[libcxx] [test] Make unord.hash/integral.pass.cpp portable.

[STL_MSFT]

Summary

Make unord.hash/integral.pass.cpp portable.

This was assuming identity hashing, which is a non-Standard assumption. Guarding this with LIBCPP_ASSERT makes the test portable.

Also fixes MSVC warning C4805 "'==': unsafe mix of type '::size_t' and type 'bool' in operation".

[EricWF]

r273345.

test/std/utilities/function.objects/unord.hash/integral.pass.cpp

 
 // template <class T>
 // struct hash
 //     : public unary_function<T, size_t>
 // {
 //     size_t operator()(T val) const;
 // };
 
-// Not very portable
-
 #include <functional>
 #include <cassert>
 #include <type_traits>
 #include <cstddef>
 #include <limits>
 
+#include "test_macros.h"
+
 template <class T>
 void
 test()
 {
     typedef std::hash<T> H;
     static_assert((std::is_same<typename H::argument_type, T>::value), "" );
     static_assert((std::is_same<typename H::result_type, std::size_t>::value), "" );
     H h;
 
     for (int i = 0; i <= 5; ++i)
     {
         T t(i);
         if (sizeof(T) <= sizeof(std::size_t))
-            assert(h(t) == t);
+        {
+            const std::size_t result = h(t);
+            LIBCPP_ASSERT(result == t);
+            ((void)result); // Prevent unused warning
+        }
     }
 }
 
 int main()
 {
     test<bool>();
     test<char>();
     test<signed char>();