1 files changed, 36 insertions, 0 deletions
diff --git a/tests/ui/borrowck/borrowck-assign-comp.rs b/tests/ui/borrowck/borrowck-assign-comp.rs
new file mode 100644
index 00000000000..98bb2d85ad7
--- /dev/null
+++ b/tests/ui/borrowck/borrowck-assign-comp.rs
@@ -0,0 +1,36 @@
+struct Point { x: isize, y: isize }
+
+fn a() {
+    let mut p = Point {x: 3, y: 4};
+    let q = &p;
+
+    // This assignment is illegal because the field x is not
+    // inherently mutable; since `p` was made immutable, `p.x` is now
+    // immutable.  Otherwise the type of &_q.x (&isize) would be wrong.
+    p.x = 5; //~ ERROR cannot assign to `p.x` because it is borrowed
+    q.x;
+}
+
+fn c() {
+    // this is sort of the opposite.  We take a loan to the interior of `p`
+    // and then try to overwrite `p` as a whole.
+
+    let mut p = Point {x: 3, y: 4};
+    let q = &p.y;
+    p = Point {x: 5, y: 7};//~ ERROR cannot assign to `p` because it is borrowed
+    p.x; // silence warning
+    *q; // stretch loan
+}
+
+fn d() {
+    // just for completeness's sake, the easy case, where we take the
+    // address of a subcomponent and then modify that subcomponent:
+
+    let mut p = Point {x: 3, y: 4};
+    let q = &p.y;
+    p.y = 5; //~ ERROR cannot assign to `p.y` because it is borrowed
+    *q;
+}
+
+fn main() {
+}