Auto merge of #68376 - Centril:move-ref-patterns, r=matthewjasper

Initial implementation of `#![feature(move_ref_pattern)]`

Following up on #45600, under the gate `#![feature(move_ref_pattern)]`, `(ref x, mut y)` is allowed subject to restrictions necessary for soundness. The match checking implementation and tests for `#![feature(bindings_after_at)]` is also adjusted as necessary.

Closes #45600.
Tracking issue: #68354.

r? @matthewjasper

1 files changed, 16 insertions, 0 deletions

diff --git a/src/test/ui/pattern/move-ref-patterns/move-ref-patterns-default-binding-modes.rs b/src/test/ui/pattern/move-ref-patterns/move-ref-patterns-default-binding-modes.rs
new file mode 100644
index 00000000000..5c51c47d979
--- /dev/null
+++ b/src/test/ui/pattern/move-ref-patterns/move-ref-patterns-default-binding-modes.rs
@@ -0,0 +1,16 @@
+#![feature(move_ref_pattern)]
+
+fn main() {
+    struct U;
+
+    // A tuple is a "non-reference pattern".
+    // A `mut` binding pattern resets the binding mode to by-value.
+
+    let p = (U, U);
+    let (a, mut b) = &p;
+    //~^ ERROR cannot move out of a shared reference
+
+    let mut p = (U, U);
+    let (a, mut b) = &mut p;
+    //~^ ERROR cannot move out of a mutable reference
+}