Tests for custom coercions

Author: Nick Cameron

src/test/run-pass/dst-coerce-custom.rs

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+// Copyright 2015 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.
+
+// Test a very simple custom DST coercion.
+
+#![feature(core)]
+
+use std::ops::CoerceUnsized;
+use std::marker::Unsize;
+
+struct Bar<T: ?Sized> {
+    x: *const T,
+}
+
+impl<T: ?Sized+Unsize<U>, U: ?Sized> CoerceUnsized<Bar<U>> for Bar<T> {}
+
+trait Baz {
+    fn get(&self) -> i32;
+}
+
+impl Baz for i32 {
+    fn get(&self) -> i32 {
+        *self
+    }
+}
+
+fn main() {
+    // Arrays.
+    let a: Bar<[i32; 3]> = Bar { x: &[1, 2, 3] };
+    // This is the actual coercion.
+    let b: Bar<[i32]> = a;
+
+    unsafe {
+        assert_eq!((*b.x)[0], 1);
+        assert_eq!((*b.x)[1], 2);
+        assert_eq!((*b.x)[2], 3);
+    }
+
+    // Trait objects.
+    let a: Bar<i32> = Bar { x: &42 };
+    let b: Bar<Baz> = a;
+    unsafe {
+        assert_eq!((*b.x).get(), 42);
+    }
+}

src/test/run-pass/dst-coerce-rc.rs

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+// Copyright 2015 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.
+
+// Test a very simple custom DST coercion.
+
+#![feature(core)]
+
+use std::rc::Rc;
+
+trait Baz {
+    fn get(&self) -> i32;
+}
+
+impl Baz for i32 {
+    fn get(&self) -> i32 {
+        *self
+    }
+}
+
+fn main() {
+    let a: Rc<[i32; 3]> = Rc::new([1, 2, 3]);
+    let b: Rc<[i32]> = a;
+    assert_eq!(b[0], 1);
+    assert_eq!(b[1], 2);
+    assert_eq!(b[2], 3);
+
+    let a: Rc<i32> = Rc::new(42);
+    let b: Rc<Baz> = a.clone();
+    assert_eq!(b.get(), 42);
+
+    let _c = b.clone();
+}