Auto merge of #32202 - arielb1:slice-patterns, r=nikomatsakis

Implement RFC495 semantics for slice patterns

non-MIR translation is still not supported for these and will happily ICE.

This is a [breaking-change] for many uses of slice_patterns.

[RFC 495 text](https://github.com/rust-lang/rfcs/blob/master/text/0495-array-pattern-changes.md)

1 files changed, 8 insertions, 5 deletions

diff --git a/src/libstd/sync/mpsc/spsc_queue.rs b/src/libstd/sync/mpsc/spsc_queue.rs
index ffd33f8518f..02506e7c2f3 100644
--- a/src/libstd/sync/mpsc/spsc_queue.rs
+++ b/src/libstd/sync/mpsc/spsc_queue.rs
@@ -265,15 +265,18 @@ mod tests {
 
             // Ensure the borrowchecker works
             match queue.peek() {
-                Some(vec) => match &**vec {
-                    // Note that `pop` is not allowed here due to borrow
-                    [1] => {}
-                    _ => return
+                Some(vec) => {
+                    assert_eq!(&*vec, &[1]);
                 },
                 None => unreachable!()
             }
 
-            queue.pop();
+            match queue.pop() {
+                Some(vec) => {
+                    assert_eq!(&*vec, &[1]);
+                },
+                None => unreachable!()
+            }
         }
     }