Fix Visual Studio 2017 warnings

src/json.hpp

@@ -5292,7 +5292,7 @@ class binary_reader
         {
             get();
             check_eof();
-            return current;
+            return static_cast<char>(current);
         });
         return result;
     }

test/CMakeLists.txt

@@ -75,8 +75,11 @@ if(MSVC)
         set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W4")
     endif()
 
-    # Disable warning C4389: '==': signed/unsigned mismatch
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /wd4389")
+    # warning C4389: '==': signed/unsigned mismatch
+	# warning C4309: 'static_cast': truncation of constant value
+	# warning C4566: character represented by universal-character-name '\uFF01' cannot be represented in the current code page (1252)
+	# warning C4996: 'nlohmann::basic_json<std::map,std::vector,std::string,bool,int64_t,uint64_t,double,std::allocator,nlohmann::adl_serializer>::operator <<': was declared deprecated
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /wd4389 /wd4309 /wd4566 /wd4996")
 endif()
 
 #############################################################################

test/src/unit-constructor1.cpp

@@ -242,7 +242,7 @@ TEST_CASE("constructors")
 
         SECTION("std::pair")
         {
-            std::pair<float, std::string> p{1.0, "string"};
+            std::pair<float, std::string> p{1.0f, "string"};
             json j(p);
 
             CHECK(j.type() == json::value_t::array);

test/src/unit-readme.cpp

@@ -38,6 +38,11 @@ using nlohmann::json;
 #include <unordered_set>
 #include <iostream>
 
+#if defined(_MSC_VER)
+#pragma warning (push)
+#pragma warning (disable : 4189) // local variable is initialized but not referenced
+#endif
+
 TEST_CASE("README", "[hide]")
 {
     {
@@ -298,3 +303,7 @@ TEST_CASE("README", "[hide]")
         std::cout.rdbuf(old_cout_buffer);
     }
 }
+
+#if defined(_MSC_VER)
+#pragma warning (pop)
+#endif
\ No newline at end of file