error[E0080]: it is undefined behavior to use this value --> $DIR/ub-ref-ptr.rs:13:1 | LL | const UNALIGNED: &u16 = unsafe { mem::transmute(&[0u8; 4]) }; | ^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered an unaligned reference (required 2 byte alignment but found 1) | = 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) { ╾─alloc3──╼ │ ╾──╼ } error[E0080]: it is undefined behavior to use this value --> $DIR/ub-ref-ptr.rs:17:1 | LL | const UNALIGNED_BOX: Box = unsafe { mem::transmute(&[0u8; 4]) }; | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered an unaligned box (required 2 byte alignment but found 1) | = 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) { ╾─alloc7──╼ │ ╾──╼ } error[E0080]: it is undefined behavior to use this value --> $DIR/ub-ref-ptr.rs:21:1 | LL | const NULL: &u16 = unsafe { mem::transmute(0usize) }; | ^^^^^^^^^^^^^^^^ constructing invalid value: encountered a null reference | = 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) { 00 00 00 00 │ .... } error[E0080]: it is undefined behavior to use this value --> $DIR/ub-ref-ptr.rs:24:1 | LL | const NULL_BOX: Box = unsafe { mem::transmute(0usize) }; | ^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered a null box | = 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) { 00 00 00 00 │ .... } 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 = 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: 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 | = 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 = 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: 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 | = 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 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 | = 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 = 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: 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 | = 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 error[E0080]: it is undefined behavior to use this value --> $DIR/ub-ref-ptr.rs:47:1 | LL | const USIZE_AS_REF: &'static u8 = unsafe { mem::transmute(1337usize) }; | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered a dangling reference (address 0x539 is unallocated) | = 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) { 39 05 00 00 │ 9... } error[E0080]: it is undefined behavior to use this value --> $DIR/ub-ref-ptr.rs:50:1 | LL | const USIZE_AS_BOX: Box = unsafe { mem::transmute(1337usize) }; | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered a dangling box (address 0x539 is unallocated) | = 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) { 39 05 00 00 │ 9... } error[E0080]: evaluation of constant value failed --> $DIR/ub-ref-ptr.rs:53:41 | LL | const UNINIT_PTR: *const i32 = unsafe { MaybeUninit { uninit: () }.init }; | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using uninitialized data, but this operation requires initialized memory error[E0080]: it is undefined behavior to use this value --> $DIR/ub-ref-ptr.rs:57:1 | LL | const NULL_FN_PTR: fn() = unsafe { mem::transmute(0usize) }; | ^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered null pointer, but expected a function 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: 4, align: 4) { 00 00 00 00 │ .... } error[E0080]: evaluation of constant value failed --> $DIR/ub-ref-ptr.rs:59:38 | LL | const UNINIT_FN_PTR: fn() = unsafe { MaybeUninit { uninit: () }.init }; | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ using uninitialized data, but this operation requires initialized memory error[E0080]: it is undefined behavior to use this value --> $DIR/ub-ref-ptr.rs:62:1 | LL | const DANGLING_FN_PTR: fn() = unsafe { mem::transmute(13usize) }; | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered 0xd[noalloc], but expected a function 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: 4, align: 4) { 0d 00 00 00 │ .... } error[E0080]: it is undefined behavior to use this value --> $DIR/ub-ref-ptr.rs:64:1 | LL | const DATA_FN_PTR: fn() = unsafe { mem::transmute(&13) }; | ^^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: encountered alloc41, but expected a function 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: 4, align: 4) { ╾─alloc41─╼ │ ╾──╼ } 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 = 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 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 = 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 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 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 = 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 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