Rollup merge of #33734 - luqmana:33387-mir_fat_ptr_coerce, r=arielb1

[MIR] Add PointerCast for Unsize casts of fat pointers.

Fixes #33387.

r? @eddyb

1 files changed, 44 insertions, 0 deletions

diff --git a/src/test/run-pass/issue-33387.rs b/src/test/run-pass/issue-33387.rs
new file mode 100644
index 00000000000..a4b85bc7a09
--- /dev/null
+++ b/src/test/run-pass/issue-33387.rs
@@ -0,0 +1,44 @@
+// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(rustc_attrs)]
+
+use std::sync::Arc;
+
+trait Foo {
+    fn get(&self) -> [u8; 2];
+}
+
+impl Foo for [u8; 2] {
+    fn get(&self) -> [u8; 2] {
+        *self
+    }
+}
+
+struct Bar<T: ?Sized>(T);
+
+#[rustc_mir]
+fn unsize_fat_ptr<'a>(x: &'a Bar<Foo + Send + 'a>) -> &'a Bar<Foo + 'a> {
+    x
+}
+
+#[rustc_mir]
+fn unsize_nested_fat_ptr(x: Arc<Foo + Send>) -> Arc<Foo> {
+    x
+}
+
+#[rustc_mir]
+fn main() {
+    let x: Box<Bar<Foo + Send>> = Box::new(Bar([1,2]));
+    assert_eq!(unsize_fat_ptr(&*x).0.get(), [1, 2]);
+
+    let x: Arc<Foo + Send> = Arc::new([3, 4]);
+    assert_eq!(unsize_nested_fat_ptr(x).get(), [3, 4]);
+}