Fixed warning "conversion may alter value" (issue #914)

CHANGELOG.md

@@ -6,6 +6,7 @@ HEAD
 
 * Fixed warning "unused variable" with GCC 4.4 (issue #912)
 * Fixed warning "cast  increases required alignment" (issue #914)
+* Fixed warning "conversion may alter value" (issue #914)
 * Added a clear error message for `StaticJsonBuffer` and `DynamicJsonBuffer`
 
 v6.9.0 (2019-02-26)

src/ArduinoJson/Json/JsonDeserializer.hpp

@@ -306,7 +306,7 @@ class JsonDeserializer {
 
   static inline uint8_t decodeHex(char c) {
     if (c < 'A') return uint8_t(c - '0');
-    c &= ~0x20;  // uppercase
+    c = char(c & ~0x20);  // uppercase
     return uint8_t(c - 'A' + 10);
   }