[libcamera-devel] [PATCH] libcamera: revert C++17 specific code for public API
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Mon Jan 4 06:54:21 CET 2021
Hi Jean-Michel,
Thank you for the patch.
On Thu, Dec 31, 2020 at 04:47:10PM +0100, Jean-Michel Hautbois wrote:
> 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 is (unfortunately :-)) a good point. I was expecting Chromium to
use a more recent C++ version, I'm a bit surprised. There seem to be two
separate questions here:
- Could we build the libcamera support in Chromium with C++17
(specifying the C++ version explicitly in the BUILD.gn file in the
corresponding subdirectory, overriding the default C++14 version) ?
- As a more general question, can we expect C++17 support in the not too
distant future in code that will use libcamera, or is that an
unreasonable expectation and should we stick to c++14 in the public
API ?
If the answer to the first question is no, then we won't have a choice
for the second question.
We could stick to C++14 in the public API as it should not block us (at
least for now), this revert isn't that bad. I'm however concerned that
C++17 features may creep in unnoticed in the API, as we can't test
building libcamera with C++14, given that the internals depend on C++17.
> This reverts commits 8e42c2feb7ff7c350ffbbf97dd963dfd54e21faa and
> 6cbdc2859963e17bc897a4022f1d68170477d888.
Reverts are usually submitted separately, to make is easier to track
changes.
> Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois at ideasonboard.com>
> ---
> include/libcamera/bound_method.h | 2 +-
> include/libcamera/controls.h | 24 +++++------
> include/libcamera/object.h | 2 +-
> include/libcamera/signal.h | 4 +-
> include/libcamera/span.h | 70 +++++++++++++++-----------------
> 5 files changed, 48 insertions(+), 54 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 3634dc43..3b7f3347 100644
> --- a/include/libcamera/controls.h
> +++ b/include/libcamera/controls.h
> @@ -96,9 +96,9 @@ 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::is_same<std::string, std::remove_cv_t<T>>::value,
> std::nullptr_t> = nullptr>
> ControlValue(const T &value)
> : type_(ControlTypeNone), numElements_(0)
> @@ -107,8 +107,8 @@ public:
> &value, 1, sizeof(T));
> }
>
> - template<typename T, typename std::enable_if_t<details::is_span_v<T> ||
> - std::is_same_v<std::string, std::remove_cv_t<T>>,
> + template<typename T, typename std::enable_if_t<details::is_span<T>::value ||
> + std::is_same<std::string, std::remove_cv_t<T>>::value,
> std::nullptr_t> = nullptr>
> #else
> template<typename T>
> @@ -141,8 +141,8 @@ public:
> }
>
> #ifndef __DOXYGEN__
> - template<typename T, typename std::enable_if_t<!details::is_span_v<T> &&
> - !std::is_same_v<std::string, std::remove_cv_t<T>>,
> + template<typename T, typename std::enable_if_t<!details::is_span<T>::value &&
> + !std::is_same<std::string, std::remove_cv_t<T>>::value,
> std::nullptr_t> = nullptr>
> T get() const
> {
> @@ -152,8 +152,8 @@ public:
> return *reinterpret_cast<const T *>(data().data());
> }
>
> - template<typename T, typename std::enable_if_t<details::is_span_v<T> ||
> - std::is_same_v<std::string, std::remove_cv_t<T>>,
> + template<typename T, typename std::enable_if_t<details::is_span<T>::value ||
> + std::is_same<std::string, std::remove_cv_t<T>>::value,
> std::nullptr_t> = nullptr>
> #else
> template<typename T>
> @@ -169,8 +169,8 @@ public:
> }
>
> #ifndef __DOXYGEN__
> - template<typename T, typename std::enable_if_t<!details::is_span_v<T> &&
> - !std::is_same_v<std::string, std::remove_cv_t<T>>,
> + template<typename T, typename std::enable_if_t<!details::is_span<T>::value &&
> + !std::is_same<std::string, std::remove_cv_t<T>>::value,
> std::nullptr_t> = nullptr>
> void set(const T &value)
> {
> @@ -178,8 +178,8 @@ public:
> reinterpret_cast<const void *>(&value), 1, sizeof(T));
> }
>
> - template<typename T, typename std::enable_if_t<details::is_span_v<T> ||
> - std::is_same_v<std::string, std::remove_cv_t<T>>,
> + template<typename T, typename std::enable_if_t<details::is_span<T>::value ||
> + 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 e7ffef12..91e9f974 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 {
> @@ -131,8 +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)
> @@ -141,8 +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())
> @@ -151,8 +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())
> @@ -161,11 +155,11 @@ public:
>
> template<class Container>
> explicit constexpr Span(Container &cont,
> - std::enable_if_t<!details::is_span_v<Container> &&
> - !details::is_array_v<Container> &&
> - !std::is_array_v<Container> &&
> - std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
> - element_type (*)[]>,
> + std::enable_if_t<!details::is_span<Container>::value &&
> + !details::is_array<Container>::value &&
> + !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))
> {
> @@ -173,11 +167,11 @@ 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::is_array_v<Container> &&
> - std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
> - element_type (*)[]>,
> + std::enable_if_t<!details::is_span<Container>::value &&
> + !details::is_array<Container>::value &&
> + !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))
> {
> @@ -186,7 +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())
> @@ -299,8 +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)
> {
> @@ -308,8 +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)
> {
> @@ -323,11 +317,11 @@ public:
>
> template<class Container>
> constexpr Span(Container &cont,
> - std::enable_if_t<!details::is_span_v<Container> &&
> - !details::is_array_v<Container> &&
> - !std::is_array_v<Container> &&
> - std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
> - element_type (*)[]>,
> + std::enable_if_t<!details::is_span<Container>::value &&
> + !details::is_array<Container>::value &&
> + !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))
> {
> @@ -335,11 +329,11 @@ public:
>
> template<class Container>
> constexpr Span(const Container &cont,
> - std::enable_if_t<!details::is_span_v<Container> &&
> - !details::is_array_v<Container> &&
> - !std::is_array_v<Container> &&
> - std::is_convertible_v<std::remove_pointer_t<decltype(utils::data(cont))> (*)[],
> - element_type (*)[]>,
> + std::enable_if_t<!details::is_span<Container>::value &&
> + !details::is_array<Container>::value &&
> + !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))
> {
> @@ -347,7 +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())
> {
--
Regards,
Laurent Pinchart
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