Fix ICEs with match/return expressions inside array lengths

src/test/ui/return-match-array-const.rs

@@ -0,0 +1,17 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+    [(); return match 0 { n => n }]; //~ ERROR: return statement outside of function body
+
+    [(); return match 0 { 0 => 0 }]; //~ ERROR: return statement outside of function body
+
+    [(); return match () { 'a' => 0, _ => 0 }]; //~ ERROR: return statement outside of function body
+}

src/test/ui/return-match-array-const.stderr

@@ -0,0 +1,21 @@
+error[E0572]: return statement outside of function body
+  --> $DIR/return-match-array-const.rs:12:10
+   |
+LL |     [(); return match 0 { n => n }]; //~ ERROR: return statement outside of function body
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0572]: return statement outside of function body
+  --> $DIR/return-match-array-const.rs:14:10
+   |
+LL |     [(); return match 0 { 0 => 0 }]; //~ ERROR: return statement outside of function body
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0572]: return statement outside of function body
+  --> $DIR/return-match-array-const.rs:16:10
+   |
+LL |     [(); return match () { 'a' => 0, _ => 0 }]; //~ ERROR: return statement outside of function body
+   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0572`.