Update re2

third_party/re2/re2/testing/exhaustive2_test.cc

 // Copyright 2008 The RE2 Authors.  All Rights Reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 // Exhaustive testing of regular expression matching.
 
 #include "util/test.h"
 #include "re2/re2.h"
 #include "re2/testing/exhaustive_tester.h"
 
 DECLARE_string(regexp_engines);
 
 namespace re2 {
 
 // Test empty string matches (aka "(?:)")
 TEST(EmptyString, Exhaustive) {
   ExhaustiveTest(2, 2, Split(" ", "(?:) a"),
                  RegexpGenerator::EgrepOps(),
                  5, Split("", "ab"), "", "");
 }
 
 // Test escaped versions of regexp syntax.
 TEST(Punctuation, Literals) {
   vector<string> alphabet = Explode("()*+?{}[]\\^$.");
   vector<string> escaped = alphabet;
-  for (int i = 0; i < escaped.size(); i++)
+  for (size_t i = 0; i < escaped.size(); i++)
     escaped[i] = "\\" + escaped[i];
   ExhaustiveTest(1, 1, escaped, RegexpGenerator::EgrepOps(),
                  2, alphabet, "", "");
 }
 
 // Test ^ $ . \A \z in presence of line endings.
 // Have to wrap the empty-width ones in (?:) so that
 // they can be repeated -- PCRE rejects ^* but allows (?:^)*
 TEST(LineEnds, Exhaustive) {
   ExhaustiveTest(2, 2, Split(" ", "(?:^) (?:$) . a \\n (?:\\A) (?:\\z)"),
@@ skipping 24 matching lines @@
 //
 // TEST(Newlines, Exhaustive) {
 //   vector<string> empty_vector;
 //   ExhaustiveTest(1, 1, Split(" ", "\\n . a [^a]"),
 //                  RegexpGenerator::EgrepOps(),
 //                  4, Explode("a\n"), "");
 // }
 
 }  // namespace re2