Added a deprecation warning for is<char>() and is<char*>()

extras/tests/Misc/deprecated.cpp

@@ -31,6 +31,16 @@ TEST_CASE("Deprecated features") {
     REQUIRE(v.as<char>() == '*');
   }
 
+  SECTION("JsonVariant::is<char*>()") {
+    JsonVariant v = doc["s"];
+    REQUIRE(v.is<char*>() == true);
+  }
+
+  SECTION("JsonVariant::is<char>()") {
+    JsonVariant v = doc["c"];
+    REQUIRE(v.is<char>() == true);
+  }
+
   SECTION("JsonVariant::set(char)") {
     JsonVariant v = doc.to<JsonVariant>();
     v.set('*');
@@ -47,6 +57,16 @@ TEST_CASE("Deprecated features") {
     REQUIRE(v.as<char>() == '*');
   }
 
+  SECTION("JsonVariantConst::is<char*>()") {
+    JsonVariantConst v = doc["s"];
+    REQUIRE(v.is<char*>() == true);
+  }
+
+  SECTION("JsonVariantConst::is<char>()") {
+    JsonVariantConst v = doc["c"];
+    REQUIRE(v.is<char>() == true);
+  }
+
   SECTION("MemberProxy::as<char*>()") {
     REQUIRE(doc["s"].as<char*>() == s);
   }
@@ -60,6 +80,16 @@ TEST_CASE("Deprecated features") {
     REQUIRE(doc["x"] == 42);
   }
 
+  SECTION("MemberProxy::is<char*>()") {
+    REQUIRE(doc["s"].is<char*>() == true);
+    REQUIRE(doc["c"].is<char*>() == false);
+  }
+
+  SECTION("MemberProxy::is<char>()") {
+    REQUIRE(doc["c"].is<char>() == true);
+    REQUIRE(doc["s"].is<char>() == false);
+  }
+
   SECTION("ElementProxy::as<char*>()") {
     REQUIRE(doc["a"][0].as<char*>() == s);
   }
@@ -72,4 +102,14 @@ TEST_CASE("Deprecated features") {
     doc["a"][0].set('*');
     REQUIRE(doc["a"][0] == 42);
   }
+
+  SECTION("ElementProxy::is<char*>()") {
+    REQUIRE(doc["a"][0].is<char*>() == true);
+    REQUIRE(doc["a"][1].is<char*>() == false);
+  }
+
+  SECTION("ElementProxy::is<char>()") {
+    REQUIRE(doc["a"][1].is<char>() == true);
+    REQUIRE(doc["a"][0].is<char>() == false);
+  }
 }

src/ArduinoJson/Variant/VariantRef.hpp

@@ -123,10 +123,28 @@ class VariantRef : public VariantRefBase<VariantData>,
   }
 
   template <typename T>
-  FORCE_INLINE bool is() const {
+  FORCE_INLINE
+      typename enable_if<!is_same<T, char *>::value && !is_same<T, char>::value,
+                         bool>::type
+      is() const {
     return Converter<T>::checkJson(*this);
   }
 
+  template <typename T>
+  FORCE_INLINE typename enable_if<is_same<T, char *>::value, bool>::type
+  ARDUINOJSON_DEPRECATED("Replace is<char*>() with is<const char*>()")
+      is() const {
+    return is<const char *>();
+  }
+
+  template <typename T>
+  FORCE_INLINE typename enable_if<is_same<T, char>::value, bool>::type
+  ARDUINOJSON_DEPRECATED(
+      "Support for char is deprecated, use int8_t or uint8_t instead")
+      is() const {
+    return is<signed char>();
+  }
+
   template <typename T>
   FORCE_INLINE operator T() const {
     return as<T>();
@@ -251,10 +269,28 @@ class VariantConstRef : public VariantRefBase<const VariantData>,
   }
 
   template <typename T>
-  FORCE_INLINE bool is() const {
+  FORCE_INLINE
+      typename enable_if<!is_same<T, char *>::value && !is_same<T, char>::value,
+                         bool>::type
+      is() const {
     return Converter<T>::checkJson(*this);
   }
 
+  template <typename T>
+  FORCE_INLINE typename enable_if<is_same<T, char *>::value, bool>::type
+  ARDUINOJSON_DEPRECATED("Replace is<char*>() with is<const char*>()")
+      is() const {
+    return is<const char *>();
+  }
+
+  template <typename T>
+  FORCE_INLINE typename enable_if<is_same<T, char>::value, bool>::type
+  ARDUINOJSON_DEPRECATED(
+      "Support for char is deprecated, use int8_t or uint8_t instead")
+      is() const {
+    return is<signed char>();
+  }
+
   template <typename T>
   FORCE_INLINE operator T() const {
     return as<T>();