rust/tests/ui/transmute/transmute-imut-to-mut.rs

// Tests that transmuting from &T to &mut T is Undefined Behavior.

use std::mem::transmute;

fn main() {
    let _a: &mut u8 = unsafe { transmute(&1u8) };
    //~^ ERROR transmuting &T to &mut T is undefined behavior, even if the reference is unused, consider instead using an UnsafeCell
}
lint: deny transmuting from immutable to mutable, since it's undefined behavior [breaking-change] Technically breaking, since code that had been using these transmutes before will no longer compile. However, it was undefined behavior, so really, it's a good thing. Fixing your code would require some re-working to use an UnsafeCell instead. Closes #13146 2015-04-13 21:49:10 +00:00			`// Tests that transmuting from &T to &mut T is Undefined Behavior.`

			`use std::mem::transmute;`

			`fn main() {`
			`let _a: &mut u8 = unsafe { transmute(&1u8) };`
Make message for &T -> &mut T transmute more accurate 2022-01-09 22:15:23 +00:00			`//~^ ERROR transmuting &T to &mut T is undefined behavior, even if the reference is unused, consider instead using an UnsafeCell`
lint: deny transmuting from immutable to mutable, since it's undefined behavior [breaking-change] Technically breaking, since code that had been using these transmutes before will no longer compile. However, it was undefined behavior, so really, it's a good thing. Fixing your code would require some re-working to use an UnsafeCell instead. Closes #13146 2015-04-13 21:49:10 +00:00			`}`