[libcamera-devel,v2,2/2] Revert "libcamera: Use helper variable template for type traits"
diff mbox series

Message ID 20210126130415.26849-3-jeanmichel.hautbois@ideasonboard.com
State Accepted
Commit c763ae023d9b64e7910c2dfc849f6c1f5081f657
Headers show
Series
  • libcamera: revert C++17 specific code for public API
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Commit Message

Jean-Michel Hautbois Jan. 26, 2021, 1:04 p.m. UTC
This reverts commit 6cbdc2859963e17bc897a4022f1d68170477d888.
---
 include/libcamera/bound_method.h |  2 +-
 include/libcamera/controls.h     | 12 ++++----
 include/libcamera/object.h       |  2 +-
 include/libcamera/signal.h       |  4 +--
 include/libcamera/span.h         | 48 ++++++++++++++++----------------
 5 files changed, 34 insertions(+), 34 deletions(-)

Comments

Jean-Michel Hautbois Jan. 31, 2021, 2:42 p.m. UTC | #1
Ahem...

On 26/01/2021 14:04, Jean-Michel Hautbois wrote:
> This reverts commit 6cbdc2859963e17bc897a4022f1d68170477d888.
Signed-off-by: Jean-Michel Hautbois  <jeanmichel.hautbois@ideasonboard.com>

> ---
>  include/libcamera/bound_method.h |  2 +-
>  include/libcamera/controls.h     | 12 ++++----
>  include/libcamera/object.h       |  2 +-
>  include/libcamera/signal.h       |  4 +--
>  include/libcamera/span.h         | 48 ++++++++++++++++----------------
>  5 files changed, 34 insertions(+), 34 deletions(-)
> 
> diff --git a/include/libcamera/bound_method.h b/include/libcamera/bound_method.h
> index feac51da..95a95653 100644
> --- a/include/libcamera/bound_method.h
> +++ b/include/libcamera/bound_method.h
> @@ -63,7 +63,7 @@ public:
>  	}
>  	virtual ~BoundMethodBase() = default;
>  
> -	template<typename T, typename std::enable_if_t<!std::is_same_v<Object, T>> * = nullptr>
> +	template<typename T, typename std::enable_if_t<!std::is_same<Object, T>::value> * = nullptr>
>  	bool match(T *obj) { return obj == obj_; }
>  	bool match(Object *object) { return object == object_; }
>  
> diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h
> index dc549a92..3b7f3347 100644
> --- a/include/libcamera/controls.h
> +++ b/include/libcamera/controls.h
> @@ -98,7 +98,7 @@ public:
>  #ifndef __DOXYGEN__
>  	template<typename T, typename std::enable_if_t<!details::is_span<T>::value &&
>  						       details::control_type<T>::value &&
> -						       !std::is_same_v<std::string, std::remove_cv_t<T>>,
> +						       !std::is_same<std::string, std::remove_cv_t<T>>::value,
>  						       std::nullptr_t> = nullptr>
>  	ControlValue(const T &value)
>  		: type_(ControlTypeNone), numElements_(0)
> @@ -108,7 +108,7 @@ public:
>  	}
>  
>  	template<typename T, typename std::enable_if_t<details::is_span<T>::value ||
> -						       std::is_same_v<std::string, std::remove_cv_t<T>>,
> +						       std::is_same<std::string, std::remove_cv_t<T>>::value,
>  						       std::nullptr_t> = nullptr>
>  #else
>  	template<typename T>
> @@ -142,7 +142,7 @@ public:
>  
>  #ifndef __DOXYGEN__
>  	template<typename T, typename std::enable_if_t<!details::is_span<T>::value &&
> -						       !std::is_same_v<std::string, std::remove_cv_t<T>>,
> +						       !std::is_same<std::string, std::remove_cv_t<T>>::value,
>  						       std::nullptr_t> = nullptr>
>  	T get() const
>  	{
> @@ -153,7 +153,7 @@ public:
>  	}
>  
>  	template<typename T, typename std::enable_if_t<details::is_span<T>::value ||
> -						       std::is_same_v<std::string, std::remove_cv_t<T>>,
> +						       std::is_same<std::string, std::remove_cv_t<T>>::value,
>  						       std::nullptr_t> = nullptr>
>  #else
>  	template<typename T>
> @@ -170,7 +170,7 @@ public:
>  
>  #ifndef __DOXYGEN__
>  	template<typename T, typename std::enable_if_t<!details::is_span<T>::value &&
> -						       !std::is_same_v<std::string, std::remove_cv_t<T>>,
> +						       !std::is_same<std::string, std::remove_cv_t<T>>::value,
>  						       std::nullptr_t> = nullptr>
>  	void set(const T &value)
>  	{
> @@ -179,7 +179,7 @@ public:
>  	}
>  
>  	template<typename T, typename std::enable_if_t<details::is_span<T>::value ||
> -						       std::is_same_v<std::string, std::remove_cv_t<T>>,
> +						       std::is_same<std::string, std::remove_cv_t<T>>::value,
>  						       std::nullptr_t> = nullptr>
>  #else
>  	template<typename T>
> diff --git a/include/libcamera/object.h b/include/libcamera/object.h
> index 423208db..a1882f05 100644
> --- a/include/libcamera/object.h
> +++ b/include/libcamera/object.h
> @@ -32,7 +32,7 @@ public:
>  	void postMessage(std::unique_ptr<Message> msg);
>  
>  	template<typename T, typename R, typename... FuncArgs, typename... Args,
> -		 typename std::enable_if_t<std::is_base_of_v<Object, T>> * = nullptr>
> +		 typename std::enable_if_t<std::is_base_of<Object, T>::value> * = nullptr>
>  	R invokeMethod(R (T::*func)(FuncArgs...), ConnectionType type,
>  		       Args... args)
>  	{
> diff --git a/include/libcamera/signal.h b/include/libcamera/signal.h
> index 46d917d5..5bcd7a77 100644
> --- a/include/libcamera/signal.h
> +++ b/include/libcamera/signal.h
> @@ -44,7 +44,7 @@ public:
>  	}
>  
>  #ifndef __DOXYGEN__
> -	template<typename T, typename R, typename std::enable_if_t<std::is_base_of_v<Object, T>> * = nullptr>
> +	template<typename T, typename R, typename std::enable_if_t<std::is_base_of<Object, T>::value> * = nullptr>
>  	void connect(T *obj, R (T::*func)(Args...),
>  		     ConnectionType type = ConnectionTypeAuto)
>  	{
> @@ -52,7 +52,7 @@ public:
>  		SignalBase::connect(new BoundMethodMember<T, void, Args...>(obj, object, func, type));
>  	}
>  
> -	template<typename T, typename R, typename std::enable_if_t<!std::is_base_of_v<Object, T>> * = nullptr>
> +	template<typename T, typename R, typename std::enable_if_t<!std::is_base_of<Object, T>::value> * = nullptr>
>  #else
>  	template<typename T, typename R>
>  #endif
> diff --git a/include/libcamera/span.h b/include/libcamera/span.h
> index d720adb8..91e9f974 100644
> --- a/include/libcamera/span.h
> +++ b/include/libcamera/span.h
> @@ -125,8 +125,8 @@ public:
>  
>  	template<std::size_t N>
>  	constexpr Span(element_type (&arr)[N],
> -		       std::enable_if_t<std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
> -							      element_type (*)[]> &&
> +		       std::enable_if_t<std::is_convertible<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
> +							    element_type (*)[]>::value &&
>  					N == Extent,
>  					std::nullptr_t> = nullptr) noexcept
>  		: data_(arr)
> @@ -135,8 +135,8 @@ public:
>  
>  	template<std::size_t N>
>  	constexpr Span(std::array<value_type, N> &arr,
> -		       std::enable_if_t<std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
> -							      element_type (*)[]> &&
> +		       std::enable_if_t<std::is_convertible<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
> +							    element_type (*)[]>::value &&
>  					N == Extent,
>  					std::nullptr_t> = nullptr) noexcept
>  		: data_(arr.data())
> @@ -145,8 +145,8 @@ public:
>  
>  	template<std::size_t N>
>  	constexpr Span(const std::array<value_type, N> &arr,
> -		       std::enable_if_t<std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
> -							      element_type (*)[]> &&
> +		       std::enable_if_t<std::is_convertible<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
> +							    element_type (*)[]>::value &&
>  					N == Extent,
>  					std::nullptr_t> = nullptr) noexcept
>  		: data_(arr.data())
> @@ -157,9 +157,9 @@ public:
>  	explicit constexpr Span(Container &cont,
>  				std::enable_if_t<!details::is_span<Container>::value &&
>  						 !details::is_array<Container>::value &&
> -						 !std::is_array_v<Container> &&
> -						 std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
> -								       element_type (*)[]>,
> +						 !std::is_array<Container>::value &&
> +						 std::is_convertible<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
> +								     element_type (*)[]>::value,
>  						 std::nullptr_t> = nullptr)
>  		: data_(utils::data(cont))
>  	{
> @@ -169,9 +169,9 @@ public:
>  	explicit constexpr Span(const Container &cont,
>  				std::enable_if_t<!details::is_span<Container>::value &&
>  						 !details::is_array<Container>::value &&
> -						 !std::is_array_v<Container> &&
> -						 std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
> -								       element_type (*)[]>,
> +						 !std::is_array<Container>::value &&
> +						 std::is_convertible<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
> +								     element_type (*)[]>::value,
>  						 std::nullptr_t> = nullptr)
>  		: data_(utils::data(cont))
>  	{
> @@ -180,7 +180,7 @@ public:
>  
>  	template<class U, std::size_t N>
>  	explicit constexpr Span(const Span<U, N> &s,
> -				std::enable_if_t<std::is_convertible_v<U (*)[], element_type (*)[]> &&
> +				std::enable_if_t<std::is_convertible<U (*)[], element_type (*)[]>::value &&
>  						 N == Extent,
>  						 std::nullptr_t> = nullptr) noexcept
>  		: data_(s.data())
> @@ -293,8 +293,8 @@ public:
>  
>  	template<std::size_t N>
>  	constexpr Span(element_type (&arr)[N],
> -		       std::enable_if_t<std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
> -							      element_type (*)[]>,
> +		       std::enable_if_t<std::is_convertible<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
> +							    element_type (*)[]>::value,
>  					std::nullptr_t> = nullptr) noexcept
>  		: data_(arr), size_(N)
>  	{
> @@ -302,8 +302,8 @@ public:
>  
>  	template<std::size_t N>
>  	constexpr Span(std::array<value_type, N> &arr,
> -		       std::enable_if_t<std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
> -							      element_type (*)[]>,
> +		       std::enable_if_t<std::is_convertible<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
> +							    element_type (*)[]>::value,
>  					std::nullptr_t> = nullptr) noexcept
>  		: data_(utils::data(arr)), size_(N)
>  	{
> @@ -319,9 +319,9 @@ public:
>  	constexpr Span(Container &cont,
>  		       std::enable_if_t<!details::is_span<Container>::value &&
>  					!details::is_array<Container>::value &&
> -					!std::is_array_v<Container> &&
> -					std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
> -							      element_type (*)[]>,
> +					!std::is_array<Container>::value &&
> +					std::is_convertible<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
> +							    element_type (*)[]>::value,
>  					std::nullptr_t> = nullptr)
>  		: data_(utils::data(cont)), size_(utils::size(cont))
>  	{
> @@ -331,9 +331,9 @@ public:
>  	constexpr Span(const Container &cont,
>  		       std::enable_if_t<!details::is_span<Container>::value &&
>  					!details::is_array<Container>::value &&
> -					!std::is_array_v<Container> &&
> -					std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
> -							      element_type (*)[]>,
> +					!std::is_array<Container>::value &&
> +					std::is_convertible<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
> +							    element_type (*)[]>::value,
>  					std::nullptr_t> = nullptr)
>  		: data_(utils::data(cont)), size_(utils::size(cont))
>  	{
> @@ -341,7 +341,7 @@ public:
>  
>  	template<class U, std::size_t N>
>  	constexpr Span(const Span<U, N> &s,
> -		       std::enable_if_t<std::is_convertible_v<U (*)[], element_type (*)[]>,
> +		       std::enable_if_t<std::is_convertible<U (*)[], element_type (*)[]>::value,
>  					std::nullptr_t> = nullptr) noexcept
>  		: data_(s.data()), size_(s.size())
>  	{
>

Patch
diff mbox series

diff --git a/include/libcamera/bound_method.h b/include/libcamera/bound_method.h
index feac51da..95a95653 100644
--- a/include/libcamera/bound_method.h
+++ b/include/libcamera/bound_method.h
@@ -63,7 +63,7 @@  public:
 	}
 	virtual ~BoundMethodBase() = default;
 
-	template<typename T, typename std::enable_if_t<!std::is_same_v<Object, T>> * = nullptr>
+	template<typename T, typename std::enable_if_t<!std::is_same<Object, T>::value> * = nullptr>
 	bool match(T *obj) { return obj == obj_; }
 	bool match(Object *object) { return object == object_; }
 
diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h
index dc549a92..3b7f3347 100644
--- a/include/libcamera/controls.h
+++ b/include/libcamera/controls.h
@@ -98,7 +98,7 @@  public:
 #ifndef __DOXYGEN__
 	template<typename T, typename std::enable_if_t<!details::is_span<T>::value &&
 						       details::control_type<T>::value &&
-						       !std::is_same_v<std::string, std::remove_cv_t<T>>,
+						       !std::is_same<std::string, std::remove_cv_t<T>>::value,
 						       std::nullptr_t> = nullptr>
 	ControlValue(const T &value)
 		: type_(ControlTypeNone), numElements_(0)
@@ -108,7 +108,7 @@  public:
 	}
 
 	template<typename T, typename std::enable_if_t<details::is_span<T>::value ||
-						       std::is_same_v<std::string, std::remove_cv_t<T>>,
+						       std::is_same<std::string, std::remove_cv_t<T>>::value,
 						       std::nullptr_t> = nullptr>
 #else
 	template<typename T>
@@ -142,7 +142,7 @@  public:
 
 #ifndef __DOXYGEN__
 	template<typename T, typename std::enable_if_t<!details::is_span<T>::value &&
-						       !std::is_same_v<std::string, std::remove_cv_t<T>>,
+						       !std::is_same<std::string, std::remove_cv_t<T>>::value,
 						       std::nullptr_t> = nullptr>
 	T get() const
 	{
@@ -153,7 +153,7 @@  public:
 	}
 
 	template<typename T, typename std::enable_if_t<details::is_span<T>::value ||
-						       std::is_same_v<std::string, std::remove_cv_t<T>>,
+						       std::is_same<std::string, std::remove_cv_t<T>>::value,
 						       std::nullptr_t> = nullptr>
 #else
 	template<typename T>
@@ -170,7 +170,7 @@  public:
 
 #ifndef __DOXYGEN__
 	template<typename T, typename std::enable_if_t<!details::is_span<T>::value &&
-						       !std::is_same_v<std::string, std::remove_cv_t<T>>,
+						       !std::is_same<std::string, std::remove_cv_t<T>>::value,
 						       std::nullptr_t> = nullptr>
 	void set(const T &value)
 	{
@@ -179,7 +179,7 @@  public:
 	}
 
 	template<typename T, typename std::enable_if_t<details::is_span<T>::value ||
-						       std::is_same_v<std::string, std::remove_cv_t<T>>,
+						       std::is_same<std::string, std::remove_cv_t<T>>::value,
 						       std::nullptr_t> = nullptr>
 #else
 	template<typename T>
diff --git a/include/libcamera/object.h b/include/libcamera/object.h
index 423208db..a1882f05 100644
--- a/include/libcamera/object.h
+++ b/include/libcamera/object.h
@@ -32,7 +32,7 @@  public:
 	void postMessage(std::unique_ptr<Message> msg);
 
 	template<typename T, typename R, typename... FuncArgs, typename... Args,
-		 typename std::enable_if_t<std::is_base_of_v<Object, T>> * = nullptr>
+		 typename std::enable_if_t<std::is_base_of<Object, T>::value> * = nullptr>
 	R invokeMethod(R (T::*func)(FuncArgs...), ConnectionType type,
 		       Args... args)
 	{
diff --git a/include/libcamera/signal.h b/include/libcamera/signal.h
index 46d917d5..5bcd7a77 100644
--- a/include/libcamera/signal.h
+++ b/include/libcamera/signal.h
@@ -44,7 +44,7 @@  public:
 	}
 
 #ifndef __DOXYGEN__
-	template<typename T, typename R, typename std::enable_if_t<std::is_base_of_v<Object, T>> * = nullptr>
+	template<typename T, typename R, typename std::enable_if_t<std::is_base_of<Object, T>::value> * = nullptr>
 	void connect(T *obj, R (T::*func)(Args...),
 		     ConnectionType type = ConnectionTypeAuto)
 	{
@@ -52,7 +52,7 @@  public:
 		SignalBase::connect(new BoundMethodMember<T, void, Args...>(obj, object, func, type));
 	}
 
-	template<typename T, typename R, typename std::enable_if_t<!std::is_base_of_v<Object, T>> * = nullptr>
+	template<typename T, typename R, typename std::enable_if_t<!std::is_base_of<Object, T>::value> * = nullptr>
 #else
 	template<typename T, typename R>
 #endif
diff --git a/include/libcamera/span.h b/include/libcamera/span.h
index d720adb8..91e9f974 100644
--- a/include/libcamera/span.h
+++ b/include/libcamera/span.h
@@ -125,8 +125,8 @@  public:
 
 	template<std::size_t N>
 	constexpr Span(element_type (&arr)[N],
-		       std::enable_if_t<std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
-							      element_type (*)[]> &&
+		       std::enable_if_t<std::is_convertible<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
+							    element_type (*)[]>::value &&
 					N == Extent,
 					std::nullptr_t> = nullptr) noexcept
 		: data_(arr)
@@ -135,8 +135,8 @@  public:
 
 	template<std::size_t N>
 	constexpr Span(std::array<value_type, N> &arr,
-		       std::enable_if_t<std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
-							      element_type (*)[]> &&
+		       std::enable_if_t<std::is_convertible<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
+							    element_type (*)[]>::value &&
 					N == Extent,
 					std::nullptr_t> = nullptr) noexcept
 		: data_(arr.data())
@@ -145,8 +145,8 @@  public:
 
 	template<std::size_t N>
 	constexpr Span(const std::array<value_type, N> &arr,
-		       std::enable_if_t<std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
-							      element_type (*)[]> &&
+		       std::enable_if_t<std::is_convertible<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
+							    element_type (*)[]>::value &&
 					N == Extent,
 					std::nullptr_t> = nullptr) noexcept
 		: data_(arr.data())
@@ -157,9 +157,9 @@  public:
 	explicit constexpr Span(Container &cont,
 				std::enable_if_t<!details::is_span<Container>::value &&
 						 !details::is_array<Container>::value &&
-						 !std::is_array_v<Container> &&
-						 std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
-								       element_type (*)[]>,
+						 !std::is_array<Container>::value &&
+						 std::is_convertible<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
+								     element_type (*)[]>::value,
 						 std::nullptr_t> = nullptr)
 		: data_(utils::data(cont))
 	{
@@ -169,9 +169,9 @@  public:
 	explicit constexpr Span(const Container &cont,
 				std::enable_if_t<!details::is_span<Container>::value &&
 						 !details::is_array<Container>::value &&
-						 !std::is_array_v<Container> &&
-						 std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
-								       element_type (*)[]>,
+						 !std::is_array<Container>::value &&
+						 std::is_convertible<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
+								     element_type (*)[]>::value,
 						 std::nullptr_t> = nullptr)
 		: data_(utils::data(cont))
 	{
@@ -180,7 +180,7 @@  public:
 
 	template<class U, std::size_t N>
 	explicit constexpr Span(const Span<U, N> &s,
-				std::enable_if_t<std::is_convertible_v<U (*)[], element_type (*)[]> &&
+				std::enable_if_t<std::is_convertible<U (*)[], element_type (*)[]>::value &&
 						 N == Extent,
 						 std::nullptr_t> = nullptr) noexcept
 		: data_(s.data())
@@ -293,8 +293,8 @@  public:
 
 	template<std::size_t N>
 	constexpr Span(element_type (&arr)[N],
-		       std::enable_if_t<std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
-							      element_type (*)[]>,
+		       std::enable_if_t<std::is_convertible<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
+							    element_type (*)[]>::value,
 					std::nullptr_t> = nullptr) noexcept
 		: data_(arr), size_(N)
 	{
@@ -302,8 +302,8 @@  public:
 
 	template<std::size_t N>
 	constexpr Span(std::array<value_type, N> &arr,
-		       std::enable_if_t<std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
-							      element_type (*)[]>,
+		       std::enable_if_t<std::is_convertible<std::remove_pointer_t<decltype(utils::data(arr))> (*)[],
+							    element_type (*)[]>::value,
 					std::nullptr_t> = nullptr) noexcept
 		: data_(utils::data(arr)), size_(N)
 	{
@@ -319,9 +319,9 @@  public:
 	constexpr Span(Container &cont,
 		       std::enable_if_t<!details::is_span<Container>::value &&
 					!details::is_array<Container>::value &&
-					!std::is_array_v<Container> &&
-					std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
-							      element_type (*)[]>,
+					!std::is_array<Container>::value &&
+					std::is_convertible<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
+							    element_type (*)[]>::value,
 					std::nullptr_t> = nullptr)
 		: data_(utils::data(cont)), size_(utils::size(cont))
 	{
@@ -331,9 +331,9 @@  public:
 	constexpr Span(const Container &cont,
 		       std::enable_if_t<!details::is_span<Container>::value &&
 					!details::is_array<Container>::value &&
-					!std::is_array_v<Container> &&
-					std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
-							      element_type (*)[]>,
+					!std::is_array<Container>::value &&
+					std::is_convertible<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
+							    element_type (*)[]>::value,
 					std::nullptr_t> = nullptr)
 		: data_(utils::data(cont)), size_(utils::size(cont))
 	{
@@ -341,7 +341,7 @@  public:
 
 	template<class U, std::size_t N>
 	constexpr Span(const Span<U, N> &s,
-		       std::enable_if_t<std::is_convertible_v<U (*)[], element_type (*)[]>,
+		       std::enable_if_t<std::is_convertible<U (*)[], element_type (*)[]>::value,
 					std::nullptr_t> = nullptr) noexcept
 		: data_(s.data()), size_(s.size())
 	{