1 files changed, 42 insertions, 0 deletions

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::<usize>());
+}