Rollup merge of #145095 - tiif:unstable_const_param, r=BoxyUwU

Migrate `UnsizedConstParamTy`  to unstable impl of `ConstParamTy_`

Now that we have ``#[unstable_feature_bound]``, we can remove ``UnsizedConstParamTy`` that was meant to be an unstable impl of stable type and ``ConstParamTy_`` trait.

r? `@BoxyUwU`

53 files changed, 266 insertions, 405 deletions

diff --git a/compiler/rustc_builtin_macros/src/deriving/bounds.rs b/compiler/rustc_builtin_macros/src/deriving/bounds.rs
index dd8f0e46a0e..63342880b09 100644
--- a/compiler/rustc_builtin_macros/src/deriving/bounds.rs
+++ b/compiler/rustc_builtin_macros/src/deriving/bounds.rs
@@ -51,43 +51,4 @@ pub(crate) fn expand_deriving_const_param_ty(
     };
 
     trait_def.expand(cx, mitem, item, push);
-
-    let trait_def = TraitDef {
-        span,
-        path: path_std!(marker::UnsizedConstParamTy),
-        skip_path_as_bound: false,
-        needs_copy_as_bound_if_packed: false,
-        additional_bounds: vec![ty::Ty::Path(path_std!(cmp::Eq))],
-        supports_unions: false,
-        methods: Vec::new(),
-        associated_types: Vec::new(),
-        is_const,
-        is_staged_api_crate: cx.ecfg.features.staged_api(),
-    };
-
-    trait_def.expand(cx, mitem, item, push);
-}
-
-pub(crate) fn expand_deriving_unsized_const_param_ty(
-    cx: &ExtCtxt<'_>,
-    span: Span,
-    mitem: &MetaItem,
-    item: &Annotatable,
-    push: &mut dyn FnMut(Annotatable),
-    is_const: bool,
-) {
-    let trait_def = TraitDef {
-        span,
-        path: path_std!(marker::UnsizedConstParamTy),
-        skip_path_as_bound: false,
-        needs_copy_as_bound_if_packed: false,
-        additional_bounds: vec![ty::Ty::Path(path_std!(cmp::Eq))],
-        supports_unions: false,
-        methods: Vec::new(),
-        associated_types: Vec::new(),
-        is_const,
-        is_staged_api_crate: cx.ecfg.features.staged_api(),
-    };
-
-    trait_def.expand(cx, mitem, item, push);
 }
diff --git a/compiler/rustc_builtin_macros/src/lib.rs b/compiler/rustc_builtin_macros/src/lib.rs
index 1bcea95fbb7..4541e2cd3b4 100644
--- a/compiler/rustc_builtin_macros/src/lib.rs
+++ b/compiler/rustc_builtin_macros/src/lib.rs
@@ -129,7 +129,6 @@ pub fn register_builtin_macros(resolver: &mut dyn ResolverExpand) {
         Clone: clone::expand_deriving_clone,
         Copy: bounds::expand_deriving_copy,
         ConstParamTy: bounds::expand_deriving_const_param_ty,
-        UnsizedConstParamTy: bounds::expand_deriving_unsized_const_param_ty,
         Debug: debug::expand_deriving_debug,
         Default: default::expand_deriving_default,
         Eq: eq::expand_deriving_eq,
diff --git a/compiler/rustc_hir/src/lang_items.rs b/compiler/rustc_hir/src/lang_items.rs
index 67d2f15d414..2e099a97b65 100644
--- a/compiler/rustc_hir/src/lang_items.rs
+++ b/compiler/rustc_hir/src/lang_items.rs
@@ -370,7 +370,6 @@ language_item_table! {
     CoercePointeeValidated, sym::coerce_pointee_validated, coerce_pointee_validated_trait, Target::Trait,     GenericRequirement::Exact(0);
 
     ConstParamTy,            sym::const_param_ty,      const_param_ty_trait,       Target::Trait,          GenericRequirement::Exact(0);
-    UnsizedConstParamTy,     sym::unsized_const_param_ty, unsized_const_param_ty_trait, Target::Trait, GenericRequirement::Exact(0);
 
     Poll,                    sym::Poll,                poll,                       Target::Enum,           GenericRequirement::None;
     PollReady,               sym::Ready,               poll_ready_variant,         Target::Variant,        GenericRequirement::None;
diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
index d33f1f3e12a..0a555c7f6e9 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -819,17 +819,7 @@ fn check_param_wf(tcx: TyCtxt<'_>, param: &ty::GenericParamDef) -> Result<(), Er
             let span = tcx.def_span(param.def_id);
             let def_id = param.def_id.expect_local();
 
-            if tcx.features().unsized_const_params() {
-                enter_wf_checking_ctxt(tcx, tcx.local_parent(def_id), |wfcx| {
-                    wfcx.register_bound(
-                        ObligationCause::new(span, def_id, ObligationCauseCode::ConstParam(ty)),
-                        wfcx.param_env,
-                        ty,
-                        tcx.require_lang_item(LangItem::UnsizedConstParamTy, span),
-                    );
-                    Ok(())
-                })
-            } else if tcx.features().adt_const_params() {
+            if tcx.features().adt_const_params() {
                 enter_wf_checking_ctxt(tcx, tcx.local_parent(def_id), |wfcx| {
                     wfcx.register_bound(
                         ObligationCause::new(span, def_id, ObligationCauseCode::ConstParam(ty)),
@@ -880,7 +870,6 @@ fn check_param_wf(tcx: TyCtxt<'_>, param: &ty::GenericParamDef) -> Result<(), Er
                     tcx,
                     tcx.param_env(param.def_id),
                     ty,
-                    LangItem::ConstParamTy,
                     cause,
                 ) {
                     // Can never implement `ConstParamTy`, don't suggest anything.
diff --git a/compiler/rustc_hir_analysis/src/coherence/builtin.rs b/compiler/rustc_hir_analysis/src/coherence/builtin.rs
index 32b175611ce..0b9a01d6042 100644
--- a/compiler/rustc_hir_analysis/src/coherence/builtin.rs
+++ b/compiler/rustc_hir_analysis/src/coherence/builtin.rs
@@ -1,7 +1,6 @@
 //! Check properties that are required by built-in traits and set
 //! up data structures required by type-checking/codegen.
 
-use std::assert_matches::assert_matches;
 use std::collections::BTreeMap;
 
 use rustc_data_structures::fx::FxHashSet;
@@ -40,10 +39,7 @@ pub(super) fn check_trait<'tcx>(
     checker.check(lang_items.async_drop_trait(), visit_implementation_of_drop)?;
     checker.check(lang_items.copy_trait(), visit_implementation_of_copy)?;
     checker.check(lang_items.const_param_ty_trait(), |checker| {
-        visit_implementation_of_const_param_ty(checker, LangItem::ConstParamTy)
-    })?;
-    checker.check(lang_items.unsized_const_param_ty_trait(), |checker| {
-        visit_implementation_of_const_param_ty(checker, LangItem::UnsizedConstParamTy)
+        visit_implementation_of_const_param_ty(checker)
     })?;
     checker.check(lang_items.coerce_unsized_trait(), visit_implementation_of_coerce_unsized)?;
     checker
@@ -138,12 +134,7 @@ fn visit_implementation_of_copy(checker: &Checker<'_>) -> Result<(), ErrorGuaran
     }
 }
 
-fn visit_implementation_of_const_param_ty(
-    checker: &Checker<'_>,
-    kind: LangItem,
-) -> Result<(), ErrorGuaranteed> {
-    assert_matches!(kind, LangItem::ConstParamTy | LangItem::UnsizedConstParamTy);
-
+fn visit_implementation_of_const_param_ty(checker: &Checker<'_>) -> Result<(), ErrorGuaranteed> {
     let tcx = checker.tcx;
     let header = checker.impl_header;
     let impl_did = checker.impl_def_id;
@@ -157,7 +148,7 @@ fn visit_implementation_of_const_param_ty(
     }
 
     let cause = traits::ObligationCause::misc(DUMMY_SP, impl_did);
-    match type_allowed_to_implement_const_param_ty(tcx, param_env, self_type, kind, cause) {
+    match type_allowed_to_implement_const_param_ty(tcx, param_env, self_type, cause) {
         Ok(()) => Ok(()),
         Err(ConstParamTyImplementationError::InfrigingFields(fields)) => {
             let span = tcx.hir_expect_item(impl_did).expect_impl().self_ty.span;
diff --git a/compiler/rustc_infer/src/traits/engine.rs b/compiler/rustc_infer/src/traits/engine.rs
index 9a66bd0574c..4a252719694 100644
--- a/compiler/rustc_infer/src/traits/engine.rs
+++ b/compiler/rustc_infer/src/traits/engine.rs
@@ -72,12 +72,27 @@ pub trait TraitEngine<'tcx, E: 'tcx>: 'tcx {
             self.register_predicate_obligation(infcx, obligation);
         }
     }
-
+    /// Go over the list of pending obligations and try to evaluate them.
+    ///
+    /// For each result:
+    /// Ok: remove the obligation from the list
+    /// Ambiguous: leave the obligation in the list to be evaluated later
+    /// Err: remove the obligation from the list and return an error
+    ///
+    /// Returns a list of errors from obligations that evaluated to Err.
     #[must_use]
     fn select_where_possible(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<E>;
 
     fn collect_remaining_errors(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<E>;
 
+    /// Evaluate all pending obligations, return error if they can't be evaluated.
+    ///
+    /// For each result:
+    /// Ok: remove the obligation from the list
+    /// Ambiguous: remove the obligation from the list and return an error
+    /// Err: remove the obligation from the list and return an error
+    ///
+    /// Returns a list of errors from obligations that evaluated to Ambiguous or Err.
     #[must_use]
     fn select_all_or_error(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<E> {
         let errors = self.select_where_possible(infcx);
diff --git a/compiler/rustc_trait_selection/src/traits/misc.rs b/compiler/rustc_trait_selection/src/traits/misc.rs
index 393f458bea2..4c25882daa9 100644
--- a/compiler/rustc_trait_selection/src/traits/misc.rs
+++ b/compiler/rustc_trait_selection/src/traits/misc.rs
@@ -1,15 +1,14 @@
 //! Miscellaneous type-system utilities that are too small to deserve their own modules.
 
-use std::assert_matches::assert_matches;
-
 use hir::LangItem;
 use rustc_ast::Mutability;
 use rustc_hir as hir;
 use rustc_infer::infer::{RegionResolutionError, TyCtxtInferExt};
 use rustc_middle::ty::{self, AdtDef, Ty, TyCtxt, TypeVisitableExt, TypingMode};
+use rustc_span::sym;
 
 use crate::regions::InferCtxtRegionExt;
-use crate::traits::{self, FulfillmentError, ObligationCause};
+use crate::traits::{self, FulfillmentError, Obligation, ObligationCause};
 
 pub enum CopyImplementationError<'tcx> {
     InfringingFields(Vec<(&'tcx ty::FieldDef, Ty<'tcx>, InfringingFieldsReason<'tcx>)>),
@@ -98,10 +97,9 @@ pub fn type_allowed_to_implement_const_param_ty<'tcx>(
     tcx: TyCtxt<'tcx>,
     param_env: ty::ParamEnv<'tcx>,
     self_type: Ty<'tcx>,
-    lang_item: LangItem,
     parent_cause: ObligationCause<'tcx>,
 ) -> Result<(), ConstParamTyImplementationError<'tcx>> {
-    assert_matches!(lang_item, LangItem::ConstParamTy | LangItem::UnsizedConstParamTy);
+    let mut need_unstable_feature_bound = false;
 
     let inner_tys: Vec<_> = match *self_type.kind() {
         // Trivially okay as these types are all:
@@ -112,18 +110,14 @@ pub fn type_allowed_to_implement_const_param_ty<'tcx>(
 
         // Handle types gated under `feature(unsized_const_params)`
         // FIXME(unsized_const_params): Make `const N: [u8]` work then forbid references
-        ty::Slice(inner_ty) | ty::Ref(_, inner_ty, Mutability::Not)
-            if lang_item == LangItem::UnsizedConstParamTy =>
-        {
+        ty::Slice(inner_ty) | ty::Ref(_, inner_ty, Mutability::Not) => {
+            need_unstable_feature_bound = true;
             vec![inner_ty]
         }
-        ty::Str if lang_item == LangItem::UnsizedConstParamTy => {
+        ty::Str => {
+            need_unstable_feature_bound = true;
             vec![Ty::new_slice(tcx, tcx.types.u8)]
         }
-        ty::Str | ty::Slice(..) | ty::Ref(_, _, Mutability::Not) => {
-            return Err(ConstParamTyImplementationError::UnsizedConstParamsFeatureRequired);
-        }
-
         ty::Array(inner_ty, _) => vec![inner_ty],
 
         // `str` morally acts like a newtype around `[u8]`
@@ -137,7 +131,7 @@ pub fn type_allowed_to_implement_const_param_ty<'tcx>(
                 adt,
                 args,
                 parent_cause.clone(),
-                lang_item,
+                LangItem::ConstParamTy,
             )
             .map_err(ConstParamTyImplementationError::InfrigingFields)?;
 
@@ -153,11 +147,25 @@ pub fn type_allowed_to_implement_const_param_ty<'tcx>(
         let infcx = tcx.infer_ctxt().build(TypingMode::non_body_analysis());
         let ocx = traits::ObligationCtxt::new_with_diagnostics(&infcx);
 
+        // Make sure impls certain types are gated with #[unstable_feature_bound(unsized_const_params)]
+        if need_unstable_feature_bound {
+            ocx.register_obligation(Obligation::new(
+                tcx,
+                parent_cause.clone(),
+                param_env,
+                ty::ClauseKind::UnstableFeature(sym::unsized_const_params),
+            ));
+
+            if !ocx.select_all_or_error().is_empty() {
+                return Err(ConstParamTyImplementationError::UnsizedConstParamsFeatureRequired);
+            }
+        }
+
         ocx.register_bound(
             parent_cause.clone(),
             param_env,
             inner_ty,
-            tcx.require_lang_item(lang_item, parent_cause.span),
+            tcx.require_lang_item(LangItem::ConstParamTy, parent_cause.span),
         );
 
         let errors = ocx.select_all_or_error();
diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs
index d03d7a43469..1c100312a9a 100644
--- a/library/core/src/marker.rs
+++ b/library/core/src/marker.rs
@@ -1083,7 +1083,7 @@ pub trait Tuple {}
 // We name this differently than the derive macro so that the `adt_const_params` can
 // be used independently of `unsized_const_params` without requiring a full path
 // to the derive macro every time it is used. This should be renamed on stabilization.
-pub trait ConstParamTy_: UnsizedConstParamTy + StructuralPartialEq + Eq {}
+pub trait ConstParamTy_: StructuralPartialEq + Eq {}
 
 /// Derive macro generating an impl of the trait `ConstParamTy`.
 #[rustc_builtin_macro]
@@ -1093,23 +1093,6 @@ pub macro ConstParamTy($item:item) {
     /* compiler built-in */
 }
 
-#[lang = "unsized_const_param_ty"]
-#[unstable(feature = "unsized_const_params", issue = "95174")]
-#[diagnostic::on_unimplemented(message = "`{Self}` can't be used as a const parameter type")]
-/// A marker for types which can be used as types of `const` generic parameters.
-///
-/// Equivalent to [`ConstParamTy_`] except that this is used by
-/// the `unsized_const_params` to allow for fake unstable impls.
-pub trait UnsizedConstParamTy: StructuralPartialEq + Eq {}
-
-/// Derive macro generating an impl of the trait `ConstParamTy`.
-#[rustc_builtin_macro]
-#[allow_internal_unstable(unsized_const_params)]
-#[unstable(feature = "unsized_const_params", issue = "95174")]
-pub macro UnsizedConstParamTy($item:item) {
-    /* compiler built-in */
-}
-
 // FIXME(adt_const_params): handle `ty::FnDef`/`ty::Closure`
 marker_impls! {
     #[unstable(feature = "adt_const_params", issue = "95174")]
@@ -1124,17 +1107,11 @@ marker_impls! {
 
 marker_impls! {
     #[unstable(feature = "unsized_const_params", issue = "95174")]
-    UnsizedConstParamTy for
-        usize, u8, u16, u32, u64, u128,
-        isize, i8, i16, i32, i64, i128,
-        bool,
-        char,
-        (),
-        {T: UnsizedConstParamTy, const N: usize} [T; N],
-
+    #[unstable_feature_bound(unsized_const_params)]
+    ConstParamTy_ for
         str,
-        {T: UnsizedConstParamTy} [T],
-        {T: UnsizedConstParamTy + ?Sized} &T,
+        {T: ConstParamTy_} [T],
+        {T: ConstParamTy_ + ?Sized} &T,
 }
 
 /// A common trait implemented by all function pointers.
diff --git a/library/core/src/mem/transmutability.rs b/library/core/src/mem/transmutability.rs
index 782b826448a..f36cb8cddb8 100644
--- a/library/core/src/mem/transmutability.rs
+++ b/library/core/src/mem/transmutability.rs
@@ -1,4 +1,4 @@
-use crate::marker::{ConstParamTy_, UnsizedConstParamTy};
+use crate::marker::ConstParamTy_;
 
 /// Marks that `Src` is transmutable into `Self`.
 ///
@@ -83,6 +83,7 @@ use crate::marker::{ConstParamTy_, UnsizedConstParamTy};
 /// Furthermore, stability does not imply portability. For example, the size of
 /// `usize` is stable, but not portable.
 #[unstable(feature = "transmutability", issue = "99571")]
+#[unstable_feature_bound(transmutability)]
 #[lang = "transmute_trait"]
 #[rustc_deny_explicit_impl]
 #[rustc_do_not_implement_via_object]
@@ -288,9 +289,8 @@ pub struct Assume {
 }
 
 #[unstable(feature = "transmutability", issue = "99571")]
+#[unstable_feature_bound(transmutability)]
 impl ConstParamTy_ for Assume {}
-#[unstable(feature = "transmutability", issue = "99571")]
-impl UnsizedConstParamTy for Assume {}
 
 impl Assume {
     /// With this, [`TransmuteFrom`] does not assume you have ensured any safety
diff --git a/library/core/src/tuple.rs b/library/core/src/tuple.rs
index 3892f831076..c57a8d81ade 100644
--- a/library/core/src/tuple.rs
+++ b/library/core/src/tuple.rs
@@ -1,7 +1,7 @@
 // See core/src/primitive_docs.rs for documentation.
 
 use crate::cmp::Ordering::{self, *};
-use crate::marker::{ConstParamTy_, StructuralPartialEq, UnsizedConstParamTy};
+use crate::marker::{ConstParamTy_, StructuralPartialEq};
 use crate::ops::ControlFlow::{self, Break, Continue};
 
 // Recursive macro for implementing n-ary tuple functions and operations
@@ -47,19 +47,13 @@ macro_rules! tuple_impls {
         maybe_tuple_doc! {
             $($T)+ @
             #[unstable(feature = "adt_const_params", issue = "95174")]
+            #[unstable_feature_bound(unsized_const_params)]
             impl<$($T: ConstParamTy_),+> ConstParamTy_ for ($($T,)+)
             {}
         }
 
         maybe_tuple_doc! {
             $($T)+ @
-            #[unstable(feature = "unsized_const_params", issue = "95174")]
-            impl<$($T: UnsizedConstParamTy),+> UnsizedConstParamTy for ($($T,)+)
-            {}
-        }
-
-        maybe_tuple_doc! {
-            $($T)+ @
             #[unstable(feature = "structural_match", issue = "31434")]
             impl<$($T),+> StructuralPartialEq for ($($T,)+)
             {}
diff --git a/tests/ui/const-generics/adt_const_params/auxiliary/unsized_const_param.rs b/tests/ui/const-generics/adt_const_params/auxiliary/unsized_const_param.rs
index e2ba459f8dd..1bfd7c34656 100644
--- a/tests/ui/const-generics/adt_const_params/auxiliary/unsized_const_param.rs
+++ b/tests/ui/const-generics/adt_const_params/auxiliary/unsized_const_param.rs
@@ -1,6 +1,6 @@
 #![feature(adt_const_params, unsized_const_params)]
 
-#[derive(std::marker::UnsizedConstParamTy, Eq, PartialEq)]
+#[derive(std::marker::ConstParamTy, Eq, PartialEq)]
 pub struct Foo([u8]);
 
 #[derive(std::marker::ConstParamTy, Eq, PartialEq)]
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_bad.rs b/tests/ui/const-generics/adt_const_params/const_param_ty_bad.rs
index 35539193a27..d482e7fad06 100644
--- a/tests/ui/const-generics/adt_const_params/const_param_ty_bad.rs
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_bad.rs
@@ -1,7 +1,7 @@
 #![allow(incomplete_features)]
 #![feature(adt_const_params, unsized_const_params)]
 
-fn check(_: impl std::marker::UnsizedConstParamTy) {}
+fn check(_: impl std::marker::ConstParamTy_) {}
 
 fn main() {
     check(main); //~ error: `fn() {main}` can't be used as a const parameter type
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_bad.stderr b/tests/ui/const-generics/adt_const_params/const_param_ty_bad.stderr
index c05584ef909..ff514f5608f 100644
--- a/tests/ui/const-generics/adt_const_params/const_param_ty_bad.stderr
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_bad.stderr
@@ -2,15 +2,15 @@ error[E0277]: `fn() {main}` can't be used as a const parameter type
   --> $DIR/const_param_ty_bad.rs:7:11
    |
 LL |     check(main);
-   |     ----- ^^^^ the trait `UnsizedConstParamTy` is not implemented for fn item `fn() {main}`
+   |     ----- ^^^^ the trait `ConstParamTy_` is not implemented for fn item `fn() {main}`
    |     |
    |     required by a bound introduced by this call
    |
 note: required by a bound in `check`
   --> $DIR/const_param_ty_bad.rs:4:18
    |
-LL | fn check(_: impl std::marker::UnsizedConstParamTy) {}
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+LL | fn check(_: impl std::marker::ConstParamTy_) {}
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
 help: use parentheses to call this function
    |
 LL |     check(main());
@@ -24,12 +24,12 @@ LL |     check(|| {});
    |     |
    |     required by a bound introduced by this call
    |
-   = help: the trait `UnsizedConstParamTy` is not implemented for closure `{closure@$DIR/const_param_ty_bad.rs:8:11: 8:13}`
+   = help: the trait `ConstParamTy_` is not implemented for closure `{closure@$DIR/const_param_ty_bad.rs:8:11: 8:13}`
 note: required by a bound in `check`
   --> $DIR/const_param_ty_bad.rs:4:18
    |
-LL | fn check(_: impl std::marker::UnsizedConstParamTy) {}
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+LL | fn check(_: impl std::marker::ConstParamTy_) {}
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
 help: use parentheses to call this closure
    |
 LL -     check(|| {});
@@ -40,15 +40,15 @@ error[E0277]: `fn()` can't be used as a const parameter type
   --> $DIR/const_param_ty_bad.rs:9:11
    |
 LL |     check(main as fn());
-   |     ----- ^^^^^^^^^^^^ the trait `UnsizedConstParamTy` is not implemented for `fn()`
+   |     ----- ^^^^^^^^^^^^ the trait `ConstParamTy_` is not implemented for `fn()`
    |     |
    |     required by a bound introduced by this call
    |
 note: required by a bound in `check`
   --> $DIR/const_param_ty_bad.rs:4:18
    |
-LL | fn check(_: impl std::marker::UnsizedConstParamTy) {}
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+LL | fn check(_: impl std::marker::ConstParamTy_) {}
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
 help: use parentheses to call this function pointer
    |
 LL |     check(main as fn()());
@@ -58,16 +58,16 @@ error[E0277]: `&mut ()` can't be used as a const parameter type
   --> $DIR/const_param_ty_bad.rs:10:11
    |
 LL |     check(&mut ());
-   |     ----- ^^^^^^^ the trait `UnsizedConstParamTy` is not implemented for `&mut ()`
+   |     ----- ^^^^^^^ the trait `ConstParamTy_` is not implemented for `&mut ()`
    |     |
    |     required by a bound introduced by this call
    |
-   = note: `UnsizedConstParamTy` is implemented for `&()`, but not for `&mut ()`
+   = note: `ConstParamTy_` is implemented for `&()`, but not for `&mut ()`
 note: required by a bound in `check`
   --> $DIR/const_param_ty_bad.rs:4:18
    |
-LL | fn check(_: impl std::marker::UnsizedConstParamTy) {}
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+LL | fn check(_: impl std::marker::ConstParamTy_) {}
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
 help: consider removing the leading `&`-reference
    |
 LL -     check(&mut ());
@@ -78,31 +78,31 @@ error[E0277]: `*mut ()` can't be used as a const parameter type
   --> $DIR/const_param_ty_bad.rs:11:11
    |
 LL |     check(&mut () as *mut ());
-   |     ----- ^^^^^^^^^^^^^^^^^^ the trait `UnsizedConstParamTy` is not implemented for `*mut ()`
+   |     ----- ^^^^^^^^^^^^^^^^^^ the trait `ConstParamTy_` is not implemented for `*mut ()`
    |     |
    |     required by a bound introduced by this call
    |
-   = help: the trait `UnsizedConstParamTy` is implemented for `()`
+   = help: the trait `ConstParamTy_` is implemented for `()`
 note: required by a bound in `check`
   --> $DIR/const_param_ty_bad.rs:4:18
    |
-LL | fn check(_: impl std::marker::UnsizedConstParamTy) {}
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+LL | fn check(_: impl std::marker::ConstParamTy_) {}
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
 
 error[E0277]: `*const ()` can't be used as a const parameter type
   --> $DIR/const_param_ty_bad.rs:12:11
    |
 LL |     check(&() as *const ());
-   |     ----- ^^^^^^^^^^^^^^^^ the trait `UnsizedConstParamTy` is not implemented for `*const ()`
+   |     ----- ^^^^^^^^^^^^^^^^ the trait `ConstParamTy_` is not implemented for `*const ()`
    |     |
    |     required by a bound introduced by this call
    |
-   = help: the trait `UnsizedConstParamTy` is implemented for `()`
+   = help: the trait `ConstParamTy_` is implemented for `()`
 note: required by a bound in `check`
   --> $DIR/const_param_ty_bad.rs:4:18
    |
-LL | fn check(_: impl std::marker::UnsizedConstParamTy) {}
-   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+LL | fn check(_: impl std::marker::ConstParamTy_) {}
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
 
 error: aborting due to 6 previous errors
 
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_dyn_compatibility.rs b/tests/ui/const-generics/adt_const_params/const_param_ty_dyn_compatibility.rs
index 6a553c2e085..2fcf872c99a 100644
--- a/tests/ui/const-generics/adt_const_params/const_param_ty_dyn_compatibility.rs
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_dyn_compatibility.rs
@@ -1,12 +1,9 @@
 #![feature(adt_const_params, unsized_const_params)]
 #![allow(incomplete_features)]
 
-use std::marker::{ConstParamTy_, UnsizedConstParamTy};
+use std::marker::ConstParamTy_;
 
 fn foo(a: &dyn ConstParamTy_) {}
 //~^ ERROR: the trait `ConstParamTy_`
 
-fn bar(a: &dyn UnsizedConstParamTy) {}
-//~^ ERROR: the trait `UnsizedConstParamTy`
-
 fn main() {}
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_dyn_compatibility.stderr b/tests/ui/const-generics/adt_const_params/const_param_ty_dyn_compatibility.stderr
index c71ec24dda3..ce695ff66d5 100644
--- a/tests/ui/const-generics/adt_const_params/const_param_ty_dyn_compatibility.stderr
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_dyn_compatibility.stderr
@@ -15,23 +15,6 @@ LL - fn foo(a: &dyn ConstParamTy_) {}
 LL + fn foo(a: &impl ConstParamTy_) {}
    |
 
-error[E0038]: the trait `UnsizedConstParamTy` is not dyn compatible
-  --> $DIR/const_param_ty_dyn_compatibility.rs:9:16
-   |
-LL | fn bar(a: &dyn UnsizedConstParamTy) {}
-   |                ^^^^^^^^^^^^^^^^^^^ `UnsizedConstParamTy` is not dyn compatible
-   |
-note: for a trait to be dyn compatible it needs to allow building a vtable
-      for more information, visit <https://doc.rust-lang.org/reference/items/traits.html#dyn-compatibility>
-  --> $SRC_DIR/core/src/cmp.rs:LL:COL
-   |
-   = note: the trait is not dyn compatible because it uses `Self` as a type parameter
-help: consider using an opaque type instead
-   |
-LL - fn bar(a: &dyn UnsizedConstParamTy) {}
-LL + fn bar(a: &impl UnsizedConstParamTy) {}
-   |
-
-error: aborting due to 2 previous errors
+error: aborting due to 1 previous error
 
 For more information about this error, try `rustc --explain E0038`.
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_generic_bounds_do_not_hold.rs b/tests/ui/const-generics/adt_const_params/const_param_ty_generic_bounds_do_not_hold.rs
index 7ffdafa33e9..a86d74275de 100644
--- a/tests/ui/const-generics/adt_const_params/const_param_ty_generic_bounds_do_not_hold.rs
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_generic_bounds_do_not_hold.rs
@@ -4,7 +4,7 @@
 #[derive(PartialEq, Eq)]
 struct NotParam;
 
-fn check<T: std::marker::UnsizedConstParamTy + ?Sized>() {}
+fn check<T: std::marker::ConstParamTy_ + ?Sized>() {}
 
 fn main() {
     check::<&NotParam>(); //~ error: `NotParam` can't be used as a const parameter type
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_generic_bounds_do_not_hold.stderr b/tests/ui/const-generics/adt_const_params/const_param_ty_generic_bounds_do_not_hold.stderr
index 158e76630f3..ca2aa3adcb7 100644
--- a/tests/ui/const-generics/adt_const_params/const_param_ty_generic_bounds_do_not_hold.stderr
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_generic_bounds_do_not_hold.stderr
@@ -4,17 +4,17 @@ error[E0277]: `NotParam` can't be used as a const parameter type
 LL |     check::<&NotParam>();
    |             ^^^^^^^^^ unsatisfied trait bound
    |
-help: the trait `UnsizedConstParamTy` is not implemented for `NotParam`
+help: the trait `ConstParamTy_` is not implemented for `NotParam`
   --> $DIR/const_param_ty_generic_bounds_do_not_hold.rs:5:1
    |
 LL | struct NotParam;
    | ^^^^^^^^^^^^^^^
-   = note: required for `&NotParam` to implement `UnsizedConstParamTy`
+   = note: required for `&NotParam` to implement `ConstParamTy_`
 note: required by a bound in `check`
   --> $DIR/const_param_ty_generic_bounds_do_not_hold.rs:7:13
    |
-LL | fn check<T: std::marker::UnsizedConstParamTy + ?Sized>() {}
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+LL | fn check<T: std::marker::ConstParamTy_ + ?Sized>() {}
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
 
 error[E0277]: `NotParam` can't be used as a const parameter type
   --> $DIR/const_param_ty_generic_bounds_do_not_hold.rs:11:13
@@ -22,17 +22,17 @@ error[E0277]: `NotParam` can't be used as a const parameter type
 LL |     check::<[NotParam]>();
    |             ^^^^^^^^^^ unsatisfied trait bound
    |
-help: the trait `UnsizedConstParamTy` is not implemented for `NotParam`
+help: the trait `ConstParamTy_` is not implemented for `NotParam`
   --> $DIR/const_param_ty_generic_bounds_do_not_hold.rs:5:1
    |
 LL | struct NotParam;
    | ^^^^^^^^^^^^^^^
-   = note: required for `[NotParam]` to implement `UnsizedConstParamTy`
+   = note: required for `[NotParam]` to implement `ConstParamTy_`
 note: required by a bound in `check`
   --> $DIR/const_param_ty_generic_bounds_do_not_hold.rs:7:13
    |
-LL | fn check<T: std::marker::UnsizedConstParamTy + ?Sized>() {}
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+LL | fn check<T: std::marker::ConstParamTy_ + ?Sized>() {}
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
 
 error[E0277]: `NotParam` can't be used as a const parameter type
   --> $DIR/const_param_ty_generic_bounds_do_not_hold.rs:12:13
@@ -40,17 +40,17 @@ error[E0277]: `NotParam` can't be used as a const parameter type
 LL |     check::<[NotParam; 17]>();
    |             ^^^^^^^^^^^^^^ unsatisfied trait bound
    |
-help: the trait `UnsizedConstParamTy` is not implemented for `NotParam`
+help: the trait `ConstParamTy_` is not implemented for `NotParam`
   --> $DIR/const_param_ty_generic_bounds_do_not_hold.rs:5:1
    |
 LL | struct NotParam;
    | ^^^^^^^^^^^^^^^
-   = note: required for `[NotParam; 17]` to implement `UnsizedConstParamTy`
+   = note: required for `[NotParam; 17]` to implement `ConstParamTy_`
 note: required by a bound in `check`
   --> $DIR/const_param_ty_generic_bounds_do_not_hold.rs:7:13
    |
-LL | fn check<T: std::marker::UnsizedConstParamTy + ?Sized>() {}
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
+LL | fn check<T: std::marker::ConstParamTy_ + ?Sized>() {}
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `check`
 
 error: aborting due to 3 previous errors
 
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_good.rs b/tests/ui/const-generics/adt_const_params/const_param_ty_good.rs
index 98a8eb6ee95..24bbc5a9a23 100644
--- a/tests/ui/const-generics/adt_const_params/const_param_ty_good.rs
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_good.rs
@@ -3,7 +3,7 @@
 #![feature(adt_const_params, unsized_const_params)]
 #![allow(incomplete_features)]
 
-use std::marker::UnsizedConstParamTy;
+use std::marker::{ConstParamTy, ConstParamTy_};
 
 #[derive(PartialEq, Eq)]
 struct S<T> {
@@ -11,15 +11,15 @@ struct S<T> {
     gen: T,
 }
 
-impl<T: UnsizedConstParamTy> UnsizedConstParamTy for S<T> {}
+impl<T: ConstParamTy_> ConstParamTy_ for S<T> {}
 
-#[derive(PartialEq, Eq, UnsizedConstParamTy)]
+#[derive(PartialEq, Eq, ConstParamTy)]
 struct D<T> {
     field: u8,
     gen: T,
 }
 
-fn check<T: UnsizedConstParamTy + ?Sized>() {}
+fn check<T: ConstParamTy_ + ?Sized>() {}
 
 fn main() {
     check::<u8>();
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_impl_bad_field.rs b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_bad_field.rs
index 8b3d0546010..0614ea97b1a 100644
--- a/tests/ui/const-generics/adt_const_params/const_param_ty_impl_bad_field.rs
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_bad_field.rs
@@ -7,10 +7,10 @@ struct NotParam;
 #[derive(PartialEq, Eq)]
 struct CantParam(NotParam);
 
-impl std::marker::UnsizedConstParamTy for CantParam {}
+impl std::marker::ConstParamTy_ for CantParam {}
 //~^ error: the trait `ConstParamTy_` cannot be implemented for this type
 
-#[derive(std::marker::UnsizedConstParamTy, Eq, PartialEq)]
+#[derive(std::marker::ConstParamTy, Eq, PartialEq)]
 //~^ error: the trait `ConstParamTy_` cannot be implemented for this type
 struct CantParamDerive(NotParam);
 
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_impl_bad_field.stderr b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_bad_field.stderr
index a4e5736d834..fd1836802c4 100644
--- a/tests/ui/const-generics/adt_const_params/const_param_ty_impl_bad_field.stderr
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_bad_field.stderr
@@ -1,17 +1,17 @@
 error[E0204]: the trait `ConstParamTy_` cannot be implemented for this type
-  --> $DIR/const_param_ty_impl_bad_field.rs:10:43
+  --> $DIR/const_param_ty_impl_bad_field.rs:10:37
    |
 LL | struct CantParam(NotParam);
    |                  -------- this field does not implement `ConstParamTy_`
 LL |
-LL | impl std::marker::UnsizedConstParamTy for CantParam {}
-   |                                           ^^^^^^^^^
+LL | impl std::marker::ConstParamTy_ for CantParam {}
+   |                                     ^^^^^^^^^
 
 error[E0204]: the trait `ConstParamTy_` cannot be implemented for this type
   --> $DIR/const_param_ty_impl_bad_field.rs:13:10
    |
-LL | #[derive(std::marker::UnsizedConstParamTy, Eq, PartialEq)]
-   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | #[derive(std::marker::ConstParamTy, Eq, PartialEq)]
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^
 LL |
 LL | struct CantParamDerive(NotParam);
    |                        -------- this field does not implement `ConstParamTy_`
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_impl_no_structural_eq.rs b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_no_structural_eq.rs
index e743b78fd13..a1c8eccfb09 100644
--- a/tests/ui/const-generics/adt_const_params/const_param_ty_impl_no_structural_eq.rs
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_no_structural_eq.rs
@@ -3,20 +3,20 @@
 
 #[derive(PartialEq, Eq)]
 struct ImplementsConstParamTy;
-impl std::marker::UnsizedConstParamTy for ImplementsConstParamTy {}
+impl std::marker::ConstParamTy_ for ImplementsConstParamTy {}
 
 struct CantParam(ImplementsConstParamTy);
 
-impl std::marker::UnsizedConstParamTy for CantParam {}
+impl std::marker::ConstParamTy_ for CantParam {}
 //~^ error: the type `CantParam` does not `#[derive(PartialEq)]`
 //~| ERROR the trait bound `CantParam: Eq` is not satisfied
 
-#[derive(std::marker::UnsizedConstParamTy)]
+#[derive(std::marker::ConstParamTy)]
 //~^ error: the type `CantParamDerive` does not `#[derive(PartialEq)]`
 //~| ERROR the trait bound `CantParamDerive: Eq` is not satisfied
 struct CantParamDerive(ImplementsConstParamTy);
 
-fn check<T: std::marker::UnsizedConstParamTy>() {}
+fn check<T: std::marker::ConstParamTy_>() {}
 
 fn main() {
     check::<ImplementsConstParamTy>();
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_impl_no_structural_eq.stderr b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_no_structural_eq.stderr
index d3141381db8..c6b791ed967 100644
--- a/tests/ui/const-generics/adt_const_params/const_param_ty_impl_no_structural_eq.stderr
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_no_structural_eq.stderr
@@ -1,10 +1,10 @@
 error[E0277]: the trait bound `CantParam: Eq` is not satisfied
-  --> $DIR/const_param_ty_impl_no_structural_eq.rs:10:43
+  --> $DIR/const_param_ty_impl_no_structural_eq.rs:10:37
    |
-LL | impl std::marker::UnsizedConstParamTy for CantParam {}
-   |                                           ^^^^^^^^^ the trait `Eq` is not implemented for `CantParam`
+LL | impl std::marker::ConstParamTy_ for CantParam {}
+   |                                     ^^^^^^^^^ the trait `Eq` is not implemented for `CantParam`
    |
-note: required by a bound in `UnsizedConstParamTy`
+note: required by a bound in `ConstParamTy_`
   --> $SRC_DIR/core/src/marker.rs:LL:COL
 help: consider annotating `CantParam` with `#[derive(Eq)]`
    |
@@ -13,26 +13,26 @@ LL | struct CantParam(ImplementsConstParamTy);
    |
 
 error[E0277]: the type `CantParam` does not `#[derive(PartialEq)]`
-  --> $DIR/const_param_ty_impl_no_structural_eq.rs:10:43
+  --> $DIR/const_param_ty_impl_no_structural_eq.rs:10:37
    |
-LL | impl std::marker::UnsizedConstParamTy for CantParam {}
-   |                                           ^^^^^^^^^ unsatisfied trait bound
+LL | impl std::marker::ConstParamTy_ for CantParam {}
+   |                                     ^^^^^^^^^ unsatisfied trait bound
    |
 help: the trait `StructuralPartialEq` is not implemented for `CantParam`
   --> $DIR/const_param_ty_impl_no_structural_eq.rs:8:1
    |
 LL | struct CantParam(ImplementsConstParamTy);
    | ^^^^^^^^^^^^^^^^
-note: required by a bound in `UnsizedConstParamTy`
+note: required by a bound in `ConstParamTy_`
   --> $SRC_DIR/core/src/marker.rs:LL:COL
 
 error[E0277]: the trait bound `CantParamDerive: Eq` is not satisfied
   --> $DIR/const_param_ty_impl_no_structural_eq.rs:14:10
    |
-LL | #[derive(std::marker::UnsizedConstParamTy)]
-   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Eq` is not implemented for `CantParamDerive`
+LL | #[derive(std::marker::ConstParamTy)]
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Eq` is not implemented for `CantParamDerive`
    |
-note: required by a bound in `UnsizedConstParamTy`
+note: required by a bound in `ConstParamTy_`
   --> $SRC_DIR/core/src/marker.rs:LL:COL
 help: consider annotating `CantParamDerive` with `#[derive(Eq)]`
    |
@@ -43,15 +43,15 @@ LL | struct CantParamDerive(ImplementsConstParamTy);
 error[E0277]: the type `CantParamDerive` does not `#[derive(PartialEq)]`
   --> $DIR/const_param_ty_impl_no_structural_eq.rs:14:10
    |
-LL | #[derive(std::marker::UnsizedConstParamTy)]
-   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unsatisfied trait bound
+LL | #[derive(std::marker::ConstParamTy)]
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^ unsatisfied trait bound
    |
 help: the trait `StructuralPartialEq` is not implemented for `CantParamDerive`
   --> $DIR/const_param_ty_impl_no_structural_eq.rs:17:1
    |
 LL | struct CantParamDerive(ImplementsConstParamTy);
    | ^^^^^^^^^^^^^^^^^^^^^^
-note: required by a bound in `UnsizedConstParamTy`
+note: required by a bound in `ConstParamTy_`
   --> $SRC_DIR/core/src/marker.rs:LL:COL
 
 error: aborting due to 4 previous errors
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_impl_union.rs b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_union.rs
index 236b3bc162a..0c9b12805f7 100644
--- a/tests/ui/const-generics/adt_const_params/const_param_ty_impl_union.rs
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_union.rs
@@ -12,10 +12,10 @@ impl PartialEq for Union {
 }
 impl Eq for Union {}
 
-impl std::marker::UnsizedConstParamTy for Union {}
+impl std::marker::ConstParamTy_ for Union {}
 //~^ ERROR the trait `ConstParamTy` may not be implemented for this type
 
-#[derive(std::marker::UnsizedConstParamTy)]
+#[derive(std::marker::ConstParamTy)]
 //~^ ERROR this trait cannot be derived for unions
 union UnionDerive {
     a: u8,
diff --git a/tests/ui/const-generics/adt_const_params/const_param_ty_impl_union.stderr b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_union.stderr
index 837c289c924..cc2147b49ae 100644
--- a/tests/ui/const-generics/adt_const_params/const_param_ty_impl_union.stderr
+++ b/tests/ui/const-generics/adt_const_params/const_param_ty_impl_union.stderr
@@ -1,14 +1,14 @@
 error: this trait cannot be derived for unions
   --> $DIR/const_param_ty_impl_union.rs:18:10
    |
-LL | #[derive(std::marker::UnsizedConstParamTy)]
-   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL | #[derive(std::marker::ConstParamTy)]
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: the trait `ConstParamTy` may not be implemented for this type
-  --> $DIR/const_param_ty_impl_union.rs:15:43
+  --> $DIR/const_param_ty_impl_union.rs:15:37
    |
-LL | impl std::marker::UnsizedConstParamTy for Union {}
-   |                                           ^^^^^ type is not a structure or enumeration
+LL | impl std::marker::ConstParamTy_ for Union {}
+   |                                     ^^^^^ type is not a structure or enumeration
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/const-generics/adt_const_params/nested_bad_const_param_ty.rs b/tests/ui/const-generics/adt_const_params/nested_bad_const_param_ty.rs
index 34ea143d254..d42ef90e1b1 100644
--- a/tests/ui/const-generics/adt_const_params/nested_bad_const_param_ty.rs
+++ b/tests/ui/const-generics/adt_const_params/nested_bad_const_param_ty.rs
@@ -5,17 +5,14 @@ use std::marker::ConstParamTy;
 
 #[derive(ConstParamTy)]
 //~^ ERROR the trait `ConstParamTy_` cannot be implemented for this ty
-//~| ERROR the trait `ConstParamTy_` cannot be implemented for this ty
 struct Foo([*const u8; 1]);
 
 #[derive(ConstParamTy)]
 //~^ ERROR the trait `ConstParamTy_` cannot be implemented for this ty
-//~| ERROR the trait `ConstParamTy_` cannot be implemented for this ty
 struct Foo2([*mut u8; 1]);
 
 #[derive(ConstParamTy)]
 //~^ ERROR the trait `ConstParamTy_` cannot be implemented for this ty
-//~| ERROR the trait `ConstParamTy_` cannot be implemented for this ty
 struct Foo3([fn(); 1]);
 
 fn main() {}
diff --git a/tests/ui/const-generics/adt_const_params/nested_bad_const_param_ty.stderr b/tests/ui/const-generics/adt_const_params/nested_bad_const_param_ty.stderr
index 6b8d2394a86..442ec6b96ce 100644
--- a/tests/ui/const-generics/adt_const_params/nested_bad_const_param_ty.stderr
+++ b/tests/ui/const-generics/adt_const_params/nested_bad_const_param_ty.stderr
@@ -3,91 +3,46 @@ error[E0204]: the trait `ConstParamTy_` cannot be implemented for this type
    |
 LL | #[derive(ConstParamTy)]
    |          ^^^^^^^^^^^^
-...
+LL |
 LL | struct Foo([*const u8; 1]);
    |            -------------- this field does not implement `ConstParamTy_`
    |
 note: the `ConstParamTy_` impl for `[*const u8; 1]` requires that `*const u8: ConstParamTy_`
-  --> $DIR/nested_bad_const_param_ty.rs:9:12
+  --> $DIR/nested_bad_const_param_ty.rs:8:12
    |
 LL | struct Foo([*const u8; 1]);
    |            ^^^^^^^^^^^^^^
 
 error[E0204]: the trait `ConstParamTy_` cannot be implemented for this type
-  --> $DIR/nested_bad_const_param_ty.rs:11:10
+  --> $DIR/nested_bad_const_param_ty.rs:10:10
    |
 LL | #[derive(ConstParamTy)]
    |          ^^^^^^^^^^^^
-...
+LL |
 LL | struct Foo2([*mut u8; 1]);
    |             ------------ this field does not implement `ConstParamTy_`
    |
 note: the `ConstParamTy_` impl for `[*mut u8; 1]` requires that `*mut u8: ConstParamTy_`
-  --> $DIR/nested_bad_const_param_ty.rs:14:13
+  --> $DIR/nested_bad_const_param_ty.rs:12:13
    |
 LL | struct Foo2([*mut u8; 1]);
    |             ^^^^^^^^^^^^
 
 error[E0204]: the trait `ConstParamTy_` cannot be implemented for this type
-  --> $DIR/nested_bad_const_param_ty.rs:16:10
+  --> $DIR/nested_bad_const_param_ty.rs:14:10
    |
 LL | #[derive(ConstParamTy)]
    |          ^^^^^^^^^^^^
-...
+LL |
 LL | struct Foo3([fn(); 1]);
    |             --------- this field does not implement `ConstParamTy_`
    |
 note: the `ConstParamTy_` impl for `[fn(); 1]` requires that `fn(): ConstParamTy_`
-  --> $DIR/nested_bad_const_param_ty.rs:19:13
+  --> $DIR/nested_bad_const_param_ty.rs:16:13
    |
 LL | struct Foo3([fn(); 1]);
    |             ^^^^^^^^^
 
-error[E0204]: the trait `ConstParamTy_` cannot be implemented for this type
-  --> $DIR/nested_bad_const_param_ty.rs:6:10
-   |
-LL | #[derive(ConstParamTy)]
-   |          ^^^^^^^^^^^^
-...
-LL | struct Foo([*const u8; 1]);
-   |            -------------- this field does not implement `ConstParamTy_`
-   |
-note: the `ConstParamTy_` impl for `[*const u8; 1]` requires that `*const u8: UnsizedConstParamTy`
-  --> $DIR/nested_bad_const_param_ty.rs:9:12
-   |
-LL | struct Foo([*const u8; 1]);
-   |            ^^^^^^^^^^^^^^
-
-error[E0204]: the trait `ConstParamTy_` cannot be implemented for this type
-  --> $DIR/nested_bad_const_param_ty.rs:11:10
-   |
-LL | #[derive(ConstParamTy)]
-   |          ^^^^^^^^^^^^
-...
-LL | struct Foo2([*mut u8; 1]);
-   |             ------------ this field does not implement `ConstParamTy_`
-   |
-note: the `ConstParamTy_` impl for `[*mut u8; 1]` requires that `*mut u8: UnsizedConstParamTy`
-  --> $DIR/nested_bad_const_param_ty.rs:14:13
-   |
-LL | struct Foo2([*mut u8; 1]);
-   |             ^^^^^^^^^^^^
-
-error[E0204]: the trait `ConstParamTy_` cannot be implemented for this type
-  --> $DIR/nested_bad_const_param_ty.rs:16:10
-   |
-LL | #[derive(ConstParamTy)]
-   |          ^^^^^^^^^^^^
-...
-LL | struct Foo3([fn(); 1]);
-   |             --------- this field does not implement `ConstParamTy_`
-   |
-note: the `ConstParamTy_` impl for `[fn(); 1]` requires that `fn(): UnsizedConstParamTy`
-  --> $DIR/nested_bad_const_param_ty.rs:19:13
-   |
-LL | struct Foo3([fn(); 1]);
-   |             ^^^^^^^^^
-
-error: aborting due to 6 previous errors
+error: aborting due to 3 previous errors
 
 For more information about this error, try `rustc --explain E0204`.
diff --git a/tests/ui/const-generics/adt_const_params/non_valtreeable_const_arg-2.stderr b/tests/ui/const-generics/adt_const_params/non_valtreeable_const_arg-2.stderr
index b13f76eabad..72dfda50ea5 100644
--- a/tests/ui/const-generics/adt_const_params/non_valtreeable_const_arg-2.stderr
+++ b/tests/ui/const-generics/adt_const_params/non_valtreeable_const_arg-2.stderr
@@ -9,11 +9,13 @@ help: you might be missing a const parameter
 LL | impl<const bar: /* Type */> Wrapper<{ bar() }> {
    |     +++++++++++++++++++++++
 
-error[E0741]: using function pointers as const generic parameters is forbidden
+error: using function pointers as const generic parameters is forbidden
   --> $DIR/non_valtreeable_const_arg-2.rs:8:25
    |
 LL | struct Wrapper<const F: fn()>;
    |                         ^^^^
+   |
+   = note: the only supported types are integers, `bool`, and `char`
 
 error[E0599]: the function or associated item `call` exists for struct `Wrapper<function>`, but its trait bounds were not satisfied
   --> $DIR/non_valtreeable_const_arg-2.rs:17:26
@@ -35,5 +37,5 @@ note: the trait `Fn` must be implemented
 
 error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0425, E0599, E0741.
+Some errors have detailed explanations: E0425, E0599.
 For more information about an error, try `rustc --explain E0425`.
diff --git a/tests/ui/const-generics/adt_const_params/reference_pointee_is_const_param-1.rs b/tests/ui/const-generics/adt_const_params/reference_pointee_is_const_param-1.rs
index a1ee1c4cdd5..937acf2e6bb 100644
--- a/tests/ui/const-generics/adt_const_params/reference_pointee_is_const_param-1.rs
+++ b/tests/ui/const-generics/adt_const_params/reference_pointee_is_const_param-1.rs
@@ -1,11 +1,11 @@
 #![feature(adt_const_params, unsized_const_params)]
 #![allow(incomplete_features)]
 
-use std::marker::UnsizedConstParamTy;
+use std::marker::ConstParamTy_;
 
 struct Foo;
 
-impl UnsizedConstParamTy for &'static Foo {}
+impl ConstParamTy_ for &'static Foo {}
 //~^ ERROR: the trait `ConstParamTy_` cannot be implemented for this type
 
 fn main() {}
diff --git a/tests/ui/const-generics/adt_const_params/reference_pointee_is_const_param-1.stderr b/tests/ui/const-generics/adt_const_params/reference_pointee_is_const_param-1.stderr
index 5ca8e6c7516..b977cf5d44e 100644
--- a/tests/ui/const-generics/adt_const_params/reference_pointee_is_const_param-1.stderr
+++ b/tests/ui/const-generics/adt_const_params/reference_pointee_is_const_param-1.stderr
@@ -1,8 +1,8 @@
 error[E0204]: the trait `ConstParamTy_` cannot be implemented for this type
-  --> $DIR/reference_pointee_is_const_param-1.rs:8:30
+  --> $DIR/reference_pointee_is_const_param-1.rs:8:24
    |
-LL | impl UnsizedConstParamTy for &'static Foo {}
-   |                              ^^^^^^^^^^^^ this field does not implement `ConstParamTy_`
+LL | impl ConstParamTy_ for &'static Foo {}
+   |                        ^^^^^^^^^^^^ this field does not implement `ConstParamTy_`
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/const-generics/adt_const_params/reference_pointee_is_const_param-2.rs b/tests/ui/const-generics/adt_const_params/reference_pointee_is_const_param-2.rs
index ac1b522f469..605fed26c9c 100644
--- a/tests/ui/const-generics/adt_const_params/reference_pointee_is_const_param-2.rs
+++ b/tests/ui/const-generics/adt_const_params/reference_pointee_is_const_param-2.rs
@@ -3,12 +3,12 @@
 
 // Regression test for #119299
 
-use std::marker::UnsizedConstParamTy;
+use std::marker::ConstParamTy_;
 
 #[derive(Eq, PartialEq)]
 struct ConstStrU(*const u8, usize);
 
-impl UnsizedConstParamTy for &'static ConstStrU {}
+impl ConstParamTy_ for &'static ConstStrU {}
 //~^ ERROR: the trait `ConstParamTy_` cannot be implemented for this type
 
 impl ConstStrU {
diff --git a/tests/ui/const-generics/adt_const_params/reference_pointee_is_const_param-2.stderr b/tests/ui/const-generics/adt_const_params/reference_pointee_is_const_param-2.stderr
index 5e5f6cc642d..0fe92f253a0 100644
--- a/tests/ui/const-generics/adt_const_params/reference_pointee_is_const_param-2.stderr
+++ b/tests/ui/const-generics/adt_const_params/reference_pointee_is_const_param-2.stderr
@@ -1,8 +1,8 @@
 error[E0204]: the trait `ConstParamTy_` cannot be implemented for this type
-  --> $DIR/reference_pointee_is_const_param-2.rs:11:30
+  --> $DIR/reference_pointee_is_const_param-2.rs:11:24
    |
-LL | impl UnsizedConstParamTy for &'static ConstStrU {}
-   |                              ^^^^^^^^^^^^^^^^^^ this field does not implement `ConstParamTy_`
+LL | impl ConstParamTy_ for &'static ConstStrU {}
+   |                        ^^^^^^^^^^^^^^^^^^ this field does not implement `ConstParamTy_`
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/const-generics/adt_const_params/trait_objects_as_a_const_generic.rs b/tests/ui/const-generics/adt_const_params/trait_objects_as_a_const_generic.rs
index b0934508399..0fe86adb291 100644
--- a/tests/ui/const-generics/adt_const_params/trait_objects_as_a_const_generic.rs
+++ b/tests/ui/const-generics/adt_const_params/trait_objects_as_a_const_generic.rs
@@ -1,11 +1,11 @@
 #![feature(adt_const_params, unsized_const_params)]
 #![allow(incomplete_features)]
 
-use std::marker::UnsizedConstParamTy;
+use std::marker::ConstParamTy_;
 
 trait Trait {}
 
-impl UnsizedConstParamTy for dyn Trait {}
+impl ConstParamTy_ for dyn Trait {}
 //~^ ERROR: the trait `ConstParamTy` may not be implemented for this type
 
 fn foo<const N: dyn Trait>() {}
diff --git a/tests/ui/const-generics/adt_const_params/trait_objects_as_a_const_generic.stderr b/tests/ui/const-generics/adt_const_params/trait_objects_as_a_const_generic.stderr
index 9933ba6e335..67c6314e297 100644
--- a/tests/ui/const-generics/adt_const_params/trait_objects_as_a_const_generic.stderr
+++ b/tests/ui/const-generics/adt_const_params/trait_objects_as_a_const_generic.stderr
@@ -1,8 +1,8 @@
 error: the trait `ConstParamTy` may not be implemented for this type
-  --> $DIR/trait_objects_as_a_const_generic.rs:8:30
+  --> $DIR/trait_objects_as_a_const_generic.rs:8:24
    |
-LL | impl UnsizedConstParamTy for dyn Trait {}
-   |                              ^^^^^^^^^ type is not a structure or enumeration
+LL | impl ConstParamTy_ for dyn Trait {}
+   |                        ^^^^^^^^^ type is not a structure or enumeration
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/const-generics/adt_const_params/unsized_field-1.rs b/tests/ui/const-generics/adt_const_params/unsized_field-1.rs
index f6e5bd6e355..5db031cb900 100644
--- a/tests/ui/const-generics/adt_const_params/unsized_field-1.rs
+++ b/tests/ui/const-generics/adt_const_params/unsized_field-1.rs
@@ -14,7 +14,10 @@ struct A([u8]);
 struct B(&'static [u8]);
 
 #[derive(ConstParamTy, Eq, PartialEq)]
-//~^ ERROR: the trait `ConstParamTy_` cannot be implemented for this type
 struct C(unsized_const_param::Foo);
 
+#[derive(std::marker::ConstParamTy, Eq, PartialEq)]
+//~^ ERROR: the trait `ConstParamTy_` cannot be implemented for this type
+struct D(unsized_const_param::GenericNotUnsizedParam<&'static [u8]>);
+
 fn main() {}
diff --git a/tests/ui/const-generics/adt_const_params/unsized_field-1.stderr b/tests/ui/const-generics/adt_const_params/unsized_field-1.stderr
index 3089b30bd76..a5ae5c726da 100644
--- a/tests/ui/const-generics/adt_const_params/unsized_field-1.stderr
+++ b/tests/ui/const-generics/adt_const_params/unsized_field-1.stderr
@@ -6,6 +6,12 @@ LL | #[derive(ConstParamTy, Eq, PartialEq)]
 LL |
 LL | struct A([u8]);
    |          ---- this field does not implement `ConstParamTy_`
+   |
+note: the `ConstParamTy_` impl for `[u8]` requires that `unstable feature: `unsized_const_params``
+  --> $DIR/unsized_field-1.rs:10:10
+   |
+LL | struct A([u8]);
+   |          ^^^^
 
 error[E0204]: the trait `ConstParamTy_` cannot be implemented for this type
   --> $DIR/unsized_field-1.rs:12:10
@@ -15,15 +21,27 @@ LL | #[derive(ConstParamTy, Eq, PartialEq)]
 LL |
 LL | struct B(&'static [u8]);
    |          ------------- this field does not implement `ConstParamTy_`
+   |
+note: the `ConstParamTy_` impl for `&'static [u8]` requires that `unstable feature: `unsized_const_params``
+  --> $DIR/unsized_field-1.rs:14:10
+   |
+LL | struct B(&'static [u8]);
+   |          ^^^^^^^^^^^^^
 
 error[E0204]: the trait `ConstParamTy_` cannot be implemented for this type
-  --> $DIR/unsized_field-1.rs:16:10
+  --> $DIR/unsized_field-1.rs:19:10
    |
-LL | #[derive(ConstParamTy, Eq, PartialEq)]
-   |          ^^^^^^^^^^^^
+LL | #[derive(std::marker::ConstParamTy, Eq, PartialEq)]
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^
 LL |
-LL | struct C(unsized_const_param::Foo);
-   |          ------------------------ this field does not implement `ConstParamTy_`
+LL | struct D(unsized_const_param::GenericNotUnsizedParam<&'static [u8]>);
+   |          ---------------------------------------------------------- this field does not implement `ConstParamTy_`
+   |
+note: the `ConstParamTy_` impl for `GenericNotUnsizedParam<&'static [u8]>` requires that `unstable feature: `unsized_const_params``
+  --> $DIR/unsized_field-1.rs:21:10
+   |
+LL | struct D(unsized_const_param::GenericNotUnsizedParam<&'static [u8]>);
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 3 previous errors
 
diff --git a/tests/ui/const-generics/adt_const_params/unsized_field-2.rs b/tests/ui/const-generics/adt_const_params/unsized_field-2.rs
deleted file mode 100644
index e4a3a481b4e..00000000000
--- a/tests/ui/const-generics/adt_const_params/unsized_field-2.rs
+++ /dev/null
@@ -1,14 +0,0 @@
-//@ aux-build:unsized_const_param.rs
-#![feature(adt_const_params, unsized_const_params)]
-//~^ WARN: the feature `unsized_const_params` is incomplete
-
-extern crate unsized_const_param;
-
-#[derive(std::marker::ConstParamTy, Eq, PartialEq)]
-//~^ ERROR: the trait `ConstParamTy_` cannot be implemented for this type
-struct A(unsized_const_param::GenericNotUnsizedParam<&'static [u8]>);
-
-#[derive(std::marker::UnsizedConstParamTy, Eq, PartialEq)]
-struct B(unsized_const_param::GenericNotUnsizedParam<&'static [u8]>);
-
-fn main() {}
diff --git a/tests/ui/const-generics/adt_const_params/unsized_field-2.stderr b/tests/ui/const-generics/adt_const_params/unsized_field-2.stderr
deleted file mode 100644
index cef70ca0463..00000000000
--- a/tests/ui/const-generics/adt_const_params/unsized_field-2.stderr
+++ /dev/null
@@ -1,27 +0,0 @@
-warning: the feature `unsized_const_params` is incomplete and may not be safe to use and/or cause compiler crashes
-  --> $DIR/unsized_field-2.rs:2:30
-   |
-LL | #![feature(adt_const_params, unsized_const_params)]
-   |                              ^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #95174 <https://github.com/rust-lang/rust/issues/95174> for more information
-   = note: `#[warn(incomplete_features)]` on by default
-
-error[E0204]: the trait `ConstParamTy_` cannot be implemented for this type
-  --> $DIR/unsized_field-2.rs:7:10
-   |
-LL | #[derive(std::marker::ConstParamTy, Eq, PartialEq)]
-   |          ^^^^^^^^^^^^^^^^^^^^^^^^^
-LL |
-LL | struct A(unsized_const_param::GenericNotUnsizedParam<&'static [u8]>);
-   |          ---------------------------------------------------------- this field does not implement `ConstParamTy_`
-   |
-note: the `ConstParamTy_` impl for `GenericNotUnsizedParam<&'static [u8]>` requires that `&'static [u8]: ConstParamTy_`
-  --> $DIR/unsized_field-2.rs:9:10
-   |
-LL | struct A(unsized_const_param::GenericNotUnsizedParam<&'static [u8]>);
-   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: aborting due to 1 previous error; 1 warning emitted
-
-For more information about this error, try `rustc --explain E0204`.
diff --git a/tests/ui/const-generics/adt_const_params/unsizing-wfcheck-issue-126272.rs b/tests/ui/const-generics/adt_const_params/unsizing-wfcheck-issue-126272.rs
index 311f507d3c7..500e8e22b0e 100644
--- a/tests/ui/const-generics/adt_const_params/unsizing-wfcheck-issue-126272.rs
+++ b/tests/ui/const-generics/adt_const_params/unsizing-wfcheck-issue-126272.rs
@@ -7,7 +7,6 @@ use std::marker::ConstParamTy;
 
 #[derive(Debug, PartialEq, Eq, ConstParamTy)]
 //~^ ERROR the trait `ConstParamTy_`
-//~| ERROR the trait `ConstParamTy_`
 struct Foo {
     nested: &'static Bar<dyn std::fmt::Debug>,
     //~^ ERROR the size for values
diff --git a/tests/ui/const-generics/adt_const_params/unsizing-wfcheck-issue-126272.stderr b/tests/ui/const-generics/adt_const_params/unsizing-wfcheck-issue-126272.stderr
index 992a27c1c0e..d4aeb91999c 100644
--- a/tests/ui/const-generics/adt_const_params/unsizing-wfcheck-issue-126272.stderr
+++ b/tests/ui/const-generics/adt_const_params/unsizing-wfcheck-issue-126272.stderr
@@ -1,17 +1,17 @@
 error[E0277]: the size for values of type `(dyn Debug + 'static)` cannot be known at compilation time
-  --> $DIR/unsizing-wfcheck-issue-126272.rs:12:13
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:11:13
    |
 LL |     nested: &'static Bar<dyn std::fmt::Debug>,
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
    |
    = help: the trait `Sized` is not implemented for `(dyn Debug + 'static)`
 note: required by an implicit `Sized` bound in `Bar`
-  --> $DIR/unsizing-wfcheck-issue-126272.rs:21:12
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:20:12
    |
 LL | struct Bar<T>(T);
    |            ^ required by the implicit `Sized` requirement on this type parameter in `Bar`
 help: you could relax the implicit `Sized` bound on `T` if it were used through indirection like `&T` or `Box<T>`
-  --> $DIR/unsizing-wfcheck-issue-126272.rs:21:12
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:20:12
    |
 LL | struct Bar<T>(T);
    |            ^  - ...if indirection were used here: `Box<T>`
@@ -26,34 +26,25 @@ LL | #[derive(Debug, PartialEq, Eq, ConstParamTy)]
 ...
 LL |     nested: &'static Bar<dyn std::fmt::Debug>,
    |     ----------------------------------------- this field does not implement `ConstParamTy_`
-
-error[E0204]: the trait `ConstParamTy_` cannot be implemented for this type
-  --> $DIR/unsizing-wfcheck-issue-126272.rs:8:32
    |
-LL | #[derive(Debug, PartialEq, Eq, ConstParamTy)]
-   |                                ^^^^^^^^^^^^
-...
-LL |     nested: &'static Bar<dyn std::fmt::Debug>,
-   |     ----------------------------------------- this field does not implement `ConstParamTy_`
-   |
-note: the `ConstParamTy_` impl for `&'static Bar<(dyn Debug + 'static)>` requires that `(dyn Debug + 'static): Eq`
-  --> $DIR/unsizing-wfcheck-issue-126272.rs:12:13
+note: the `ConstParamTy_` impl for `&'static Bar<(dyn Debug + 'static)>` requires that `(dyn Debug + 'static): ConstParamTy_`
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:11:13
    |
 LL |     nested: &'static Bar<dyn std::fmt::Debug>,
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-note: the `ConstParamTy_` impl for `&'static Bar<(dyn Debug + 'static)>` requires that `(dyn Debug + 'static): Sized`
-  --> $DIR/unsizing-wfcheck-issue-126272.rs:12:13
+note: the `ConstParamTy_` impl for `&'static Bar<(dyn Debug + 'static)>` requires that `(dyn Debug + 'static): Eq`
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:11:13
    |
 LL |     nested: &'static Bar<dyn std::fmt::Debug>,
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-note: the `ConstParamTy_` impl for `&'static Bar<(dyn Debug + 'static)>` requires that `(dyn Debug + 'static): UnsizedConstParamTy`
-  --> $DIR/unsizing-wfcheck-issue-126272.rs:12:13
+note: the `ConstParamTy_` impl for `&'static Bar<(dyn Debug + 'static)>` requires that `(dyn Debug + 'static): Sized`
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:11:13
    |
 LL |     nested: &'static Bar<dyn std::fmt::Debug>,
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0277]: the size for values of type `(dyn Debug + 'static)` cannot be known at compilation time
-  --> $DIR/unsizing-wfcheck-issue-126272.rs:12:5
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:11:5
    |
 LL | #[derive(Debug, PartialEq, Eq, ConstParamTy)]
    |          ----- in this derive macro expansion
@@ -64,7 +55,7 @@ LL |     nested: &'static Bar<dyn std::fmt::Debug>,
    = help: the trait `Sized` is not implemented for `(dyn Debug + 'static)`
    = help: the trait `Debug` is implemented for `Bar<T>`
 note: required for `Bar<(dyn Debug + 'static)>` to implement `Debug`
-  --> $DIR/unsizing-wfcheck-issue-126272.rs:20:10
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:19:10
    |
 LL | #[derive(Debug, PartialEq, Eq, ConstParamTy)]
    |          ^^^^^
@@ -75,7 +66,7 @@ LL | struct Bar<T>(T);
    = note: required for the cast from `&&&'static Bar<(dyn Debug + 'static)>` to `&dyn Debug`
 
 error[E0369]: binary operation `==` cannot be applied to type `&Bar<dyn Debug>`
-  --> $DIR/unsizing-wfcheck-issue-126272.rs:12:5
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:11:5
    |
 LL | #[derive(Debug, PartialEq, Eq, ConstParamTy)]
    |                 --------- in this derive macro expansion
@@ -84,7 +75,7 @@ LL |     nested: &'static Bar<dyn std::fmt::Debug>,
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0277]: the trait bound `dyn Debug: Eq` is not satisfied
-  --> $DIR/unsizing-wfcheck-issue-126272.rs:12:5
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:11:5
    |
 LL | #[derive(Debug, PartialEq, Eq, ConstParamTy)]
    |                            -- in this derive macro expansion
@@ -94,7 +85,7 @@ LL |     nested: &'static Bar<dyn std::fmt::Debug>,
    |
    = help: the trait `Eq` is implemented for `Bar<T>`
 note: required for `Bar<dyn Debug>` to implement `Eq`
-  --> $DIR/unsizing-wfcheck-issue-126272.rs:20:28
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:19:28
    |
 LL | #[derive(Debug, PartialEq, Eq, ConstParamTy)]
    |                            ^^ unsatisfied trait bound introduced in this `derive` macro
@@ -104,7 +95,7 @@ note: required by a bound in `AssertParamIsEq`
   --> $SRC_DIR/core/src/cmp.rs:LL:COL
 
 error[E0277]: the size for values of type `dyn Debug` cannot be known at compilation time
-  --> $DIR/unsizing-wfcheck-issue-126272.rs:12:5
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:11:5
    |
 LL | #[derive(Debug, PartialEq, Eq, ConstParamTy)]
    |                            -- in this derive macro expansion
@@ -114,12 +105,12 @@ LL |     nested: &'static Bar<dyn std::fmt::Debug>,
    |
    = help: the trait `Sized` is not implemented for `dyn Debug`
 note: required by an implicit `Sized` bound in `Bar`
-  --> $DIR/unsizing-wfcheck-issue-126272.rs:21:12
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:20:12
    |
 LL | struct Bar<T>(T);
    |            ^ required by the implicit `Sized` requirement on this type parameter in `Bar`
 help: you could relax the implicit `Sized` bound on `T` if it were used through indirection like `&T` or `Box<T>`
-  --> $DIR/unsizing-wfcheck-issue-126272.rs:21:12
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:20:12
    |
 LL | struct Bar<T>(T);
    |            ^  - ...if indirection were used here: `Box<T>`
@@ -127,26 +118,26 @@ LL | struct Bar<T>(T);
    |            this could be changed to `T: ?Sized`...
 
 error[E0277]: the size for values of type `(dyn Debug + 'static)` cannot be known at compilation time
-  --> $DIR/unsizing-wfcheck-issue-126272.rs:26:33
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:25:33
    |
 LL |     let x: Test<{ Foo { nested: &Bar(4) } }> = Test;
    |                                 ^^^^^^^ doesn't have a size known at compile-time
    |
    = help: the trait `Sized` is not implemented for `(dyn Debug + 'static)`
 note: required by an implicit `Sized` bound in `Bar`
-  --> $DIR/unsizing-wfcheck-issue-126272.rs:21:12
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:20:12
    |
 LL | struct Bar<T>(T);
    |            ^ required by the implicit `Sized` requirement on this type parameter in `Bar`
 help: you could relax the implicit `Sized` bound on `T` if it were used through indirection like `&T` or `Box<T>`
-  --> $DIR/unsizing-wfcheck-issue-126272.rs:21:12
+  --> $DIR/unsizing-wfcheck-issue-126272.rs:20:12
    |
 LL | struct Bar<T>(T);
    |            ^  - ...if indirection were used here: `Box<T>`
    |            |
    |            this could be changed to `T: ?Sized`...
 
-error: aborting due to 8 previous errors
+error: aborting due to 7 previous errors
 
 Some errors have detailed explanations: E0204, E0277, E0369.
 For more information about an error, try `rustc --explain E0204`.
diff --git a/tests/ui/const-generics/const-param-with-additional-obligations.rs b/tests/ui/const-generics/const-param-with-additional-obligations.rs
index 98097e86c7d..5110f95d5bf 100644
--- a/tests/ui/const-generics/const-param-with-additional-obligations.rs
+++ b/tests/ui/const-generics/const-param-with-additional-obligations.rs
@@ -1,14 +1,14 @@
 #![feature(adt_const_params, unsized_const_params)]
 #![allow(incomplete_features)]
 
-use std::marker::UnsizedConstParamTy;
+use std::marker::ConstParamTy_;
 
 #[derive(Eq, PartialEq)]
 struct Foo<T>(T);
 
 trait Other {}
 
-impl<T> UnsizedConstParamTy for Foo<T> where T: Other + UnsizedConstParamTy {}
+impl<T> ConstParamTy_ for Foo<T> where T: Other + ConstParamTy_ {}
 
 fn foo<const N: Foo<u8>>() {}
 //~^ ERROR `Foo<u8>` must implement `ConstParamTy` to be used as the type of a const generic parameter
diff --git a/tests/ui/const-generics/generic_const_parameter_types/no_const_param_ty_bound.stderr b/tests/ui/const-generics/generic_const_parameter_types/no_const_param_ty_bound.stderr
index 4ea323f4a5c..1eacc28b262 100644
--- a/tests/ui/const-generics/generic_const_parameter_types/no_const_param_ty_bound.stderr
+++ b/tests/ui/const-generics/generic_const_parameter_types/no_const_param_ty_bound.stderr
@@ -4,7 +4,7 @@ error[E0741]: `[T; N]` can't be used as a const parameter type
 LL | struct UsesType<T, const N: usize, const M: [T; N]>(PhantomData<T>);
    |                                             ^^^^^^
    |
-   = note: `T` must implement `UnsizedConstParamTy`, but it does not
+   = note: `T` must implement `ConstParamTy_`, but it does not
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/const-generics/issue-66451.rs b/tests/ui/const-generics/issue-66451.rs
index 0b8693e0e67..9ce7658586a 100644
--- a/tests/ui/const-generics/issue-66451.rs
+++ b/tests/ui/const-generics/issue-66451.rs
@@ -1,15 +1,15 @@
 #![feature(adt_const_params, unsized_const_params)]
 #![allow(incomplete_features)]
 
-use std::marker::UnsizedConstParamTy;
+use std::marker::ConstParamTy;
 
-#[derive(Debug, PartialEq, Eq, UnsizedConstParamTy)]
+#[derive(Debug, PartialEq, Eq, ConstParamTy)]
 struct Foo {
     value: i32,
     nested: &'static Bar<i32>,
 }
 
-#[derive(Debug, PartialEq, Eq, UnsizedConstParamTy)]
+#[derive(Debug, PartialEq, Eq, ConstParamTy)]
 struct Bar<T>(T);
 
 struct Test<const F: Foo>;
diff --git a/tests/ui/const-generics/issues/issue-63322-forbid-dyn.full.stderr b/tests/ui/const-generics/issues/issue-63322-forbid-dyn.full.stderr
index 8ea96428deb..1301ca92f01 100644
--- a/tests/ui/const-generics/issues/issue-63322-forbid-dyn.full.stderr
+++ b/tests/ui/const-generics/issues/issue-63322-forbid-dyn.full.stderr
@@ -4,7 +4,7 @@ error[E0741]: `&'static (dyn A + 'static)` can't be used as a const parameter ty
 LL | fn test<const T: &'static dyn A>() {
    |                  ^^^^^^^^^^^^^^
    |
-   = note: `(dyn A + 'static)` must implement `UnsizedConstParamTy`, but it does not
+   = note: `(dyn A + 'static)` must implement `ConstParamTy_`, but it does not
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/const-generics/slice-const-param-mismatch.adt_const_params.stderr b/tests/ui/const-generics/slice-const-param-mismatch.adt_const_params.stderr
index bcb2bd255da..d970b12df6a 100644
--- a/tests/ui/const-generics/slice-const-param-mismatch.adt_const_params.stderr
+++ b/tests/ui/const-generics/slice-const-param-mismatch.adt_const_params.stderr
@@ -1,14 +1,22 @@
-error[E0741]: `&'static str` can't be used as a const parameter type
-  --> $DIR/slice-const-param-mismatch.rs:8:29
+error[E0658]: use of unstable library feature `unsized_const_params`
+  --> $DIR/slice-const-param-mismatch.rs:8:20
    |
 LL | struct ConstString<const T: &'static str>;
-   |                             ^^^^^^^^^^^^
+   |                    ^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(unsized_const_params)]` 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 for `&'static str` to implement `ConstParamTy_`
 
-error[E0741]: `&'static [u8]` can't be used as a const parameter type
-  --> $DIR/slice-const-param-mismatch.rs:11:28
+error[E0658]: use of unstable library feature `unsized_const_params`
+  --> $DIR/slice-const-param-mismatch.rs:11:19
    |
 LL | struct ConstBytes<const T: &'static [u8]>;
-   |                            ^^^^^^^^^^^^^
+   |                   ^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(unsized_const_params)]` 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 for `&'static [u8]` to implement `ConstParamTy_`
 
 error[E0308]: mismatched types
   --> $DIR/slice-const-param-mismatch.rs:17:35
@@ -45,5 +53,5 @@ LL |     let _: ConstBytes<b"AAA"> = ConstBytes::<b"BBB">;
 
 error: aborting due to 5 previous errors
 
-Some errors have detailed explanations: E0308, E0741.
+Some errors have detailed explanations: E0308, E0658.
 For more information about an error, try `rustc --explain E0308`.
diff --git a/tests/ui/const-generics/slice-const-param.rs b/tests/ui/const-generics/slice-const-param.rs
index 1c5088b5283..8b5e934149e 100644
--- a/tests/ui/const-generics/slice-const-param.rs
+++ b/tests/ui/const-generics/slice-const-param.rs
@@ -12,7 +12,7 @@ pub fn function_with_bytes<const BYTES: &'static [u8]>() -> &'static [u8] {
 }
 
 // Also check the codepaths for custom DST
-#[derive(std::marker::UnsizedConstParamTy, PartialEq, Eq)]
+#[derive(std::marker::ConstParamTy, PartialEq, Eq)]
 struct MyStr(str);
 
 fn function_with_my_str<const S: &'static MyStr>() -> &'static MyStr {
diff --git a/tests/ui/const-generics/transmute-const-param-static-reference.adt_const_params.stderr b/tests/ui/const-generics/transmute-const-param-static-reference.adt_const_params.stderr
index 7a936ced030..c2351c707d7 100644
--- a/tests/ui/const-generics/transmute-const-param-static-reference.adt_const_params.stderr
+++ b/tests/ui/const-generics/transmute-const-param-static-reference.adt_const_params.stderr
@@ -1,9 +1,13 @@
-error[E0741]: `&'static ()` can't be used as a const parameter type
-  --> $DIR/transmute-const-param-static-reference.rs:9:23
+error[E0658]: use of unstable library feature `unsized_const_params`
+  --> $DIR/transmute-const-param-static-reference.rs:9:14
    |
 LL | struct Const<const P: &'static ()>;
-   |                       ^^^^^^^^^^^
+   |              ^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(unsized_const_params)]` 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 for `&'static ()` to implement `ConstParamTy_`
 
 error: aborting due to 1 previous error
 
-For more information about this error, try `rustc --explain E0741`.
+For more information about this error, try `rustc --explain E0658`.
diff --git a/tests/ui/const-generics/transmute-const-param-static-reference.rs b/tests/ui/const-generics/transmute-const-param-static-reference.rs
index 0b47fd31eaf..bf164bdadb0 100644
--- a/tests/ui/const-generics/transmute-const-param-static-reference.rs
+++ b/tests/ui/const-generics/transmute-const-param-static-reference.rs
@@ -8,7 +8,7 @@
 
 struct Const<const P: &'static ()>;
 //[min]~^ ERROR `&'static ()` is forbidden as the type of a const generic parameter
-//[adt_const_params]~^^ ERROR `&'static ()` can't be used as a const parameter type
+//[adt_const_params]~^^ ERROR use of unstable library feature `unsized_const_params`
 
 fn main() {
     const A: &'static () = unsafe { std::mem::transmute(10 as *const ()) };
diff --git a/tests/ui/const-generics/unsized_const_params/symbol_mangling_v0_str.rs b/tests/ui/const-generics/unsized_const_params/symbol_mangling_v0_str.rs
index 359126f1251..429c401af1f 100644
--- a/tests/ui/const-generics/unsized_const_params/symbol_mangling_v0_str.rs
+++ b/tests/ui/const-generics/unsized_const_params/symbol_mangling_v0_str.rs
@@ -1,13 +1,13 @@
 //@ check-pass
 //@ compile-flags: -Csymbol-mangling-version=v0
 #![allow(incomplete_features)]
-#![feature(unsized_const_params)]
+#![feature(adt_const_params, unsized_const_params)]
 
 // Regression test for #116303
 
 #[derive(PartialEq, Eq)]
 struct MyStr(str);
-impl std::marker::UnsizedConstParamTy for MyStr {}
+impl std::marker::ConstParamTy_ for MyStr {}
 
 fn function_with_my_str<const S: &'static MyStr>() -> &'static MyStr {
     S
diff --git a/tests/ui/feature-gates/feature-gate-adt_const_params.rs b/tests/ui/feature-gates/feature-gate-adt_const_params.rs
index 8a3bcf25963..7efa529c557 100644
--- a/tests/ui/feature-gates/feature-gate-adt_const_params.rs
+++ b/tests/ui/feature-gates/feature-gate-adt_const_params.rs
@@ -1,2 +1,6 @@
-struct Foo<const NAME: &'static str>; //~ ERROR `&'static str` is forbidden
+struct Bar(u8);
+
+struct Foo<const N: Bar>;
+//~^ ERROR: `Bar` is forbidden as the type of a const generic parameter
+
 fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-adt_const_params.stderr b/tests/ui/feature-gates/feature-gate-adt_const_params.stderr
index 18d514f8cb5..7ea91a8f4c2 100644
--- a/tests/ui/feature-gates/feature-gate-adt_const_params.stderr
+++ b/tests/ui/feature-gates/feature-gate-adt_const_params.stderr
@@ -1,18 +1,14 @@
-error: `&'static str` is forbidden as the type of a const generic parameter
-  --> $DIR/feature-gate-adt_const_params.rs:1:24
+error: `Bar` is forbidden as the type of a const generic parameter
+  --> $DIR/feature-gate-adt_const_params.rs:3:21
    |
-LL | struct Foo<const NAME: &'static str>;
-   |                        ^^^^^^^^^^^^
+LL | struct Foo<const N: Bar>;
+   |                     ^^^
    |
    = note: the only supported types are integers, `bool`, and `char`
 help: add `#![feature(adt_const_params)]` to the crate attributes to enable more complex and user defined types
    |
 LL + #![feature(adt_const_params)]
    |
-help: add `#![feature(unsized_const_params)]` to the crate attributes to enable references to implement the `ConstParamTy` trait
-   |
-LL + #![feature(unsized_const_params)]
-   |
 
 error: aborting due to 1 previous error
 
diff --git a/tests/ui/layout/thaw-transmute-invalid-enum.rs b/tests/ui/layout/thaw-transmute-invalid-enum.rs
index a7c2e1a86de..20fc8d46359 100644
--- a/tests/ui/layout/thaw-transmute-invalid-enum.rs
+++ b/tests/ui/layout/thaw-transmute-invalid-enum.rs
@@ -9,6 +9,7 @@ mod assert {
     where
         Dst: TransmuteFrom<Src>,
         //~^ ERROR: use of unstable library feature `transmutability`
+        //~^^ ERROR: use of unstable library feature `transmutability`
     {
     }
 }
diff --git a/tests/ui/layout/thaw-transmute-invalid-enum.stderr b/tests/ui/layout/thaw-transmute-invalid-enum.stderr
index d12fc4694e0..2b89159c263 100644
--- a/tests/ui/layout/thaw-transmute-invalid-enum.stderr
+++ b/tests/ui/layout/thaw-transmute-invalid-enum.stderr
@@ -1,5 +1,5 @@
 error[E0412]: cannot find type `Subset` in this scope
-  --> $DIR/thaw-transmute-invalid-enum.rs:34:41
+  --> $DIR/thaw-transmute-invalid-enum.rs:35:41
    |
 LL |     assert::is_transmutable::<Superset, Subset>();
    |                                         ^^^^^^ not found in this scope
@@ -10,7 +10,7 @@ LL | fn test<Subset>() {
    |        ++++++++
 
 error[E0517]: attribute should be applied to a struct or union
-  --> $DIR/thaw-transmute-invalid-enum.rs:21:11
+  --> $DIR/thaw-transmute-invalid-enum.rs:22:11
    |
 LL |   #[repr(C, packed(2))]
    |             ^^^^^^^^^
@@ -50,8 +50,19 @@ LL |         Dst: TransmuteFrom<Src>,
    = help: add `#![feature(transmutability)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
+error[E0658]: use of unstable library feature `transmutability`
+  --> $DIR/thaw-transmute-invalid-enum.rs:10:14
+   |
+LL |         Dst: TransmuteFrom<Src>,
+   |              ^^^^^^^^^^^^^^^^^^
+   |
+   = help: add `#![feature(transmutability)]` 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 by a bound in `TransmuteFrom`
+  --> $SRC_DIR/core/src/mem/transmutability.rs:LL:COL
+
 error[E0740]: field must implement `Copy` or be wrapped in `ManuallyDrop<...>` to be used in a union
-  --> $DIR/thaw-transmute-invalid-enum.rs:29:9
+  --> $DIR/thaw-transmute-invalid-enum.rs:30:9
    |
 LL |         a: Ox00,
    |         ^^^^^^^
@@ -62,7 +73,7 @@ help: wrap the field type in `ManuallyDrop<...>`
 LL |         a: std::mem::ManuallyDrop<Ox00>,
    |            +++++++++++++++++++++++    +
 
-error: aborting due to 6 previous errors
+error: aborting due to 7 previous errors
 
 Some errors have detailed explanations: E0412, E0517, E0658, E0740.
 For more information about an error, try `rustc --explain E0412`.
diff --git a/tests/ui/symbol-names/const-generics-structural-demangling.rs b/tests/ui/symbol-names/const-generics-structural-demangling.rs
index 06e3ce51fa6..0b4af61f991 100644
--- a/tests/ui/symbol-names/const-generics-structural-demangling.rs
+++ b/tests/ui/symbol-names/const-generics-structural-demangling.rs
@@ -6,7 +6,7 @@
 #![feature(adt_const_params, unsized_const_params, decl_macro, rustc_attrs)]
 #![allow(incomplete_features)]
 
-use std::marker::UnsizedConstParamTy;
+use std::marker::ConstParamTy;
 
 pub struct RefByte<const RB: &'static u8>;
 
@@ -42,7 +42,7 @@ pub struct TupleByteBool<const TBB: (u8, bool)>;
 //~| ERROR demangling-alt(<c::TupleByteBool<{(1, false)}>>)
 impl TupleByteBool<{ (1, false) }> {}
 
-#[derive(PartialEq, Eq, UnsizedConstParamTy)]
+#[derive(PartialEq, Eq, ConstParamTy)]
 pub enum MyOption<T> {
     Some(T),
     None,
@@ -66,7 +66,7 @@ impl OptionUsize<{ MyOption::None }> {}
 //~| ERROR demangling-alt(<c::OptionUsize<{c::MyOption::<usize>::Some(0)}>>)
 impl OptionUsize<{ MyOption::Some(0) }> {}
 
-#[derive(PartialEq, Eq, UnsizedConstParamTy)]
+#[derive(PartialEq, Eq, ConstParamTy)]
 pub struct Foo {
     s: &'static str,
     ch: char,
@@ -83,7 +83,7 @@ impl Foo_<{ Foo { s: "abc", ch: 'x', slice: &[1, 2, 3] } }> {}
 // NOTE(eddyb) this tests specifically the use of disambiguators in field names,
 // using macros 2.0 hygiene to create a `struct` with conflicting field names.
 macro duplicate_field_name_test($x:ident) {
-    #[derive(PartialEq, Eq, UnsizedConstParamTy)]
+    #[derive(PartialEq, Eq, ConstParamTy)]
     pub struct Bar {
         $x: u8,
         x: u16,