Distinguish tuple elements by index in mem_categorization. Fixes #5362.

src/test/compile-fail/borrowck-anon-fields-struct.rs

@@ -0,0 +1,37 @@
+// Tests that we are able to distinguish when loans borrow different
+// anonymous fields of an tuple vs the same anonymous field.
+
+struct Y(uint, uint);
+
+fn distinct_variant() {
+    let mut y = Y(1, 2);
+
+    let a = match y {
+        Y(ref mut a, _) => a
+    };
+
+    let b = match y {
+        Y(_, ref mut b) => b
+    };
+
+    *a += 1;
+    *b += 1;
+}
+
+fn same_variant() {
+    let mut y = Y(1, 2);
+
+    let a = match y {
+        Y(ref mut a, _) => a
+    };
+
+    let b = match y {
+        Y(ref mut b, _) => b //~ ERROR cannot borrow
+    };
+
+    *a += 1;
+    *b += 1;
+}
+
+fn main() {
+}

src/test/compile-fail/borrowck-anon-fields-tuple.rs

@@ -0,0 +1,35 @@
+// Tests that we are able to distinguish when loans borrow different
+// anonymous fields of a tuple vs the same anonymous field.
+
+fn distinct_variant() {
+    let mut y = (1, 2);
+
+    let a = match y {
+        (ref mut a, _) => a
+    };
+
+    let b = match y {
+        (_, ref mut b) => b
+    };
+
+    *a += 1;
+    *b += 1;
+}
+
+fn same_variant() {
+    let mut y = (1, 2);
+
+    let a = match y {
+        (ref mut a, _) => a
+    };
+
+    let b = match y {
+        (ref mut b, _) => b //~ ERROR cannot borrow
+    };
+
+    *a += 1;
+    *b += 1;
+}
+
+fn main() {
+}

src/test/compile-fail/borrowck-anon-fields-variant.rs

@@ -0,0 +1,43 @@
+// Tests that we are able to distinguish when loans borrow different
+// anonymous fields of an enum variant vs the same anonymous field.
+
+enum Foo {
+    X, Y(uint, uint)
+}
+
+fn distinct_variant() {
+    let mut y = Y(1, 2);
+
+    let a = match y {
+      Y(ref mut a, _) => a,
+      X => fail!()
+    };
+
+    let b = match y {
+      Y(_, ref mut b) => b,
+      X => fail!()
+    };
+
+    *a += 1;
+    *b += 1;
+}
+
+fn same_variant() {
+    let mut y = Y(1, 2);
+
+    let a = match y {
+      Y(ref mut a, _) => a,
+      X => fail!()
+    };
+
+    let b = match y {
+      Y(ref mut b, _) => b, //~ ERROR cannot borrow
+      X => fail!()
+    };
+
+    *a += 1;
+    *b += 1;
+}
+
+fn main() {
+}