use pattern matching for slices destructuring

5 files changed, 13 insertions, 13 deletions

diff --git a/src/libsyntax_ext/deriving/cmp/ord.rs b/src/libsyntax_ext/deriving/cmp/ord.rs
index b25a9e4c50f..844865d57c7 100644
--- a/src/libsyntax_ext/deriving/cmp/ord.rs
+++ b/src/libsyntax_ext/deriving/cmp/ord.rs
@@ -82,8 +82,8 @@ pub fn cs_cmp(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_>) -> P<
         // }
 
         let new = {
-            let other_f = match (other_fs.len(), other_fs.get(0)) {
-                (1, Some(o_f)) => o_f,
+            let other_f = match other_fs {
+                [o_f] => o_f,
                 _ => cx.span_bug(span, "not exactly 2 arguments in `derive(Ord)`"),
             };
 
diff --git a/src/libsyntax_ext/deriving/cmp/partial_eq.rs b/src/libsyntax_ext/deriving/cmp/partial_eq.rs
index 6172f27261e..732bb234389 100644
--- a/src/libsyntax_ext/deriving/cmp/partial_eq.rs
+++ b/src/libsyntax_ext/deriving/cmp/partial_eq.rs
@@ -25,8 +25,8 @@ pub fn expand_deriving_partial_eq(cx: &mut ExtCtxt<'_>,
              -> P<Expr>
     {
         let op = |cx: &mut ExtCtxt<'_>, span: Span, self_f: P<Expr>, other_fs: &[P<Expr>]| {
-            let other_f = match (other_fs.len(), other_fs.get(0)) {
-                (1, Some(o_f)) => o_f,
+            let other_f = match other_fs {
+                [o_f] => o_f,
                 _ => cx.span_bug(span, "not exactly 2 arguments in `derive(PartialEq)`"),
             };
 
diff --git a/src/libsyntax_ext/deriving/cmp/partial_ord.rs b/src/libsyntax_ext/deriving/cmp/partial_ord.rs
index 3980741f252..a30a7d78222 100644
--- a/src/libsyntax_ext/deriving/cmp/partial_ord.rs
+++ b/src/libsyntax_ext/deriving/cmp/partial_ord.rs
@@ -143,8 +143,8 @@ pub fn cs_partial_cmp(cx: &mut ExtCtxt<'_>, span: Span, substr: &Substructure<'_
                 // }
 
                 let new = {
-                    let other_f = match (other_fs.len(), other_fs.get(0)) {
-                        (1, Some(o_f)) => o_f,
+                    let other_f = match other_fs {
+                        [o_f] => o_f,
                                 _ => {
                                     cx.span_bug(span,
                                         "not exactly 2 arguments in `derive(PartialOrd)`")
@@ -193,8 +193,8 @@ fn cs_op(less: bool,
     };
 
     let par_cmp = |cx: &mut ExtCtxt<'_>, span, self_f: P<Expr>, other_fs: &[P<Expr>], default| {
-        let other_f = match (other_fs.len(), other_fs.get(0)) {
-            (1, Some(o_f)) => o_f,
+        let other_f = match other_fs {
+            [o_f] => o_f,
             _ => cx.span_bug(span, "not exactly 2 arguments in `derive(PartialOrd)`"),
         };
 
diff --git a/src/libsyntax_ext/deriving/hash.rs b/src/libsyntax_ext/deriving/hash.rs
index e7f99d45782..7ad04aebf6e 100644
--- a/src/libsyntax_ext/deriving/hash.rs
+++ b/src/libsyntax_ext/deriving/hash.rs
@@ -52,8 +52,8 @@ pub fn expand_deriving_hash(cx: &mut ExtCtxt<'_>,
 }
 
 fn hash_substructure(cx: &mut ExtCtxt<'_>, trait_span: Span, substr: &Substructure<'_>) -> P<Expr> {
-    let state_expr = match (substr.nonself_args.len(), substr.nonself_args.get(0)) {
-        (1, Some(o_f)) => o_f,
+    let state_expr = match &substr.nonself_args {
+        &[o_f] => o_f,
         _ => {
             cx.span_bug(trait_span,
                         "incorrect number of arguments in `derive(Hash)`")
diff --git a/src/libsyntax_ext/trace_macros.rs b/src/libsyntax_ext/trace_macros.rs
index 6c74f77ff1f..512513e9b41 100644
--- a/src/libsyntax_ext/trace_macros.rs
+++ b/src/libsyntax_ext/trace_macros.rs
@@ -16,11 +16,11 @@ pub fn expand_trace_macros(cx: &mut ExtCtxt<'_>,
                                        feature_gate::EXPLAIN_TRACE_MACROS);
     }
 
-    match (tt.len(), tt.first()) {
-        (1, Some(TokenTree::Token(token))) if token.is_keyword(kw::True) => {
+    match tt {
+        [TokenTree::Token(token)] if token.is_keyword(kw::True) => {
             cx.set_trace_macros(true);
         }
-        (1, Some(TokenTree::Token(token))) if token.is_keyword(kw::False) => {
+        [TokenTree::Token(token)] if token.is_keyword(kw::False) => {
             cx.set_trace_macros(false);
         }
         _ => cx.span_err(sp, "trace_macros! accepts only `true` or `false`"),