| #![feature(untagged_unions)] |
| use std::mem::ManuallyDrop; |
| |
| union U1 { |
| a: u8 |
| } |
| |
| union U2 { |
| a: ManuallyDrop<String> |
| } |
| |
| union U3<T> { |
| a: ManuallyDrop<T> |
| } |
| |
| union U4<T: Copy> { |
| a: T |
| } |
| |
| fn generic_noncopy<T: Default>() { |
| let mut u3 = U3 { a: ManuallyDrop::new(T::default()) }; |
| u3.a = ManuallyDrop::new(T::default()); //~ ERROR assignment to non-`Copy` union field is unsafe |
| *u3.a = T::default(); //~ ERROR access to union field is unsafe |
| } |
| |
| fn generic_copy<T: Copy + Default>() { |
| let mut u3 = U3 { a: ManuallyDrop::new(T::default()) }; |
| u3.a = ManuallyDrop::new(T::default()); // OK |
| *u3.a = T::default(); //~ ERROR access to union field is unsafe |
| |
| let mut u4 = U4 { a: T::default() }; |
| u4.a = T::default(); // OK |
| } |
| |
| fn main() { |
| let mut u1 = U1 { a: 10 }; // OK |
| let a = u1.a; //~ ERROR access to union field is unsafe |
| u1.a = 11; // OK |
| |
| let U1 { a } = u1; //~ ERROR access to union field is unsafe |
| if let U1 { a: 12 } = u1 {} //~ ERROR access to union field is unsafe |
| // let U1 { .. } = u1; // OK |
| |
| let mut u2 = U2 { a: ManuallyDrop::new(String::from("old")) }; // OK |
| u2.a = ManuallyDrop::new(String::from("new")); //~ ERROR assignment to non-`Copy` union |
| *u2.a = String::from("new"); //~ ERROR access to union field is unsafe |
| |
| let mut u3 = U3 { a: ManuallyDrop::new(0) }; // OK |
| u3.a = ManuallyDrop::new(1); // OK |
| *u3.a = 1; //~ ERROR access to union field is unsafe |
| |
| let mut u3 = U3 { a: ManuallyDrop::new(String::from("old")) }; // OK |
| u3.a = ManuallyDrop::new(String::from("new")); //~ ERROR assignment to non-`Copy` union |
| *u3.a = String::from("new"); //~ ERROR access to union field is unsafe |
| } |