From 218caa410aa38c29984be31a5229b9fa717560ee Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 17 Apr 2024 14:19:13 +0200 Subject: Merging upstream version 1.68.2+dfsg1. Signed-off-by: Daniel Baumann --- tests/ui/issues/issue-49298.rs | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 tests/ui/issues/issue-49298.rs (limited to 'tests/ui/issues/issue-49298.rs') diff --git a/tests/ui/issues/issue-49298.rs b/tests/ui/issues/issue-49298.rs new file mode 100644 index 000000000..e3ffa8e7c --- /dev/null +++ b/tests/ui/issues/issue-49298.rs @@ -0,0 +1,42 @@ +// 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 + +// 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::()); +} -- cgit v1.2.3