Fix implicit conversion warnings in tuple_test.

Fixes #2329.
diff --git a/test/tuple_test.cpp b/test/tuple_test.cpp
index b40c457..8d8a5aa 100644
--- a/test/tuple_test.cpp
+++ b/test/tuple_test.cpp
@@ -47,24 +47,24 @@
   VERIFY_IS_EQUAL(tuple_impl::get<2>(tuple3), 13.0);
   
   // tuple_impl::tuple_size.
-  VERIFY_IS_EQUAL(tuple_impl::tuple_size<decltype(tuple0)>::value, 0);
-  VERIFY_IS_EQUAL(tuple_impl::tuple_size<decltype(tuple1)>::value, 1);
-  VERIFY_IS_EQUAL(tuple_impl::tuple_size<decltype(tuple2)>::value, 2);
-  VERIFY_IS_EQUAL(tuple_impl::tuple_size<decltype(tuple3)>::value, 3);
+  VERIFY_IS_EQUAL(tuple_impl::tuple_size<decltype(tuple0)>::value, size_t(0));
+  VERIFY_IS_EQUAL(tuple_impl::tuple_size<decltype(tuple1)>::value, size_t(1));
+  VERIFY_IS_EQUAL(tuple_impl::tuple_size<decltype(tuple2)>::value, size_t(2));
+  VERIFY_IS_EQUAL(tuple_impl::tuple_size<decltype(tuple3)>::value, size_t(3));
   
   // tuple_impl::tuple_cat.
   auto tuple2cat3 = tuple_impl::tuple_cat(tuple2, tuple3);
-  VERIFY_IS_EQUAL(tuple_impl::tuple_size<decltype(tuple2cat3)>::value, 5);
+  VERIFY_IS_EQUAL(tuple_impl::tuple_size<decltype(tuple2cat3)>::value, size_t(5));
   VERIFY_IS_EQUAL(tuple_impl::get<1>(tuple2cat3), 5.0f);
   VERIFY_IS_EQUAL(tuple_impl::get<3>(tuple2cat3), 11.0f);
   auto tuple3cat0 = tuple_impl::tuple_cat(tuple3, tuple0);
-  VERIFY_IS_EQUAL(tuple_impl::tuple_size<decltype(tuple3cat0)>::value, 3);
+  VERIFY_IS_EQUAL(tuple_impl::tuple_size<decltype(tuple3cat0)>::value, size_t(3));
   auto singlecat = tuple_impl::tuple_cat(tuple3);
-  VERIFY_IS_EQUAL(tuple_impl::tuple_size<decltype(singlecat)>::value, 3);
+  VERIFY_IS_EQUAL(tuple_impl::tuple_size<decltype(singlecat)>::value, size_t(3));
   auto emptycat = tuple_impl::tuple_cat();
-  VERIFY_IS_EQUAL(tuple_impl::tuple_size<decltype(emptycat)>::value, 0);
+  VERIFY_IS_EQUAL(tuple_impl::tuple_size<decltype(emptycat)>::value, size_t(0));
   auto tuple0cat1cat2cat3 = tuple_impl::tuple_cat(tuple0, tuple1, tuple2, tuple3);
-  VERIFY_IS_EQUAL(tuple_impl::tuple_size<decltype(tuple0cat1cat2cat3)>::value, 6);
+  VERIFY_IS_EQUAL(tuple_impl::tuple_size<decltype(tuple0cat1cat2cat3)>::value, size_t(6));
   
   // make_tuple.
   // The tuple types should uses values for the second and fourth parameters.
@@ -86,10 +86,10 @@
                               decltype(tuple1)&,
                               decltype(tuple2)&,
                               decltype(tuple3)&> >::value) );
-  VERIFY_IS_EQUAL( (tuple_impl::get<1>(tuple_impl::get<2>(tuple_tie))), 5.0 );
+  VERIFY_IS_EQUAL( (tuple_impl::get<1>(tuple_impl::get<2>(tuple_tie))), 5.0f );
   // Modify value and ensure tuple2 is updated.
-  tuple_impl::get<1>(tuple_impl::get<2>(tuple_tie)) = 10.0;
-  VERIFY_IS_EQUAL( (tuple_impl::get<1>(tuple2)), 10.0 );
+  tuple_impl::get<1>(tuple_impl::get<2>(tuple_tie)) = 10.0f;
+  VERIFY_IS_EQUAL( (tuple_impl::get<1>(tuple2)), 10.0f );
   
   // Assignment.
   int x = -1;