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#[derive(Clone, Copy)]
union U {
a: u8,
b: u64,
}
fn main() {
unsafe {
let mut u = U { b: 0 };
// Imm borrow, same field
{
let ra = &u.a;
let ra2 = &u.a; // OK
drop(ra);
}
{
let ra = &u.a;
let a = u.a; // OK
drop(ra);
}
{
let ra = &u.a;
let rma = &mut u.a; //~ ERROR cannot borrow `u.a` as mutable because it is also borrowed as immutable
drop(ra);
}
{
let ra = &u.a;
u.a = 1; //~ ERROR cannot assign to `u.a` because it is borrowed
drop(ra);
}
// Imm borrow, other field
{
let ra = &u.a;
let rb = &u.b; // OK
drop(ra);
}
{
let ra = &u.a;
let b = u.b; // OK
drop(ra);
}
{
let ra = &u.a;
let rmb = &mut u.b; //~ ERROR cannot borrow `u` (via `u.b`) as mutable because it is also borrowed as immutable (via `u.a`)
drop(ra);
}
{
let ra = &u.a;
u.b = 1; //~ ERROR cannot assign to `u.b` because it is borrowed
drop(ra);
}
// Mut borrow, same field
{
let rma = &mut u.a;
let ra = &u.a; //~ ERROR cannot borrow `u.a` as immutable because it is also borrowed as mutable
drop(rma);
}
{
let ra = &mut u.a;
let a = u.a; //~ ERROR cannot use `u.a` because it was mutably borrowed
drop(ra);
}
{
let rma = &mut u.a;
let rma2 = &mut u.a; //~ ERROR cannot borrow `u.a` as mutable more than once at a time
drop(rma);
}
{
let rma = &mut u.a;
u.a = 1; //~ ERROR cannot assign to `u.a` because it is borrowed
drop(rma);
}
// Mut borrow, other field
{
let rma = &mut u.a;
let rb = &u.b; //~ ERROR cannot borrow `u` (via `u.b`) as immutable because it is also borrowed as mutable (via `u.a`)
drop(rma);
}
{
let ra = &mut u.a;
let b = u.b; //~ ERROR cannot use `u.b` because it was mutably borrowed
drop(ra);
}
{
let rma = &mut u.a;
let rmb2 = &mut u.b; //~ ERROR cannot borrow `u` (via `u.b`) as mutable more than once at a time
drop(rma);
}
{
let rma = &mut u.a;
u.b = 1; //~ ERROR cannot assign to `u.b` because it is borrowed
drop(rma);
}
}
}
|
