From 218caa410aa38c29984be31a5229b9fa717560ee Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Wed, 17 Apr 2024 14:19:13 +0200
Subject: Merging upstream version 1.68.2+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 .../unions/should_reject_contraction.rs            | 36 ++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 tests/ui/transmutability/unions/should_reject_contraction.rs

(limited to 'tests/ui/transmutability/unions/should_reject_contraction.rs')

diff --git a/tests/ui/transmutability/unions/should_reject_contraction.rs b/tests/ui/transmutability/unions/should_reject_contraction.rs
new file mode 100644
index 000000000..a24dfccd3
--- /dev/null
+++ b/tests/ui/transmutability/unions/should_reject_contraction.rs
@@ -0,0 +1,36 @@
+//! Validity may not be contracted, unless validity is assumed.
+
+#![crate_type = "lib"]
+#![feature(transmutability)]
+#![allow(dead_code, incomplete_features, non_camel_case_types)]
+
+mod assert {
+    use std::mem::{Assume, BikeshedIntrinsicFrom};
+    pub struct Context;
+
+    pub fn is_transmutable<Src, Dst>()
+    where
+        Dst: BikeshedIntrinsicFrom<Src, Context, { Assume::SAFETY }>
+    {}
+}
+
+#[derive(Clone, Copy)] #[repr(u8)] enum Ox00 { V = 0x00 }
+#[derive(Clone, Copy)] #[repr(u8)] enum Ox01 { V = 0x01 }
+#[derive(Clone, Copy)] #[repr(u8)] enum OxFF { V = 0xFF }
+
+fn test() {
+    #[repr(C)]
+    union Subset {
+        a: Ox00,
+        b: OxFF,
+    }
+
+    #[repr(C)]
+    union Superset {
+        a: Ox00,
+        b: OxFF,
+        c: Ox01,
+    }
+
+    assert::is_transmutable::<Superset, Subset>(); //~ ERROR cannot be safely transmuted
+}
-- 
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