rust/src/test/ui/consts/const-eval/ub-wide-ptr.32bit.stderr

error[E0080]: it is undefined behavior to use this value
  --> $DIR/ub-wide-ptr.rs:37:1
   |
LL | const STR_TOO_LONG: &str = unsafe { mem::transmute((&42u8, 999usize)) };
   | ^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered a dangling reference (going beyond the bounds of its allocation)
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 8, align: 4) {
               ╾─allocN──╼ e7 03 00 00                         │ ╾──╼....
           }

error[E0080]: it is undefined behavior to use this value
  --> $DIR/ub-wide-ptr.rs:39:1
   |
LL | const NESTED_STR_MUCH_TOO_LONG: (&str,) = (unsafe { mem::transmute((&42, usize::MAX)) },);
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered invalid reference metadata: slice is bigger than largest supported object
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 8, align: 4) {
               ╾─allocN─╼ ff ff ff ff                         │ ╾──╼....
           }

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
   |
   = 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>
   = help: this code performed an operation that depends on the underlying bytes representing a pointer
   = help: the absolute address of a pointer is not known at compile-time, so such operations are not supported
   = note: `#[deny(const_err)]` on by default

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
   |
   = 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>
   = help: this code performed an operation that depends on the underlying bytes representing a pointer
   = help: the absolute address of a pointer is not known at compile-time, so such operations are not supported

error[E0080]: it is undefined behavior to use this value
  --> $DIR/ub-wide-ptr.rs:49:1
   |
LL | const MY_STR_MUCH_TOO_LONG: &MyStr = unsafe { mem::transmute((&42u8, usize::MAX)) };
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered invalid reference metadata: slice is bigger than largest supported object
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 8, align: 4) {
               ╾─allocN─╼ ff ff ff ff                         │ ╾──╼....
           }

error[E0080]: it is undefined behavior to use this value
  --> $DIR/ub-wide-ptr.rs:53:1
   |
LL | const STR_NO_INIT: &str = unsafe { mem::transmute::<&[_], _>(&[MaybeUninit::<u8> { uninit: () }]) };
   | ^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>: encountered uninitialized data in `str`
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 8, align: 4) {
               ╾─allocN─╼ 01 00 00 00                         │ ╾──╼....
           }

error[E0080]: it is undefined behavior to use this value
  --> $DIR/ub-wide-ptr.rs:56:1
   |
LL | const MYSTR_NO_INIT: &MyStr = unsafe { mem::transmute::<&[_], _>(&[MaybeUninit::<u8> { uninit: () }]) };
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>.0: encountered uninitialized data in `str`
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 8, align: 4) {
               ╾─allocN─╼ 01 00 00 00                         │ ╾──╼....
           }

error[E0080]: evaluation of constant value failed
  --> $DIR/ub-wide-ptr.rs:63:1
   |
LL | const SLICE_LENGTH_UNINIT: &[u8] = unsafe {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using uninitialized data, but this operation requires initialized memory

error[E0080]: it is undefined behavior to use this value
  --> $DIR/ub-wide-ptr.rs:70:1
   |
LL | const SLICE_TOO_LONG: &[u8] = unsafe { mem::transmute((&42u8, 999usize)) };
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered a dangling reference (going beyond the bounds of its allocation)
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 8, align: 4) {
               ╾─allocN─╼ e7 03 00 00                         │ ╾──╼....
           }

error[E0080]: it is undefined behavior to use this value
  --> $DIR/ub-wide-ptr.rs:73:1
   |
LL | const SLICE_TOO_LONG_OVERFLOW: &[u32] = unsafe { mem::transmute((&42u32, isize::MAX)) };
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered invalid reference metadata: slice is bigger than largest supported object
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 8, align: 4) {
               ╾─allocN─╼ ff ff ff 7f                         │ ╾──╼....
           }

error: any use of this value will cause an error
  --> $DIR/ub-wide-ptr.rs:76:1
   |
LL | const SLICE_LENGTH_PTR: &[u8] = unsafe { mem::transmute((&42u8, &3)) };
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
   |
   = 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>
   = help: this code performed an operation that depends on the underlying bytes representing a pointer
   = help: the absolute address of a pointer is not known at compile-time, so such operations are not supported

error[E0080]: it is undefined behavior to use this value
  --> $DIR/ub-wide-ptr.rs:80:1
   |
LL | const SLICE_TOO_LONG_BOX: Box<[u8]> = unsafe { mem::transmute((&42u8, 999usize)) };
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered a dangling box (going beyond the bounds of its allocation)
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 8, align: 4) {
               ╾─allocN─╼ e7 03 00 00                         │ ╾──╼....
           }

error: any use of this value will cause an error
  --> $DIR/ub-wide-ptr.rs:83:1
   |
LL | const SLICE_LENGTH_PTR_BOX: Box<[u8]> = unsafe { mem::transmute((&42u8, &3)) };
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
   |
   = 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>
   = help: this code performed an operation that depends on the underlying bytes representing a pointer
   = help: the absolute address of a pointer is not known at compile-time, so such operations are not supported

error[E0080]: it is undefined behavior to use this value
  --> $DIR/ub-wide-ptr.rs:88:1
   |
LL | const SLICE_CONTENT_INVALID: &[bool] = &[unsafe { mem::transmute(3u8) }];
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>[0]: encountered 0x03, but expected a boolean
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 4, align: 4) {
               ╾─allocN─╼                                     │ ╾──╼
           }

error: any use of this value will cause an error
  --> $DIR/ub-wide-ptr.rs:88:40
   |
LL | const SLICE_CONTENT_INVALID: &[bool] = &[unsafe { mem::transmute(3u8) }];
   | ------------------------------------   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ referenced constant has errors
   |
   = 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>

error[E0080]: it is undefined behavior to use this value
  --> $DIR/ub-wide-ptr.rs:96:1
   |
LL | const MYSLICE_PREFIX_BAD: &MySliceBool = &MySlice(unsafe { mem::transmute(3u8) }, [false]);
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>.0: encountered 0x03, but expected a boolean
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 4, align: 4) {
               ╾allocN─╼                                     │ ╾──╼
           }

error: any use of this value will cause an error
  --> $DIR/ub-wide-ptr.rs:96:42
   |
LL | const MYSLICE_PREFIX_BAD: &MySliceBool = &MySlice(unsafe { mem::transmute(3u8) }, [false]);
   | --------------------------------------   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ referenced constant has errors
   |
   = 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>

error[E0080]: it is undefined behavior to use this value
  --> $DIR/ub-wide-ptr.rs:101:1
   |
LL | const MYSLICE_SUFFIX_BAD: &MySliceBool = &MySlice(true, [unsafe { mem::transmute(3u8) }]);
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>.1[0]: encountered 0x03, but expected a boolean
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 4, align: 4) {
               ╾allocN─╼                                     │ ╾──╼
           }

error: any use of this value will cause an error
  --> $DIR/ub-wide-ptr.rs:101:42
   |
LL | const MYSLICE_SUFFIX_BAD: &MySliceBool = &MySlice(true, [unsafe { mem::transmute(3u8) }]);
   | --------------------------------------   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ referenced constant has errors
   |
   = 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>

error[E0080]: evaluation of constant value failed
  --> $DIR/ub-wide-ptr.rs:110:1
   |
LL | const RAW_SLICE_LENGTH_UNINIT: *const [u8] = unsafe {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using uninitialized data, but this operation requires initialized memory

error[E0080]: it is undefined behavior to use this value
  --> $DIR/ub-wide-ptr.rs:119:1
   |
LL | const TRAIT_OBJ_SHORT_VTABLE_1: W<&dyn Trait> = unsafe { mem::transmute(W((&92u8, &3u8))) };
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered allocN, but expected a vtable pointer
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 8, align: 4) {
               ╾allocN─╼ ╾allocN─╼                         │ ╾──╼╾──╼
           }

error[E0080]: it is undefined behavior to use this value
  --> $DIR/ub-wide-ptr.rs:123:1
   |
LL | const TRAIT_OBJ_SHORT_VTABLE_2: W<&dyn Trait> = unsafe { mem::transmute(W((&92u8, &3u64))) };
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered allocN, but expected a vtable pointer
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 8, align: 4) {
               ╾allocN─╼ ╾allocN─╼                         │ ╾──╼╾──╼
           }

error[E0080]: it is undefined behavior to use this value
  --> $DIR/ub-wide-ptr.rs:127:1
   |
LL | const TRAIT_OBJ_INT_VTABLE: W<&dyn Trait> = unsafe { mem::transmute(W((&92u8, 4usize))) };
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered 0x4[noalloc], but expected a vtable pointer
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 8, align: 4) {
               ╾allocN─╼ 04 00 00 00                         │ ╾──╼....
           }

error[E0080]: evaluation of constant value failed
  --> $DIR/ub-wide-ptr.rs:130:57
   |
LL | const TRAIT_OBJ_UNALIGNED_VTABLE: &dyn Trait = unsafe { mem::transmute((&92u8, &[0u8; 128])) };
   |                                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using allocN as vtable pointer but it does not point to a vtable

error[E0080]: evaluation of constant value failed
  --> $DIR/ub-wide-ptr.rs:133:57
   |
LL | const TRAIT_OBJ_BAD_DROP_FN_NULL: &dyn Trait = unsafe { mem::transmute((&92u8, &[0usize; 8])) };
   |                                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using allocN as vtable pointer but it does not point to a vtable

error[E0080]: evaluation of constant value failed
  --> $DIR/ub-wide-ptr.rs:136:56
   |
LL | const TRAIT_OBJ_BAD_DROP_FN_INT: &dyn Trait = unsafe { mem::transmute((&92u8, &[1usize; 8])) };
   |                                                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using allocN as vtable pointer but it does not point to a vtable

error[E0080]: it is undefined behavior to use this value
  --> $DIR/ub-wide-ptr.rs:139:1
   |
LL | const TRAIT_OBJ_BAD_DROP_FN_NOT_FN_PTR: W<&dyn Trait> = unsafe { mem::transmute(W((&92u8, &[&42u8; 8]))) };
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .0: encountered allocN, but expected a vtable pointer
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 8, align: 4) {
               ╾allocN─╼ ╾allocN─╼                         │ ╾──╼╾──╼
           }

error[E0080]: it is undefined behavior to use this value
  --> $DIR/ub-wide-ptr.rs:144:1
   |
LL | const TRAIT_OBJ_CONTENT_INVALID: &dyn Trait = unsafe { mem::transmute::<_, &bool>(&3u8) };
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value at .<deref>.<dyn-downcast>: encountered 0x03, but expected a boolean
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 8, align: 4) {
               ╾allocN─╼ ╾allocN─╼                         │ ╾──╼╾──╼
           }

error[E0080]: it is undefined behavior to use this value
  --> $DIR/ub-wide-ptr.rs:149:1
   |
LL | const RAW_TRAIT_OBJ_VTABLE_NULL: *const dyn Trait = unsafe { mem::transmute((&92u8, 0usize)) };
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered null pointer, but expected a vtable pointer
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 8, align: 4) {
               ╾allocN─╼ 00 00 00 00                         │ ╾──╼....
           }

error[E0080]: it is undefined behavior to use this value
  --> $DIR/ub-wide-ptr.rs:151:1
   |
LL | const RAW_TRAIT_OBJ_VTABLE_INVALID: *const dyn Trait = unsafe { mem::transmute((&92u8, &3u64)) };
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered allocN, but expected a vtable pointer
   |
   = note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rustc repository if you believe it should not be considered undefined behavior.
   = note: the raw bytes of the constant (size: 8, align: 4) {
               ╾allocN─╼ ╾allocN─╼                         │ ╾──╼╾──╼
           }

error[E0080]: could not evaluate static initializer
  --> $DIR/ub-wide-ptr.rs:157:5
   |
LL |     mem::transmute::<_, &dyn Trait>((&92u8, 0usize))
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ out-of-bounds pointer use: null pointer is a dangling pointer (it has no provenance)

error[E0080]: could not evaluate static initializer
  --> $DIR/ub-wide-ptr.rs:161:5
   |
LL |     mem::transmute::<_, &dyn Trait>((&92u8, &3u64))
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using allocN as vtable pointer but it does not point to a vtable

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
   |
   = 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>
   = help: this code performed an operation that depends on the underlying bytes representing a pointer
   = help: the absolute address of a pointer is not known at compile-time, so such operations are not supported
   = note: `#[deny(const_err)]` on by default

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
   |
   = 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>
   = help: this code performed an operation that depends on the underlying bytes representing a pointer
   = help: the absolute address of a pointer is not known at compile-time, so such operations are not supported
   = note: `#[deny(const_err)]` on by default

Future breakage diagnostic:
error: any use of this value will cause an error
  --> $DIR/ub-wide-ptr.rs:76:1
   |
LL | const SLICE_LENGTH_PTR: &[u8] = unsafe { mem::transmute((&42u8, &3)) };
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
   |
   = 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>
   = help: this code performed an operation that depends on the underlying bytes representing a pointer
   = help: the absolute address of a pointer is not known at compile-time, so such operations are not supported
   = note: `#[deny(const_err)]` on by default

Future breakage diagnostic:
error: any use of this value will cause an error
  --> $DIR/ub-wide-ptr.rs:83:1
   |
LL | const SLICE_LENGTH_PTR_BOX: Box<[u8]> = unsafe { mem::transmute((&42u8, &3)) };
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unable to turn pointer into raw bytes
   |
   = 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>
   = help: this code performed an operation that depends on the underlying bytes representing a pointer
   = help: the absolute address of a pointer is not known at compile-time, so such operations are not supported
   = note: `#[deny(const_err)]` on by default

Future breakage diagnostic:
error: any use of this value will cause an error
  --> $DIR/ub-wide-ptr.rs:88:40
   |
LL | const SLICE_CONTENT_INVALID: &[bool] = &[unsafe { mem::transmute(3u8) }];
   | ------------------------------------   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ referenced constant has errors
   |
   = 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: `#[deny(const_err)]` on by default

Future breakage diagnostic:
error: any use of this value will cause an error
  --> $DIR/ub-wide-ptr.rs:96:42
   |
LL | const MYSLICE_PREFIX_BAD: &MySliceBool = &MySlice(unsafe { mem::transmute(3u8) }, [false]);
   | --------------------------------------   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ referenced constant has errors
   |
   = 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: `#[deny(const_err)]` on by default

Future breakage diagnostic:
error: any use of this value will cause an error
  --> $DIR/ub-wide-ptr.rs:101:42
   |
LL | const MYSLICE_SUFFIX_BAD: &MySliceBool = &MySlice(true, [unsafe { mem::transmute(3u8) }]);
   | --------------------------------------   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ referenced constant has errors
   |
   = 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: `#[deny(const_err)]` on by default