Convert alt to match. Stop parsing alt

src/rustc/middle/check_loop.rs

@@ -10,7 +10,7 @@ fn check_crate(tcx: ty::ctxt, crate: @crate) {
             visit::visit_item(i, {in_loop: false, can_ret: true}, v);
         },
         visit_expr: |e: @expr, cx: ctx, v: visit::vt<ctx>| {
-            alt e.node {
+            match e.node {
               expr_while(e, b) => {
                 v.visit_expr(e, cx, v);
                 v.visit_block(b, {in_loop: true with cx}, v);