From a4441e5171be9140515e70ade83384d80315488c Mon Sep 17 00:00:00 2001
From: Benoit Blanchon <git@benoitblanchon.fr>
Date: Mon, 23 Dec 2024 15:40:07 +0100
Subject: [PATCH] Replace all the `typename =`

---
 src/ArduinoJson/Array/JsonArray.hpp           |  2 +-
 src/ArduinoJson/Array/Utilities.hpp           | 23 +++++-----
 .../Deserialization/deserialize.hpp           | 11 ++---
 src/ArduinoJson/Document/JsonDocument.hpp     | 43 +++++++++++--------
 src/ArduinoJson/Object/JsonObject.hpp         | 12 +++---
 src/ArduinoJson/Object/JsonObjectConst.hpp    | 10 ++---
 src/ArduinoJson/Object/MemberProxy.hpp        |  2 +-
 src/ArduinoJson/Strings/JsonString.hpp        |  7 +--
 src/ArduinoJson/Strings/StringAdapter.hpp     |  2 +-
 src/ArduinoJson/Variant/JsonVariantConst.hpp  | 12 +++---
 src/ArduinoJson/Variant/VariantOperators.hpp  | 14 +++---
 src/ArduinoJson/Variant/VariantRefBase.hpp    | 14 +++---
 .../Variant/VariantRefBaseImpl.hpp            |  2 +-
 13 files changed, 79 insertions(+), 75 deletions(-)

diff --git a/src/ArduinoJson/Array/JsonArray.hpp b/src/ArduinoJson/Array/JsonArray.hpp
index 940156e32..7f02f9872 100644
--- a/src/ArduinoJson/Array/JsonArray.hpp
+++ b/src/ArduinoJson/Array/JsonArray.hpp
@@ -69,7 +69,7 @@ class JsonArray : public detail::VariantOperators<JsonArray> {
   // Appends a value to the array.
   // https://arduinojson.org/v7/api/jsonarray/add/
   template <typename T,
-            typename = detail::enable_if_t<!detail::is_const<T>::value>>
+            detail::enable_if_t<!detail::is_const<T>::value, int> = 0>
   bool add(T* value) const {
     return detail::ArrayData::addValue(data_, value, resources_);
   }
diff --git a/src/ArduinoJson/Array/Utilities.hpp b/src/ArduinoJson/Array/Utilities.hpp
index 2f0638f0e..200cb66b8 100644
--- a/src/ArduinoJson/Array/Utilities.hpp
+++ b/src/ArduinoJson/Array/Utilities.hpp
@@ -11,8 +11,7 @@ ARDUINOJSON_BEGIN_PUBLIC_NAMESPACE
 
 // Copies a value to a JsonVariant.
 // This is a degenerated form of copyArray() to stop the recursion.
-template <typename T,
-          typename = detail::enable_if_t<!detail::is_array<T>::value>>
+template <typename T, detail::enable_if_t<!detail::is_array<T>::value, int> = 0>
 inline bool copyArray(const T& src, JsonVariant dst) {
   return dst.set(src);
 }
@@ -20,8 +19,8 @@ inline bool copyArray(const T& src, JsonVariant dst) {
 // Copies values from an array to a JsonArray or a JsonVariant.
 // https://arduinojson.org/v7/api/misc/copyarray/
 template <typename T, size_t N, typename TDestination,
-          typename = detail::enable_if_t<
-              !detail::is_base_of<JsonDocument, TDestination>::value>>
+          detail::enable_if_t<
+              !detail::is_base_of<JsonDocument, TDestination>::value, int> = 0>
 inline bool copyArray(T (&src)[N], const TDestination& dst) {
   return copyArray(src, N, dst);
 }
@@ -29,8 +28,8 @@ inline bool copyArray(T (&src)[N], const TDestination& dst) {
 // Copies values from an array to a JsonArray or a JsonVariant.
 // https://arduinojson.org/v7/api/misc/copyarray/
 template <typename T, typename TDestination,
-          typename = detail::enable_if_t<
-              !detail::is_base_of<JsonDocument, TDestination>::value>>
+          detail::enable_if_t<
+              !detail::is_base_of<JsonDocument, TDestination>::value, int> = 0>
 inline bool copyArray(const T* src, size_t len, const TDestination& dst) {
   bool ok = true;
   for (size_t i = 0; i < len; i++) {
@@ -62,8 +61,7 @@ inline bool copyArray(const T* src, size_t len, JsonDocument& dst) {
 
 // Copies a value from a JsonVariant.
 // This is a degenerated form of copyArray() to stop the recursion.
-template <typename T,
-          typename = detail::enable_if_t<!detail::is_array<T>::value>>
+template <typename T, detail::enable_if_t<!detail::is_array<T>::value, int> = 0>
 inline size_t copyArray(JsonVariantConst src, T& dst) {
   dst = src.as<T>();
   return 1;
@@ -102,10 +100,11 @@ inline size_t copyArray(JsonVariantConst src, char (&dst)[N]) {
 
 // Copies values from a JsonDocument to an array.
 // https://arduinojson.org/v7/api/misc/copyarray/
-template <typename TSource, typename T,
-          typename = detail::enable_if_t<
-              detail::is_array<T>::value &&
-              detail::is_base_of<JsonDocument, TSource>::value>>
+template <
+    typename TSource, typename T,
+    detail::enable_if_t<detail::is_array<T>::value &&
+                            detail::is_base_of<JsonDocument, TSource>::value,
+                        int> = 0>
 inline size_t copyArray(const TSource& src, T& dst) {
   return copyArray(src.template as<JsonArrayConst>(), dst);
 }
diff --git a/src/ArduinoJson/Deserialization/deserialize.hpp b/src/ArduinoJson/Deserialization/deserialize.hpp
index a95049a3b..c1963a8fa 100644
--- a/src/ArduinoJson/Deserialization/deserialize.hpp
+++ b/src/ArduinoJson/Deserialization/deserialize.hpp
@@ -55,10 +55,11 @@ DeserializationError doDeserialize(TDestination&& dst, TReader reader,
   return err;
 }
 
-template <template <typename> class TDeserializer, typename TDestination,
-          typename TStream, typename... Args,
-          typename = enable_if_t<  // issue #1897
-              !is_integral<typename first_or_void<Args...>::type>::value>>
+template <
+    template <typename> class TDeserializer, typename TDestination,
+    typename TStream, typename... Args,
+    enable_if_t<  // issue #1897
+        !is_integral<typename first_or_void<Args...>::type>::value, int> = 0>
 DeserializationError deserialize(TDestination&& dst, TStream&& input,
                                  Args... args) {
   return doDeserialize<TDeserializer>(
@@ -68,7 +69,7 @@ DeserializationError deserialize(TDestination&& dst, TStream&& input,
 
 template <template <typename> class TDeserializer, typename TDestination,
           typename TChar, typename Size, typename... Args,
-          typename = enable_if_t<is_integral<Size>::value>>
+          enable_if_t<is_integral<Size>::value, int> = 0>
 DeserializationError deserialize(TDestination&& dst, TChar* input,
                                  Size inputSize, Args... args) {
   return doDeserialize<TDeserializer>(dst, makeReader(input, size_t(inputSize)),
diff --git a/src/ArduinoJson/Document/JsonDocument.hpp b/src/ArduinoJson/Document/JsonDocument.hpp
index 16c2c2e19..090762321 100644
--- a/src/ArduinoJson/Document/JsonDocument.hpp
+++ b/src/ArduinoJson/Document/JsonDocument.hpp
@@ -36,12 +36,13 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   }
 
   // Construct from variant, array, or object
-  template <typename T, typename = detail::enable_if_t<
-                            detail::IsVariant<T>::value ||
-                            detail::is_same<T, JsonArray>::value ||
-                            detail::is_same<T, JsonArrayConst>::value ||
-                            detail::is_same<T, JsonObject>::value ||
-                            detail::is_same<T, JsonObjectConst>::value>>
+  template <typename T,
+            detail::enable_if_t<detail::IsVariant<T>::value ||
+                                    detail::is_same<T, JsonArray>::value ||
+                                    detail::is_same<T, JsonArrayConst>::value ||
+                                    detail::is_same<T, JsonObject>::value ||
+                                    detail::is_same<T, JsonObjectConst>::value,
+                                int> = 0>
   JsonDocument(const T& src,
                Allocator* alloc = detail::DefaultAllocator::instance())
       : JsonDocument(alloc) {
@@ -136,8 +137,9 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
 
   // Replaces the root with the specified value.
   // https://arduinojson.org/v7/api/jsondocument/set/
-  template <typename T, typename = detail::enable_if_t<
-                            !detail::is_base_of<JsonDocument, T>::value>>
+  template <
+      typename T,
+      detail::enable_if_t<!detail::is_base_of<JsonDocument, T>::value, int> = 0>
   bool set(const T& src) {
     return to<JsonVariant>().set(src);
   }
@@ -145,7 +147,7 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   // Replaces the root with the specified value.
   // https://arduinojson.org/v7/api/jsondocument/set/
   template <typename TChar,
-            typename = detail::enable_if_t<!detail::is_const<TChar>::value>>
+            detail::enable_if_t<!detail::is_const<TChar>::value, int> = 0>
   bool set(TChar* src) {
     return to<JsonVariant>().set(src);
   }
@@ -187,7 +189,7 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   // Gets or sets a root object's member.
   // https://arduinojson.org/v7/api/jsondocument/subscript/
   template <typename TString,
-            typename = detail::enable_if_t<detail::IsString<TString>::value>>
+            detail::enable_if_t<detail::IsString<TString>::value, int> = 0>
   detail::MemberProxy<JsonDocument&, detail::AdaptedString<TString>> operator[](
       const TString& key) {
     return {*this, detail::adaptString(key)};
@@ -196,8 +198,9 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   // Gets or sets a root object's member.
   // https://arduinojson.org/v7/api/jsondocument/subscript/
   template <typename TChar,
-            typename = detail::enable_if_t<detail::IsString<TChar*>::value &&
-                                           !detail::is_const<TChar>::value>>
+            detail::enable_if_t<detail::IsString<TChar*>::value &&
+                                    !detail::is_const<TChar>::value,
+                                int> = 0>
   detail::MemberProxy<JsonDocument&, detail::AdaptedString<TChar*>> operator[](
       TChar* key) {
     return {*this, detail::adaptString(key)};
@@ -206,7 +209,7 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   // Gets a root object's member.
   // https://arduinojson.org/v7/api/jsondocument/subscript/
   template <typename TString,
-            typename = detail::enable_if_t<detail::IsString<TString>::value>>
+            detail::enable_if_t<detail::IsString<TString>::value, int> = 0>
   JsonVariantConst operator[](const TString& key) const {
     return JsonVariantConst(
         data_.getMember(detail::adaptString(key), &resources_), &resources_);
@@ -215,8 +218,9 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   // Gets a root object's member.
   // https://arduinojson.org/v7/api/jsondocument/subscript/
   template <typename TChar,
-            typename = detail::enable_if_t<detail::IsString<TChar*>::value &&
-                                           !detail::is_const<TChar>::value>>
+            detail::enable_if_t<detail::IsString<TChar*>::value &&
+                                    !detail::is_const<TChar>::value,
+                                int> = 0>
   JsonVariantConst operator[](TChar* key) const {
     return JsonVariantConst(
         data_.getMember(detail::adaptString(key), &resources_), &resources_);
@@ -276,7 +280,7 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   // Appends a value to the root array.
   // https://arduinojson.org/v7/api/jsondocument/add/
   template <typename TChar,
-            typename = detail::enable_if_t<!detail::is_const<TChar>::value>>
+            detail::enable_if_t<!detail::is_const<TChar>::value, int> = 0>
   bool add(TChar* value) {
     return data_.addValue(value, &resources_);
   }
@@ -284,7 +288,7 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   // Removes an element of the root array.
   // https://arduinojson.org/v7/api/jsondocument/remove/
   template <typename T,
-            typename = detail::enable_if_t<detail::is_integral<T>::value>>
+            detail::enable_if_t<detail::is_integral<T>::value, int> = 0>
   void remove(T index) {
     detail::VariantData::removeElement(getData(), size_t(index),
                                        getResourceManager());
@@ -293,8 +297,9 @@ class JsonDocument : public detail::VariantOperators<const JsonDocument&> {
   // Removes a member of the root object.
   // https://arduinojson.org/v7/api/jsondocument/remove/
   template <typename TChar,
-            typename = detail::enable_if_t<detail::IsString<TChar*>::value &&
-                                           !detail::is_const<TChar>::value>>
+            detail::enable_if_t<detail::IsString<TChar*>::value &&
+                                    !detail::is_const<TChar>::value,
+                                int> = 0>
   void remove(TChar* key) {
     detail::VariantData::removeMember(getData(), detail::adaptString(key),
                                       getResourceManager());
diff --git a/src/ArduinoJson/Object/JsonObject.hpp b/src/ArduinoJson/Object/JsonObject.hpp
index 2c8c61fe3..088cea917 100644
--- a/src/ArduinoJson/Object/JsonObject.hpp
+++ b/src/ArduinoJson/Object/JsonObject.hpp
@@ -102,7 +102,7 @@ class JsonObject : public detail::VariantOperators<JsonObject> {
   // Gets or sets the member with specified key.
   // https://arduinojson.org/v7/api/jsonobject/subscript/
   template <typename TString,
-            typename = detail::enable_if_t<detail::IsString<TString>::value>>
+            detail::enable_if_t<detail::IsString<TString>::value, int> = 0>
   detail::MemberProxy<JsonObject, detail::AdaptedString<TString>> operator[](
       const TString& key) const {
     return {*this, detail::adaptString(key)};
@@ -111,8 +111,9 @@ class JsonObject : public detail::VariantOperators<JsonObject> {
   // Gets or sets the member with specified key.
   // https://arduinojson.org/v7/api/jsonobject/subscript/
   template <typename TChar,
-            typename = detail::enable_if_t<detail::IsString<TChar*>::value &&
-                                           !detail::is_const<TChar>::value>>
+            detail::enable_if_t<detail::IsString<TChar*>::value &&
+                                    !detail::is_const<TChar>::value,
+                                int> = 0>
   detail::MemberProxy<JsonObject, detail::AdaptedString<TChar*>> operator[](
       TChar* key) const {
     return {*this, detail::adaptString(key)};
@@ -121,7 +122,7 @@ class JsonObject : public detail::VariantOperators<JsonObject> {
   // Gets or sets the member with specified key.
   // https://arduinojson.org/v7/api/jsonobject/subscript/
   template <typename TVariant,
-            typename = detail::enable_if_t<detail::IsVariant<TVariant>::value>>
+            detail::enable_if_t<detail::IsVariant<TVariant>::value, int> = 0>
   detail::MemberProxy<JsonObject, detail::AdaptedString<JsonString>> operator[](
       const TVariant& key) const {
     return {*this, detail::adaptString(key.template as<JsonString>())};
@@ -184,8 +185,7 @@ class JsonObject : public detail::VariantOperators<JsonObject> {
   // DEPRECATED: use obj[key].is<T>() instead
   // https://arduinojson.org/v7/api/jsonobject/containskey/
   template <typename TVariant,
-            typename = detail::enable_if_t<detail::IsVariant<TVariant>::value>,
-            int = 0>
+            detail::enable_if_t<detail::IsVariant<TVariant>::value, int> = 0>
   ARDUINOJSON_DEPRECATED("use obj[key].is<T>() instead")
   bool containsKey(const TVariant& key) const {
     return containsKey(key.template as<const char*>());
diff --git a/src/ArduinoJson/Object/JsonObjectConst.hpp b/src/ArduinoJson/Object/JsonObjectConst.hpp
index 665105565..6a7218fe4 100644
--- a/src/ArduinoJson/Object/JsonObjectConst.hpp
+++ b/src/ArduinoJson/Object/JsonObjectConst.hpp
@@ -99,8 +99,7 @@ class JsonObjectConst : public detail::VariantOperators<JsonObjectConst> {
   // Gets the member with specified key.
   // https://arduinojson.org/v7/api/jsonobjectconst/subscript/
   template <typename TString,
-            typename = detail::enable_if_t<detail::IsString<TString>::value>,
-            short = 1>
+            detail::enable_if_t<detail::IsString<TString>::value, int> = 0>
   JsonVariantConst operator[](const TString& key) const {
     return JsonVariantConst(detail::ObjectData::getMember(
                                 data_, detail::adaptString(key), resources_),
@@ -110,8 +109,9 @@ class JsonObjectConst : public detail::VariantOperators<JsonObjectConst> {
   // Gets the member with specified key.
   // https://arduinojson.org/v7/api/jsonobjectconst/subscript/
   template <typename TChar,
-            typename = detail::enable_if_t<detail::IsString<TChar*>::value &&
-                                           !detail::is_const<TChar>::value>>
+            detail::enable_if_t<detail::IsString<TChar*>::value &&
+                                    !detail::is_const<TChar>::value,
+                                int> = 0>
   JsonVariantConst operator[](TChar* key) const {
     return JsonVariantConst(detail::ObjectData::getMember(
                                 data_, detail::adaptString(key), resources_),
@@ -121,7 +121,7 @@ class JsonObjectConst : public detail::VariantOperators<JsonObjectConst> {
   // Gets the member with specified key.
   // https://arduinojson.org/v7/api/jsonobjectconst/subscript/
   template <typename TVariant,
-            typename = detail::enable_if_t<detail::IsVariant<TVariant>::value>>
+            detail::enable_if_t<detail::IsVariant<TVariant>::value, int> = 0>
   JsonVariantConst operator[](const TVariant& key) const {
     if (key.template is<JsonString>())
       return operator[](key.template as<JsonString>());
diff --git a/src/ArduinoJson/Object/MemberProxy.hpp b/src/ArduinoJson/Object/MemberProxy.hpp
index ffd89939d..f1e9b421e 100644
--- a/src/ArduinoJson/Object/MemberProxy.hpp
+++ b/src/ArduinoJson/Object/MemberProxy.hpp
@@ -39,7 +39,7 @@ class MemberProxy
     return *this;
   }
 
-  template <typename T, typename = enable_if_t<!is_const<T>::value>>
+  template <typename T, enable_if_t<!is_const<T>::value, int> = 0>
   MemberProxy& operator=(T* src) {
     this->set(src);
     return *this;
diff --git a/src/ArduinoJson/Strings/JsonString.hpp b/src/ArduinoJson/Strings/JsonString.hpp
index 475bda165..76011da9f 100644
--- a/src/ArduinoJson/Strings/JsonString.hpp
+++ b/src/ArduinoJson/Strings/JsonString.hpp
@@ -24,9 +24,10 @@ class JsonString {
   JsonString(const char* data, bool isStatic = false)
       : str_(data, data ? ::strlen(data) : 0, isStatic) {}
 
-  template <typename TSize, typename = detail::enable_if_t<
-                                detail::is_integral<TSize>::value &&
-                                !detail::is_same<TSize, bool>::value>>
+  template <typename TSize,
+            detail::enable_if_t<detail::is_integral<TSize>::value &&
+                                    !detail::is_same<TSize, bool>::value,
+                                int> = 0>
   JsonString(const char* data, TSize sz, bool isStatic = false)
       : str_(data, size_t(sz), isStatic) {}
 
diff --git a/src/ArduinoJson/Strings/StringAdapter.hpp b/src/ArduinoJson/Strings/StringAdapter.hpp
index 50324ffb6..cd19e41b0 100644
--- a/src/ArduinoJson/Strings/StringAdapter.hpp
+++ b/src/ArduinoJson/Strings/StringAdapter.hpp
@@ -34,7 +34,7 @@ AdaptedString<TString> adaptString(TString&& s) {
   return StringAdapterFor<TString>::adapt(detail::forward<TString>(s));
 }
 
-template <typename TChar, typename = enable_if_t<!is_const<TChar>::value>>
+template <typename TChar, enable_if_t<!is_const<TChar>::value, int> = 0>
 AdaptedString<TChar*> adaptString(TChar* p) {
   return StringAdapter<TChar*>::adapt(p);
 }
diff --git a/src/ArduinoJson/Variant/JsonVariantConst.hpp b/src/ArduinoJson/Variant/JsonVariantConst.hpp
index 7ab5bbb77..b1eb66e01 100644
--- a/src/ArduinoJson/Variant/JsonVariantConst.hpp
+++ b/src/ArduinoJson/Variant/JsonVariantConst.hpp
@@ -68,14 +68,14 @@ class JsonVariantConst : public detail::VariantTag,
   // Casts the value to the specified type.
   // https://arduinojson.org/v7/api/jsonvariantconst/as/
   template <typename T,
-            typename = detail::enable_if_t<ConversionSupported<T>::value>>
+            detail::enable_if_t<ConversionSupported<T>::value, int> = 0>
   T as() const {
     return Converter<T>::fromJson(*this);
   }
 
   // Invalid conversion. Will not compile.
-  template <typename T, typename = detail::enable_if_t<
-                            !ConversionSupported<T>::value, bool>>
+  template <typename T,
+            detail::enable_if_t<!ConversionSupported<T>::value, int> = 0>
   detail::InvalidConversion<JsonVariantConst, T> as() const;
 
   // Returns true if the value is of the specified type.
@@ -102,7 +102,7 @@ class JsonVariantConst : public detail::VariantTag,
   // Gets array's element at specified index.
   // https://arduinojson.org/v7/api/jsonvariantconst/subscript/
   template <typename T,
-            typename = detail::enable_if_t<detail::is_integral<T>::value>>
+            detail::enable_if_t<detail::is_integral<T>::value, int> = 0>
   JsonVariantConst operator[](T index) const {
     return JsonVariantConst(
         detail::VariantData::getElement(data_, size_t(index), resources_),
@@ -112,7 +112,7 @@ class JsonVariantConst : public detail::VariantTag,
   // Gets object's member with specified key.
   // https://arduinojson.org/v7/api/jsonvariantconst/subscript/
   template <typename TString,
-            typename = detail::enable_if_t<detail::IsString<TString>::value>>
+            detail::enable_if_t<detail::IsString<TString>::value, int> = 0>
   JsonVariantConst operator[](const TString& key) const {
     return JsonVariantConst(detail::VariantData::getMember(
                                 data_, detail::adaptString(key), resources_),
@@ -146,7 +146,7 @@ class JsonVariantConst : public detail::VariantTag,
   // DEPRECATED: use obj[key].is<T>() instead
   // https://arduinojson.org/v7/api/jsonvariantconst/containskey/
   template <typename TString,
-            typename = detail::enable_if_t<detail::IsString<TString>::value>>
+            detail::enable_if_t<detail::IsString<TString>::value, int> = 0>
   ARDUINOJSON_DEPRECATED("use var[key].is<T>() instead")
   bool containsKey(const TString& key) const {
     return detail::VariantData::getMember(getData(), detail::adaptString(key),
diff --git a/src/ArduinoJson/Variant/VariantOperators.hpp b/src/ArduinoJson/Variant/VariantOperators.hpp
index 25b9a5d0c..d17e7cb49 100644
--- a/src/ArduinoJson/Variant/VariantOperators.hpp
+++ b/src/ArduinoJson/Variant/VariantOperators.hpp
@@ -31,7 +31,7 @@ struct VariantOperators : VariantOperatorTag {
   // float operator|(JsonVariant, float)
   // bool operator|(JsonVariant, bool)
   template <typename T,
-            typename = enable_if_t<!IsVariant<T>::value && !is_array<T>::value>>
+            enable_if_t<!IsVariant<T>::value && !is_array<T>::value, int> = 0>
   friend T operator|(const TVariant& variant, const T& defaultValue) {
     if (variant.template is<T>())
       return variant.template as<T>();
@@ -74,7 +74,7 @@ struct VariantOperators : VariantOperatorTag {
     return compare(lhs, rhs) == COMPARE_RESULT_EQUAL;
   }
   template <typename T,
-            typename = enable_if_t<!is_base_of<VariantOperatorTag, T>::value>>
+            enable_if_t<!is_base_of<VariantOperatorTag, T>::value, int> = 0>
   friend bool operator==(const TVariant& lhs, const T& rhs) {
     return compare(lhs, rhs) == COMPARE_RESULT_EQUAL;
   }
@@ -95,7 +95,7 @@ struct VariantOperators : VariantOperatorTag {
     return compare(lhs, rhs) != COMPARE_RESULT_EQUAL;
   }
   template <typename T,
-            typename = enable_if_t<!is_base_of<VariantOperatorTag, T>::value>>
+            enable_if_t<!is_base_of<VariantOperatorTag, T>::value, int> = 0>
   friend bool operator!=(TVariant lhs, const T& rhs) {
     return compare(lhs, rhs) != COMPARE_RESULT_EQUAL;
   }
@@ -116,7 +116,7 @@ struct VariantOperators : VariantOperatorTag {
     return compare(lhs, rhs) == COMPARE_RESULT_LESS;
   }
   template <typename T,
-            typename = enable_if_t<!is_base_of<VariantOperatorTag, T>::value>>
+            enable_if_t<!is_base_of<VariantOperatorTag, T>::value, int> = 0>
   friend bool operator<(TVariant lhs, const T& rhs) {
     return compare(lhs, rhs) == COMPARE_RESULT_LESS;
   }
@@ -137,7 +137,7 @@ struct VariantOperators : VariantOperatorTag {
     return (compare(lhs, rhs) & COMPARE_RESULT_LESS_OR_EQUAL) != 0;
   }
   template <typename T,
-            typename = enable_if_t<!is_base_of<VariantOperatorTag, T>::value>>
+            enable_if_t<!is_base_of<VariantOperatorTag, T>::value, int> = 0>
   friend bool operator<=(TVariant lhs, const T& rhs) {
     return (compare(lhs, rhs) & COMPARE_RESULT_LESS_OR_EQUAL) != 0;
   }
@@ -158,7 +158,7 @@ struct VariantOperators : VariantOperatorTag {
     return compare(lhs, rhs) == COMPARE_RESULT_GREATER;
   }
   template <typename T,
-            typename = enable_if_t<!is_base_of<VariantOperatorTag, T>::value>>
+            enable_if_t<!is_base_of<VariantOperatorTag, T>::value, int> = 0>
   friend bool operator>(TVariant lhs, const T& rhs) {
     return compare(lhs, rhs) == COMPARE_RESULT_GREATER;
   }
@@ -179,7 +179,7 @@ struct VariantOperators : VariantOperatorTag {
     return (compare(lhs, rhs) & COMPARE_RESULT_GREATER_OR_EQUAL) != 0;
   }
   template <typename T,
-            typename = enable_if_t<!is_base_of<VariantOperatorTag, T>::value>>
+            enable_if_t<!is_base_of<VariantOperatorTag, T>::value, int> = 0>
   friend bool operator>=(const TVariant& lhs, const T& rhs) {
     return (compare(lhs, rhs) & COMPARE_RESULT_GREATER_OR_EQUAL) != 0;
   }
diff --git a/src/ArduinoJson/Variant/VariantRefBase.hpp b/src/ArduinoJson/Variant/VariantRefBase.hpp
index 7c96b8ce7..544fe42cf 100644
--- a/src/ArduinoJson/Variant/VariantRefBase.hpp
+++ b/src/ArduinoJson/Variant/VariantRefBase.hpp
@@ -48,7 +48,7 @@ class VariantRefBase : public VariantTag {
   template <typename T>
   T as() const;
 
-  template <typename T, typename = enable_if_t<!is_same<T, TDerived>::value>>
+  template <typename T, enable_if_t<!is_same<T, TDerived>::value, int> = 0>
   operator T() const {
     return as<T>();
   }
@@ -85,7 +85,7 @@ class VariantRefBase : public VariantTag {
   // Copies the specified value.
   // https://arduinojson.org/v7/api/jsonvariant/set/
   template <typename T,
-            typename = detail::enable_if_t<!detail::is_const<T>::value>>
+            detail::enable_if_t<!detail::is_const<T>::value, int> = 0>
   bool set(T* value) const {
     return doSet<Converter<T*>>(value);
   }
@@ -126,7 +126,7 @@ class VariantRefBase : public VariantTag {
 
   // Appends a value to the array.
   // https://arduinojson.org/v7/api/jsonvariant/add/
-  template <typename T, typename = enable_if_t<!is_const<T>::value>>
+  template <typename T, enable_if_t<!is_const<T>::value, int> = 0>
   bool add(T* value) const {
     return detail::VariantData::addValue(getOrCreateData(), value,
                                          getResourceManager());
@@ -140,7 +140,7 @@ class VariantRefBase : public VariantTag {
 
   // Removes a member of the object.
   // https://arduinojson.org/v7/api/jsonvariant/remove/
-  template <typename TChar, typename = enable_if_t<IsString<TChar*>::value>>
+  template <typename TChar, enable_if_t<IsString<TChar*>::value, int> = 0>
   void remove(TChar* key) const {
     VariantData::removeMember(getData(), adaptString(key),
                               getResourceManager());
@@ -182,8 +182,7 @@ class VariantRefBase : public VariantTag {
 
   // DEPRECATED: use obj[key].is<T>() instead
   // https://arduinojson.org/v7/api/jsonvariant/containskey/
-  template <typename TVariant,
-            typename = enable_if_t<IsVariant<TVariant>::value>, int = 0>
+  template <typename TVariant, enable_if_t<IsVariant<TVariant>::value, int> = 0>
   ARDUINOJSON_DEPRECATED("use obj[key].is<T>() instead")
   bool containsKey(const TVariant& key) const;
 
@@ -203,8 +202,7 @@ class VariantRefBase : public VariantTag {
 
   // Gets an object member or an array element.
   // https://arduinojson.org/v7/api/jsonvariant/subscript/
-  template <typename TVariant,
-            typename = enable_if_t<IsVariant<TVariant>::value>>
+  template <typename TVariant, enable_if_t<IsVariant<TVariant>::value, int> = 0>
   JsonVariantConst operator[](const TVariant& key) const {
     if (key.template is<size_t>())
       return operator[](key.template as<size_t>());
diff --git a/src/ArduinoJson/Variant/VariantRefBaseImpl.hpp b/src/ArduinoJson/Variant/VariantRefBaseImpl.hpp
index bf4e5b859..1c87cc11d 100644
--- a/src/ArduinoJson/Variant/VariantRefBaseImpl.hpp
+++ b/src/ArduinoJson/Variant/VariantRefBaseImpl.hpp
@@ -89,7 +89,7 @@ inline bool VariantRefBase<TDerived>::containsKey(TChar* key) const {
 }
 
 template <typename TDerived>
-template <typename TVariant, typename, int>
+template <typename TVariant, enable_if_t<IsVariant<TVariant>::value, int>>
 inline bool VariantRefBase<TDerived>::containsKey(const TVariant& key) const {
   return containsKey(key.template as<const char*>());
 }