1error[E0308]: mismatched types 2 --> tests/ui-nightly/transmute-mut-src-not-a-reference.rs:17:53 3 | 417 | const SRC_NOT_A_REFERENCE: &mut u8 = transmute_mut!(0usize); 5 | ---------------^^^^^^- 6 | | | 7 | | expected `&mut _`, found `usize` 8 | expected due to this 9 | 10 = note: expected mutable reference `&mut _` 11 found type `usize` 12help: consider mutably borrowing here 13 | 1417 | const SRC_NOT_A_REFERENCE: &mut u8 = transmute_mut!(&mut 0usize); 15 | ++++ 16 17warning: this function depends on never type fallback being `()` 18 --> tests/ui-nightly/transmute-mut-src-not-a-reference.rs:17:1 19 | 2017 | const SRC_NOT_A_REFERENCE: &mut u8 = transmute_mut!(0usize); 21 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 22 | 23 = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release! 24 = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748> 25 = help: specify the types explicitly 26note: in edition 2024, the requirement `!: FromBytes` will fail 27 --> tests/ui-nightly/transmute-mut-src-not-a-reference.rs:17:38 28 | 2917 | const SRC_NOT_A_REFERENCE: &mut u8 = transmute_mut!(0usize); 30 | ^^^^^^^^^^^^^^^^^^^^^^ 31 = note: `#[warn(dependency_on_unit_never_type_fallback)]` on by default 32 = note: this warning originates in the macro `transmute_mut` (in Nightly builds, run with -Z macro-backtrace for more info) 33 34warning: never type fallback affects this call to an `unsafe` function 35 --> tests/ui-nightly/transmute-mut-src-not-a-reference.rs:17:38 36 | 3717 | const SRC_NOT_A_REFERENCE: &mut u8 = transmute_mut!(0usize); 38 | ^^^^^^^^^^^^^^^^^^^^^^ 39 | 40 = warning: this will change its meaning in a future release! 41 = note: for more information, see issue #123748 <https://github.com/rust-lang/rust/issues/123748> 42 = help: specify the type explicitly 43 = note: `#[warn(never_type_fallback_flowing_into_unsafe)]` on by default 44 = note: this warning originates in the macro `$crate::assert_size_eq` which comes from the expansion of the macro `transmute_mut` (in Nightly builds, run with -Z macro-backtrace for more info) 45