Revert "libcamera: span: Provide and use helper variable templates for type traits"

Some applications may not be compliant with C++17 (Chromium, as an
example). Keep the C++17 features for libcamera internals, and C++14
compliance for public API.

This reverts commit 8e42c2feb7ff7c350ffbbf97dd963dfd54e21faa.

Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

2 files changed, 14 insertions, 20 deletions

diff --git a/include/libcamera/controls.h b/include/libcamera/controls.h
index 3634dc43..dc549a92 100644
--- a/include/libcamera/controls.h
+++ b/include/libcamera/controls.h
@@ -96,7 +96,7 @@ public:
 	ControlValue();
 
 #ifndef __DOXYGEN__
-	template<typename T, typename std::enable_if_t<!details::is_span_v<T> &&
+	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::nullptr_t> = nullptr>
@@ -107,7 +107,7 @@ public:
 		    &value, 1, sizeof(T));
 	}
 
-	template<typename T, typename std::enable_if_t<details::is_span_v<T> ||
+	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::nullptr_t> = nullptr>
 #else
@@ -141,7 +141,7 @@ public:
 	}
 
 #ifndef __DOXYGEN__
-	template<typename T, typename std::enable_if_t<!details::is_span_v<T> &&
+	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::nullptr_t> = nullptr>
 	T get() const
@@ -152,7 +152,7 @@ public:
 		return *reinterpret_cast<const T *>(data().data());
 	}
 
-	template<typename T, typename std::enable_if_t<details::is_span_v<T> ||
+	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::nullptr_t> = nullptr>
 #else
@@ -169,7 +169,7 @@ public:
 	}
 
 #ifndef __DOXYGEN__
-	template<typename T, typename std::enable_if_t<!details::is_span_v<T> &&
+	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::nullptr_t> = nullptr>
 	void set(const T &value)
@@ -178,7 +178,7 @@ public:
 		    reinterpret_cast<const void *>(&value), 1, sizeof(T));
 	}
 
-	template<typename T, typename std::enable_if_t<details::is_span_v<T> ||
+	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::nullptr_t> = nullptr>
 #else
diff --git a/include/libcamera/span.h b/include/libcamera/span.h
index e7ffef12..d720adb8 100644
--- a/include/libcamera/span.h
+++ b/include/libcamera/span.h
@@ -31,9 +31,6 @@ template<typename U, std::size_t N>
 struct is_array<std::array<U, N>> : public std::true_type {
 };
 
-template<typename T>
-inline constexpr bool is_array_v = is_array<T>::value;
-
 template<typename U>
 struct is_span : public std::false_type {
 };
@@ -42,9 +39,6 @@ template<typename U, std::size_t Extent>
 struct is_span<Span<U, Extent>> : public std::true_type {
 };
 
-template<typename T>
-inline constexpr bool is_span_v = is_span<T>::value;
-
 } /* namespace details */
 
 namespace utils {
@@ -161,8 +155,8 @@ public:
 
 	template<class Container>
 	explicit constexpr Span(Container &cont,
-				std::enable_if_t<!details::is_span_v<Container> &&
-						 !details::is_array_v<Container> &&
+				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 (*)[]>,
@@ -173,8 +167,8 @@ public:
 
 	template<class Container>
 	explicit constexpr Span(const Container &cont,
-				std::enable_if_t<!details::is_span_v<Container> &&
-						 !details::is_array_v<Container> &&
+				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 (*)[]>,
@@ -323,8 +317,8 @@ public:
 
 	template<class Container>
 	constexpr Span(Container &cont,
-		       std::enable_if_t<!details::is_span_v<Container> &&
-					!details::is_array_v<Container> &&
+		       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 (*)[]>,
@@ -335,8 +329,8 @@ public:
 
 	template<class Container>
 	constexpr Span(const Container &cont,
-		       std::enable_if_t<!details::is_span_v<Container> &&
-					!details::is_array_v<Container> &&
+		       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 (*)[]>,