1 files changed, 96 insertions, 0 deletions
diff --git a/tests/ui/nll/match-on-borrowed.rs b/tests/ui/nll/match-on-borrowed.rs
new file mode 100644
index 000000000..447dabeb4
--- /dev/null
+++ b/tests/ui/nll/match-on-borrowed.rs
@@ -0,0 +1,96 @@
+// Test that a (partially) mutably borrowed place can be matched on, so long as
+// we don't have to read any values that are mutably borrowed to determine
+// which arm to take.
+//
+// Test that we don't allow mutating the value being matched on in a way that
+// changes which patterns it matches, until we have chosen an arm.
+
+struct A(i32, i32);
+
+fn struct_example(mut a: A) {
+    let x = &mut a.0;
+    match a { // OK, no access of borrowed data
+        _ if false => (),
+        A(_, r) => (),
+    }
+    x;
+}
+
+fn indirect_struct_example(mut b: &mut A) {
+    let x = &mut b.0;
+    match *b { // OK, no access of borrowed data
+        _ if false => (),
+        A(_, r) => (),
+    }
+    x;
+}
+
+fn underscore_example(mut c: i32) {
+    let r = &mut c;
+    match c { // OK, no access of borrowed data (or any data at all)
+        _ if false => (),
+        _ => (),
+    }
+    r;
+}
+
+enum E {
+    V(i32, i32),
+    W,
+}
+
+fn enum_example(mut e: E) {
+    let x = match e {
+        E::V(ref mut x, _) => x,
+        E::W => panic!(),
+    };
+    match e { // Don't know that E uses a tag for its discriminant
+        //~^ ERROR
+        _ if false => (),
+        E::V(_, r) => (),
+        E::W => (),
+    }
+    x;
+}
+
+fn indirect_enum_example(mut f: &mut E) {
+    let x = match *f {
+        E::V(ref mut x, _) => x,
+        E::W => panic!(),
+    };
+    match f { // Don't know that E uses a tag for its discriminant
+        //~^ ERROR
+        _ if false => (),
+        E::V(_, r) => (),
+        E::W => (),
+    }
+    x;
+}
+
+fn match_on_muatbly_borrowed_ref(mut p: &bool) {
+    let r = &mut p;
+    match *p { // OK, no access at all
+        _ if false => (),
+        _ => (),
+    }
+    r;
+}
+
+fn match_on_borrowed(mut t: bool) {
+    let x = &mut t;
+    match t {
+        //~^ ERROR
+        true => (),
+        false => (),
+    }
+    x;
+}
+
+enum Never {}
+
+fn never_init() {
+    let n: Never;
+    match n {} //~ ERROR
+}
+
+fn main() {}