bless after rebase

16 files changed, 750 insertions, 23 deletions

diff --git a/src/test/ui/borrowck/issue-81899.stderr b/src/test/ui/borrowck/issue-81899.stderr
index 92ebd5a220d..e7345ff3f9a 100644
--- a/src/test/ui/borrowck/issue-81899.stderr
+++ b/src/test/ui/borrowck/issue-81899.stderr
@@ -27,3 +27,16 @@ LL | const _CONST: &[u8] = &f(&[], |_| {});
 error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0080`.
+Future incompatibility report: Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/issue-81899.rs:4:23
+   |
+LL | const _CONST: &[u8] = &f(&[], |_| {});
+   | ----------------------^^^^^^^^^^^^^^^-
+   |                       |
+   |                       referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
diff --git a/src/test/ui/borrowck/issue-88434-minimal-example.stderr b/src/test/ui/borrowck/issue-88434-minimal-example.stderr
index d46cd862e34..47d83c65355 100644
--- a/src/test/ui/borrowck/issue-88434-minimal-example.stderr
+++ b/src/test/ui/borrowck/issue-88434-minimal-example.stderr
@@ -27,3 +27,16 @@ LL | const _CONST: &() = &f(&|_| {});
 error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0080`.
+Future incompatibility report: Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/issue-88434-minimal-example.rs:3:21
+   |
+LL | const _CONST: &() = &f(&|_| {});
+   | --------------------^^^^^^^^^^^-
+   |                     |
+   |                     referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
diff --git a/src/test/ui/borrowck/issue-88434-removal-index-should-be-less.stderr b/src/test/ui/borrowck/issue-88434-removal-index-should-be-less.stderr
index e6b07aba74d..b08a7cfc7fe 100644
--- a/src/test/ui/borrowck/issue-88434-removal-index-should-be-less.stderr
+++ b/src/test/ui/borrowck/issue-88434-removal-index-should-be-less.stderr
@@ -27,3 +27,16 @@ LL | const _CONST: &[u8] = &f(&[], |_| {});
 error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0080`.
+Future incompatibility report: Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/issue-88434-removal-index-should-be-less.rs:3:23
+   |
+LL | const _CONST: &[u8] = &f(&[], |_| {});
+   | ----------------------^^^^^^^^^^^^^^^-
+   |                       |
+   |                       referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
diff --git a/src/test/ui/consts/const-eval/const-eval-query-stack.stderr b/src/test/ui/consts/const-eval/const-eval-query-stack.stderr
index fb4c92861cb..bbec2a830e6 100644
--- a/src/test/ui/consts/const-eval/const-eval-query-stack.stderr
+++ b/src/test/ui/consts/const-eval/const-eval-query-stack.stderr
@@ -37,7 +37,7 @@ query stack during panic:
 end of query stack
 Future incompatibility report: Future breakage diagnostic:
 warning: any use of this value will cause an error
-  --> $DIR/const-eval-query-stack.rs:20:16
+  --> $DIR/const-eval-query-stack.rs:19:16
    |
 LL | const X: i32 = 1 / 0;
    | ---------------^^^^^-
@@ -45,10 +45,21 @@ LL | const X: i32 = 1 / 0;
    |                attempt to divide `1_i32` by zero
    |
 note: the lint level is defined here
-  --> $DIR/const-eval-query-stack.rs:19:8
+  --> $DIR/const-eval-query-stack.rs:18:8
    |
 LL | #[warn(const_err)]
    |        ^^^^^^^^^
    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
    = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
 
+Future breakage diagnostic:
+error: erroneous constant used
+  --> $DIR/const-eval-query-stack.rs:23:27
+   |
+LL |     let x: &'static i32 = &X;
+   |                           ^^ referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
diff --git a/src/test/ui/consts/const-eval/const-pointer-values-in-various-types.64bit.stderr b/src/test/ui/consts/const-eval/const-pointer-values-in-various-types.64bit.stderr
index 9fcb27f04ab..b004637fd83 100644
--- a/src/test/ui/consts/const-eval/const-pointer-values-in-various-types.64bit.stderr
+++ b/src/test/ui/consts/const-eval/const-pointer-values-in-various-types.64bit.stderr
@@ -323,7 +323,20 @@ error: aborting due to 29 previous errors
 For more information about this error, try `rustc --explain E0080`.
 Future incompatibility report: Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:29:43
+  --> $DIR/const-pointer-values-in-various-types.rs:26:49
+   |
+LL |     const I32_REF_USIZE_UNION: usize = unsafe { Nonsense { int_32_ref: &3 }.u };
+   |     --------------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
+   |                                                 |
+   |                                                 unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/const-pointer-values-in-various-types.rs:30:43
    |
 LL |     const I32_REF_U8_UNION: u8 = unsafe { Nonsense { int_32_ref: &3 }.uint_8 };
    |     --------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -336,7 +349,7 @@ LL |     const I32_REF_U8_UNION: u8 = unsafe { Nonsense { int_32_ref: &3 }.uint_
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:33:45
+  --> $DIR/const-pointer-values-in-various-types.rs:34:45
    |
 LL |     const I32_REF_U16_UNION: u16 = unsafe { Nonsense { int_32_ref: &3 }.uint_16 };
    |     ----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -349,7 +362,7 @@ LL |     const I32_REF_U16_UNION: u16 = unsafe { Nonsense { int_32_ref: &3 }.uin
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:37:45
+  --> $DIR/const-pointer-values-in-various-types.rs:38:45
    |
 LL |     const I32_REF_U32_UNION: u32 = unsafe { Nonsense { int_32_ref: &3 }.uint_32 };
    |     ----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -362,7 +375,20 @@ LL |     const I32_REF_U32_UNION: u32 = unsafe { Nonsense { int_32_ref: &3 }.uin
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:47:43
+  --> $DIR/const-pointer-values-in-various-types.rs:42:45
+   |
+LL |     const I32_REF_U64_UNION: u64 = unsafe { Nonsense { int_32_ref: &3 }.uint_64 };
+   |     ----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
+   |                                             |
+   |                                             unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/const-pointer-values-in-various-types.rs:49:43
    |
 LL |     const I32_REF_I8_UNION: i8 = unsafe { Nonsense { int_32_ref: &3 }.int_8 };
    |     --------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -375,7 +401,7 @@ LL |     const I32_REF_I8_UNION: i8 = unsafe { Nonsense { int_32_ref: &3 }.int_8
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:51:45
+  --> $DIR/const-pointer-values-in-various-types.rs:53:45
    |
 LL |     const I32_REF_I16_UNION: i16 = unsafe { Nonsense { int_32_ref: &3 }.int_16 };
    |     ----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -388,7 +414,7 @@ LL |     const I32_REF_I16_UNION: i16 = unsafe { Nonsense { int_32_ref: &3 }.int
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:55:45
+  --> $DIR/const-pointer-values-in-various-types.rs:57:45
    |
 LL |     const I32_REF_I32_UNION: i32 = unsafe { Nonsense { int_32_ref: &3 }.int_32 };
    |     ----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -401,7 +427,20 @@ LL |     const I32_REF_I32_UNION: i32 = unsafe { Nonsense { int_32_ref: &3 }.int
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:65:45
+  --> $DIR/const-pointer-values-in-various-types.rs:61:45
+   |
+LL |     const I32_REF_I64_UNION: i64 = unsafe { Nonsense { int_32_ref: &3 }.int_64 };
+   |     ----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
+   |                                             |
+   |                                             unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/const-pointer-values-in-various-types.rs:68:45
    |
 LL |     const I32_REF_F32_UNION: f32 = unsafe { Nonsense { int_32_ref: &3 }.float_32 };
    |     ----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -414,7 +453,20 @@ LL |     const I32_REF_F32_UNION: f32 = unsafe { Nonsense { int_32_ref: &3 }.flo
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:72:47
+  --> $DIR/const-pointer-values-in-various-types.rs:72:45
+   |
+LL |     const I32_REF_F64_UNION: f64 = unsafe { Nonsense { int_32_ref: &3 }.float_64 };
+   |     ----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
+   |                                             |
+   |                                             unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/const-pointer-values-in-various-types.rs:76:47
    |
 LL |     const I32_REF_BOOL_UNION: bool = unsafe { Nonsense { int_32_ref: &3 }.truthy_falsey };
    |     ------------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -427,7 +479,7 @@ LL |     const I32_REF_BOOL_UNION: bool = unsafe { Nonsense { int_32_ref: &3 }.t
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:76:47
+  --> $DIR/const-pointer-values-in-various-types.rs:80:47
    |
 LL |     const I32_REF_CHAR_UNION: char = unsafe { Nonsense { int_32_ref: &3 }.character };
    |     ------------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -440,7 +492,7 @@ LL |     const I32_REF_CHAR_UNION: char = unsafe { Nonsense { int_32_ref: &3 }.c
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:80:39
+  --> $DIR/const-pointer-values-in-various-types.rs:84:39
    |
 LL |     const STR_U8_UNION: u8 = unsafe { Nonsense { stringy: "3" }.uint_8 };
    |     ----------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -453,7 +505,7 @@ LL |     const STR_U8_UNION: u8 = unsafe { Nonsense { stringy: "3" }.uint_8 };
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:84:41
+  --> $DIR/const-pointer-values-in-various-types.rs:88:41
    |
 LL |     const STR_U16_UNION: u16 = unsafe { Nonsense { stringy: "3" }.uint_16 };
    |     ------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -466,7 +518,7 @@ LL |     const STR_U16_UNION: u16 = unsafe { Nonsense { stringy: "3" }.uint_16 }
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:88:41
+  --> $DIR/const-pointer-values-in-various-types.rs:92:41
    |
 LL |     const STR_U32_UNION: u32 = unsafe { Nonsense { stringy: "3" }.uint_32 };
    |     ------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -479,7 +531,20 @@ LL |     const STR_U32_UNION: u32 = unsafe { Nonsense { stringy: "3" }.uint_32 }
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:95:43
+  --> $DIR/const-pointer-values-in-various-types.rs:96:41
+   |
+LL |     const STR_U64_UNION: u64 = unsafe { Nonsense { stringy: "3" }.uint_64 };
+   |     ------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
+   |                                         |
+   |                                         unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/const-pointer-values-in-various-types.rs:100:43
    |
 LL |     const STR_U128_UNION: u128 = unsafe { Nonsense { stringy: "3" }.uint_128 };
    |     --------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -492,7 +557,7 @@ LL |     const STR_U128_UNION: u128 = unsafe { Nonsense { stringy: "3" }.uint_12
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:99:39
+  --> $DIR/const-pointer-values-in-various-types.rs:104:39
    |
 LL |     const STR_I8_UNION: i8 = unsafe { Nonsense { stringy: "3" }.int_8 };
    |     ----------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -505,7 +570,7 @@ LL |     const STR_I8_UNION: i8 = unsafe { Nonsense { stringy: "3" }.int_8 };
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:103:41
+  --> $DIR/const-pointer-values-in-various-types.rs:108:41
    |
 LL |     const STR_I16_UNION: i16 = unsafe { Nonsense { stringy: "3" }.int_16 };
    |     ------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -518,7 +583,7 @@ LL |     const STR_I16_UNION: i16 = unsafe { Nonsense { stringy: "3" }.int_16 };
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:107:41
+  --> $DIR/const-pointer-values-in-various-types.rs:112:41
    |
 LL |     const STR_I32_UNION: i32 = unsafe { Nonsense { stringy: "3" }.int_32 };
    |     ------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -531,7 +596,20 @@ LL |     const STR_I32_UNION: i32 = unsafe { Nonsense { stringy: "3" }.int_32 };
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:114:43
+  --> $DIR/const-pointer-values-in-various-types.rs:116:41
+   |
+LL |     const STR_I64_UNION: i64 = unsafe { Nonsense { stringy: "3" }.int_64 };
+   |     ------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
+   |                                         |
+   |                                         unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/const-pointer-values-in-various-types.rs:120:43
    |
 LL |     const STR_I128_UNION: i128 = unsafe { Nonsense { stringy: "3" }.int_128 };
    |     --------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -544,7 +622,7 @@ LL |     const STR_I128_UNION: i128 = unsafe { Nonsense { stringy: "3" }.int_128
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:118:41
+  --> $DIR/const-pointer-values-in-various-types.rs:124:41
    |
 LL |     const STR_F32_UNION: f32 = unsafe { Nonsense { stringy: "3" }.float_32 };
    |     ------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -557,7 +635,20 @@ LL |     const STR_F32_UNION: f32 = unsafe { Nonsense { stringy: "3" }.float_32
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:125:43
+  --> $DIR/const-pointer-values-in-various-types.rs:128:41
+   |
+LL |     const STR_F64_UNION: f64 = unsafe { Nonsense { stringy: "3" }.float_64 };
+   |     ------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
+   |                                         |
+   |                                         unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/const-pointer-values-in-various-types.rs:132:43
    |
 LL |     const STR_BOOL_UNION: bool = unsafe { Nonsense { stringy: "3" }.truthy_falsey };
    |     --------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
@@ -570,7 +661,7 @@ LL |     const STR_BOOL_UNION: bool = unsafe { Nonsense { stringy: "3" }.truthy_
 
 Future breakage diagnostic:
 error: any use of this value will cause an error
-  --> $DIR/const-pointer-values-in-various-types.rs:129:43
+  --> $DIR/const-pointer-values-in-various-types.rs:136:43
    |
 LL |     const STR_CHAR_UNION: char = unsafe { Nonsense { stringy: "3" }.character };
    |     --------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
diff --git a/src/test/ui/consts/const-eval/format.stderr b/src/test/ui/consts/const-eval/format.stderr
index 44f436ae4e3..b00cadcea99 100644
--- a/src/test/ui/consts/const-eval/format.stderr
+++ b/src/test/ui/consts/const-eval/format.stderr
@@ -76,3 +76,49 @@ LL |     println!("{:?}", 0);
 error: aborting due to 8 previous errors
 
 For more information about this error, try `rustc --explain E0015`.
+Future incompatibility report: Future breakage diagnostic:
+error: erroneous constant used
+  --> $DIR/format.rs:2:12
+   |
+LL |     panic!("{:?}", 0);
+   |            ^^^^^^ referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: erroneous constant used
+  --> $DIR/format.rs:2:20
+   |
+LL |     panic!("{:?}", 0);
+   |                    ^ referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+   = note: this error originates in the macro `$crate::const_format_args` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+Future breakage diagnostic:
+error: erroneous constant used
+  --> $DIR/format.rs:11:14
+   |
+LL |     println!("{:?}", 0);
+   |              ^^^^^^ referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: erroneous constant used
+  --> $DIR/format.rs:11:22
+   |
+LL |     println!("{:?}", 0);
+   |                      ^ referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+   = note: this error originates in the macro `$crate::format_args_nl` (in Nightly builds, run with -Z macro-backtrace for more info)
+
diff --git a/src/test/ui/consts/const-eval/ref_to_int_match.32bit.stderr b/src/test/ui/consts/const-eval/ref_to_int_match.32bit.stderr
index 83ac6c90a43..a55fd8c156e 100644
--- a/src/test/ui/consts/const-eval/ref_to_int_match.32bit.stderr
+++ b/src/test/ui/consts/const-eval/ref_to_int_match.32bit.stderr
@@ -24,3 +24,16 @@ LL |         10..=BAR => {},
 
 error: aborting due to 3 previous errors
 
+Future incompatibility report: Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ref_to_int_match.rs:25:27
+   |
+LL | const BAR: Int = unsafe { Foo { r: &42 }.f };
+   | --------------------------^^^^^^^^^^^^^^^^---
+   |                           |
+   |                           unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
diff --git a/src/test/ui/consts/const-eval/ref_to_int_match.64bit.stderr b/src/test/ui/consts/const-eval/ref_to_int_match.64bit.stderr
index 83ac6c90a43..a55fd8c156e 100644
--- a/src/test/ui/consts/const-eval/ref_to_int_match.64bit.stderr
+++ b/src/test/ui/consts/const-eval/ref_to_int_match.64bit.stderr
@@ -24,3 +24,16 @@ LL |         10..=BAR => {},
 
 error: aborting due to 3 previous errors
 
+Future incompatibility report: Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ref_to_int_match.rs:25:27
+   |
+LL | const BAR: Int = unsafe { Foo { r: &42 }.f };
+   | --------------------------^^^^^^^^^^^^^^^^---
+   |                           |
+   |                           unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
diff --git a/src/test/ui/consts/const-eval/ub-enum.32bit.stderr b/src/test/ui/consts/const-eval/ub-enum.32bit.stderr
index c6fa14d0534..2440cd2272c 100644
--- a/src/test/ui/consts/const-eval/ub-enum.32bit.stderr
+++ b/src/test/ui/consts/const-eval/ub-enum.32bit.stderr
@@ -125,3 +125,58 @@ LL | const BAD_UNINHABITED_WITH_DATA2: Result<(i32, !), (i32, Never)> = unsafe {
 error: aborting due to 13 previous errors
 
 For more information about this error, try `rustc --explain E0080`.
+Future incompatibility report: Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-enum.rs:26:1
+   |
+LL | const BAD_ENUM_PTR: Enum = unsafe { mem::transmute(&1) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-enum.rs:30:1
+   |
+LL | const BAD_ENUM_WRAPPED: Wrap<Enum> = unsafe { mem::transmute(&1) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-enum.rs:45:1
+   |
+LL | const BAD_ENUM2_PTR: Enum2 = unsafe { mem::transmute(&0) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-enum.rs:49:1
+   |
+LL | const BAD_ENUM2_WRAPPED: Wrap<Enum2> = unsafe { mem::transmute(&0) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-enum.rs:63:1
+   |
+LL | const BAD_ENUM2_OPTION_PTR: Option<Enum2> = unsafe { mem::transmute(&0) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
diff --git a/src/test/ui/consts/const-eval/ub-enum.64bit.stderr b/src/test/ui/consts/const-eval/ub-enum.64bit.stderr
index 25be593ab83..e9b4023068e 100644
--- a/src/test/ui/consts/const-eval/ub-enum.64bit.stderr
+++ b/src/test/ui/consts/const-eval/ub-enum.64bit.stderr
@@ -125,3 +125,58 @@ LL | const BAD_UNINHABITED_WITH_DATA2: Result<(i32, !), (i32, Never)> = unsafe {
 error: aborting due to 13 previous errors
 
 For more information about this error, try `rustc --explain E0080`.
+Future incompatibility report: Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-enum.rs:26:1
+   |
+LL | const BAD_ENUM_PTR: Enum = unsafe { mem::transmute(&1) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-enum.rs:30:1
+   |
+LL | const BAD_ENUM_WRAPPED: Wrap<Enum> = unsafe { mem::transmute(&1) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-enum.rs:45:1
+   |
+LL | const BAD_ENUM2_PTR: Enum2 = unsafe { mem::transmute(&0) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-enum.rs:49:1
+   |
+LL | const BAD_ENUM2_WRAPPED: Wrap<Enum2> = unsafe { mem::transmute(&0) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-enum.rs:63:1
+   |
+LL | const BAD_ENUM2_OPTION_PTR: Option<Enum2> = unsafe { mem::transmute(&0) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
diff --git a/src/test/ui/consts/const-eval/ub-ref-ptr.32bit.stderr b/src/test/ui/consts/const-eval/ub-ref-ptr.32bit.stderr
index 8a4f23c033e..10a0ccd552b 100644
--- a/src/test/ui/consts/const-eval/ub-ref-ptr.32bit.stderr
+++ b/src/test/ui/consts/const-eval/ub-ref-ptr.32bit.stderr
@@ -176,3 +176,66 @@ LL | const DATA_FN_PTR: fn() = unsafe { mem::transmute(&13) };
 error: aborting due to 16 previous errors
 
 For more information about this error, try `rustc --explain E0080`.
+Future incompatibility report: Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-ref-ptr.rs:31:1
+   |
+LL | const REF_AS_USIZE: usize = unsafe { mem::transmute(&0) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-ref-ptr.rs:35:39
+   |
+LL | const REF_AS_USIZE_SLICE: &[usize] = &[unsafe { mem::transmute(&0) }];
+   | --------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-
+   |                                       |
+   |                                       unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-ref-ptr.rs:35:38
+   |
+LL | const REF_AS_USIZE_SLICE: &[usize] = &[unsafe { mem::transmute(&0) }];
+   | -------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-
+   |                                      |
+   |                                      referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-ref-ptr.rs:41:86
+   |
+LL | const REF_AS_USIZE_BOX_SLICE: Box<[usize]> = unsafe { mem::transmute::<&[usize], _>(&[mem::transmute(&0)]) };
+   | -------------------------------------------------------------------------------------^^^^^^^^^^^^^^^^^^^^----
+   |                                                                                      |
+   |                                                                                      unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-ref-ptr.rs:41:85
+   |
+LL | const REF_AS_USIZE_BOX_SLICE: Box<[usize]> = unsafe { mem::transmute::<&[usize], _>(&[mem::transmute(&0)]) };
+   | ------------------------------------------------------------------------------------^^^^^^^^^^^^^^^^^^^^^----
+   |                                                                                     |
+   |                                                                                     referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
diff --git a/src/test/ui/consts/const-eval/ub-ref-ptr.64bit.stderr b/src/test/ui/consts/const-eval/ub-ref-ptr.64bit.stderr
index da1c6d1a07f..e9fcefe12c7 100644
--- a/src/test/ui/consts/const-eval/ub-ref-ptr.64bit.stderr
+++ b/src/test/ui/consts/const-eval/ub-ref-ptr.64bit.stderr
@@ -176,3 +176,66 @@ LL | const DATA_FN_PTR: fn() = unsafe { mem::transmute(&13) };
 error: aborting due to 16 previous errors
 
 For more information about this error, try `rustc --explain E0080`.
+Future incompatibility report: Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-ref-ptr.rs:31:1
+   |
+LL | const REF_AS_USIZE: usize = unsafe { mem::transmute(&0) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-ref-ptr.rs:35:39
+   |
+LL | const REF_AS_USIZE_SLICE: &[usize] = &[unsafe { mem::transmute(&0) }];
+   | --------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-
+   |                                       |
+   |                                       unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-ref-ptr.rs:35:38
+   |
+LL | const REF_AS_USIZE_SLICE: &[usize] = &[unsafe { mem::transmute(&0) }];
+   | -------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-
+   |                                      |
+   |                                      referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-ref-ptr.rs:41:86
+   |
+LL | const REF_AS_USIZE_BOX_SLICE: Box<[usize]> = unsafe { mem::transmute::<&[usize], _>(&[mem::transmute(&0)]) };
+   | -------------------------------------------------------------------------------------^^^^^^^^^^^^^^^^^^^^----
+   |                                                                                      |
+   |                                                                                      unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-ref-ptr.rs:41:85
+   |
+LL | const REF_AS_USIZE_BOX_SLICE: Box<[usize]> = unsafe { mem::transmute::<&[usize], _>(&[mem::transmute(&0)]) };
+   | ------------------------------------------------------------------------------------^^^^^^^^^^^^^^^^^^^^^----
+   |                                                                                     |
+   |                                                                                     referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
diff --git a/src/test/ui/consts/const-eval/ub-wide-ptr.32bit.stderr b/src/test/ui/consts/const-eval/ub-wide-ptr.32bit.stderr
index a78cff11589..0c398f5bfd4 100644
--- a/src/test/ui/consts/const-eval/ub-wide-ptr.32bit.stderr
+++ b/src/test/ui/consts/const-eval/ub-wide-ptr.32bit.stderr
@@ -344,3 +344,86 @@ LL |     mem::transmute::<_, &dyn Trait>((&92u8, &3u64))
 error: aborting due to 32 previous errors
 
 For more information about this error, try `rustc --explain E0080`.
+Future incompatibility report: Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-wide-ptr.rs:42:1
+   |
+LL | const STR_LENGTH_PTR: &str = unsafe { mem::transmute((&42u8, &3)) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-wide-ptr.rs:46:1
+   |
+LL | const MY_STR_LENGTH_PTR: &MyStr = unsafe { mem::transmute((&42u8, &3)) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-wide-ptr.rs:75:1
+   |
+LL | const SLICE_LENGTH_PTR: &[u8] = unsafe { mem::transmute((&42u8, &3)) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-wide-ptr.rs:82:1
+   |
+LL | const SLICE_LENGTH_PTR_BOX: Box<[u8]> = unsafe { mem::transmute((&42u8, &3)) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-wide-ptr.rs:87:40
+   |
+LL | const SLICE_CONTENT_INVALID: &[bool] = &[unsafe { mem::transmute(3u8) }];
+   | ---------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-
+   |                                        |
+   |                                        referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-wide-ptr.rs:95:42
+   |
+LL | const MYSLICE_PREFIX_BAD: &MySliceBool = &MySlice(unsafe { mem::transmute(3u8) }, [false]);
+   | -----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-
+   |                                          |
+   |                                          referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-wide-ptr.rs:100:42
+   |
+LL | const MYSLICE_SUFFIX_BAD: &MySliceBool = &MySlice(true, [unsafe { mem::transmute(3u8) }]);
+   | -----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-
+   |                                          |
+   |                                          referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
diff --git a/src/test/ui/consts/const-eval/ub-wide-ptr.64bit.stderr b/src/test/ui/consts/const-eval/ub-wide-ptr.64bit.stderr
index 69a61d9caed..bf53995d956 100644
--- a/src/test/ui/consts/const-eval/ub-wide-ptr.64bit.stderr
+++ b/src/test/ui/consts/const-eval/ub-wide-ptr.64bit.stderr
@@ -344,3 +344,86 @@ LL |     mem::transmute::<_, &dyn Trait>((&92u8, &3u64))
 error: aborting due to 32 previous errors
 
 For more information about this error, try `rustc --explain E0080`.
+Future incompatibility report: Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-wide-ptr.rs:42:1
+   |
+LL | const STR_LENGTH_PTR: &str = unsafe { mem::transmute((&42u8, &3)) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-wide-ptr.rs:46:1
+   |
+LL | const MY_STR_LENGTH_PTR: &MyStr = unsafe { mem::transmute((&42u8, &3)) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-wide-ptr.rs:75:1
+   |
+LL | const SLICE_LENGTH_PTR: &[u8] = unsafe { mem::transmute((&42u8, &3)) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-wide-ptr.rs:82:1
+   |
+LL | const SLICE_LENGTH_PTR_BOX: Box<[u8]> = unsafe { mem::transmute((&42u8, &3)) };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-wide-ptr.rs:87:40
+   |
+LL | const SLICE_CONTENT_INVALID: &[bool] = &[unsafe { mem::transmute(3u8) }];
+   | ---------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-
+   |                                        |
+   |                                        referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-wide-ptr.rs:95:42
+   |
+LL | const MYSLICE_PREFIX_BAD: &MySliceBool = &MySlice(unsafe { mem::transmute(3u8) }, [false]);
+   | -----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-
+   |                                          |
+   |                                          referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/ub-wide-ptr.rs:100:42
+   |
+LL | const MYSLICE_SUFFIX_BAD: &MySliceBool = &MySlice(true, [unsafe { mem::transmute(3u8) }]);
+   | -----------------------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-
+   |                                          |
+   |                                          referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
diff --git a/src/test/ui/consts/const-float-bits-reject-conv.stderr b/src/test/ui/consts/const-float-bits-reject-conv.stderr
index f3fd098e848..d822171df72 100644
--- a/src/test/ui/consts/const-float-bits-reject-conv.stderr
+++ b/src/test/ui/consts/const-float-bits-reject-conv.stderr
@@ -214,3 +214,115 @@ LL |         const_assert!(f64::from_bits(MASKED_NAN2).to_bits(), MASKED_NAN2);
 error: aborting due to 12 previous errors
 
 For more information about this error, try `rustc --explain E0080`.
+Future incompatibility report: Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/const-float-bits-reject-conv.rs:30:34
+   |
+LL |             const _: () = assert!($a);
+   |             --------------------------
+...
+LL |     const_assert!(f32::from_bits(MASKED_NAN1).is_nan());
+   |                                  ^^^^^^^^^^^ referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/const-float-bits-reject-conv.rs:33:34
+   |
+LL |             const _: () = assert!($a);
+   |             --------------------------
+...
+LL |     const_assert!(f32::from_bits(MASKED_NAN1).is_nan());
+   |                                  ^^^^^^^^^^^ referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/const-float-bits-reject-conv.rs:41:38
+   |
+LL |             const _: () = assert!($a == $b);
+   |             --------------------------------
+...
+LL |         const_assert!(f32::from_bits(MASKED_NAN1).to_bits(), MASKED_NAN1);
+   |                                      ^^^^^^^^^^^ referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/const-float-bits-reject-conv.rs:44:38
+   |
+LL |             const _: () = assert!($a == $b);
+   |             --------------------------------
+...
+LL |         const_assert!(f32::from_bits(MASKED_NAN2).to_bits(), MASKED_NAN2);
+   |                                      ^^^^^^^^^^^ referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/const-float-bits-reject-conv.rs:57:34
+   |
+LL |             const _: () = assert!($a);
+   |             --------------------------
+...
+LL |     const_assert!(f64::from_bits(MASKED_NAN1).is_nan());
+   |                                  ^^^^^^^^^^^ referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/const-float-bits-reject-conv.rs:60:34
+   |
+LL |             const _: () = assert!($a);
+   |             --------------------------
+...
+LL |     const_assert!(f64::from_bits(MASKED_NAN1).is_nan());
+   |                                  ^^^^^^^^^^^ referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/const-float-bits-reject-conv.rs:66:38
+   |
+LL |             const _: () = assert!($a == $b);
+   |             --------------------------------
+...
+LL |         const_assert!(f64::from_bits(MASKED_NAN1).to_bits(), MASKED_NAN1);
+   |                                      ^^^^^^^^^^^ referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
+Future breakage diagnostic:
+error: any use of this value will cause an error
+  --> $DIR/const-float-bits-reject-conv.rs:69:38
+   |
+LL |             const _: () = assert!($a == $b);
+   |             --------------------------------
+...
+LL |         const_assert!(f64::from_bits(MASKED_NAN2).to_bits(), MASKED_NAN2);
+   |                                      ^^^^^^^^^^^ referenced constant has errors
+   |
+   = note: `#[deny(const_err)]` on by default
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #71800 <https://github.com/rust-lang/rust/issues/71800>
+
diff --git a/src/test/ui/consts/ptr_comparisons.stderr b/src/test/ui/consts/ptr_comparisons.stderr
index 7ff3faead6a..594576fe2cf 100644
--- a/src/test/ui/consts/ptr_comparisons.stderr
+++ b/src/test/ui/consts/ptr_comparisons.stderr
@@ -62,7 +62,7 @@ error: any use of this value will cause an error
   --> $DIR/ptr_comparisons.rs:70:27
    |
 LL | const _: usize = unsafe { *std::mem::transmute::<&&usize, &usize>(&FOO) + 4 };
-   | --------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---
+   | --------------------------^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^-------
    |                           |
    |                           unable to turn pointer into raw bytes
    |