Fix pointer value punning.

Seems this doesn't trigger error on LLVM 15, but let's fix it for better compatibility.

1 files changed, 21 insertions, 0 deletions

diff --git a/src/test/ui/codegen/issue-99551.rs b/src/test/ui/codegen/issue-99551.rs
new file mode 100644
index 00000000000..f24874c992e
--- /dev/null
+++ b/src/test/ui/codegen/issue-99551.rs
@@ -0,0 +1,21 @@
+// build-pass
+#![feature(trait_upcasting)]
+#![allow(incomplete_features)]
+
+pub trait A {}
+pub trait B {}
+
+pub trait C: A + B {}
+impl<X: A + B> C for X {}
+
+pub fn test<'a, T>(view: T) -> Option<&'a mut dyn B>
+where
+    T: IntoIterator<Item = &'a mut dyn B>,
+{
+    return Some(view.into_iter().next().unwrap());
+}
+
+fn main() {
+    let mut a: Vec<Box<dyn C>> = Vec::new();
+    test(a.iter_mut().map(|c| c.as_mut() as &mut dyn B));
+}