mirror of https://github.com/rust-lang/rust
43 lines
1.4 KiB
Rust
43 lines
1.4 KiB
Rust
//@ run-pass
|
|
#![feature(test)]
|
|
#![allow(unused_mut)] // under NLL we get warning about `x` below: rust-lang/rust#54499
|
|
|
|
// This test is bogus (i.e., should be check-fail) during the period
|
|
// where #54986 is implemented and #54987 is *not* implemented. For
|
|
// now: just ignore it
|
|
//
|
|
//@ ignore-test (#54987)
|
|
|
|
// This test is checking that the space allocated for `x.1` does not
|
|
// overlap with `y`. (The reason why such a thing happened at one
|
|
// point was because `x.0: Void` and thus the whole type of `x` was
|
|
// uninhabited, and so the compiler thought it was safe to use the
|
|
// space of `x.1` to hold `y`.)
|
|
//
|
|
// That's a fine thing to test when this code is accepted by the
|
|
// compiler, and this code is being transcribed accordingly into
|
|
// the ui test issue-21232-partial-init-and-use.rs
|
|
|
|
extern crate test;
|
|
|
|
enum Void {}
|
|
|
|
fn main() {
|
|
let mut x: (Void, usize);
|
|
let mut y = 42;
|
|
x.1 = 13;
|
|
|
|
// Make sure `y` stays on the stack.
|
|
test::black_box(&mut y);
|
|
|
|
// Check that the write to `x.1` did not overwrite `y`.
|
|
// Note that this doesn't fail with optimizations enabled,
|
|
// because we can't keep `x.1` on the stack, like we can `y`,
|
|
// as we can't borrow partially initialized variables.
|
|
assert_eq!(y.to_string(), "42");
|
|
|
|
// Check that `(Void, usize)` has space for the `usize` field.
|
|
assert_eq!(std::mem::size_of::<(Void, usize)>(),
|
|
std::mem::size_of::<usize>());
|
|
}
|