1 files changed, 105 insertions, 0 deletions
diff --git a/src/test/ui/dynamically-sized-types/dst-trait.rs b/src/test/ui/dynamically-sized-types/dst-trait.rs
new file mode 100644
index 000000000..ec6bc7219
--- /dev/null
+++ b/src/test/ui/dynamically-sized-types/dst-trait.rs
@@ -0,0 +1,105 @@
+// run-pass
+#![feature(box_syntax)]
+
+struct Fat<T: ?Sized> {
+    f1: isize,
+    f2: &'static str,
+    ptr: T
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+struct Bar;
+
+#[derive(Copy, Clone, PartialEq, Eq)]
+struct Bar1 {
+    f: isize
+}
+
+trait ToBar {
+    fn to_bar(&self) -> Bar;
+    fn to_val(&self) -> isize;
+}
+
+impl ToBar for Bar {
+    fn to_bar(&self) -> Bar {
+        *self
+    }
+    fn to_val(&self) -> isize {
+        0
+    }
+}
+impl ToBar for Bar1 {
+    fn to_bar(&self) -> Bar {
+        Bar
+    }
+    fn to_val(&self) -> isize {
+        self.f
+    }
+}
+
+// x is a fat pointer
+fn foo(x: &Fat<dyn ToBar>) {
+    assert_eq!(x.f1, 5);
+    assert_eq!(x.f2, "some str");
+    assert_eq!(x.ptr.to_bar(), Bar);
+    assert_eq!(x.ptr.to_val(), 42);
+
+    let y = &x.ptr;
+    assert_eq!(y.to_bar(), Bar);
+    assert_eq!(y.to_val(), 42);
+}
+
+fn bar(x: &dyn ToBar) {
+    assert_eq!(x.to_bar(), Bar);
+    assert_eq!(x.to_val(), 42);
+}
+
+fn baz(x: &Fat<Fat<dyn ToBar>>) {
+    assert_eq!(x.f1, 5);
+    assert_eq!(x.f2, "some str");
+    assert_eq!(x.ptr.f1, 8);
+    assert_eq!(x.ptr.f2, "deep str");
+    assert_eq!(x.ptr.ptr.to_bar(), Bar);
+    assert_eq!(x.ptr.ptr.to_val(), 42);
+
+    let y = &x.ptr.ptr;
+    assert_eq!(y.to_bar(), Bar);
+    assert_eq!(y.to_val(), 42);
+
+}
+
+pub fn main() {
+    let f1 = Fat { f1: 5, f2: "some str", ptr: Bar1 {f :42} };
+    foo(&f1);
+    let f2 = &f1;
+    foo(f2);
+    let f3: &Fat<dyn ToBar> = f2;
+    foo(f3);
+    let f4: &Fat<dyn ToBar> = &f1;
+    foo(f4);
+    let f5: &Fat<dyn ToBar> = &Fat { f1: 5, f2: "some str", ptr: Bar1 {f :42} };
+    foo(f5);
+
+    // Zero size object.
+    let f6: &Fat<dyn ToBar> = &Fat { f1: 5, f2: "some str", ptr: Bar };
+    assert_eq!(f6.ptr.to_bar(), Bar);
+
+    // &*
+    //
+    let f7: Box<dyn ToBar> = Box::new(Bar1 {f :42});
+    bar(&*f7);
+
+    // Deep nesting
+    let f1 =
+        Fat { f1: 5, f2: "some str", ptr: Fat { f1: 8, f2: "deep str", ptr: Bar1 {f :42}} };
+    baz(&f1);
+    let f2 = &f1;
+    baz(f2);
+    let f3: &Fat<Fat<dyn ToBar>> = f2;
+    baz(f3);
+    let f4: &Fat<Fat<dyn ToBar>> = &f1;
+    baz(f4);
+    let f5: &Fat<Fat<dyn ToBar>> =
+        &Fat { f1: 5, f2: "some str", ptr: Fat { f1: 8, f2: "deep str", ptr: Bar1 {f :42}} };
+    baz(f5);
+}