diff --git a/src/test/ui/const-generics/const_trait_fn-issue-88433.rs b/src/test/ui/const-generics/const_trait_fn-issue-88433.rs
index 8724fa69825..6e04cfaec31 100644
--- a/src/test/ui/const-generics/const_trait_fn-issue-88433.rs
+++ b/src/test/ui/const-generics/const_trait_fn-issue-88433.rs
@@ -2,6 +2,7 @@
 
 #![feature(const_trait_impl)]
 
+#[const_trait]
 trait Func<T> {
     type Output;
 
diff --git a/src/test/ui/const-generics/issues/issue-88119.rs b/src/test/ui/const-generics/issues/issue-88119.rs
index 70dfa7f708b..647b0eea86d 100644
--- a/src/test/ui/const-generics/issues/issue-88119.rs
+++ b/src/test/ui/const-generics/issues/issue-88119.rs
@@ -3,6 +3,7 @@
 #![allow(incomplete_features)]
 #![feature(const_trait_impl, generic_const_exprs)]
 
+#[const_trait]
 trait ConstName {
     const NAME_BYTES: &'static [u8];
 }
diff --git a/src/test/ui/const-generics/issues/issue-98629.rs b/src/test/ui/const-generics/issues/issue-98629.rs
index fc8666bbcdb..1d2d3012a6e 100644
--- a/src/test/ui/const-generics/issues/issue-98629.rs
+++ b/src/test/ui/const-generics/issues/issue-98629.rs
@@ -1,5 +1,6 @@
 #![feature(const_trait_impl)]
 
+#[const_trait]
 trait Trait {
     const N: usize;
 }
diff --git a/src/test/ui/const-generics/issues/issue-98629.stderr b/src/test/ui/const-generics/issues/issue-98629.stderr
index 53570220882..4a248be76a9 100644
--- a/src/test/ui/const-generics/issues/issue-98629.stderr
+++ b/src/test/ui/const-generics/issues/issue-98629.stderr
@@ -1,5 +1,5 @@
 error[E0046]: not all trait items implemented, missing: `N`
-  --> $DIR/issue-98629.rs:7:1
+  --> $DIR/issue-98629.rs:8:1
    |
 LL |     const N: usize;
    |     -------------- `N` from trait
diff --git a/src/test/ui/consts/const-eval/const-eval-overflow-3b.stderr b/src/test/ui/consts/const-eval/const-eval-overflow-3b.stderr
index 0e6be6d01ed..c685922c456 100644
--- a/src/test/ui/consts/const-eval/const-eval-overflow-3b.stderr
+++ b/src/test/ui/consts/const-eval/const-eval-overflow-3b.stderr
@@ -4,13 +4,13 @@ error[E0308]: mismatched types
 LL |     = [0; (i8::MAX + 1u8) as usize];
    |                      ^^^ expected `i8`, found `u8`
 
-error[E0277]: cannot add `u8` to `i8`
+error[E0277]: cannot add `u8` to `i8` in const contexts
   --> $DIR/const-eval-overflow-3b.rs:16:20
    |
 LL |     = [0; (i8::MAX + 1u8) as usize];
    |                    ^ no implementation for `i8 + u8`
    |
-   = help: the trait `Add<u8>` is not implemented for `i8`
+   = help: the trait `~const Add<u8>` is not implemented for `i8`
    = help: the following other types implement trait `Add<Rhs>`:
              <&'a f32 as Add<f32>>
              <&'a f64 as Add<f64>>
diff --git a/src/test/ui/consts/const-eval/const-eval-overflow-4b.stderr b/src/test/ui/consts/const-eval/const-eval-overflow-4b.stderr
index 4fa017e04e9..b396079240a 100644
--- a/src/test/ui/consts/const-eval/const-eval-overflow-4b.stderr
+++ b/src/test/ui/consts/const-eval/const-eval-overflow-4b.stderr
@@ -4,13 +4,13 @@ error[E0308]: mismatched types
 LL |     : [u32; (i8::MAX as i8 + 1u8) as usize]
    |                              ^^^ expected `i8`, found `u8`
 
-error[E0277]: cannot add `u8` to `i8`
+error[E0277]: cannot add `u8` to `i8` in const contexts
   --> $DIR/const-eval-overflow-4b.rs:9:28
    |
 LL |     : [u32; (i8::MAX as i8 + 1u8) as usize]
    |                            ^ no implementation for `i8 + u8`
    |
-   = help: the trait `Add<u8>` is not implemented for `i8`
+   = help: the trait `~const Add<u8>` is not implemented for `i8`
    = help: the following other types implement trait `Add<Rhs>`:
              <&'a f32 as Add<f32>>
              <&'a f64 as Add<f64>>
diff --git a/src/test/ui/consts/const-fn-error.rs b/src/test/ui/consts/const-fn-error.rs
index abe68c17a0d..5884a893f8b 100644
--- a/src/test/ui/consts/const-fn-error.rs
+++ b/src/test/ui/consts/const-fn-error.rs
@@ -3,9 +3,7 @@ const X : usize = 2;
 const fn f(x: usize) -> usize {
     let mut sum = 0;
     for i in 0..x {
-        //~^ ERROR mutable references
-        //~| ERROR cannot convert
-        //~| ERROR cannot call non-const fn
+        //~^ ERROR the trait bound
         //~| ERROR `for` is not allowed in a `const fn`
         sum += i;
     }
diff --git a/src/test/ui/consts/const-fn-error.stderr b/src/test/ui/consts/const-fn-error.stderr
index e36324f0b3e..040de150659 100644
--- a/src/test/ui/consts/const-fn-error.stderr
+++ b/src/test/ui/consts/const-fn-error.stderr
@@ -4,8 +4,6 @@ error[E0658]: `for` is not allowed in a `const fn`
 LL | /     for i in 0..x {
 LL | |
 LL | |
-LL | |
-LL | |
 LL | |         sum += i;
 LL | |     }
    | |_____^
@@ -13,37 +11,25 @@ LL | |     }
    = note: see issue #87575 <https://github.com/rust-lang/rust/issues/87575> for more information
    = help: add `#![feature(const_for)]` to the crate attributes to enable
 
-error[E0015]: cannot convert `std::ops::Range<usize>` into an iterator in constant functions
+error[E0277]: the trait bound `std::ops::Range<usize>: Iterator` is not satisfied
+  --> $DIR/const-fn-error.rs:5:14
+   |
+LL |     for i in 0..x {
+   |              ^^^^ `std::ops::Range<usize>` is not an iterator
+   |
+   = help: the trait `~const Iterator` is not implemented for `std::ops::Range<usize>`
+note: the trait `Iterator` is implemented for `std::ops::Range<usize>`, but that implementation is not `const`
   --> $DIR/const-fn-error.rs:5:14
    |
 LL |     for i in 0..x {
    |              ^^^^
+   = note: required for `std::ops::Range<usize>` to implement `~const IntoIterator`
+help: consider introducing a `where` clause, but there might be an alternative better way to express this requirement
    |
-note: impl defined here, but it is not `const`
-  --> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
-   |
-LL | impl<I: ~const Iterator> const IntoIterator for I {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
+LL | const fn f(x: usize) -> usize where std::ops::Range<usize>: ~const Iterator {
+   |                               +++++++++++++++++++++++++++++++++++++++++++++
 
-error[E0658]: mutable references are not allowed in constant functions
-  --> $DIR/const-fn-error.rs:5:14
-   |
-LL |     for i in 0..x {
-   |              ^^^^
-   |
-   = note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
-   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
+error: aborting due to 2 previous errors
 
-error[E0015]: cannot call non-const fn `<std::ops::Range<usize> as Iterator>::next` in constant functions
-  --> $DIR/const-fn-error.rs:5:14
-   |
-LL |     for i in 0..x {
-   |              ^^^^
-   |
-   = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
-
-error: aborting due to 4 previous errors
-
-Some errors have detailed explanations: E0015, E0658.
-For more information about an error, try `rustc --explain E0015`.
+Some errors have detailed explanations: E0277, E0658.
+For more information about an error, try `rustc --explain E0277`.
diff --git a/src/test/ui/consts/const-for-feature-gate.rs b/src/test/ui/consts/const-for-feature-gate.rs
index bec7b808905..8afc25fe3e5 100644
--- a/src/test/ui/consts/const-for-feature-gate.rs
+++ b/src/test/ui/consts/const-for-feature-gate.rs
@@ -3,6 +3,7 @@
 const _: () = {
     for _ in 0..5 {}
     //~^ error: `for` is not allowed in a `const`
+    //~| error: the trait bound
 };
 
 fn main() {}
diff --git a/src/test/ui/consts/const-for-feature-gate.stderr b/src/test/ui/consts/const-for-feature-gate.stderr
index 2ea377e09f6..f0887953891 100644
--- a/src/test/ui/consts/const-for-feature-gate.stderr
+++ b/src/test/ui/consts/const-for-feature-gate.stderr
@@ -7,6 +7,21 @@ LL |     for _ in 0..5 {}
    = note: see issue #87575 <https://github.com/rust-lang/rust/issues/87575> for more information
    = help: add `#![feature(const_for)]` to the crate attributes to enable
 
-error: aborting due to previous error
+error[E0277]: the trait bound `std::ops::Range<{integer}>: Iterator` is not satisfied
+  --> $DIR/const-for-feature-gate.rs:4:14
+   |
+LL |     for _ in 0..5 {}
+   |              ^^^^ `std::ops::Range<{integer}>` is not an iterator
+   |
+   = help: the trait `~const Iterator` is not implemented for `std::ops::Range<{integer}>`
+note: the trait `Iterator` is implemented for `std::ops::Range<{integer}>`, but that implementation is not `const`
+  --> $DIR/const-for-feature-gate.rs:4:14
+   |
+LL |     for _ in 0..5 {}
+   |              ^^^^
+   = note: required for `std::ops::Range<{integer}>` to implement `~const IntoIterator`
 
-For more information about this error, try `rustc --explain E0658`.
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0277, E0658.
+For more information about an error, try `rustc --explain E0277`.
diff --git a/src/test/ui/consts/const-for.rs b/src/test/ui/consts/const-for.rs
index 58bcb5f74cc..c6e958a9a95 100644
--- a/src/test/ui/consts/const-for.rs
+++ b/src/test/ui/consts/const-for.rs
@@ -3,8 +3,7 @@
 
 const _: () = {
     for _ in 0..5 {}
-    //~^ error: cannot convert
-    //~| error: cannot call non-const fn
+    //~^ error: the trait bound
 };
 
 fn main() {}
diff --git a/src/test/ui/consts/const-for.stderr b/src/test/ui/consts/const-for.stderr
index f2e1c8a4991..56637536310 100644
--- a/src/test/ui/consts/const-for.stderr
+++ b/src/test/ui/consts/const-for.stderr
@@ -1,24 +1,17 @@
-error[E0015]: cannot convert `std::ops::Range<i32>` into an iterator in constants
+error[E0277]: the trait bound `std::ops::Range<{integer}>: Iterator` is not satisfied
+  --> $DIR/const-for.rs:5:14
+   |
+LL |     for _ in 0..5 {}
+   |              ^^^^ `std::ops::Range<{integer}>` is not an iterator
+   |
+   = help: the trait `~const Iterator` is not implemented for `std::ops::Range<{integer}>`
+note: the trait `Iterator` is implemented for `std::ops::Range<{integer}>`, but that implementation is not `const`
   --> $DIR/const-for.rs:5:14
    |
 LL |     for _ in 0..5 {}
    |              ^^^^
-   |
-note: impl defined here, but it is not `const`
-  --> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
-   |
-LL | impl<I: ~const Iterator> const IntoIterator for I {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: calls in constants are limited to constant functions, tuple structs and tuple variants
+   = note: required for `std::ops::Range<{integer}>` to implement `~const IntoIterator`
 
-error[E0015]: cannot call non-const fn `<std::ops::Range<i32> as Iterator>::next` in constants
-  --> $DIR/const-for.rs:5:14
-   |
-LL |     for _ in 0..5 {}
-   |              ^^^^
-   |
-   = note: calls in constants are limited to constant functions, tuple structs and tuple variants
+error: aborting due to previous error
 
-error: aborting due to 2 previous errors
-
-For more information about this error, try `rustc --explain E0015`.
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/consts/control-flow/loop.rs b/src/test/ui/consts/control-flow/loop.rs
index 2b8561a2644..36daa685c5a 100644
--- a/src/test/ui/consts/control-flow/loop.rs
+++ b/src/test/ui/consts/control-flow/loop.rs
@@ -51,10 +51,12 @@ const _: i32 = {
     let mut x = 0;
 
     for i in 0..4 { //~ ERROR `for` is not allowed in a `const`
+        //~^ ERROR the trait bound
         x += i;
     }
 
     for i in 0..4 { //~ ERROR `for` is not allowed in a `const`
+        //~^ ERROR the trait bound
         x += i;
     }
 
diff --git a/src/test/ui/consts/control-flow/loop.stderr b/src/test/ui/consts/control-flow/loop.stderr
index 5f6ad8c105d..747729befde 100644
--- a/src/test/ui/consts/control-flow/loop.stderr
+++ b/src/test/ui/consts/control-flow/loop.stderr
@@ -2,6 +2,7 @@ error[E0658]: `for` is not allowed in a `const`
   --> $DIR/loop.rs:53:5
    |
 LL | /     for i in 0..4 {
+LL | |
 LL | |         x += i;
 LL | |     }
    | |_____^
@@ -10,9 +11,10 @@ LL | |     }
    = help: add `#![feature(const_for)]` to the crate attributes to enable
 
 error[E0658]: `for` is not allowed in a `const`
-  --> $DIR/loop.rs:57:5
+  --> $DIR/loop.rs:58:5
    |
 LL | /     for i in 0..4 {
+LL | |
 LL | |         x += i;
 LL | |     }
    | |_____^
@@ -20,6 +22,35 @@ LL | |     }
    = note: see issue #87575 <https://github.com/rust-lang/rust/issues/87575> for more information
    = help: add `#![feature(const_for)]` to the crate attributes to enable
 
-error: aborting due to 2 previous errors
+error[E0277]: the trait bound `std::ops::Range<{integer}>: Iterator` is not satisfied
+  --> $DIR/loop.rs:53:14
+   |
+LL |     for i in 0..4 {
+   |              ^^^^ `std::ops::Range<{integer}>` is not an iterator
+   |
+   = help: the trait `~const Iterator` is not implemented for `std::ops::Range<{integer}>`
+note: the trait `Iterator` is implemented for `std::ops::Range<{integer}>`, but that implementation is not `const`
+  --> $DIR/loop.rs:53:14
+   |
+LL |     for i in 0..4 {
+   |              ^^^^
+   = note: required for `std::ops::Range<{integer}>` to implement `~const IntoIterator`
 
-For more information about this error, try `rustc --explain E0658`.
+error[E0277]: the trait bound `std::ops::Range<{integer}>: Iterator` is not satisfied
+  --> $DIR/loop.rs:58:14
+   |
+LL |     for i in 0..4 {
+   |              ^^^^ `std::ops::Range<{integer}>` is not an iterator
+   |
+   = help: the trait `~const Iterator` is not implemented for `std::ops::Range<{integer}>`
+note: the trait `Iterator` is implemented for `std::ops::Range<{integer}>`, but that implementation is not `const`
+  --> $DIR/loop.rs:58:14
+   |
+LL |     for i in 0..4 {
+   |              ^^^^
+   = note: required for `std::ops::Range<{integer}>` to implement `~const IntoIterator`
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0277, E0658.
+For more information about an error, try `rustc --explain E0277`.
diff --git a/src/test/ui/consts/issue-94675.rs b/src/test/ui/consts/issue-94675.rs
index 0604aab3bcd..ce21ebdb9ac 100644
--- a/src/test/ui/consts/issue-94675.rs
+++ b/src/test/ui/consts/issue-94675.rs
@@ -7,9 +7,8 @@ struct Foo<'a> {
 impl<'a> Foo<'a> {
     const fn spam(&mut self, baz: &mut Vec<u32>) {
         self.bar[0] = baz.len();
-        //~^ ERROR cannot call non-const fn `Vec::<u32>::len` in constant functions
-        //~| ERROR the trait bound `Vec<usize>: ~const IndexMut<usize>` is not satisfied
-        //~| ERROR cannot call non-const operator in constant functions
+        //~^ the trait bound `Vec<usize>: ~const Index<_>` is not satisfied
+        //~| the trait bound `Vec<usize>: ~const IndexMut<usize>` is not satisfied
     }
 }
 
diff --git a/src/test/ui/consts/issue-94675.stderr b/src/test/ui/consts/issue-94675.stderr
index 6665e42835b..7ae293ffbf8 100644
--- a/src/test/ui/consts/issue-94675.stderr
+++ b/src/test/ui/consts/issue-94675.stderr
@@ -1,10 +1,15 @@
-error[E0015]: cannot call non-const fn `Vec::<u32>::len` in constant functions
-  --> $DIR/issue-94675.rs:9:27
+error[E0277]: the trait bound `Vec<usize>: ~const Index<_>` is not satisfied
+  --> $DIR/issue-94675.rs:9:9
    |
 LL |         self.bar[0] = baz.len();
-   |                           ^^^^^
+   |         ^^^^^^^^^^^ vector indices are of type `usize` or ranges of `usize`
    |
-   = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
+   = help: the trait `~const Index<_>` is not implemented for `Vec<usize>`
+note: the trait `Index<_>` is implemented for `Vec<usize>`, but that implementation is not `const`
+  --> $DIR/issue-94675.rs:9:9
+   |
+LL |         self.bar[0] = baz.len();
+   |         ^^^^^^^^^^^
 
 error[E0277]: the trait bound `Vec<usize>: ~const IndexMut<usize>` is not satisfied
   --> $DIR/issue-94675.rs:9:9
@@ -18,21 +23,11 @@ note: the trait `IndexMut<usize>` is implemented for `Vec<usize>`, but that impl
    |
 LL |         self.bar[0] = baz.len();
    |         ^^^^^^^^^^^
-
-error[E0015]: cannot call non-const operator in constant functions
-  --> $DIR/issue-94675.rs:9:9
+help: consider introducing a `where` clause, but there might be an alternative better way to express this requirement
    |
-LL |         self.bar[0] = baz.len();
-   |         ^^^^^^^^^^^
-   |
-note: impl defined here, but it is not `const`
-  --> $SRC_DIR/alloc/src/vec/mod.rs:LL:COL
-   |
-LL | impl<T, I: SliceIndex<[T]>, A: Allocator> IndexMut<I> for Vec<T, A> {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
+LL | impl<'a> Foo<'a> where Vec<usize>: ~const IndexMut<usize> {
+   |                  ++++++++++++++++++++++++++++++++++++++++
 
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
-Some errors have detailed explanations: E0015, E0277.
-For more information about an error, try `rustc --explain E0015`.
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/did_you_mean/issue-49746-unicode-confusable-in-float-literal-expt.stderr b/src/test/ui/did_you_mean/issue-49746-unicode-confusable-in-float-literal-expt.stderr
index 26986684f0c..81f3f269432 100644
--- a/src/test/ui/did_you_mean/issue-49746-unicode-confusable-in-float-literal-expt.stderr
+++ b/src/test/ui/did_you_mean/issue-49746-unicode-confusable-in-float-literal-expt.stderr
@@ -15,13 +15,13 @@ help: Unicode character '−' (Minus Sign) looks like '-' (Minus/Hyphen), but it
 LL | const UNIVERSAL_GRAVITATIONAL_CONSTANT: f64 = 6.674e-11; // m³⋅kg⁻¹⋅s⁻²
    |                                                     ~
 
-error[E0277]: cannot subtract `{integer}` from `{float}`
+error[E0277]: cannot subtract `{integer}` from `{float}` in const contexts
   --> $DIR/issue-49746-unicode-confusable-in-float-literal-expt.rs:1:53
    |
 LL | const UNIVERSAL_GRAVITATIONAL_CONSTANT: f64 = 6.674e−11; // m³⋅kg⁻¹⋅s⁻²
    |                                                     ^ no implementation for `{float} - {integer}`
    |
-   = help: the trait `Sub<{integer}>` is not implemented for `{float}`
+   = help: the trait `~const Sub<{integer}>` is not implemented for `{float}`
    = help: the following other types implement trait `Sub<Rhs>`:
              <&'a f32 as Sub<f32>>
              <&'a f64 as Sub<f64>>
diff --git a/src/test/ui/issues/issue-20605.stderr b/src/test/ui/issues/issue-20605.stderr
index e1858b63989..c8e1313f573 100644
--- a/src/test/ui/issues/issue-20605.stderr
+++ b/src/test/ui/issues/issue-20605.stderr
@@ -2,7 +2,7 @@ error[E0277]: the size for values of type `dyn Iterator<Item = &'a mut u8>` cann
   --> $DIR/issue-20605.rs:2:17
    |
 LL |     for item in *things { *item = 0 }
-   |                 ^^^^^^^ the trait `IntoIterator` is not implemented for `dyn Iterator<Item = &'a mut u8>`
+   |                 ^^^^^^^ the trait `~const IntoIterator` is not implemented for `dyn Iterator<Item = &'a mut u8>`
    |
    = note: the trait bound `dyn Iterator<Item = &'a mut u8>: IntoIterator` is not satisfied
    = note: required for `dyn Iterator<Item = &'a mut u8>` to implement `IntoIterator`
diff --git a/src/test/ui/issues/issue-25901.rs b/src/test/ui/issues/issue-25901.rs
index ba12e1ad021..1f7b341a97e 100644
--- a/src/test/ui/issues/issue-25901.rs
+++ b/src/test/ui/issues/issue-25901.rs
@@ -2,7 +2,7 @@ struct A;
 struct B;
 
 static S: &'static B = &A;
-//~^ ERROR cannot perform deref coercion on `A` in statics
+//~^ ERROR the trait bound
 
 use std::ops::Deref;
 
diff --git a/src/test/ui/issues/issue-25901.stderr b/src/test/ui/issues/issue-25901.stderr
index c6c80e41cf6..b9cac32229a 100644
--- a/src/test/ui/issues/issue-25901.stderr
+++ b/src/test/ui/issues/issue-25901.stderr
@@ -1,23 +1,15 @@
-error[E0015]: cannot perform deref coercion on `A` in statics
+error[E0277]: the trait bound `A: Deref` is not satisfied
+  --> $DIR/issue-25901.rs:4:24
+   |
+LL | static S: &'static B = &A;
+   |                        ^^ the trait `~const Deref` is not implemented for `A`
+   |
+note: the trait `Deref` is implemented for `A`, but that implementation is not `const`
   --> $DIR/issue-25901.rs:4:24
    |
 LL | static S: &'static B = &A;
    |                        ^^
-   |
-   = note: attempting to deref into `B`
-note: deref defined here
-  --> $DIR/issue-25901.rs:10:5
-   |
-LL |     type Target = B;
-   |     ^^^^^^^^^^^
-note: impl defined here, but it is not `const`
-  --> $DIR/issue-25901.rs:9:1
-   |
-LL | impl Deref for A {
-   | ^^^^^^^^^^^^^^^^
-   = note: calls in statics are limited to constant functions, tuple structs and tuple variants
-   = note: consider wrapping this expression in `Lazy::new(|| ...)` from the `once_cell` crate: https://crates.io/crates/once_cell
 
 error: aborting due to previous error
 
-For more information about this error, try `rustc --explain E0015`.
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/issues/issue-32709.stderr b/src/test/ui/issues/issue-32709.stderr
index 1d595ca5649..355b110b465 100644
--- a/src/test/ui/issues/issue-32709.stderr
+++ b/src/test/ui/issues/issue-32709.stderr
@@ -7,9 +7,7 @@ LL |     Err(5)?;
    |           ^ the trait `From<{integer}>` is not implemented for `()`
    |
    = note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
-   = help: the following other types implement trait `FromResidual<R>`:
-             <Result<T, F> as FromResidual<Result<Infallible, E>>>
-             <Result<T, F> as FromResidual<Yeet<E>>>
+   = help: the trait `FromResidual<Result<Infallible, E>>` is implemented for `Result<T, F>`
    = note: required for `Result<i32, ()>` to implement `FromResidual<Result<Infallible, {integer}>>`
 
 error: aborting due to previous error
diff --git a/src/test/ui/issues/issue-50582.rs b/src/test/ui/issues/issue-50582.rs
index 2d5c9358752..9848cf0b0b1 100644
--- a/src/test/ui/issues/issue-50582.rs
+++ b/src/test/ui/issues/issue-50582.rs
@@ -2,4 +2,5 @@ fn main() {
     Vec::<[(); 1 + for x in 0..1 {}]>::new();
     //~^ ERROR cannot add
     //~| ERROR `for` is not allowed in a `const`
+    //~| ERROR the trait bound
 }
diff --git a/src/test/ui/issues/issue-50582.stderr b/src/test/ui/issues/issue-50582.stderr
index 3d527eb6b4e..3b1936bb58c 100644
--- a/src/test/ui/issues/issue-50582.stderr
+++ b/src/test/ui/issues/issue-50582.stderr
@@ -7,13 +7,27 @@ LL |     Vec::<[(); 1 + for x in 0..1 {}]>::new();
    = note: see issue #87575 <https://github.com/rust-lang/rust/issues/87575> for more information
    = help: add `#![feature(const_for)]` to the crate attributes to enable
 
-error[E0277]: cannot add `()` to `{integer}`
+error[E0277]: the trait bound `std::ops::Range<{integer}>: Iterator` is not satisfied
+  --> $DIR/issue-50582.rs:2:29
+   |
+LL |     Vec::<[(); 1 + for x in 0..1 {}]>::new();
+   |                             ^^^^ `std::ops::Range<{integer}>` is not an iterator
+   |
+   = help: the trait `~const Iterator` is not implemented for `std::ops::Range<{integer}>`
+note: the trait `Iterator` is implemented for `std::ops::Range<{integer}>`, but that implementation is not `const`
+  --> $DIR/issue-50582.rs:2:29
+   |
+LL |     Vec::<[(); 1 + for x in 0..1 {}]>::new();
+   |                             ^^^^
+   = note: required for `std::ops::Range<{integer}>` to implement `~const IntoIterator`
+
+error[E0277]: cannot add `()` to `{integer}` in const contexts
   --> $DIR/issue-50582.rs:2:18
    |
 LL |     Vec::<[(); 1 + for x in 0..1 {}]>::new();
    |                  ^ no implementation for `{integer} + ()`
    |
-   = help: the trait `Add<()>` is not implemented for `{integer}`
+   = help: the trait `~const Add<()>` is not implemented for `{integer}`
    = help: the following other types implement trait `Add<Rhs>`:
              <&'a f32 as Add<f32>>
              <&'a f64 as Add<f64>>
@@ -25,7 +39,7 @@ LL |     Vec::<[(); 1 + for x in 0..1 {}]>::new();
              <&'a isize as Add<isize>>
            and 48 others
 
-error: aborting due to 2 previous errors
+error: aborting due to 3 previous errors
 
 Some errors have detailed explanations: E0277, E0658.
 For more information about an error, try `rustc --explain E0277`.
diff --git a/src/test/ui/issues/issue-50585.rs b/src/test/ui/issues/issue-50585.rs
index a2f11c98d5a..3ec56739d4b 100644
--- a/src/test/ui/issues/issue-50585.rs
+++ b/src/test/ui/issues/issue-50585.rs
@@ -2,4 +2,5 @@ fn main() {
     |y: Vec<[(); for x in 0..2 {}]>| {};
     //~^ ERROR mismatched types
     //~| ERROR `for` is not allowed in a `const`
+    //~| ERROR the trait bound
 }
diff --git a/src/test/ui/issues/issue-50585.stderr b/src/test/ui/issues/issue-50585.stderr
index e43cc20cbb5..ecd69f771c3 100644
--- a/src/test/ui/issues/issue-50585.stderr
+++ b/src/test/ui/issues/issue-50585.stderr
@@ -7,13 +7,27 @@ LL |     |y: Vec<[(); for x in 0..2 {}]>| {};
    = note: see issue #87575 <https://github.com/rust-lang/rust/issues/87575> for more information
    = help: add `#![feature(const_for)]` to the crate attributes to enable
 
+error[E0277]: the trait bound `std::ops::Range<{integer}>: Iterator` is not satisfied
+  --> $DIR/issue-50585.rs:2:27
+   |
+LL |     |y: Vec<[(); for x in 0..2 {}]>| {};
+   |                           ^^^^ `std::ops::Range<{integer}>` is not an iterator
+   |
+   = help: the trait `~const Iterator` is not implemented for `std::ops::Range<{integer}>`
+note: the trait `Iterator` is implemented for `std::ops::Range<{integer}>`, but that implementation is not `const`
+  --> $DIR/issue-50585.rs:2:27
+   |
+LL |     |y: Vec<[(); for x in 0..2 {}]>| {};
+   |                           ^^^^
+   = note: required for `std::ops::Range<{integer}>` to implement `~const IntoIterator`
+
 error[E0308]: mismatched types
   --> $DIR/issue-50585.rs:2:18
    |
 LL |     |y: Vec<[(); for x in 0..2 {}]>| {};
    |                  ^^^^^^^^^^^^^^^^ expected `usize`, found `()`
 
-error: aborting due to 2 previous errors
+error: aborting due to 3 previous errors
 
-Some errors have detailed explanations: E0308, E0658.
-For more information about an error, try `rustc --explain E0308`.
+Some errors have detailed explanations: E0277, E0308, E0658.
+For more information about an error, try `rustc --explain E0277`.
diff --git a/src/test/ui/never_type/issue-52443.rs b/src/test/ui/never_type/issue-52443.rs
index cebcca944af..1b87e916853 100644
--- a/src/test/ui/never_type/issue-52443.rs
+++ b/src/test/ui/never_type/issue-52443.rs
@@ -8,7 +8,5 @@ fn main() {
 
     [(); { for _ in 0usize.. {}; 0}];
     //~^ ERROR `for` is not allowed in a `const`
-    //~| ERROR cannot convert
-    //~| ERROR mutable references are not allowed in constants
-    //~| ERROR cannot call non-const fn
+    //~| ERROR the trait bound
 }
diff --git a/src/test/ui/never_type/issue-52443.stderr b/src/test/ui/never_type/issue-52443.stderr
index 3c0daa4c55f..4a89d4f6d37 100644
--- a/src/test/ui/never_type/issue-52443.stderr
+++ b/src/test/ui/never_type/issue-52443.stderr
@@ -38,37 +38,25 @@ LL |     [(); loop { break }];
    |                 expected `usize`, found `()`
    |                 help: give it a value of the expected type: `break 42`
 
-error[E0015]: cannot convert `RangeFrom<usize>` into an iterator in constants
+error[E0277]: the trait bound `RangeFrom<usize>: Iterator` is not satisfied
+  --> $DIR/issue-52443.rs:9:21
+   |
+LL |     [(); { for _ in 0usize.. {}; 0}];
+   |                     ^^^^^^^^ `RangeFrom<usize>` is not an iterator
+   |
+   = help: the trait `~const Iterator` is not implemented for `RangeFrom<usize>`
+note: the trait `Iterator` is implemented for `RangeFrom<usize>`, but that implementation is not `const`
   --> $DIR/issue-52443.rs:9:21
    |
 LL |     [(); { for _ in 0usize.. {}; 0}];
    |                     ^^^^^^^^
+   = note: required for `RangeFrom<usize>` to implement `~const IntoIterator`
+help: consider introducing a `where` clause, but there might be an alternative better way to express this requirement
    |
-note: impl defined here, but it is not `const`
-  --> $SRC_DIR/core/src/iter/traits/collect.rs:LL:COL
-   |
-LL | impl<I: ~const Iterator> const IntoIterator for I {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: calls in constants are limited to constant functions, tuple structs and tuple variants
+LL | fn main() where RangeFrom<usize>: ~const Iterator {
+   |           +++++++++++++++++++++++++++++++++++++++
 
-error[E0658]: mutable references are not allowed in constants
-  --> $DIR/issue-52443.rs:9:21
-   |
-LL |     [(); { for _ in 0usize.. {}; 0}];
-   |                     ^^^^^^^^
-   |
-   = note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
-   = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
+error: aborting due to 4 previous errors; 1 warning emitted
 
-error[E0015]: cannot call non-const fn `<RangeFrom<usize> as Iterator>::next` in constants
-  --> $DIR/issue-52443.rs:9:21
-   |
-LL |     [(); { for _ in 0usize.. {}; 0}];
-   |                     ^^^^^^^^
-   |
-   = note: calls in constants are limited to constant functions, tuple structs and tuple variants
-
-error: aborting due to 6 previous errors; 1 warning emitted
-
-Some errors have detailed explanations: E0015, E0308, E0658.
-For more information about an error, try `rustc --explain E0015`.
+Some errors have detailed explanations: E0277, E0308, E0658.
+For more information about an error, try `rustc --explain E0277`.
diff --git a/src/test/ui/rfc-2632-const-trait-impl/assoc-type.rs b/src/test/ui/rfc-2632-const-trait-impl/assoc-type.rs
index 99eacaa837f..7d9dae52cf1 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/assoc-type.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/assoc-type.rs
@@ -10,6 +10,7 @@ impl std::ops::Add for NonConstAdd {
     }
 }
 
+#[const_trait]
 trait Foo {
     type Bar: ~const std::ops::Add;
 }
@@ -19,6 +20,7 @@ impl const Foo for NonConstAdd {
     //~^ ERROR: cannot add `NonConstAdd` to `NonConstAdd` in const contexts
 }
 
+#[const_trait]
 trait Baz {
     type Qux: std::ops::Add;
 }
diff --git a/src/test/ui/rfc-2632-const-trait-impl/assoc-type.stderr b/src/test/ui/rfc-2632-const-trait-impl/assoc-type.stderr
index 64501c52374..ce2425010ad 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/assoc-type.stderr
+++ b/src/test/ui/rfc-2632-const-trait-impl/assoc-type.stderr
@@ -1,17 +1,17 @@
 error[E0277]: cannot add `NonConstAdd` to `NonConstAdd` in const contexts
-  --> $DIR/assoc-type.rs:18:16
+  --> $DIR/assoc-type.rs:19:16
    |
 LL |     type Bar = NonConstAdd;
    |                ^^^^^^^^^^^ no implementation for `NonConstAdd + NonConstAdd`
    |
    = help: the trait `~const Add` is not implemented for `NonConstAdd`
 note: the trait `Add` is implemented for `NonConstAdd`, but that implementation is not `const`
-  --> $DIR/assoc-type.rs:18:16
+  --> $DIR/assoc-type.rs:19:16
    |
 LL |     type Bar = NonConstAdd;
    |                ^^^^^^^^^^^
 note: required by a bound in `Foo::Bar`
-  --> $DIR/assoc-type.rs:14:15
+  --> $DIR/assoc-type.rs:15:15
    |
 LL |     type Bar: ~const std::ops::Add;
    |               ^^^^^^^^^^^^^^^^^^^^ required by this bound in `Foo::Bar`
diff --git a/src/test/ui/rfc-2632-const-trait-impl/auxiliary/staged-api.rs b/src/test/ui/rfc-2632-const-trait-impl/auxiliary/staged-api.rs
index 19e9006094b..589e3f02420 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/auxiliary/staged-api.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/auxiliary/staged-api.rs
@@ -3,6 +3,7 @@
 #![stable(feature = "rust1", since = "1.0.0")]
 
 #[stable(feature = "rust1", since = "1.0.0")]
+#[const_trait]
 pub trait MyTrait {
     #[stable(feature = "rust1", since = "1.0.0")]
     fn func();
diff --git a/src/test/ui/rfc-2632-const-trait-impl/call-const-trait-method-fail.rs b/src/test/ui/rfc-2632-const-trait-impl/call-const-trait-method-fail.rs
index 24b9235bb9a..dd993397420 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/call-const-trait-method-fail.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/call-const-trait-method-fail.rs
@@ -1,5 +1,6 @@
 #![feature(const_trait_impl)]
 
+#[const_trait]
 pub trait Plus {
     fn plus(self, rhs: Self) -> Self;
 }
@@ -23,7 +24,6 @@ pub const fn add_i32(a: i32, b: i32) -> i32 {
 pub const fn add_u32(a: u32, b: u32) -> u32 {
     a.plus(b)
     //~^ ERROR the trait bound
-    //~| ERROR cannot call non-const fn
 }
 
 fn main() {}
diff --git a/src/test/ui/rfc-2632-const-trait-impl/call-const-trait-method-fail.stderr b/src/test/ui/rfc-2632-const-trait-impl/call-const-trait-method-fail.stderr
index 1fc9db27761..d9ad8043153 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/call-const-trait-method-fail.stderr
+++ b/src/test/ui/rfc-2632-const-trait-impl/call-const-trait-method-fail.stderr
@@ -1,24 +1,19 @@
 error[E0277]: the trait bound `u32: ~const Plus` is not satisfied
-  --> $DIR/call-const-trait-method-fail.rs:24:7
+  --> $DIR/call-const-trait-method-fail.rs:25:7
    |
 LL |     a.plus(b)
-   |       ^^^^^^^ the trait `~const Plus` is not implemented for `u32`
+   |       ^^^^ the trait `~const Plus` is not implemented for `u32`
    |
 note: the trait `Plus` is implemented for `u32`, but that implementation is not `const`
-  --> $DIR/call-const-trait-method-fail.rs:24:7
+  --> $DIR/call-const-trait-method-fail.rs:25:7
    |
 LL |     a.plus(b)
-   |       ^^^^^^^
-
-error[E0015]: cannot call non-const fn `<u32 as Plus>::plus` in constant functions
-  --> $DIR/call-const-trait-method-fail.rs:24:7
+   |       ^^^^
+help: consider introducing a `where` clause, but there might be an alternative better way to express this requirement
    |
-LL |     a.plus(b)
-   |       ^^^^^^^
-   |
-   = note: calls in constant functions are limited to constant functions, tuple structs and tuple variants
+LL | pub const fn add_u32(a: u32, b: u32) -> u32 where u32: ~const Plus {
+   |                                             ++++++++++++++++++++++
 
-error: aborting due to 2 previous errors
+error: aborting due to previous error
 
-Some errors have detailed explanations: E0015, E0277.
-For more information about an error, try `rustc --explain E0015`.
+For more information about this error, try `rustc --explain E0277`.
diff --git a/src/test/ui/rfc-2632-const-trait-impl/call-const-trait-method-pass.rs b/src/test/ui/rfc-2632-const-trait-impl/call-const-trait-method-pass.rs
index cf38bc3c964..b64161b6aa0 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/call-const-trait-method-pass.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/call-const-trait-method-pass.rs
@@ -21,6 +21,7 @@ impl const PartialEq for Int {
     }
 }
 
+#[const_trait]
 pub trait Plus {
     fn plus(self, rhs: Self) -> Self;
 }
diff --git a/src/test/ui/rfc-2632-const-trait-impl/call-generic-in-impl.rs b/src/test/ui/rfc-2632-const-trait-impl/call-generic-in-impl.rs
index 89dc47aad3d..50c46579086 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/call-generic-in-impl.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/call-generic-in-impl.rs
@@ -1,6 +1,7 @@
 // check-pass
 #![feature(const_trait_impl)]
 
+#[const_trait]
 trait MyPartialEq {
     fn eq(&self, other: &Self) -> bool;
 }
diff --git a/src/test/ui/rfc-2632-const-trait-impl/const-check-fns-in-const-impl.rs b/src/test/ui/rfc-2632-const-trait-impl/const-check-fns-in-const-impl.rs
index b3e3dd62be8..52984fb6be4 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/const-check-fns-in-const-impl.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/const-check-fns-in-const-impl.rs
@@ -1,6 +1,7 @@
 #![feature(const_trait_impl)]
 
 struct S;
+#[const_trait]
 trait T {
     fn foo();
 }
diff --git a/src/test/ui/rfc-2632-const-trait-impl/const-check-fns-in-const-impl.stderr b/src/test/ui/rfc-2632-const-trait-impl/const-check-fns-in-const-impl.stderr
index 9e49785c589..c8783de4c3e 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/const-check-fns-in-const-impl.stderr
+++ b/src/test/ui/rfc-2632-const-trait-impl/const-check-fns-in-const-impl.stderr
@@ -1,5 +1,5 @@
 error[E0015]: cannot call non-const fn `non_const` in constant functions
-  --> $DIR/const-check-fns-in-const-impl.rs:11:16
+  --> $DIR/const-check-fns-in-const-impl.rs:12:16
    |
 LL |     fn foo() { non_const() }
    |                ^^^^^^^^^^^
diff --git a/src/test/ui/rfc-2632-const-trait-impl/const-drop.rs b/src/test/ui/rfc-2632-const-trait-impl/const-drop.rs
index 04462c0a11b..8b4c4065815 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/const-drop.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/const-drop.rs
@@ -48,6 +48,7 @@ mod t {
     pub struct HasConstDrop(pub ConstDrop);
     pub struct TrivialFields(pub u8, pub i8, pub usize, pub isize);
 
+    #[const_trait]
     pub trait SomeTrait {
         fn foo();
     }
diff --git a/src/test/ui/rfc-2632-const-trait-impl/const-impl-recovery.rs b/src/test/ui/rfc-2632-const-trait-impl/const-impl-recovery.rs
index 470c653dd47..837124db04e 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/const-impl-recovery.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/const-impl-recovery.rs
@@ -1,9 +1,11 @@
 #![feature(const_trait_impl)]
 
+#[const_trait]
 trait Foo {}
 
 const impl Foo for i32 {} //~ ERROR: expected identifier, found keyword
 
+#[const_trait]
 trait Bar {}
 
 const impl<T: Foo> Bar for T {} //~ ERROR: expected identifier, found keyword
diff --git a/src/test/ui/rfc-2632-const-trait-impl/const-impl-recovery.stderr b/src/test/ui/rfc-2632-const-trait-impl/const-impl-recovery.stderr
index 709084c86e0..7217fc85543 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/const-impl-recovery.stderr
+++ b/src/test/ui/rfc-2632-const-trait-impl/const-impl-recovery.stderr
@@ -1,5 +1,5 @@
 error: expected identifier, found keyword `impl`
-  --> $DIR/const-impl-recovery.rs:5:7
+  --> $DIR/const-impl-recovery.rs:6:7
    |
 LL | const impl Foo for i32 {}
    |       ^^^^ expected identifier, found keyword
@@ -11,7 +11,7 @@ LL + impl const Foo for i32 {}
    |
 
 error: expected identifier, found keyword `impl`
-  --> $DIR/const-impl-recovery.rs:9:7
+  --> $DIR/const-impl-recovery.rs:11:7
    |
 LL | const impl<T: Foo> Bar for T {}
    |       ^^^^ expected identifier, found keyword
diff --git a/src/test/ui/rfc-2632-const-trait-impl/feature-gate.gated.stderr b/src/test/ui/rfc-2632-const-trait-impl/feature-gate.gated.stderr
index af4d3909e40..4c630d33c55 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/feature-gate.gated.stderr
+++ b/src/test/ui/rfc-2632-const-trait-impl/feature-gate.gated.stderr
@@ -1,5 +1,5 @@
 error: fatal error triggered by #[rustc_error]
-  --> $DIR/feature-gate.rs:13:1
+  --> $DIR/feature-gate.rs:14:1
    |
 LL | fn main() {}
    | ^^^^^^^^^
diff --git a/src/test/ui/rfc-2632-const-trait-impl/feature-gate.rs b/src/test/ui/rfc-2632-const-trait-impl/feature-gate.rs
index 7bac72e1bb6..0b409fbaac9 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/feature-gate.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/feature-gate.rs
@@ -5,6 +5,7 @@
 #![feature(rustc_attrs)]
 
 struct S;
+#[const_trait] //[stock]~ ERROR `const_trait` is a temporary placeholder
 trait T {}
 impl const T for S {}
 //[stock]~^ ERROR const trait impls are experimental
diff --git a/src/test/ui/rfc-2632-const-trait-impl/feature-gate.stock.stderr b/src/test/ui/rfc-2632-const-trait-impl/feature-gate.stock.stderr
index 91a8bb578a8..0e938c1c55d 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/feature-gate.stock.stderr
+++ b/src/test/ui/rfc-2632-const-trait-impl/feature-gate.stock.stderr
@@ -1,5 +1,5 @@
 error[E0658]: const trait impls are experimental
-  --> $DIR/feature-gate.rs:9:6
+  --> $DIR/feature-gate.rs:10:6
    |
 LL | impl const T for S {}
    |      ^^^^^
@@ -7,6 +7,15 @@ LL | impl const T for S {}
    = note: see issue #67792 <https://github.com/rust-lang/rust/issues/67792> for more information
    = help: add `#![feature(const_trait_impl)]` to the crate attributes to enable
 
-error: aborting due to previous error
+error[E0658]: `const_trait` is a temporary placeholder for marking a trait that is suitable for `const` `impls` and all default bodies as `const`, which may be removed or renamed in the future.
+  --> $DIR/feature-gate.rs:8:1
+   |
+LL | #[const_trait]
+   | ^^^^^^^^^^^^^^
+   |
+   = note: see issue #67792 <https://github.com/rust-lang/rust/issues/67792> for more information
+   = help: add `#![feature(const_trait_impl)]` to the crate attributes to enable
+
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0658`.
diff --git a/src/test/ui/rfc-2632-const-trait-impl/hir-const-check.rs b/src/test/ui/rfc-2632-const-trait-impl/hir-const-check.rs
index 80a4442de2c..337c733403b 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/hir-const-check.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/hir-const-check.rs
@@ -2,6 +2,7 @@
 
 #![feature(const_trait_impl)]
 
+#[const_trait]
 pub trait MyTrait {
     fn method(&self) -> Option<()>;
 }
diff --git a/src/test/ui/rfc-2632-const-trait-impl/hir-const-check.stderr b/src/test/ui/rfc-2632-const-trait-impl/hir-const-check.stderr
index 32df63e449d..6d2be1daa37 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/hir-const-check.stderr
+++ b/src/test/ui/rfc-2632-const-trait-impl/hir-const-check.stderr
@@ -1,5 +1,5 @@
 error[E0658]: `?` is not allowed in a `const fn`
-  --> $DIR/hir-const-check.rs:11:9
+  --> $DIR/hir-const-check.rs:12:9
    |
 LL |         Some(())?;
    |         ^^^^^^^^^
diff --git a/src/test/ui/rfc-2632-const-trait-impl/inherent-impl-const-bounds.rs b/src/test/ui/rfc-2632-const-trait-impl/inherent-impl-const-bounds.rs
index 2cef803a90e..f8ac793e4c1 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/inherent-impl-const-bounds.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/inherent-impl-const-bounds.rs
@@ -3,7 +3,9 @@
 
 struct S;
 
+#[const_trait]
 trait A {}
+#[const_trait]
 trait B {}
 
 impl const A for S {}
diff --git a/src/test/ui/rfc-2632-const-trait-impl/issue-100222.rs b/src/test/ui/rfc-2632-const-trait-impl/issue-100222.rs
index 1004bb28c59..9f3f38ad4bc 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/issue-100222.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/issue-100222.rs
@@ -16,6 +16,7 @@ pub trait IndexMut where Self: Index {
 
 impl Index for () { type Output = (); }
 
+#[cfg(not(any(nn, yn)))]
 impl const IndexMut for <() as Index>::Output {
     const C: <Self as Index>::Output = ();
     type Assoc = <Self as Index>::Output;
@@ -24,6 +25,15 @@ impl const IndexMut for <() as Index>::Output {
     {}
 }
 
+#[cfg(any(nn, yn))]
+impl IndexMut for <() as Index>::Output {
+    const C: <Self as Index>::Output = ();
+    type Assoc = <Self as Index>::Output;
+    fn foo(&mut self, x: <Self as Index>::Output) -> <Self as Index>::Output
+        where <Self as Index>::Output:,
+    {}
+}
+
 const C: <() as Index>::Output = ();
 
 fn main() {}
diff --git a/src/test/ui/rfc-2632-const-trait-impl/issue-92230-wf-super-trait-env.rs b/src/test/ui/rfc-2632-const-trait-impl/issue-92230-wf-super-trait-env.rs
index 97c27ce1a1c..4d346965394 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/issue-92230-wf-super-trait-env.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/issue-92230-wf-super-trait-env.rs
@@ -4,7 +4,9 @@
 
 #![feature(const_trait_impl)]
 
+#[const_trait]
 pub trait Super {}
+#[const_trait]
 pub trait Sub: Super {}
 
 impl<A> const Super for &A where A: ~const Super {}
diff --git a/src/test/ui/rfc-2632-const-trait-impl/non-const-op-in-closure-in-const.rs b/src/test/ui/rfc-2632-const-trait-impl/non-const-op-in-closure-in-const.rs
index defef9e0409..1a4509b1869 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/non-const-op-in-closure-in-const.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/non-const-op-in-closure-in-const.rs
@@ -2,6 +2,7 @@
 
 #![feature(const_trait_impl)]
 
+#[const_trait]
 trait Convert<T> {
     fn to(self) -> T;
 }
diff --git a/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail.rs b/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail.rs
index af465cad3d2..3e2b81368a5 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail.rs
@@ -1,8 +1,10 @@
 #![feature(const_trait_impl)]
 
+#[const_trait]
 trait Foo {
     fn a(&self);
 }
+#[const_trait]
 trait Bar: ~const Foo {}
 
 struct S;
diff --git a/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail.stderr b/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail.stderr
index 9e8b8f8c6ba..9787792ab13 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail.stderr
+++ b/src/test/ui/rfc-2632-const-trait-impl/super-traits-fail.stderr
@@ -1,16 +1,16 @@
 error[E0277]: the trait bound `S: ~const Foo` is not satisfied
-  --> $DIR/super-traits-fail.rs:13:12
+  --> $DIR/super-traits-fail.rs:15:12
    |
 LL | impl const Bar for S {}
    |            ^^^ the trait `~const Foo` is not implemented for `S`
    |
 note: the trait `Foo` is implemented for `S`, but that implementation is not `const`
-  --> $DIR/super-traits-fail.rs:13:12
+  --> $DIR/super-traits-fail.rs:15:12
    |
 LL | impl const Bar for S {}
    |            ^^^
 note: required by a bound in `Bar`
-  --> $DIR/super-traits-fail.rs:6:12
+  --> $DIR/super-traits-fail.rs:8:12
    |
 LL | trait Bar: ~const Foo {}
    |            ^^^^^^^^^^ required by this bound in `Bar`
diff --git a/src/test/ui/rfc-2632-const-trait-impl/super-traits.rs b/src/test/ui/rfc-2632-const-trait-impl/super-traits.rs
index aded4ca9a99..df96f6fb4ab 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/super-traits.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/super-traits.rs
@@ -1,9 +1,12 @@
 // check-pass
 #![feature(const_trait_impl)]
 
+#[const_trait]
 trait Foo {
     fn a(&self);
 }
+
+#[const_trait]
 trait Bar: ~const Foo {}
 
 struct S;
diff --git a/src/test/ui/rfc-2632-const-trait-impl/trait-where-clause-run.rs b/src/test/ui/rfc-2632-const-trait-impl/trait-where-clause-run.rs
index b7cf9a13b79..4b8b004069d 100644
--- a/src/test/ui/rfc-2632-const-trait-impl/trait-where-clause-run.rs
+++ b/src/test/ui/rfc-2632-const-trait-impl/trait-where-clause-run.rs
@@ -2,6 +2,7 @@
 
 #![feature(const_trait_impl)]
 
+#[const_trait]
 trait Bar {
     fn bar() -> u8;
 }
diff --git a/src/test/ui/stability-attribute/missing-const-stability.rs b/src/test/ui/stability-attribute/missing-const-stability.rs
index d89886af314..6eff899bfbf 100644
--- a/src/test/ui/stability-attribute/missing-const-stability.rs
+++ b/src/test/ui/stability-attribute/missing-const-stability.rs
@@ -19,6 +19,7 @@ impl Foo {
 }
 
 #[stable(feature = "stable", since = "1.0.0")]
+#[const_trait]
 pub trait Bar {
     #[stable(feature = "stable", since = "1.0.0")]
     fn fun();
diff --git a/src/test/ui/stability-attribute/missing-const-stability.stderr b/src/test/ui/stability-attribute/missing-const-stability.stderr
index 10978728fa3..4cfbe152891 100644
--- a/src/test/ui/stability-attribute/missing-const-stability.stderr
+++ b/src/test/ui/stability-attribute/missing-const-stability.stderr
@@ -5,7 +5,7 @@ LL | pub const fn foo() {}
    | ^^^^^^^^^^^^^^^^^^^^^
 
 error: implementation has missing const stability attribute
-  --> $DIR/missing-const-stability.rs:27:1
+  --> $DIR/missing-const-stability.rs:28:1
    |
 LL | / impl const Bar for Foo {
 LL | |
diff --git a/src/test/ui/suggestions/slice-issue-87994.stderr b/src/test/ui/suggestions/slice-issue-87994.stderr
index 84ecd749b0d..c6eb690ba5a 100644
--- a/src/test/ui/suggestions/slice-issue-87994.stderr
+++ b/src/test/ui/suggestions/slice-issue-87994.stderr
@@ -2,7 +2,7 @@ error[E0277]: the size for values of type `[i32]` cannot be known at compilation
   --> $DIR/slice-issue-87994.rs:3:12
    |
 LL |   for _ in v[1..] {
-   |            ^^^^^^ the trait `IntoIterator` is not implemented for `[i32]`
+   |            ^^^^^^ the trait `~const IntoIterator` is not implemented for `[i32]`
    |
    = note: the trait bound `[i32]: IntoIterator` is not satisfied
    = note: required for `[i32]` to implement `IntoIterator`
@@ -17,7 +17,7 @@ error[E0277]: `[i32]` is not an iterator
   --> $DIR/slice-issue-87994.rs:3:12
    |
 LL |   for _ in v[1..] {
-   |            ^^^^^^ the trait `IntoIterator` is not implemented for `[i32]`
+   |            ^^^^^^ the trait `~const IntoIterator` is not implemented for `[i32]`
    |
    = note: the trait bound `[i32]: IntoIterator` is not satisfied
    = note: required for `[i32]` to implement `IntoIterator`
@@ -32,7 +32,7 @@ error[E0277]: the size for values of type `[K]` cannot be known at compilation t
   --> $DIR/slice-issue-87994.rs:11:13
    |
 LL |   for i2 in v2[1..] {
-   |             ^^^^^^^ the trait `IntoIterator` is not implemented for `[K]`
+   |             ^^^^^^^ the trait `~const IntoIterator` is not implemented for `[K]`
    |
    = note: the trait bound `[K]: IntoIterator` is not satisfied
    = note: required for `[K]` to implement `IntoIterator`
@@ -47,7 +47,7 @@ error[E0277]: `[K]` is not an iterator
   --> $DIR/slice-issue-87994.rs:11:13
    |
 LL |   for i2 in v2[1..] {
-   |             ^^^^^^^ the trait `IntoIterator` is not implemented for `[K]`
+   |             ^^^^^^^ the trait `~const IntoIterator` is not implemented for `[K]`
    |
    = note: the trait bound `[K]: IntoIterator` is not satisfied
    = note: required for `[K]` to implement `IntoIterator`