits;
@@ -9,11 +8,12 @@ use crate::lints::{SupertraitAsDerefTarget, SupertraitAsDerefTargetLabel};
 use crate::{LateContext, LateLintPass, LintContext};
 
 declare_lint! {
-    /// The `deref_into_dyn_supertrait` lint is output whenever there is a use of the
+    /// The `deref_into_dyn_supertrait` lint is emitted whenever there is a `Deref` implementation
-    /// `Deref` implementation with a `dyn SuperTrait` type as `Output`.
+    /// for `dyn SubTrait` with a `dyn SuperTrait` type as the `Output` type.
     ///
-    /// These implementations will become shadowed when the `trait_upcasting` feature is stabilized.
+    /// These implementations are "shadowed" by trait upcasting (stabilized since
-    /// The `deref` functions will no longer be called implicitly, so there might be behavior change.
+    /// CURRENT_RUSTC_VERSION). The `deref` functions is no longer called implicitly, which might
+    /// change behavior compared to previous rustc versions.
     ///
     /// ### Example
     ///
@@ -43,15 +43,14 @@ declare_lint! {
     ///
     /// ### Explanation
     ///
-    /// The dyn upcasting coercion feature adds new coercion rules, taking priority
+    /// The trait upcasting coercion added a new coercion rule, taking priority over certain other
-    /// over certain other coercion rules, which will cause some behavior change.
+    /// coercion rules, which causes some behavior change compared to older `rustc` versions.
+    ///
+    /// `deref` can be still called explicitly, it just isn't called as part of a deref coercion
+    /// (since trait upcasting coercion takes priority).
     pub DEREF_INTO_DYN_SUPERTRAIT,
-    Warn,
+    Allow,
-    "`Deref` implementation usage with a supertrait trait object for output might be shadowed in the future",
+    "`Deref` implementation with a supertrait trait object for output is shadowed by trait upcasting",
-    @future_incompatible = FutureIncompatibleInfo {
-        reason: FutureIncompatibilityReason::FutureReleaseSemanticsChange,
-        reference: "issue #89460 <https://github.com/rust-lang/rust/issues/89460>",
-    };
 }
 
 declare_lint_pass!(DerefIntoDynSupertrait => [DEREF_INTO_DYN_SUPERTRAIT]);

compiler/rustc_lint/src/lib.rs

@@ -21,6 +21,7 @@
 
 // tidy-alphabetical-start
 #![allow(internal_features)]
+#![cfg_attr(bootstrap, feature(trait_upcasting))]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
 #![feature(array_windows)]
@@ -32,7 +33,6 @@
 #![feature(let_chains)]
 #![feature(rustc_attrs)]
 #![feature(rustdoc_internals)]
-#![feature(trait_upcasting)]
 #![warn(unreachable_pub)]
 // tidy-alphabetical-end
 

compiler/rustc_middle/src/lib.rs

@@ -29,6 +29,7 @@
 #![allow(rustc::diagnostic_outside_of_impl)]
 #![allow(rustc::potential_query_instability)]
 #![allow(rustc::untranslatable_diagnostic)]
+#![cfg_attr(bootstrap, feature(trait_upcasting))]
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![doc(rust_logo)]
 #![feature(allocator_api)]
@@ -56,7 +57,6 @@
 #![feature(ptr_alignment_type)]
 #![feature(rustc_attrs)]
 #![feature(rustdoc_internals)]
-#![feature(trait_upcasting)]
 #![feature(trusted_len)]
 #![feature(try_blocks)]
 #![feature(try_trait_v2)]

compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs

@@ -12,9 +12,7 @@ use hir::LangItem;
 use hir::def_id::DefId;
 use rustc_data_structures::fx::{FxHashSet, FxIndexSet};
 use rustc_hir as hir;
-use rustc_infer::traits::{
+use rustc_infer::traits::{Obligation, PolyTraitObligation, SelectionError};
-    Obligation, ObligationCause, PolyTraitObligation, PredicateObligations, SelectionError,
-};
 use rustc_middle::ty::fast_reject::DeepRejectCtxt;
 use rustc_middle::ty::{self, Ty, TypeVisitableExt, TypingMode};
 use rustc_middle::{bug, span_bug};
@@ -23,8 +21,6 @@ use tracing::{debug, instrument, trace};
 
 use super::SelectionCandidate::*;
 use super::{BuiltinImplConditions, SelectionCandidateSet, SelectionContext, TraitObligationStack};
-use crate::traits;
-use crate::traits::query::evaluate_obligation::InferCtxtExt;
 use crate::traits::util;
 
 impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
@@ -904,54 +900,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         })
     }
 
-    /// Temporary migration for #89190
-    fn need_migrate_deref_output_trait_object(
-        &mut self,
-        ty: Ty<'tcx>,
-        param_env: ty::ParamEnv<'tcx>,
-        cause: &ObligationCause<'tcx>,
-    ) -> Option<ty::PolyExistentialTraitRef<'tcx>> {
-        // Don't drop any candidates in intercrate mode, as it's incomplete.
-        // (Not that it matters, since `Unsize` is not a stable trait.)
-        //
-        // FIXME(@lcnr): This should probably only trigger during analysis,
-        // disabling candidates during codegen is also questionable.
-        if let TypingMode::Coherence = self.infcx.typing_mode() {
-            return None;
-        }
-
-        let tcx = self.tcx();
-        if tcx.features().trait_upcasting() {
-            return None;
-        }
-
-        // <ty as Deref>
-        let trait_ref = ty::TraitRef::new(tcx, tcx.lang_items().deref_trait()?, [ty]);
-
-        let obligation =
-            traits::Obligation::new(tcx, cause.clone(), param_env, ty::Binder::dummy(trait_ref));
-        if !self.infcx.predicate_may_hold(&obligation) {
-            return None;
-        }
-
-        self.infcx.probe(|_| {
-            let ty = traits::normalize_projection_ty(
-                self,
-                param_env,
-                ty::AliasTy::new_from_args(tcx, tcx.lang_items().deref_target()?, trait_ref.args),
-                cause.clone(),
-                0,
-                // We're *intentionally* throwing these away,
-                // since we don't actually use them.
-                &mut PredicateObligations::new(),
-            )
-            .as_type()
-            .unwrap();
-
-            if let ty::Dynamic(data, ..) = ty.kind() { data.principal() } else { None }
-        })
-    }
-
     /// Searches for unsizing that might apply to `obligation`.
     fn assemble_candidates_for_unsizing(
         &mut self,
@@ -1019,15 +967,6 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                     let principal_a = a_data.principal().unwrap();
                     let target_trait_did = principal_def_id_b.unwrap();
                     let source_trait_ref = principal_a.with_self_ty(self.tcx(), source);
-                    if let Some(deref_trait_ref) = self.need_migrate_deref_output_trait_object(
-                        source,
-                        obligation.param_env,
-                        &obligation.cause,
-                    ) {
-                        if deref_trait_ref.def_id() == target_trait_did {
-                            return;
-                        }
-                    }
 
                     for (idx, upcast_trait_ref) in
                         util::supertraits(self.tcx(), source_trait_ref).enumerate()

compiler/rustc_type_ir/src/solve/mod.rs

@@ -179,9 +179,7 @@ pub enum BuiltinImplSource {
     Object(usize),
     /// A built-in implementation of `Upcast` for trait objects to other trait objects.
     ///
-    /// This can be removed when `feature(dyn_upcasting)` is stabilized, since we only
+    /// The index is only used for winnowing.
-    /// use it to detect when upcasting traits in hir typeck. The index is only used
-    /// for winnowing.
     TraitUpcasting(usize),
     /// Unsizing a tuple like `(A, B, ..., X)` to `(A, B, ..., Y)` if `X` unsizes to `Y`.
     ///

library/coretests/tests/lib.rs

@@ -81,7 +81,6 @@
 #![feature(strict_provenance_atomic_ptr)]
 #![feature(strict_provenance_lints)]
 #![feature(test)]
-#![feature(trait_upcasting)]
 #![feature(trusted_len)]
 #![feature(trusted_random_access)]
 #![feature(try_blocks)]

src/doc/unstable-book/src/language-features/trait-upcasting.md

@@ -1,26 +0,0 @@
-# `trait_upcasting`
-
-The tracking issue for this feature is: [#65991]
-
-[#65991]: https://github.com/rust-lang/rust/issues/65991
-
-------------------------
-
-The `trait_upcasting` feature adds support for trait upcasting coercion. This allows a
-trait object of type `dyn Bar` to be cast to a trait object of type `dyn Foo`
-so long as `Bar: Foo`.
-
-```rust,edition2018
-#![feature(trait_upcasting)]
-
-trait Foo {}
-
-trait Bar: Foo {}
-
-impl Foo for i32 {}
-
-impl<T: Foo + ?Sized> Bar for T {}
-
-let bar: &dyn Bar = &123;
-let foo: &dyn Foo = bar;
-```

src/tools/miri/src/lib.rs

@@ -1,3 +1,4 @@
+#![cfg_attr(bootstrap, feature(trait_upcasting))]
 #![feature(rustc_private)]
 #![feature(cell_update)]
 #![feature(float_gamma)]
@@ -9,7 +10,6 @@
 #![feature(yeet_expr)]
 #![feature(nonzero_ops)]
 #![feature(let_chains)]
-#![feature(trait_upcasting)]
 #![feature(strict_overflow_ops)]
 #![feature(pointer_is_aligned_to)]
 #![feature(unqualified_local_imports)]

src/tools/miri/tests/fail/dyn-upcast-trait-mismatch.rs

@@ -1,9 +1,6 @@
 // Validation stops this too early.
 //@compile-flags: -Zmiri-disable-validation
 
-#![feature(trait_upcasting)]
-#![allow(incomplete_features)]
-
 trait Foo: PartialEq<i32> + std::fmt::Debug + Send + Sync {
     #[allow(dead_code)]
     fn a(&self) -> i32 {

src/tools/miri/tests/pass/box-custom-alloc.rs

@@ -1,7 +1,6 @@
 //@revisions: stack tree
 //@[tree]compile-flags: -Zmiri-tree-borrows
-#![allow(incomplete_features)] // for trait upcasting
+#![feature(allocator_api)]
-#![feature(allocator_api, trait_upcasting)]
 
 use std::alloc::{AllocError, Allocator, Layout};
 use std::cell::Cell;

src/tools/miri/tests/pass/dyn-upcast.rs

@@ -1,6 +1,3 @@
-#![feature(trait_upcasting)]
-#![allow(incomplete_features)]
-
 use std::fmt;
 
 fn main() {

tests/codegen/vtable-upcast.rs

@@ -2,7 +2,6 @@
 //@ compile-flags: -C no-prepopulate-passes -Copt-level=0
 
 #![crate_type = "lib"]
-#![feature(trait_upcasting)]
 
 pub trait Base {
     fn base(&self);

tests/crashes/131886.rs

@@ -1,6 +1,6 @@
 //@ known-bug: #131886
 //@ compile-flags: -Zvalidate-mir --crate-type=lib
-#![feature(trait_upcasting, type_alias_impl_trait)]
+#![feature(type_alias_impl_trait)]
 
 type Tait = impl Sized;
 

tests/ui/codegen/issue-99551.rs

@@ -1,5 +1,4 @@
 //@ build-pass
-#![feature(trait_upcasting)]
 
 pub trait A {}
 pub trait B {}

tests/ui/dyn-star/no-unsize-coerce-dyn-trait.rs

@@ -1,5 +1,5 @@
-#![feature(dyn_star, trait_upcasting)]
+#![expect(incomplete_features)]
-//~^ WARN the feature `dyn_star` is incomplete and may not be safe to use and/or cause compiler crashes
+#![feature(dyn_star)]
 
 trait A: B {}
 trait B {}

tests/ui/dyn-star/no-unsize-coerce-dyn-trait.stderr

@@ -1,12 +1,3 @@
-warning: the feature `dyn_star` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/no-unsize-coerce-dyn-trait.rs:1:12
-   |
-LL | #![feature(dyn_star, trait_upcasting)]
-   |            ^^^^^^^^
-   |
-   = note: see issue #102425 <https://github.com/rust-lang/rust/issues/102425> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
 error[E0308]: mismatched types
   --> $DIR/no-unsize-coerce-dyn-trait.rs:11:26
    |
@@ -18,6 +9,6 @@ LL |     let y: Box<dyn* B> = x;
    = note: expected struct `Box<dyn* B>`
               found struct `Box<dyn* A>`
 
-error: aborting due to 1 previous error; 1 warning emitted
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0308`.

tests/ui/dyn-star/upcast.rs

@@ -1,6 +1,6 @@
 //@ known-bug: #104800
 
-#![feature(dyn_star, trait_upcasting)]
+#![feature(dyn_star)]
 
 trait Foo: Bar {
     fn hello(&self);

tests/ui/dyn-star/upcast.stderr

@@ -1,7 +1,7 @@
 warning: the feature `dyn_star` is incomplete and may not be safe to use and/or cause compiler crashes
   --> $DIR/upcast.rs:3:12
    |
-LL | #![feature(dyn_star, trait_upcasting)]
+LL | #![feature(dyn_star)]
    |            ^^^^^^^^
    |
    = note: see issue #102425 <https://github.com/rust-lang/rust/issues/102425> for more information

tests/ui/feature-gates/feature-gate-trait_upcasting.rs

@@ -1,13 +0,0 @@
-trait Foo {}
-
-trait Bar: Foo {}
-
-impl Foo for () {}
-
-impl Bar for () {}
-
-fn main() {
-    let bar: &dyn Bar = &();
-    let foo: &dyn Foo = bar;
-    //~^ ERROR trait upcasting coercion is experimental [E0658]
-}

tests/ui/feature-gates/feature-gate-trait_upcasting.stderr

@@ -1,14 +0,0 @@
-error[E0658]: cannot cast `dyn Bar` to `dyn Foo`, trait upcasting coercion is experimental
-  --> $DIR/feature-gate-trait_upcasting.rs:11:25
-   |
-LL |     let foo: &dyn Foo = bar;
-   |                         ^^^
-   |
-   = note: see issue #65991 <https://github.com/rust-lang/rust/issues/65991> for more information
-   = help: add `#![feature(trait_upcasting)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-   = note: required when coercing `&dyn Bar` into `&dyn Foo`
-
-error: aborting due to 1 previous error
-
-For more information about this error, try `rustc --explain E0658`.

tests/ui/impl-trait/unsized_coercion5.old.stderr

@@ -1,5 +1,5 @@
 error[E0277]: the size for values of type `impl Trait + ?Sized` cannot be known at compilation time
-  --> $DIR/unsized_coercion5.rs:17:32
+  --> $DIR/unsized_coercion5.rs:15:32
    |
 LL |         let y: Box<dyn Send> = x as Box<dyn Trait + Send>;
    |                                ^ doesn't have a size known at compile-time

tests/ui/impl-trait/unsized_coercion5.rs

@@ -5,8 +5,6 @@
 //@[next] compile-flags: -Znext-solver
 //@[next] check-pass
 
-#![feature(trait_upcasting)]
-
 trait Trait {}
 
 impl Trait for u32 {}

tests/ui/sanitizer/cfi/supertraits.rs

@@ -1,4 +1,3 @@
-#![feature(trait_upcasting)]
 // Check that super-traits are callable.
 
 //@ revisions: cfi kcfi

tests/ui/traits/next-solver/normalize/normalize-unsize-rhs.rs

@@ -1,6 +1,5 @@
 //@ compile-flags: -Znext-solver
 //@ check-pass
-#![feature(trait_upcasting)]
 
 trait A {}
 trait B: A {}

tests/ui/traits/next-solver/trait-upcast-lhs-needs-normalization.rs

@@ -1,6 +1,5 @@
 //@ check-pass
 //@ compile-flags: -Znext-solver
-#![feature(trait_upcasting)]
 
 pub trait A {}
 pub trait B: A {}

tests/ui/traits/next-solver/upcast-right-substs.rs

@@ -1,6 +1,5 @@
 //@ compile-flags: -Znext-solver
 //@ check-pass
-#![feature(trait_upcasting)]
 
 trait Foo: Bar<i32> + Bar<u32> {}
 

tests/ui/traits/trait-upcasting/add-supertrait-auto-traits.rs

@@ -3,8 +3,6 @@
 //@ ignore-compare-mode-next-solver (explicit revisions)
 //@[next] compile-flags: -Znext-solver
 
-#![feature(trait_upcasting)]
-
 trait Target {}
 trait Source: Send + Target {}
 

tests/ui/traits/trait-upcasting/alias-where-clause-isnt-supertrait.rs

@@ -1,4 +1,3 @@
-#![feature(trait_upcasting)]
 #![feature(trait_alias)]
 
 // Although we *elaborate* `T: Alias` to `i32: B`, we should

tests/ui/traits/trait-upcasting/alias-where-clause-isnt-supertrait.stderr

@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/alias-where-clause-isnt-supertrait.rs:27:5
+  --> $DIR/alias-where-clause-isnt-supertrait.rs:26:5
    |
 LL | fn test(x: &dyn C) -> &dyn B {
    |                       ------ expected `&dyn B` because of return type

tests/ui/traits/trait-upcasting/basic.rs

@@ -1,7 +1,5 @@
 //@ run-pass
 
-#![feature(trait_upcasting)]
-
 trait Foo: PartialEq<i32> + std::fmt::Debug + Send + Sync {
     fn a(&self) -> i32 {
         10

tests/ui/traits/trait-upcasting/correct-supertrait-substitution.rs

@@ -1,5 +1,4 @@
 //@ run-pass
-#![feature(trait_upcasting)]
 
 trait Foo<T: Default + ToString>: Bar<i32> + Bar<T> {}
 trait Bar<T: Default + ToString> {

tests/ui/traits/trait-upcasting/deref-upcast-behavioral-change.rs

@@ -1,35 +0,0 @@
-#![deny(deref_into_dyn_supertrait)]
-use std::ops::Deref;
-
-trait Bar<T> {}
-impl<T, U> Bar<U> for T {}
-
-trait Foo: Bar<i32> {
-    fn as_dyn_bar_u32<'a>(&self) -> &(dyn Bar<u32> + 'a);
-}
-
-impl Foo for () {
-    fn as_dyn_bar_u32<'a>(&self) -> &(dyn Bar<u32> + 'a) {
-        self
-    }
-}
-
-impl<'a> Deref for dyn Foo + 'a {
-    //~^ ERROR this `Deref` implementation is covered by an implicit supertrait coercion
-    //~| WARN this will change its meaning in a future release!
-    type Target = dyn Bar<u32> + 'a;
-
-    fn deref(&self) -> &Self::Target {
-        self.as_dyn_bar_u32()
-    }
-}
-
-fn take_dyn<T>(x: &dyn Bar<T>) -> T {
-    todo!()
-}
-
-fn main() {
-    let x: &dyn Foo = &();
-    let y = take_dyn(x);
-    let z: u32 = y;
-}

tests/ui/traits/trait-upcasting/deref-upcast-behavioral-change.stderr

@@ -1,19 +0,0 @@
-error: this `Deref` implementation is covered by an implicit supertrait coercion
-  --> $DIR/deref-upcast-behavioral-change.rs:17:1
-   |
-LL | impl<'a> Deref for dyn Foo + 'a {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `dyn Foo` implements `Deref<Target = dyn Bar<u32>>` which conflicts with supertrait `Bar<i32>`
-...
-LL |     type Target = dyn Bar<u32> + 'a;
-   |     -------------------------------- target type is a supertrait of `dyn Foo`
-   |
-   = warning: this will change its meaning in a future release!
-   = note: for more information, see issue #89460 <https://github.com/rust-lang/rust/issues/89460>
-note: the lint level is defined here
-  --> $DIR/deref-upcast-behavioral-change.rs:1:9
-   |
-LL | #![deny(deref_into_dyn_supertrait)]
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: aborting due to 1 previous error
-

tests/ui/traits/trait-upcasting/deref-upcast-shadowing-lint.rs

@@ -0,0 +1,17 @@
+//@ check-pass
+#![warn(deref_into_dyn_supertrait)]
+use std::ops::Deref;
+
+trait Bar<T> {}
+trait Foo: Bar<i32> {}
+
+impl<'a> Deref for dyn Foo + 'a {
+    //~^ warn: this `Deref` implementation is covered by an implicit supertrait coercion
+    type Target = dyn Bar<u32> + 'a;
+
+    fn deref(&self) -> &Self::Target {
+        todo!()
+    }
+}
+
+fn main() {}

tests/ui/traits/trait-upcasting/deref-upcast-shadowing-lint.stderr

@@ -0,0 +1,17 @@
+warning: this `Deref` implementation is covered by an implicit supertrait coercion
+  --> $DIR/deref-upcast-shadowing-lint.rs:8:1
+   |
+LL | impl<'a> Deref for dyn Foo + 'a {
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `dyn Foo` implements `Deref<Target = dyn Bar<u32>>` which conflicts with supertrait `Bar<i32>`
+LL |
+LL |     type Target = dyn Bar<u32> + 'a;
+   |     -------------------------------- target type is a supertrait of `dyn Foo`
+   |
+note: the lint level is defined here
+  --> $DIR/deref-upcast-shadowing-lint.rs:2:9
+   |
+LL | #![warn(deref_into_dyn_supertrait)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+warning: 1 warning emitted
+

tests/ui/traits/trait-upcasting/diamond.rs

@@ -1,7 +1,5 @@
 //@ run-pass
 
-#![feature(trait_upcasting)]
-
 trait Foo: PartialEq<i32> + std::fmt::Debug + Send + Sync {
     fn a(&self) -> i32 {
         10

tests/ui/traits/trait-upcasting/fewer-associated.rs

@@ -4,8 +4,6 @@
 //@ ignore-compare-mode-next-solver (explicit revisions)
 //@[next] compile-flags: -Znext-solver
 
-#![feature(trait_upcasting)]
-
 trait A: B {
     type Assoc;
 }

tests/ui/traits/trait-upcasting/higher-ranked-upcasting-ok.rs

@@ -6,8 +6,6 @@
 // Check that we are able to instantiate a binder during trait upcasting,
 // and that it doesn't cause any issues with codegen either.
 
-#![feature(trait_upcasting)]
-
 trait Supertrait<'a, 'b> {}
 trait Subtrait<'a, 'b>: Supertrait<'a, 'b> {}
 

tests/ui/traits/trait-upcasting/higher-ranked-upcasting-ub.rs

@@ -5,7 +5,7 @@
 // We previously wrongly instantiated binders during trait upcasting,
 // allowing the super trait to be more generic than the sub trait.
 // This was unsound.
-#![feature(trait_upcasting)]
+
 trait Supertrait<'a, 'b> {
     fn cast(&self, x: &'a str) -> &'b str;
 }

tests/ui/traits/trait-upcasting/illegal-upcast-from-impl.current.stderr

@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/illegal-upcast-from-impl.rs:17:66
+  --> $DIR/illegal-upcast-from-impl.rs:15:66
    |
 LL | fn illegal(x: &dyn Sub<Assoc = ()>) -> &dyn Super<Assoc = i32> { x }
    |                                        -----------------------   ^ expected trait `Super`, found trait `Sub`

tests/ui/traits/trait-upcasting/illegal-upcast-from-impl.next.stderr

@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/illegal-upcast-from-impl.rs:17:66
+  --> $DIR/illegal-upcast-from-impl.rs:15:66
    |
 LL | fn illegal(x: &dyn Sub<Assoc = ()>) -> &dyn Super<Assoc = i32> { x }
    |                                        -----------------------   ^ expected trait `Super`, found trait `Sub`

tests/ui/traits/trait-upcasting/illegal-upcast-from-impl.rs

@@ -2,8 +2,6 @@
 //@ ignore-compare-mode-next-solver (explicit revisions)
 //@[next] compile-flags: -Znext-solver
 
-#![feature(trait_upcasting)]
-
 trait Super {
     type Assoc;
 }

tests/ui/traits/trait-upcasting/illegal-upcast-to-impl-opaque.rs

@@ -9,8 +9,6 @@
 //@[next] rustc-env:RUST_BACKTRACE=0
 //@ check-pass
 
-#![feature(trait_upcasting)]
-
 trait Super {
     type Assoc;
 }

tests/ui/traits/trait-upcasting/inference-behavior-change-deref.rs

@@ -1,6 +1,3 @@
-#![deny(deref_into_dyn_supertrait)]
-#![feature(trait_upcasting)] // remove this and the test compiles
-
 use std::ops::Deref;
 
 trait Bar<T> {}
@@ -32,5 +29,5 @@ fn main() {
     let x: &dyn Foo = &();
     let y = take_dyn(x);
     let z: u32 = y;
-    //~^ ERROR mismatched types
+    //~^ error: mismatched types
 }

tests/ui/traits/trait-upcasting/inference-behavior-change-deref.stderr

@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/inference-behavior-change-deref.rs:34:18
+  --> $DIR/inference-behavior-change-deref.rs:31:18
    |
 LL |     let z: u32 = y;
    |            ---   ^ expected `u32`, found `i32`

tests/ui/traits/trait-upcasting/invalid-upcast.rs

@@ -1,5 +1,3 @@
-#![feature(trait_upcasting)]
-
 trait Foo {
     fn a(&self) -> i32 {
         10

tests/ui/traits/trait-upcasting/invalid-upcast.stderr

@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/invalid-upcast.rs:53:35
+  --> $DIR/invalid-upcast.rs:51:35
    |
 LL |     let _: &dyn std::fmt::Debug = baz;
    |            --------------------   ^^^ expected trait `Debug`, found trait `Baz`
@@ -10,7 +10,7 @@ LL |     let _: &dyn std::fmt::Debug = baz;
               found reference `&dyn Baz`
 
 error[E0308]: mismatched types
-  --> $DIR/invalid-upcast.rs:55:24
+  --> $DIR/invalid-upcast.rs:53:24
    |
 LL |     let _: &dyn Send = baz;
    |            ---------   ^^^ expected trait `Send`, found trait `Baz`
@@ -21,7 +21,7 @@ LL |     let _: &dyn Send = baz;
               found reference `&dyn Baz`
 
 error[E0308]: mismatched types
-  --> $DIR/invalid-upcast.rs:57:24
+  --> $DIR/invalid-upcast.rs:55:24
    |
 LL |     let _: &dyn Sync = baz;
    |            ---------   ^^^ expected trait `Sync`, found trait `Baz`
@@ -32,7 +32,7 @@ LL |     let _: &dyn Sync = baz;
               found reference `&dyn Baz`
 
 error[E0308]: mismatched types
-  --> $DIR/invalid-upcast.rs:60:25
+  --> $DIR/invalid-upcast.rs:58:25
    |
 LL |     let bar: &dyn Bar = baz;
    |              --------   ^^^ expected trait `Bar`, found trait `Baz`
@@ -43,7 +43,7 @@ LL |     let bar: &dyn Bar = baz;
               found reference `&dyn Baz`
 
 error[E0308]: mismatched types
-  --> $DIR/invalid-upcast.rs:62:35
+  --> $DIR/invalid-upcast.rs:60:35
    |
 LL |     let _: &dyn std::fmt::Debug = bar;
    |            --------------------   ^^^ expected trait `Debug`, found trait `Bar`
@@ -54,7 +54,7 @@ LL |     let _: &dyn std::fmt::Debug = bar;
               found reference `&dyn Bar`
 
 error[E0308]: mismatched types
-  --> $DIR/invalid-upcast.rs:64:24
+  --> $DIR/invalid-upcast.rs:62:24
    |
 LL |     let _: &dyn Send = bar;
    |            ---------   ^^^ expected trait `Send`, found trait `Bar`
@@ -65,7 +65,7 @@ LL |     let _: &dyn Send = bar;
               found reference `&dyn Bar`
 
 error[E0308]: mismatched types
-  --> $DIR/invalid-upcast.rs:66:24
+  --> $DIR/invalid-upcast.rs:64:24
    |
 LL |     let _: &dyn Sync = bar;
    |            ---------   ^^^ expected trait `Sync`, found trait `Bar`
@@ -76,7 +76,7 @@ LL |     let _: &dyn Sync = bar;
               found reference `&dyn Bar`
 
 error[E0308]: mismatched types
-  --> $DIR/invalid-upcast.rs:69:25
+  --> $DIR/invalid-upcast.rs:67:25
    |
 LL |     let foo: &dyn Foo = baz;
    |              --------   ^^^ expected trait `Foo`, found trait `Baz`
@@ -87,7 +87,7 @@ LL |     let foo: &dyn Foo = baz;
               found reference `&dyn Baz`
 
 error[E0308]: mismatched types
-  --> $DIR/invalid-upcast.rs:71:35
+  --> $DIR/invalid-upcast.rs:69:35
    |
 LL |     let _: &dyn std::fmt::Debug = foo;
    |            --------------------   ^^^ expected trait `Debug`, found trait `Foo`
@@ -98,7 +98,7 @@ LL |     let _: &dyn std::fmt::Debug = foo;
               found reference `&dyn Foo`
 
 error[E0308]: mismatched types
-  --> $DIR/invalid-upcast.rs:73:24
+  --> $DIR/invalid-upcast.rs:71:24
    |
 LL |     let _: &dyn Send = foo;
    |            ---------   ^^^ expected trait `Send`, found trait `Foo`
@@ -109,7 +109,7 @@ LL |     let _: &dyn Send = foo;
               found reference `&dyn Foo`
 
 error[E0308]: mismatched types
-  --> $DIR/invalid-upcast.rs:75:24
+  --> $DIR/invalid-upcast.rs:73:24
    |
 LL |     let _: &dyn Sync = foo;
    |            ---------   ^^^ expected trait `Sync`, found trait `Foo`
@@ -120,7 +120,7 @@ LL |     let _: &dyn Sync = foo;
               found reference `&dyn Foo`
 
 error[E0308]: mismatched types
-  --> $DIR/invalid-upcast.rs:78:25
+  --> $DIR/invalid-upcast.rs:76:25
    |
 LL |     let foo: &dyn Foo = bar;
    |              --------   ^^^ expected trait `Foo`, found trait `Bar`
@@ -131,7 +131,7 @@ LL |     let foo: &dyn Foo = bar;
               found reference `&dyn Bar`
 
 error[E0308]: mismatched types
-  --> $DIR/invalid-upcast.rs:80:35
+  --> $DIR/invalid-upcast.rs:78:35
    |
 LL |     let _: &dyn std::fmt::Debug = foo;
    |            --------------------   ^^^ expected trait `Debug`, found trait `Foo`
@@ -142,7 +142,7 @@ LL |     let _: &dyn std::fmt::Debug = foo;
               found reference `&dyn Foo`
 
 error[E0308]: mismatched types
-  --> $DIR/invalid-upcast.rs:82:24
+  --> $DIR/invalid-upcast.rs:80:24
    |
 LL |     let _: &dyn Send = foo;
    |            ---------   ^^^ expected trait `Send`, found trait `Foo`
@@ -153,7 +153,7 @@ LL |     let _: &dyn Send = foo;
               found reference `&dyn Foo`
 
 error[E0308]: mismatched types
-  --> $DIR/invalid-upcast.rs:84:24
+  --> $DIR/invalid-upcast.rs:82:24
    |
 LL |     let _: &dyn Sync = foo;
    |            ---------   ^^^ expected trait `Sync`, found trait `Foo`

tests/ui/traits/trait-upcasting/issue-11515-upcast-fn_mut-fn.rs

@@ -1,5 +1,4 @@
 //@ run-pass
-#![feature(trait_upcasting)]
 
 struct Test {
     func: Box<dyn FnMut() + 'static>,

tests/ui/traits/trait-upcasting/issue-11515.current.stderr

@@ -1,14 +0,0 @@
-error[E0658]: cannot cast `dyn Fn()` to `dyn FnMut()`, trait upcasting coercion is experimental
-  --> $DIR/issue-11515.rs:11:38
-   |
-LL |     let test = Box::new(Test { func: closure });
-   |                                      ^^^^^^^
-   |
-   = note: see issue #65991 <https://github.com/rust-lang/rust/issues/65991> for more information
-   = help: add `#![feature(trait_upcasting)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-   = note: required when coercing `Box<(dyn Fn() + 'static)>` into `Box<(dyn FnMut() + 'static)>`
-
-error: aborting due to 1 previous error
-
-For more information about this error, try `rustc --explain E0658`.

tests/ui/traits/trait-upcasting/issue-11515.next.stderr

@@ -1,14 +0,0 @@
-error[E0658]: cannot cast `dyn Fn()` to `dyn FnMut()`, trait upcasting coercion is experimental
-  --> $DIR/issue-11515.rs:11:38
-   |
-LL |     let test = Box::new(Test { func: closure });
-   |                                      ^^^^^^^
-   |
-   = note: see issue #65991 <https://github.com/rust-lang/rust/issues/65991> for more information
-   = help: add `#![feature(trait_upcasting)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-   = note: required when coercing `Box<(dyn Fn() + 'static)>` into `Box<(dyn FnMut() + 'static)>`
-
-error: aborting due to 1 previous error
-
-For more information about this error, try `rustc --explain E0658`.

tests/ui/traits/trait-upcasting/issue-11515.rs

@@ -1,3 +1,4 @@
+//@ check-pass
 //@ revisions: current next
 //@ ignore-compare-mode-next-solver (explicit revisions)
 //@[next] compile-flags: -Znext-solver
@@ -8,5 +9,5 @@ struct Test {
 
 fn main() {
     let closure: Box<dyn Fn() + 'static> = Box::new(|| ());
-    let test = Box::new(Test { func: closure }); //~ ERROR trait upcasting coercion is experimental [E0658]
+    let test = Box::new(Test { func: closure });
 }

tests/ui/traits/trait-upcasting/lifetime.rs

@@ -1,7 +1,5 @@
 //@ run-pass
 
-#![feature(trait_upcasting)]
-
 trait Foo: PartialEq<i32> + std::fmt::Debug + Send + Sync {
     fn a(&self) -> i32 {
         10

tests/ui/traits/trait-upcasting/lifetime.stderr

@@ -1,5 +1,5 @@
 warning: methods `z` and `y` are never used
-  --> $DIR/lifetime.rs:10:8
+  --> $DIR/lifetime.rs:8:8
    |
 LL | trait Foo: PartialEq<i32> + std::fmt::Debug + Send + Sync {
    |       --- methods in this trait
@@ -13,7 +13,7 @@ LL |     fn y(&self) -> i32 {
    = note: `#[warn(dead_code)]` on by default
 
 warning: method `w` is never used
-  --> $DIR/lifetime.rs:24:8
+  --> $DIR/lifetime.rs:22:8
    |
 LL | trait Bar: Foo {
    |       --- method in this trait

tests/ui/traits/trait-upcasting/migrate-lint-deny-regions.rs

@@ -1,4 +1,5 @@
-#![deny(deref_into_dyn_supertrait)]
+//@ check-pass
+#![warn(deref_into_dyn_supertrait)]
 
 use std::ops::Deref;
 
@@ -6,8 +7,7 @@ trait Bar<'a> {}
 trait Foo<'a>: Bar<'a> {}
 
 impl<'a> Deref for dyn Foo<'a> {
-    //~^ ERROR this `Deref` implementation is covered by an implicit supertrait coercion
+    //~^ warn: this `Deref` implementation is covered by an implicit supertrait coercion
-    //~| WARN this will change its meaning in a future release!
     type Target = dyn Bar<'a>;
 
     fn deref(&self) -> &Self::Target {

tests/ui/traits/trait-upcasting/migrate-lint-deny-regions.stderr

@@ -1,19 +1,17 @@
-error: this `Deref` implementation is covered by an implicit supertrait coercion
+warning: this `Deref` implementation is covered by an implicit supertrait coercion
-  --> $DIR/migrate-lint-deny-regions.rs:8:1
+  --> $DIR/migrate-lint-deny-regions.rs:9:1
    |
 LL | impl<'a> Deref for dyn Foo<'a> {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `dyn Foo<'_>` implements `Deref<Target = dyn Bar<'_>>` which conflicts with supertrait `Bar<'_>`
-...
+LL |
 LL |     type Target = dyn Bar<'a>;
    |     -------------------------- target type is a supertrait of `dyn Foo<'_>`
    |
-   = warning: this will change its meaning in a future release!
-   = note: for more information, see issue #89460 <https://github.com/rust-lang/rust/issues/89460>
 note: the lint level is defined here
-  --> $DIR/migrate-lint-deny-regions.rs:1:9
+  --> $DIR/migrate-lint-deny-regions.rs:2:9
    |
-LL | #![deny(deref_into_dyn_supertrait)]
+LL | #![warn(deref_into_dyn_supertrait)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 1 previous error
+warning: 1 warning emitted
 

tests/ui/traits/trait-upcasting/migrate-lint-deny.rs

@@ -1,25 +0,0 @@
-#![deny(deref_into_dyn_supertrait)]
-
-use std::ops::Deref;
-
-// issue 89190
-trait A {}
-trait B: A {}
-
-impl<'a> Deref for dyn 'a + B {
-    //~^ ERROR this `Deref` implementation is covered by an implicit supertrait coercion
-    //~| WARN this will change its meaning in a future release!
-
-    type Target = dyn A;
-    fn deref(&self) -> &Self::Target {
-        todo!()
-    }
-}
-
-fn take_a(_: &dyn A) {}
-
-fn whoops(b: &dyn B) {
-    take_a(b)
-}
-
-fn main() {}

tests/ui/traits/trait-upcasting/migrate-lint-deny.stderr

@@ -1,19 +0,0 @@
-error: this `Deref` implementation is covered by an implicit supertrait coercion
-  --> $DIR/migrate-lint-deny.rs:9:1
-   |
-LL | impl<'a> Deref for dyn 'a + B {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `dyn B` implements `Deref<Target = dyn A>` which conflicts with supertrait `A`
-...
-LL |     type Target = dyn A;
-   |     -------------------- target type is a supertrait of `dyn B`
-   |
-   = warning: this will change its meaning in a future release!
-   = note: for more information, see issue #89460 <https://github.com/rust-lang/rust/issues/89460>
-note: the lint level is defined here
-  --> $DIR/migrate-lint-deny.rs:1:9
-   |
-LL | #![deny(deref_into_dyn_supertrait)]
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: aborting due to 1 previous error
-

tests/ui/traits/trait-upcasting/migrate-lint-different-substs.rs

@@ -1,4 +1,5 @@
 //@ check-pass
+#![warn(deref_into_dyn_supertrait)]
 
 use std::ops::Deref;
 
@@ -9,8 +10,7 @@ trait Foo: Bar<i32> {
 }
 
 impl<'a> Deref for dyn Foo + 'a {
-    //~^ WARN this `Deref` implementation is covered by an implicit supertrait coercion
+    //~^ warn: this `Deref` implementation is covered by an implicit supertrait coercion
-    //~| WARN this will change its meaning in a future release!
     type Target = dyn Bar<u32> + 'a;
 
     fn deref(&self) -> &Self::Target {

tests/ui/traits/trait-upcasting/migrate-lint-different-substs.stderr

@@ -1,15 +1,17 @@
 warning: this `Deref` implementation is covered by an implicit supertrait coercion
-  --> $DIR/migrate-lint-different-substs.rs:11:1
+  --> $DIR/migrate-lint-different-substs.rs:12:1
    |
 LL | impl<'a> Deref for dyn Foo + 'a {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `dyn Foo` implements `Deref<Target = dyn Bar<u32>>` which conflicts with supertrait `Bar<i32>`
-...
+LL |
 LL |     type Target = dyn Bar<u32> + 'a;
    |     -------------------------------- target type is a supertrait of `dyn Foo`
    |
-   = warning: this will change its meaning in a future release!
+note: the lint level is defined here
-   = note: for more information, see issue #89460 <https://github.com/rust-lang/rust/issues/89460>
+  --> $DIR/migrate-lint-different-substs.rs:2:9
-   = note: `#[warn(deref_into_dyn_supertrait)]` on by default
+   |
+LL | #![warn(deref_into_dyn_supertrait)]
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^
 
 warning: 1 warning emitted
 

tests/ui/traits/trait-upcasting/mono-impossible.rs

@@ -1,7 +1,5 @@
 //@ build-pass
 
-#![feature(trait_upcasting)]
-
 trait Supertrait<T> {
     fn method(&self) {}
 }

tests/ui/traits/trait-upcasting/multiple-occurrence-ambiguousity.rs

@@ -1,5 +1,4 @@
 //@ check-fail
-#![feature(trait_upcasting)]
 
 trait Bar<T> {
     fn bar(&self, _: T) {}

tests/ui/traits/trait-upcasting/multiple-occurrence-ambiguousity.stderr

@@ -1,5 +1,5 @@
 error[E0308]: mismatched types
-  --> $DIR/multiple-occurrence-ambiguousity.rs:20:26
+  --> $DIR/multiple-occurrence-ambiguousity.rs:19:26
    |
 LL |     let t: &dyn Bar<_> = s;
    |            -----------   ^ expected trait `Bar`, found trait `Foo`

tests/ui/traits/trait-upcasting/multiple-supertraits-modulo-binder.rs

@@ -1,10 +1,8 @@
+// Test for <https://github.com/rust-lang/rust/issues/135316>.
+//
 //@ run-pass
 //@ check-run-results
 
-// Test for <https://github.com/rust-lang/rust/issues/135316>.
-
-#![feature(trait_upcasting)]
-
 trait Supertrait<T> {
     fn _print_numbers(&self, mem: &[usize; 100]) {
         println!("{mem:?}");

tests/ui/traits/trait-upcasting/multiple-supertraits-modulo-normalization-vtable.rs

@@ -1,5 +1,4 @@
 #![feature(rustc_attrs)]
-#![feature(trait_upcasting)]
 
 // Test for <https://github.com/rust-lang/rust/issues/135315>.
 

tests/ui/traits/trait-upcasting/multiple-supertraits-modulo-normalization-vtable.stderr

@@ -5,7 +5,7 @@ error: vtable entries: [
            Method(<() as Supertrait<()>>::_print_numbers),
            Method(<() as Middle<()>>::say_hello),
        ]
-  --> $DIR/multiple-supertraits-modulo-normalization-vtable.rs:30:1
+  --> $DIR/multiple-supertraits-modulo-normalization-vtable.rs:29:1
    |
 LL | impl Trait for () {}
    | ^^^^^^^^^^^^^^^^^
@@ -17,7 +17,7 @@ error: vtable entries: [
            Method(<dyn Middle<()> as Supertrait<()>>::_print_numbers - shim(reify)),
            Method(<dyn Middle<()> as Middle<()>>::say_hello - shim(reify)),
        ]
-  --> $DIR/multiple-supertraits-modulo-normalization-vtable.rs:34:1
+  --> $DIR/multiple-supertraits-modulo-normalization-vtable.rs:33:1
    |
 LL | type Virtual = dyn Middle<()>;
    | ^^^^^^^^^^^^

tests/ui/traits/trait-upcasting/multiple-supertraits-modulo-normalization.rs

@@ -1,10 +1,8 @@
+// Test for <https://github.com/rust-lang/rust/issues/135315>.
+//
 //@ run-pass
 //@ check-run-results
 
-#![feature(trait_upcasting)]
-
-// Test for <https://github.com/rust-lang/rust/issues/135315>.
-
 trait Supertrait<T> {
     fn _print_numbers(&self, mem: &[usize; 100]) {
         println!("{mem:?}");

tests/ui/traits/trait-upcasting/normalization.rs

@@ -4,8 +4,6 @@
 //@ ignore-compare-mode-next-solver (explicit revisions)
 //@[next] compile-flags: -Znext-solver
 
-#![feature(trait_upcasting)]
-
 trait Mirror {
     type Assoc;
 }

tests/ui/traits/trait-upcasting/prefer-lower-candidates.rs

@@ -6,8 +6,6 @@
 // Ensure we don't have ambiguity when upcasting to two supertraits
 // that are identical modulo normalization.
 
-#![feature(trait_upcasting)]
-
 trait Supertrait<T> {
     fn method(&self) {}
 }

tests/ui/traits/trait-upcasting/replace-vptr.rs

@@ -1,7 +1,5 @@
 //@ run-pass
 
-#![feature(trait_upcasting)]
-
 trait A {
     fn foo_a(&self); //~ WARN method `foo_a` is never used
 }

tests/ui/traits/trait-upcasting/replace-vptr.stderr

@@ -1,5 +1,5 @@
 warning: method `foo_a` is never used
-  --> $DIR/replace-vptr.rs:6:8
+  --> $DIR/replace-vptr.rs:4:8
    |
 LL | trait A {
    |       - method in this trait
@@ -9,7 +9,7 @@ LL |     fn foo_a(&self);
    = note: `#[warn(dead_code)]` on by default
 
 warning: method `foo_c` is never used
-  --> $DIR/replace-vptr.rs:14:8
+  --> $DIR/replace-vptr.rs:12:8
    |
 LL | trait C: A + B {
    |       - method in this trait

tests/ui/traits/trait-upcasting/struct.rs

@@ -1,7 +1,5 @@
 //@ run-pass
 
-#![feature(trait_upcasting)]
-
 use std::rc::Rc;
 use std::sync::Arc;
 

tests/ui/traits/trait-upcasting/subtrait-method.rs

@@ -1,5 +1,3 @@
-#![feature(trait_upcasting)]
-
 trait Foo: PartialEq<i32> + std::fmt::Debug + Send + Sync {
     fn a(&self) -> i32 {
         10

tests/ui/traits/trait-upcasting/subtrait-method.stderr

@@ -1,12 +1,12 @@
 error[E0599]: no method named `c` found for reference `&dyn Bar` in the current scope
-  --> $DIR/subtrait-method.rs:55:9
+  --> $DIR/subtrait-method.rs:53:9
    |
 LL |     bar.c();
    |         ^
    |
    = help: items from traits can only be used if the trait is implemented and in scope
 note: `Baz` defines an item `c`, perhaps you need to implement it
-  --> $DIR/subtrait-method.rs:27:1
+  --> $DIR/subtrait-method.rs:25:1
    |
 LL | trait Baz: Bar {
    | ^^^^^^^^^^^^^^
@@ -16,14 +16,14 @@ LL |     bar.a();
    |         ~
 
 error[E0599]: no method named `b` found for reference `&dyn Foo` in the current scope
-  --> $DIR/subtrait-method.rs:59:9
+  --> $DIR/subtrait-method.rs:57:9
    |
 LL |     foo.b();
    |         ^
    |
    = help: items from traits can only be used if the trait is implemented and in scope
 note: `Bar` defines an item `b`, perhaps you need to implement it
-  --> $DIR/subtrait-method.rs:17:1
+  --> $DIR/subtrait-method.rs:15:1
    |
 LL | trait Bar: Foo {
    | ^^^^^^^^^^^^^^
@@ -33,14 +33,14 @@ LL |     foo.a();
    |         ~
 
 error[E0599]: no method named `c` found for reference `&dyn Foo` in the current scope
-  --> $DIR/subtrait-method.rs:61:9
+  --> $DIR/subtrait-method.rs:59:9
    |
 LL |     foo.c();
    |         ^
    |
    = help: items from traits can only be used if the trait is implemented and in scope
 note: `Baz` defines an item `c`, perhaps you need to implement it
-  --> $DIR/subtrait-method.rs:27:1
+  --> $DIR/subtrait-method.rs:25:1
    |
 LL | trait Baz: Bar {
    | ^^^^^^^^^^^^^^
@@ -50,14 +50,14 @@ LL |     foo.a();
    |         ~
 
 error[E0599]: no method named `b` found for reference `&dyn Foo` in the current scope
-  --> $DIR/subtrait-method.rs:65:9
+  --> $DIR/subtrait-method.rs:63:9
    |
 LL |     foo.b();
    |         ^
    |
    = help: items from traits can only be used if the trait is implemented and in scope
 note: `Bar` defines an item `b`, perhaps you need to implement it
-  --> $DIR/subtrait-method.rs:17:1
+  --> $DIR/subtrait-method.rs:15:1
    |
 LL | trait Bar: Foo {
    | ^^^^^^^^^^^^^^
@@ -67,14 +67,14 @@ LL |     foo.a();
    |         ~
 
 error[E0599]: no method named `c` found for reference `&dyn Foo` in the current scope
-  --> $DIR/subtrait-method.rs:67:9
+  --> $DIR/subtrait-method.rs:65:9
    |
 LL |     foo.c();
    |         ^
    |
    = help: items from traits can only be used if the trait is implemented and in scope
 note: `Baz` defines an item `c`, perhaps you need to implement it
-  --> $DIR/subtrait-method.rs:27:1
+  --> $DIR/subtrait-method.rs:25:1
    |
 LL | trait Baz: Bar {
    | ^^^^^^^^^^^^^^

tests/ui/traits/trait-upcasting/supertraits-modulo-inner-binder.rs

@@ -1,7 +1,5 @@
 //@ run-pass
 
-#![feature(trait_upcasting)]
-
 trait Super<U> {
     fn call(&self)
     where

tests/ui/traits/trait-upcasting/type-checking-test-1.current.stderr

@@ -1,5 +1,5 @@
 error[E0605]: non-primitive cast: `&dyn Foo` as `&dyn Bar<_>`
-  --> $DIR/type-checking-test-1.rs:20:13
+  --> $DIR/type-checking-test-1.rs:18:13
    |
 LL |     let _ = x as &dyn Bar<_>; // Ambiguous
    |             ^^^^^^^^^^^^^^^^ an `as` expression can only be used to convert between primitive types or to coerce to a specific trait object

tests/ui/traits/trait-upcasting/type-checking-test-1.next.stderr

@@ -1,5 +1,5 @@
 error[E0605]: non-primitive cast: `&dyn Foo` as `&dyn Bar<_>`
-  --> $DIR/type-checking-test-1.rs:20:13
+  --> $DIR/type-checking-test-1.rs:18:13
    |
 LL |     let _ = x as &dyn Bar<_>; // Ambiguous
    |             ^^^^^^^^^^^^^^^^ an `as` expression can only be used to convert between primitive types or to coerce to a specific trait object

tests/ui/traits/trait-upcasting/type-checking-test-1.rs

@@ -2,8 +2,6 @@
 //@ ignore-compare-mode-next-solver (explicit revisions)
 //@[next] compile-flags: -Znext-solver
 
-#![feature(trait_upcasting)]
-
 trait Foo: Bar<i32> + Bar<u32> {}
 trait Bar<T> {
     fn bar(&self) -> Option<T> {

tests/ui/traits/trait-upcasting/type-checking-test-2.rs

@@ -1,5 +1,3 @@
-#![feature(trait_upcasting)]
-
 trait Foo<T>: Bar<i32> + Bar<T> {}
 trait Bar<T> {
     fn bar(&self) -> Option<T> {

tests/ui/traits/trait-upcasting/type-checking-test-2.stderr

@@ -1,11 +1,11 @@
 error[E0605]: non-primitive cast: `&dyn Foo<i32>` as `&dyn Bar<u32>`
-  --> $DIR/type-checking-test-2.rs:19:13
+  --> $DIR/type-checking-test-2.rs:17:13
    |
 LL |     let _ = x as &dyn Bar<u32>; // Error
    |             ^^^^^^^^^^^^^^^^^^ an `as` expression can only be used to convert between primitive types or to coerce to a specific trait object
 
 error[E0605]: non-primitive cast: `&dyn Foo<u32>` as `&dyn Bar<_>`
-  --> $DIR/type-checking-test-2.rs:24:13
+  --> $DIR/type-checking-test-2.rs:22:13
    |
 LL |     let a = x as &dyn Bar<_>; // Ambiguous
    |             ^^^^^^^^^^^^^^^^ an `as` expression can only be used to convert between primitive types or to coerce to a specific trait object

tests/ui/traits/trait-upcasting/type-checking-test-3.rs

@@ -1,5 +1,3 @@
-#![feature(trait_upcasting)]
-
 trait Foo<'a>: Bar<'a> {}
 trait Bar<'a> {}
 

tests/ui/traits/trait-upcasting/type-checking-test-3.stderr

@@ -1,5 +1,5 @@
 error: lifetime may not live long enough
-  --> $DIR/type-checking-test-3.rs:11:13
+  --> $DIR/type-checking-test-3.rs:9:13
    |
 LL | fn test_wrong1<'a>(x: &dyn Foo<'static>, y: &'a u32) {
    |                -- lifetime `'a` defined here
@@ -7,7 +7,7 @@ LL |     let _ = x as &dyn Bar<'a>; // Error
    |             ^^^^^^^^^^^^^^^^^ cast requires that `'a` must outlive `'static`
 
 error: lifetime may not live long enough
-  --> $DIR/type-checking-test-3.rs:16:18
+  --> $DIR/type-checking-test-3.rs:14:18
    |
 LL | fn test_wrong2<'a>(x: &dyn Foo<'a>) {
    |                -- lifetime `'a` defined here

tests/ui/traits/trait-upcasting/type-checking-test-4.rs

@@ -1,5 +1,3 @@
-#![feature(trait_upcasting)]
-
 trait Foo<'a>: Bar<'a, 'a> {}
 trait Bar<'a, 'b> {
     fn get_b(&self) -> Option<&'a u32> {

tests/ui/traits/trait-upcasting/type-checking-test-4.stderr

@@ -1,5 +1,5 @@
 error: lifetime may not live long enough
-  --> $DIR/type-checking-test-4.rs:19:13
+  --> $DIR/type-checking-test-4.rs:17:13
    |
 LL | fn test_wrong1<'a>(x: &dyn Foo<'static>, y: &'a u32) {
    |                -- lifetime `'a` defined here
@@ -7,7 +7,7 @@ LL |     let _ = x as &dyn Bar<'static, 'a>; // Error
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^ cast requires that `'a` must outlive `'static`
 
 error: lifetime may not live long enough
-  --> $DIR/type-checking-test-4.rs:24:18
+  --> $DIR/type-checking-test-4.rs:22:18
    |
 LL | fn test_wrong2<'a>(x: &dyn Foo<'static>, y: &'a u32) {
    |                -- lifetime `'a` defined here
@@ -15,7 +15,7 @@ LL |     let _ = x as &dyn Bar<'a, 'static>; // Error
    |                  ^^^^^^^^^^^^^^^^^^^^^ type annotation requires that `'a` must outlive `'static`
 
 error: lifetime may not live long enough
-  --> $DIR/type-checking-test-4.rs:30:5
+  --> $DIR/type-checking-test-4.rs:28:5
    |
 LL | fn test_wrong3<'a>(x: &dyn Foo<'a>) -> Option<&'static u32> {
    |                -- lifetime `'a` defined here
@@ -24,7 +24,7 @@ LL |     y.get_b() // ERROR
    |     ^^^^^^^^^ returning this value requires that `'a` must outlive `'static`
 
 error: lifetime may not live long enough
-  --> $DIR/type-checking-test-4.rs:35:5
+  --> $DIR/type-checking-test-4.rs:33:5
    |
 LL | fn test_wrong4<'a>(x: &dyn Foo<'a>) -> Option<&'static u32> {
    |                -- lifetime `'a` defined here
@@ -32,7 +32,7 @@ LL |     <_ as Bar>::get_b(x) // ERROR
    |     ^^^^^^^^^^^^^^^^^^^^ returning this value requires that `'a` must outlive `'static`
 
 error: lifetime may not live long enough
-  --> $DIR/type-checking-test-4.rs:40:5
+  --> $DIR/type-checking-test-4.rs:38:5
    |
 LL | fn test_wrong5<'a>(x: &dyn Foo<'a>) -> Option<&'static u32> {
    |                -- lifetime `'a` defined here
@@ -40,7 +40,7 @@ LL |     <_ as Bar<'_, '_>>::get_b(x) // ERROR
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ returning this value requires that `'a` must outlive `'static`
 
 error: lifetime may not live long enough
-  --> $DIR/type-checking-test-4.rs:48:5
+  --> $DIR/type-checking-test-4.rs:46:5
    |
 LL | fn test_wrong6<'a>(x: &dyn Foo<'a>) -> Option<&'static u32> {
    |                -- lifetime `'a` defined here

tests/ui/traits/trait-upcasting/type-checking-test-opaques.rs

@@ -1,4 +1,4 @@
-#![feature(trait_upcasting, type_alias_impl_trait)]
+#![feature(type_alias_impl_trait)]
 
 //@ check-pass
 

tests/ui/traits/trait-upcasting/upcast-defining-opaque.rs

@@ -3,7 +3,7 @@
 //@ ignore-compare-mode-next-solver (explicit revisions)
 //@check-pass
 
-#![feature(trait_upcasting, type_alias_impl_trait)]
+#![feature(type_alias_impl_trait)]
 
 trait Super {
     type Assoc;

tests/ui/traits/trait-upcasting/upcast-through-struct-tail.current.stderr

@@ -1,14 +0,0 @@
-error[E0658]: cannot cast `dyn A` to `dyn B`, trait upcasting coercion is experimental
-  --> $DIR/upcast-through-struct-tail.rs:11:5
-   |
-LL |     x
-   |     ^
-   |
-   = note: see issue #65991 <https://github.com/rust-lang/rust/issues/65991> for more information
-   = help: add `#![feature(trait_upcasting)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-   = note: required when coercing `Box<Wrapper<(dyn A + 'a)>>` into `Box<Wrapper<(dyn B + 'a)>>`
-
-error: aborting due to 1 previous error
-
-For more information about this error, try `rustc --explain E0658`.

tests/ui/traits/trait-upcasting/upcast-through-struct-tail.next.stderr

@@ -1,14 +0,0 @@
-error[E0658]: cannot cast `dyn A` to `dyn B`, trait upcasting coercion is experimental
-  --> $DIR/upcast-through-struct-tail.rs:11:5
-   |
-LL |     x
-   |     ^
-   |
-   = note: see issue #65991 <https://github.com/rust-lang/rust/issues/65991> for more information
-   = help: add `#![feature(trait_upcasting)]` to the crate attributes to enable
-   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
-   = note: required when coercing `Box<Wrapper<(dyn A + 'a)>>` into `Box<Wrapper<(dyn B + 'a)>>`
-
-error: aborting due to 1 previous error
-
-For more information about this error, try `rustc --explain E0658`.

tests/ui/traits/trait-upcasting/upcast-through-struct-tail.rs

@@ -1,3 +1,4 @@
+//@ check-pass
 //@ revisions: current next
 //@ ignore-compare-mode-next-solver (explicit revisions)
 //@[next] compile-flags: -Znext-solver
@@ -9,7 +10,6 @@ trait B {}
 
 fn test<'a>(x: Box<Wrapper<dyn A + 'a>>) -> Box<Wrapper<dyn B + 'a>> {
     x
-    //~^ ERROR cannot cast `dyn A` to `dyn B`, trait upcasting coercion is experimental
 }
 
 fn main() {}

tests/ui/traits/upcast_reorder.rs

@@ -2,8 +2,6 @@
 //
 // issue: <https://github.com/rust-lang/rust/issues/131813>
 
-#![feature(trait_upcasting)]
-
 trait Pollable {
     #[allow(unused)]
     fn poll(&self) {}

tests/ui/traits/upcast_soundness_bug.rs

@@ -1,4 +1,3 @@
-#![feature(trait_upcasting)]
 //@ check-fail
 //
 // issue: <https://github.com/rust-lang/rust/pull/120222>

tests/ui/traits/upcast_soundness_bug.stderr

@@ -1,5 +1,5 @@
 error[E0606]: casting `*const dyn Trait<u8, u8>` as `*const dyn Trait<u8, u16>` is invalid
-  --> $DIR/upcast_soundness_bug.rs:59:13
+  --> $DIR/upcast_soundness_bug.rs:58:13
    |
 LL |     let p = p as *const dyn Trait<u8, u16>; // <- this is bad!
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^