libsyntax: Don't ICE on macro invocation in count expr of fixed array type.

src/libsyntax/ext/expand.rs

@@ -536,13 +536,16 @@ fn expand_non_macro_stmt(s: &Stmt, fld: &mut MacroExpander)
                 } => {
                     // take it apart:
                     let Local {
-                        ty: _,
+                        ty: ty,
                         pat: pat,
                         init: init,
                         id: id,
                         span: span,
                         source: source,
                     } = **local;
+                    // expand the ty since TyFixedLengthVec contains an Expr
+                    // and thus may have a macro use
+                    let expanded_ty = fld.fold_ty(ty);
                     // expand the pat (it might contain macro uses):
                     let expanded_pat = fld.fold_pat(pat);
                     // find the PatIdents in the pattern:
@@ -566,7 +569,7 @@ fn expand_non_macro_stmt(s: &Stmt, fld: &mut MacroExpander)
                     let new_init_opt = init.map(|e| fld.fold_expr(e));
                     let rewritten_local =
                         box(GC) Local {
-                            ty: local.ty,
+                            ty: expanded_ty,
                             pat: rewritten_pat,
                             init: new_init_opt,
                             id: id,

src/test/run-pass/macro-invocation-in-count-expr-fixed-array-type.rs

@@ -0,0 +1,18 @@
+// Copyright 2014 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.
+
+#![feature(macro_rules)]
+
+macro_rules! four (
+    () => (4)
+)
+fn main() {
+    let _x: [u16, ..four!()];
+}