From 1f542cd2640fd969cba328ca3b4059acd6428a83 Mon Sep 17 00:00:00 2001
From: Alex Crichton <alex@alexcrichton.com>
Date: Sun, 19 Jan 2014 00:00:39 -0800
Subject: [PATCH] Fix a pathological const checking case

The included test case would essentially never finish compiling without this
patch. It recursies twice at every ExprParen meaning that the branching factor
is 2^n

The included test case will take so long to parse on the old compiler that it'll
surely never let this crop up again.
---
 src/librustc/middle/check_const.rs            |  3 +--
 src/test/run-pass/super-fast-paren-parsing.rs | 25 +++++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)
 create mode 100644 src/test/run-pass/super-fast-paren-parsing.rs

diff --git a/src/librustc/middle/check_const.rs b/src/librustc/middle/check_const.rs
index e13f6f8c537..31a3e6ce8ff 100644
--- a/src/librustc/middle/check_const.rs
+++ b/src/librustc/middle/check_const.rs
@@ -177,11 +177,10 @@ pub fn check_expr(v: &mut CheckCrateVisitor,
                 }
             }
           }
-          ExprParen(e) => { check_expr(v, sess, def_map, method_map,
-                                        tcx, e, is_const); }
           ExprVstore(_, ExprVstoreSlice) |
           ExprVec(_, MutImmutable) |
           ExprAddrOf(MutImmutable, _) |
+          ExprParen(..) |
           ExprField(..) |
           ExprIndex(..) |
           ExprTup(..) |
diff --git a/src/test/run-pass/super-fast-paren-parsing.rs b/src/test/run-pass/super-fast-paren-parsing.rs
new file mode 100644
index 00000000000..759b066c8db
--- /dev/null
+++ b/src/test/run-pass/super-fast-paren-parsing.rs
@@ -0,0 +1,25 @@
+// 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.
+
+static a: int =
+(((((((((((((((((((((((((((((((((((((((((((((((((((
+(((((((((((((((((((((((((((((((((((((((((((((((((((
+(((((((((((((((((((((((((((((((((((((((((((((((((((
+(((((((((((((((((((((((((((((((((((((((((((((((((((
+(((((((((((((((((((((((((((((((((((((((((((((((((((
+1
+)))))))))))))))))))))))))))))))))))))))))))))))))))
+)))))))))))))))))))))))))))))))))))))))))))))))))))
+)))))))))))))))))))))))))))))))))))))))))))))))))))
+)))))))))))))))))))))))))))))))))))))))))))))))))))
+)))))))))))))))))))))))))))))))))))))))))))))))))))
+;
+
+pub fn main() {}
-- 
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