Unexpected compile pass when pattern matching on union without unsafe

[SamZhang3]

I tried this code:

union U {
    a: i32,
    b: (),
}

fn main() {
    let u = U {a: 123};
    match u {
        U {b: ()} => println!("Hello, world!"),
    }
}

I expected to see this happen: Compiler error, since pattern matching on a union is done without using unsafe; see the reference.

Instead, this happened: Compile succeeds.

It seems that this only works when matching with a zero-sized union field, and it does not appear possible to actually extract the field's value by binding it to a name.

Meta

rustc --version --verbose:

rustc 1.68.2 (9eb3afe9e 2023-03-27)
binary: rustc
commit-hash: 9eb3afe9ebe9c7d2b84b71002d44f4a0edac95e0
commit-date: 2023-03-27
host: x86_64-apple-darwin
release: 1.68.2
LLVM version: 15.0.6

[Noratrieb]

There's more discussion about this in #87520.
Thank you for the report, but closing as a duplicate