use the slice_pat hack in libstd too

Author: arielb1

src/libstd/lib.rs

@@ -467,3 +467,15 @@ pub mod __rand {
 // the rustdoc documentation for primitive types. Using `include!`
 // because rustdoc only looks for these modules at the crate level.
 include!("primitive_docs.rs");
+
+// FIXME(stage0): remove this after a snapshot
+// HACK: this is needed because the interpretation of slice
+// patterns changed between stage0 and now.
+#[cfg(stage0)]
+fn slice_pat<'a, 'b, T>(t: &'a &'b [T]) -> &'a &'b [T] {
+    t
+}
+#[cfg(not(stage0))]
+fn slice_pat<'a, 'b, T>(t: &'a &'b [T]) -> &'b [T] {
+    *t
+}

src/libstd/sys/common/wtf8.rs

@@ -560,20 +560,15 @@ impl Wtf8 {
         }
     }
 
-    // FIXME(stage0): use slice patterns after snapshot
     #[inline]
     fn final_lead_surrogate(&self) -> Option<u16> {
         let len = self.len();
         if len < 3 {
             return None
         }
-        if self.bytes[len-3] == 0xed &&
-            self.bytes[len-2] >= 0xa0 &&
-            self.bytes[len-2] <= 0xaf
-        {
-            Some(decode_surrogate(self.bytes[len-2], self.bytes[len-1]))
-        } else {
-            None
+        match ::slice_pat(&&self.bytes[(len - 3)..]) {
+            &[0xED, b2 @ 0xA0...0xAF, b3] => Some(decode_surrogate(b2, b3)),
+            _ => None
         }
     }
 
@@ -583,13 +578,9 @@ impl Wtf8 {
         if len < 3 {
             return None
         }
-        if self.bytes[0] == 0xed &&
-            self.bytes[1] >= 0xb0 &&
-            self.bytes[1] <= 0xbf
-        {
-            Some(decode_surrogate(self.bytes[1], self.bytes[2]))
-        } else {
-            None
+        match ::slice_pat(&&self.bytes[..3]) {
+            &[0xED, b2 @ 0xB0...0xBF, b3] => Some(decode_surrogate(b2, b3)),
+            _ => None
         }
     }
 }

src/libstd/sys/windows/fs.rs

@@ -117,10 +117,10 @@ impl Drop for FindNextFileHandle {
 
 impl DirEntry {
     fn new(root: &Arc<PathBuf>, wfd: &c::WIN32_FIND_DATAW) -> Option<DirEntry> {
-        match &wfd.cFileName[0..3] {
+        match ::slice_pat(&&wfd.cFileName[0..3]) {
             // check for '.' and '..'
-            [46, 0, ..] |
-            [46, 46, 0, ..] => return None,
+            &[46, 0, ..] |
+            &[46, 46, 0, ..] => return None,
             _ => {}
         }