parse.y: Fix for nth_ref_max

* parse.y (parse_numvar): NTH_REF must be less than a half of
  INT_MAX, as it is left-shifted to be ORed with back-ref flag.
  [ruby-core:74444] [Bug#12192] [Fix GH-1296]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54172 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 7 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index c34a0648f2..2dfa7d6c9a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Fri Mar 18 16:22:24 2016  Victor Nawothnig  <Victor.Nawothnig@gmail.com>
+
+	* parse.y (parse_numvar): NTH_REF must be less than a half of
+	  INT_MAX, as it is left-shifted to be ORed with back-ref flag.
+	  [ruby-core:74444] [Bug#12192] [Fix GH-1296]
+
 Fri Mar 18 12:25:30 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* gc.c (tick): fix missing close parenthesis.  [Fix GH-1291]
diff --git a/parse.y b/parse.y
index dbdcb95127..4303bea5b2 100644
--- a/parse.y
+++ b/parse.y
@@ -7833,7 +7833,7 @@ parse_numvar(struct parser_params *parser)
     int overflow;
     unsigned long n = ruby_scan_digits(tok()+1, toklen()-1, 10, &len, &overflow);
     const unsigned long nth_ref_max =
-	(FIXNUM_MAX / 2 < INT_MAX) ? FIXNUM_MAX / 2 : INT_MAX;
+	((FIXNUM_MAX < INT_MAX) ? FIXNUM_MAX : INT_MAX) >> 1;
     /* NTH_REF is left-shifted to be ORed with back-ref flag and
      * turned into a Fixnum, in compile.c */