From e138e8760da3d75def4d23567ae944d65b2d4e89 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Wed, 18 Sep 2024 17:05:44 -0400
Subject: Never patterns constitute a read for unsafety

---
 .../never-pattern-is-a-read.rs                       | 16 ++++++++++++++++
 .../never-pattern-is-a-read.stderr                   | 20 ++++++++++++++++++++
 2 files changed, 36 insertions(+)
 create mode 100644 tests/ui/rfcs/rfc-0000-never_patterns/never-pattern-is-a-read.rs
 create mode 100644 tests/ui/rfcs/rfc-0000-never_patterns/never-pattern-is-a-read.stderr

(limited to 'tests/ui/rfcs')

diff --git a/tests/ui/rfcs/rfc-0000-never_patterns/never-pattern-is-a-read.rs b/tests/ui/rfcs/rfc-0000-never_patterns/never-pattern-is-a-read.rs
new file mode 100644
index 00000000000..a66c4464417
--- /dev/null
+++ b/tests/ui/rfcs/rfc-0000-never_patterns/never-pattern-is-a-read.rs
@@ -0,0 +1,16 @@
+// Make sure we consider `!` to be a union read.
+
+#![feature(never_type, never_patterns)]
+//~^ WARN the feature `never_patterns` is incomplete
+
+union U {
+    a: !,
+    b: usize,
+}
+
+fn foo<T>(u: U) -> ! {
+    let U { a: ! } = u;
+    //~^ ERROR access to union field is unsafe
+}
+
+fn main() {}
diff --git a/tests/ui/rfcs/rfc-0000-never_patterns/never-pattern-is-a-read.stderr b/tests/ui/rfcs/rfc-0000-never_patterns/never-pattern-is-a-read.stderr
new file mode 100644
index 00000000000..d7dc7a47e72
--- /dev/null
+++ b/tests/ui/rfcs/rfc-0000-never_patterns/never-pattern-is-a-read.stderr
@@ -0,0 +1,20 @@
+warning: the feature `never_patterns` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/never-pattern-is-a-read.rs:3:24
+   |
+LL | #![feature(never_type, never_patterns)]
+   |                        ^^^^^^^^^^^^^^
+   |
+   = note: see issue #118155 <https://github.com/rust-lang/rust/issues/118155> for more information
+   = note: `#[warn(incomplete_features)]` on by default
+
+error[E0133]: access to union field is unsafe and requires unsafe function or block
+  --> $DIR/never-pattern-is-a-read.rs:12:16
+   |
+LL |     let U { a: ! } = u;
+   |                ^ access to union field
+   |
+   = note: the field may not be properly initialized: using uninitialized data will cause undefined behavior
+
+error: aborting due to 1 previous error; 1 warning emitted
+
+For more information about this error, try `rustc --explain E0133`.
-- 
cgit 1.4.1-3-g733a5