1 files changed, 60 insertions, 0 deletions
diff --git a/src/test/ui/span/borrowck-borrow-overloaded-deref-mut.rs b/src/test/ui/span/borrowck-borrow-overloaded-deref-mut.rs
new file mode 100644
index 000000000..8d43d5da4
--- /dev/null
+++ b/src/test/ui/span/borrowck-borrow-overloaded-deref-mut.rs
@@ -0,0 +1,60 @@
+// Test how overloaded deref interacts with borrows when DerefMut
+// is implemented.
+
+use std::ops::{Deref, DerefMut};
+
+struct Own<T> {
+    value: *mut T
+}
+
+impl<T> Deref for Own<T> {
+    type Target = T;
+
+    fn deref<'a>(&'a self) -> &'a T {
+        unsafe { &*self.value }
+    }
+}
+
+impl<T> DerefMut for Own<T> {
+    fn deref_mut<'a>(&'a mut self) -> &'a mut T {
+        unsafe { &mut *self.value }
+    }
+}
+
+fn deref_imm(x: Own<isize>) {
+    let __isize = &*x;
+}
+
+fn deref_mut1(x: Own<isize>) {
+    let __isize = &mut *x; //~ ERROR cannot borrow
+}
+
+fn deref_mut2(mut x: Own<isize>) {
+    let __isize = &mut *x;
+}
+
+fn deref_extend<'a>(x: &'a Own<isize>) -> &'a isize {
+    &**x
+}
+
+fn deref_extend_mut1<'a>(x: &'a Own<isize>) -> &'a mut isize {
+    &mut **x //~ ERROR cannot borrow
+}
+
+fn deref_extend_mut2<'a>(x: &'a mut Own<isize>) -> &'a mut isize {
+    &mut **x
+}
+
+fn assign1<'a>(x: Own<isize>) {
+    *x = 3; //~ ERROR cannot borrow
+}
+
+fn assign2<'a>(x: &'a Own<isize>) {
+    **x = 3; //~ ERROR cannot borrow
+}
+
+fn assign3<'a>(x: &'a mut Own<isize>) {
+    **x = 3;
+}
+
+pub fn main() {}