From afca613c57be5df8768b675df7015788ca64fe2e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=94=D0=BE=D0=B1=D1=80=D1=8B=D0=B8=CC=86=20=D0=AD=D1=8D?=
 =?UTF-8?q?=D1=85?= <bukharaev@gmail.com>
Date: Tue, 24 Jan 2017 12:48:39 +0300
Subject: [PATCH] [base] fix signed/unsigned checked_cast

---
 base/checked_cast.hpp | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/base/checked_cast.hpp b/base/checked_cast.hpp
index 363840c785..bc37f13418 100644
--- a/base/checked_cast.hpp
+++ b/base/checked_cast.hpp
@@ -2,19 +2,31 @@
 
 #include "base/assert.hpp"
 
+#include <type_traits>
+
 namespace base
 {
 template <typename ReturnType, typename ParameterType>
 ReturnType checked_cast(ParameterType v)
 {
-  CHECK_EQUAL(static_cast<ParameterType>(static_cast<ReturnType>(v)), v, ());
-  return static_cast<ReturnType>(v);
+  static_assert(std::is_integral<ParameterType>::value, "ParameterType should be integral");
+  static_assert(std::is_integral<ReturnType>::value, "ReturnType should be integral");
+
+  ReturnType const result = static_cast<ReturnType>(v);
+  CHECK_EQUAL(static_cast<ParameterType>(result), v, ());
+  CHECK((result > 0) == (v > 0), ("checked_cast failed, value =", v, ", result =", result));
+  return result;
 }
 
 template <typename ReturnType, typename ParameterType>
 ReturnType asserted_cast(ParameterType v)
 {
-  ASSERT_EQUAL(static_cast<ParameterType>(static_cast<ReturnType>(v)), v, ());
-  return static_cast<ReturnType>(v);
+  static_assert(std::is_integral<ParameterType>::value, "ParameterType should be integral");
+  static_assert(std::is_integral<ReturnType>::value, "ReturnType should be integral");
+
+  ReturnType const result = static_cast<ReturnType>(v);
+  ASSERT_EQUAL(static_cast<ParameterType>(result), v, ());
+  ASSERT((result > 0) == (v > 0), ("asserted_cast failed, value =", v, ", result =", result));
+  return result;
 }
 }  // namespace base