[build] Build fix for libstdc++.

2 files changed, 4 insertions, 4 deletions

diff --git a/base/base_tests/string_utils_test.cpp b/base/base_tests/string_utils_test.cpp
index 7612468777..6d09bd530d 100644
--- a/base/base_tests/string_utils_test.cpp
+++ b/base/base_tests/string_utils_test.cpp
@@ -7,7 +7,6 @@
 #include "std/fstream.hpp"
 #include "std/iomanip.hpp"
 #include "std/map.hpp"
-#include "std/type_traits.hpp"
 #include "std/unordered_map.hpp"
 #include "std/vector.hpp"
 
@@ -459,9 +458,6 @@ UNIT_TEST(Tokenize)
     TEST_EQUAL(strings::Tokenize<vector>("acb def ghi", " " /* delims */), vector<string>(expected), ());
     TEST_EQUAL(strings::Tokenize<set>("acb def ghi", " " /* delims */), set<string>(expected), ());
   }
-  {
-    static_assert(is_same<vector<string>, decltype(strings::Tokenize("", ""))>::value);
-  }
 }
 
 UNIT_TEST(LastUniChar)
diff --git a/base/string_utils.hpp b/base/string_utils.hpp
index 8d7c37e8a6..179a5d560b 100644
--- a/base/string_utils.hpp
+++ b/base/string_utils.hpp
@@ -10,6 +10,7 @@
 #include "std/regex.hpp"
 #include "std/sstream.hpp"
 #include "std/string.hpp"
+#include "std/type_traits.hpp"
 
 #include "3party/utfcpp/source/utf8/unchecked.h"
 
@@ -315,6 +316,9 @@ Collection<string> Tokenize(string const & str, char const * delims)
   return c;
 }
 
+static_assert(is_same<vector<string>, decltype(strings::Tokenize("", ""))>::value,
+              "Tokenize() should return vector<string> by default.");
+
 /// Splits a string by the delimiter, keeps empty parts, on an empty string returns an empty vector.
 /// Does not support quoted columns, newlines in columns and escaped quotes.
 void ParseCSVRow(string const & s, char const delimiter, vector<string> & target);