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, 4 insertions, 4 deletions

diff --git a/src/libstd/sys/common/wtf8.rs b/src/libstd/sys/common/wtf8.rs
index 55e485e5811..d705b8986d0 100644
--- a/src/libstd/sys/common/wtf8.rs
+++ b/src/libstd/sys/common/wtf8.rs
@@ -566,8 +566,8 @@ impl Wtf8 {
         if len < 3 {
             return None
         }
-        match &self.bytes[(len - 3)..] {
-            [0xED, b2 @ 0xA0...0xAF, b3] => Some(decode_surrogate(b2, b3)),
+        match ::slice_pat(&&self.bytes[(len - 3)..]) {
+            &[0xED, b2 @ 0xA0...0xAF, b3] => Some(decode_surrogate(b2, b3)),
             _ => None
         }
     }
@@ -578,8 +578,8 @@ impl Wtf8 {
         if len < 3 {
             return None
         }
-        match &self.bytes[..3] {
-            [0xED, b2 @ 0xB0...0xBF, b3] => Some(decode_surrogate(b2, b3)),
+        match ::slice_pat(&&self.bytes[..3]) {
+            &[0xED, b2 @ 0xB0...0xBF, b3] => Some(decode_surrogate(b2, b3)),
             _ => None
         }
     }