syntax: Remove uses of #[feature(slice_patterns)]

Author: erickt

src/libsyntax/config.rs

@@ -284,8 +284,15 @@ impl<'a> fold::Folder for CfgAttrFolder<'a> {
             return fold::noop_fold_attribute(attr, self);
         }
 
-        let (cfg, mi) = match attr.meta_item_list() {
-            Some([ref cfg, ref mi]) => (cfg, mi),
+        let attr_list = match attr.meta_item_list() {
+            Some(attr_list) => attr_list,
+            None => {
+                self.diag.span_err(attr.span, "expected `#[cfg_attr(<cfg pattern>, <attr>)]`");
+                return None;
+            }
+        };
+        let (cfg, mi) = match (attr_list.len(), attr_list.get(0), attr_list.get(1)) {
+            (2, Some(cfg), Some(mi)) => (cfg, mi),
             _ => {
                 self.diag.span_err(attr.span, "expected `#[cfg_attr(<cfg pattern>, <attr>)]`");
                 return None;

src/libsyntax/diagnostics/plugin.rs

@@ -51,8 +51,8 @@ pub fn expand_diagnostic_used<'cx>(ecx: &'cx mut ExtCtxt,
                                    span: Span,
                                    token_tree: &[TokenTree])
                                    -> Box<MacResult+'cx> {
-    let code = match token_tree {
-        [ast::TtToken(_, token::Ident(code, _))] => code,
+    let code = match (token_tree.len(), token_tree.get(0)) {
+        (1, Some(&ast::TtToken(_, token::Ident(code, _)))) => code,
         _ => unreachable!()
     };
     with_used_diagnostics(|diagnostics| {
@@ -81,13 +81,13 @@ pub fn expand_register_diagnostic<'cx>(ecx: &'cx mut ExtCtxt,
                                        span: Span,
                                        token_tree: &[TokenTree])
                                        -> Box<MacResult+'cx> {
-    let (code, description) = match token_tree {
-        [ast::TtToken(_, token::Ident(ref code, _))] => {
+    let (code, description) = match (token_tree.len(), token_tree.get(0), token_tree.get(1), token_tree.get(2)) {
+        (1, Some(&ast::TtToken(_, token::Ident(ref code, _))), None, None) => {
             (code, None)
         },
-        [ast::TtToken(_, token::Ident(ref code, _)),
-         ast::TtToken(_, token::Comma),
-         ast::TtToken(_, token::Literal(token::StrRaw(description, _), None))] => {
+        (3, Some(&ast::TtToken(_, token::Ident(ref code, _))),
+            Some(&ast::TtToken(_, token::Comma)),
+            Some(&ast::TtToken(_, token::Literal(token::StrRaw(description, _), None)))) => {
             (code, Some(description))
         }
         _ => unreachable!()
@@ -109,8 +109,8 @@ pub fn expand_build_diagnostic_array<'cx>(ecx: &'cx mut ExtCtxt,
                                           span: Span,
                                           token_tree: &[TokenTree])
                                           -> Box<MacResult+'cx> {
-    let name = match token_tree {
-        [ast::TtToken(_, token::Ident(ref name, _))] => name,
+    let name = match (token_tree.len(), token_tree.get(0)) {
+        (1, Some(&ast::TtToken(_, token::Ident(ref name, _)))) => name,
         _ => unreachable!()
     };
 

src/libsyntax/ext/deriving/cmp/eq.rs

@@ -30,8 +30,8 @@ pub fn expand_deriving_eq<F>(cx: &mut ExtCtxt,
         cs_fold(
             true,  // use foldl
             |cx, span, subexpr, self_f, other_fs| {
-                let other_f = match other_fs {
-                    [ref o_f] => o_f,
+                let other_f = match (other_fs.len(), other_fs.get(0)) {
+                    (1, Some(o_f)) => o_f,
                     _ => cx.span_bug(span, "not exactly 2 arguments in `derive(PartialEq)`")
                 };
 
@@ -47,8 +47,8 @@ pub fn expand_deriving_eq<F>(cx: &mut ExtCtxt,
         cs_fold(
             true,  // use foldl
             |cx, span, subexpr, self_f, other_fs| {
-                let other_f = match other_fs {
-                    [ref o_f] => o_f,
+                let other_f = match (other_fs.len(), other_fs.get(0)) {
+                    (1, Some(o_f)) => o_f,
                     _ => cx.span_bug(span, "not exactly 2 arguments in `derive(PartialEq)`")
                 };
 

src/libsyntax/ext/deriving/cmp/ord.rs

@@ -151,8 +151,8 @@ pub fn cs_partial_cmp(cx: &mut ExtCtxt, span: Span,
             // }
 
             let new = {
-                let other_f = match other_fs {
-                    [ref o_f] => o_f,
+                let other_f = match (other_fs.len(), other_fs.get(0)) {
+                    (1, Some(o_f)) => o_f,
                     _ => cx.span_bug(span, "not exactly 2 arguments in `derive(PartialOrd)`"),
                 };
 
@@ -209,8 +209,8 @@ fn cs_op(less: bool, equal: bool, cx: &mut ExtCtxt,
             get use the binops to avoid auto-deref dereferencing too many
             layers of pointers, if the type includes pointers.
             */
-            let other_f = match other_fs {
-                [ref o_f] => o_f,
+            let other_f = match (other_fs.len(), other_fs.get(0)) {
+                (1, Some(o_f)) => o_f,
                 _ => cx.span_bug(span, "not exactly 2 arguments in `derive(PartialOrd)`")
             };
 

src/libsyntax/ext/deriving/cmp/totalord.rs

@@ -107,8 +107,8 @@ pub fn cs_cmp(cx: &mut ExtCtxt, span: Span,
             // }
 
             let new = {
-                let other_f = match other_fs {
-                    [ref o_f] => o_f,
+                let other_f = match (other_fs.len(), other_fs.get(0)) {
+                    (1, Some(o_f)) => o_f,
                     _ => cx.span_bug(span, "not exactly 2 arguments in `derive(PartialOrd)`"),
                 };
 

src/libsyntax/ext/deriving/hash.rs

@@ -57,8 +57,8 @@ pub fn expand_deriving_hash<F>(cx: &mut ExtCtxt,
 }
 
 fn hash_substructure(cx: &mut ExtCtxt, trait_span: Span, substr: &Substructure) -> P<Expr> {
-    let state_expr = match substr.nonself_args {
-        [ref state_expr] => state_expr,
+    let state_expr = match (substr.nonself_args.len(), substr.nonself_args.get(0)) {
+        (1, Some(o_f)) => o_f,
         _ => cx.span_bug(trait_span, "incorrect number of arguments in `derive(Hash)`")
     };
     let call_hash = |span, thing_expr| {

src/libsyntax/ext/deriving/primitive.rs

@@ -72,8 +72,8 @@ pub fn expand_deriving_from_primitive<F>(cx: &mut ExtCtxt,
 }
 
 fn cs_from(name: &str, cx: &mut ExtCtxt, trait_span: Span, substr: &Substructure) -> P<Expr> {
-    let n = match substr.nonself_args {
-        [ref n] => n,
+    let n = match (substr.nonself_args.len(), substr.nonself_args.get(0)) {
+        (1, Some(o_f)) => o_f,
         _ => cx.span_bug(trait_span, "incorrect number of arguments in `derive(FromPrimitive)`")
     };
 

src/libsyntax/ext/trace_macros.rs

@@ -28,12 +28,11 @@ pub fn expand_trace_macros(cx: &mut ExtCtxt,
         return base::DummyResult::any(sp);
     }
 
-
-    match tt {
-        [ast::TtToken(_, ref tok)] if tok.is_keyword(keywords::True) => {
+    match (tt.len(), tt.first()) {
+        (1, Some(&ast::TtToken(_, ref tok))) if tok.is_keyword(keywords::True) => {
             cx.set_trace_macros(true);
         }
-        [ast::TtToken(_, ref tok)] if tok.is_keyword(keywords::False) => {
+        (1, Some(&ast::TtToken(_, ref tok))) if tok.is_keyword(keywords::False) => {
             cx.set_trace_macros(false);
         }
         _ => cx.span_err(sp, "trace_macros! accepts only `true` or `false`"),

src/libsyntax/lib.rs

@@ -35,7 +35,6 @@
 #![feature(path_ext)]
 #![feature(str_char)]
 #![feature(into_cow)]
-#![feature(slice_patterns)]
 
 extern crate arena;
 extern crate fmt_macros;