[NFC][SYCL] Use C++17 nested namespaces (#7692)

The change was done semi-automtically via clang-tidy with subsequent
manual review to revert incorrect changes followed by clang-format run
to update the comments on the namespace closing bracket.

Author: aelovikov-intel

sycl/include/sycl/accessor.hpp

@@ -212,16 +212,10 @@
 namespace sycl {
 __SYCL_INLINE_VER_NAMESPACE(_V1) {
 class stream;
-namespace ext {
-namespace intel {
-namespace esimd {
-namespace detail {
+namespace ext::intel::esimd::detail {
 // Forward declare a "back-door" access class to support ESIMD.
 class AccessorPrivateProxy;
-} // namespace detail
-} // namespace esimd
-} // namespace intel
-} // namespace ext
+} // namespace ext::intel::esimd::detail
 
 template <typename DataT, int Dimensions = 1,
           access::mode AccessMode = access::mode::read_write,

sycl/include/sycl/aliases.hpp

@@ -17,11 +17,9 @@
 namespace sycl {
 __SYCL_INLINE_VER_NAMESPACE(_V1) {
 template <typename T, int N> class vec;
-namespace detail {
-namespace half_impl {
+namespace detail::half_impl {
 class half;
-} // namespace half_impl
-} // namespace detail
+} // namespace detail::half_impl
 } // __SYCL_INLINE_VER_NAMESPACE(_V1)
 } // namespace sycl
 

sycl/include/sycl/buffer.hpp

@@ -36,11 +36,9 @@ class host_accessor;
 template <typename T, int Dimensions, typename AllocatorT, typename Enable>
 class buffer;
 
-namespace ext {
-namespace oneapi {
+namespace ext::oneapi {
 template <typename SYCLObjT> class weak_object;
-} // namespace oneapi
-} // namespace ext
+} // namespace ext::oneapi
 
 namespace detail {
 

sycl/include/sycl/builtins.hpp

@@ -889,16 +889,14 @@ std::enable_if_t<detail::is_geninteger<T>::value, T> ctz(T x) __NOEXC {
 }
 
 // geninteger ctz (geninteger x) for calls with deprecated namespace
-namespace ext {
-namespace intel {
+namespace ext::intel {
 template <typename T>
 __SYCL_DEPRECATED(
     "'sycl::ext::intel::ctz' is deprecated, use 'sycl::ctz' instead")
 std::enable_if_t<sycl::detail::is_geninteger<T>::value, T> ctz(T x) __NOEXC {
   return sycl::ctz(x);
 }
-} // namespace intel
-} // namespace ext
+} // namespace ext::intel
 
 namespace __SYCL2020_DEPRECATED("use 'ext::intel' instead") intel {
 using namespace ext::intel;

sycl/include/sycl/detail/generic_type_lists.hpp

@@ -22,11 +22,9 @@ namespace sycl {
 __SYCL_INLINE_VER_NAMESPACE(_V1) {
 template <typename T, int N> class vec;
 template <typename Type, std::size_t NumElements> class marray;
-namespace detail {
-namespace half_impl {
+namespace detail::half_impl {
 class half;
-}
-} // namespace detail
+} // namespace detail::half_impl
 using half = detail::half_impl::half;
 } // __SYCL_INLINE_VER_NAMESPACE(_V1)
 } // namespace sycl

sycl/include/sycl/detail/type_traits.hpp

@@ -20,8 +20,7 @@
 namespace sycl {
 __SYCL_INLINE_VER_NAMESPACE(_V1) {
 template <int Dimensions> class group;
-namespace ext {
-namespace oneapi {
+namespace ext::oneapi {
 struct sub_group;
 
 namespace experimental {
@@ -35,8 +34,7 @@ struct is_group_helper<group_with_scratchpad<Group, Extent>> : std::true_type {
 };
 } // namespace detail
 } // namespace experimental
-} // namespace oneapi
-} // namespace ext
+} // namespace ext::oneapi
 
 namespace detail {
 

sycl/include/sycl/detail/usm_impl.hpp

@@ -13,8 +13,7 @@
 
 namespace sycl {
 __SYCL_INLINE_VER_NAMESPACE(_V1) {
-namespace detail {
-namespace usm {
+namespace detail::usm {
 
 __SYCL_EXPORT void *alignedAlloc(size_t Alignment, size_t Bytes,
                                  const context &Ctxt, const device &Dev,
@@ -28,7 +27,6 @@ __SYCL_EXPORT void *alignedAllocHost(size_t Alignment, size_t Bytes,
 __SYCL_EXPORT void free(void *Ptr, const context &Ctxt,
                         const code_location &CL);
 
-} // namespace usm
-} // namespace detail
+} // namespace detail::usm
 } // __SYCL_INLINE_VER_NAMESPACE(_V1)
 } // namespace sycl

sycl/include/sycl/device.hpp

@@ -35,12 +35,10 @@ class device_impl;
 auto getDeviceComparisonLambda();
 } // namespace detail
 
-namespace ext {
-namespace oneapi {
+namespace ext::oneapi {
 // Forward declaration
 class filter_selector;
-} // namespace oneapi
-} // namespace ext
+} // namespace ext::oneapi
 
 /// The SYCL device class encapsulates a single SYCL device on which kernels
 /// may be executed.

sycl/include/sycl/device_selector.hpp

@@ -21,11 +21,9 @@ __SYCL_INLINE_VER_NAMESPACE(_V1) {
 // Forward declarations
 class device;
 
-namespace ext {
-namespace oneapi {
+namespace ext::oneapi {
 class filter_selector;
-}
-} // namespace ext
+} // namespace ext::oneapi
 
 /// The SYCL 1.2.1 device_selector class provides ability to choose the
 /// best SYCL device based on heuristics specified by the user.

sycl/include/sycl/ext/codeplay/experimental/fusion_properties.hpp

@@ -14,10 +14,7 @@
 
 namespace sycl {
 __SYCL_INLINE_VER_NAMESPACE(_V1) {
-namespace ext {
-namespace codeplay {
-namespace experimental {
-namespace property {
+namespace ext::codeplay::experimental::property {
 
 class promote_private
     : public detail::DataLessProperty<detail::FusionPromotePrivate> {};
@@ -33,10 +30,7 @@ namespace queue {
 class enable_fusion : public detail::DataLessProperty<detail::FusionEnable> {};
 } // namespace queue
 
-} // namespace property
-} // namespace experimental
-} // namespace codeplay
-} // namespace ext
+} // namespace ext::codeplay::experimental::property
 
 // Forward declarations
 template <typename T, int Dimensions, typename AllocatorT, typename Enable>

sycl/include/sycl/ext/codeplay/experimental/fusion_wrapper.hpp

@@ -17,9 +17,7 @@ namespace detail {
 class fusion_wrapper_impl;
 }
 
-namespace ext {
-namespace codeplay {
-namespace experimental {
+namespace ext::codeplay::experimental {
 
 ///
 /// A wrapper wrapping a sycl::queue to provide access to the kernel fusion API,
@@ -91,8 +89,6 @@ class __SYCL_EXPORT fusion_wrapper {
 private:
   std::shared_ptr<detail::fusion_wrapper_impl> MImpl;
 };
-} // namespace experimental
-} // namespace codeplay
-} // namespace ext
+} // namespace ext::codeplay::experimental
 } // __SYCL_INLINE_VER_NAMESPACE(_V1)
 } // namespace sycl

sycl/include/sycl/ext/intel/esimd/detail/host_util.hpp

@@ -23,11 +23,9 @@
 
 namespace sycl {
 __SYCL_INLINE_VER_NAMESPACE(_V1) {
-namespace detail {
-namespace half_impl {
+namespace detail::half_impl {
 class half;
-} // namespace half_impl
-} // namespace detail
+} // namespace detail::half_impl
 } // __SYCL_INLINE_VER_NAMESPACE(_V1)
 } // namespace sycl
 

sycl/include/sycl/ext/intel/esimd/detail/region.hpp

@@ -19,9 +19,7 @@
 
 namespace sycl {
 __SYCL_INLINE_VER_NAMESPACE(_V1) {
-namespace ext {
-namespace intel {
-namespace esimd {
+namespace ext::intel::esimd {
 
 /// @cond ESIMD_DETAIL
 // TODO move to detail?
@@ -135,9 +133,7 @@ template <typename T, typename U> T getBaseRegion(std::pair<T, U> Reg) {
 
 /// @endcond ESIMD_DETAIL
 
-} // namespace esimd
-} // namespace intel
-} // namespace ext
+} // namespace ext::intel::esimd
 } // __SYCL_INLINE_VER_NAMESPACE(_V1)
 } // namespace sycl
 

sycl/include/sycl/ext/intel/esimd/detail/sycl_util.hpp

@@ -17,10 +17,7 @@
 
 namespace sycl {
 __SYCL_INLINE_VER_NAMESPACE(_V1) {
-namespace ext {
-namespace intel {
-namespace esimd {
-namespace detail {
+namespace ext::intel::esimd::detail {
 
 // Checks that given type is a SYCL accessor type. Sets its static field
 // \c value accordingly. Also, if the check is succesful, sets \c mode and
@@ -82,10 +79,7 @@ template <typename T, accessor_mode_cap_val_t Capability,
 using EnableIfAccessor = std::enable_if_t<
     detail::is_sycl_accessor_with<T, Capability, AccessTarget>::value, RetT>;
 
-} // namespace detail
-} // namespace esimd
-} // namespace intel
-} // namespace ext
+} // namespace ext::intel::esimd::detail
 } // __SYCL_INLINE_VER_NAMESPACE(_V1)
 } // namespace sycl
 

sycl/include/sycl/ext/intel/esimd/native/common.hpp

@@ -16,9 +16,7 @@
 
 namespace sycl {
 __SYCL_INLINE_VER_NAMESPACE(_V1) {
-namespace ext::intel::esimd {
-namespace native {
-namespace lsc {
+namespace ext::intel::esimd::native::lsc {
 
 /// @addtogroup sycl_esimd_memory
 /// @{
@@ -62,8 +60,6 @@ enum class atomic_op : uint8_t {
 
 /// @} sycl_esimd_memory_lsc
 
-} // namespace lsc
-} // namespace native
-} // namespace ext::intel::esimd
+} // namespace ext::intel::esimd::native::lsc
 } // __SYCL_INLINE_VER_NAMESPACE(_V1)
 } // namespace sycl

sycl/include/sycl/ext/intel/experimental/esimd/memory.hpp

@@ -17,10 +17,8 @@
 
 namespace sycl {
 __SYCL_INLINE_VER_NAMESPACE(_V1) {
-namespace ext {
-namespace intel {
-namespace experimental {
-namespace esimd {
+namespace ext::intel {
+namespace experimental::esimd {
 
 /// @addtogroup sycl_esimd_memory
 /// @{
@@ -1723,8 +1721,7 @@ __ESIMD_API void lsc_fence(__ESIMD_NS::simd_mask<N> pred = 1) {
 
 /// @} sycl_esimd_memory_lsc
 
-} // namespace esimd
-} // namespace experimental
+} // namespace experimental::esimd
 
 namespace esimd {
 
@@ -1759,7 +1756,6 @@ __ESIMD_API simd<T, N> atomic_update(T *p, simd<unsigned, N> offset,
 }
 
 } // namespace esimd
-} // namespace intel
-} // namespace ext
+} // namespace ext::intel
 } // __SYCL_INLINE_VER_NAMESPACE(_V1)
 } // namespace sycl

sycl/include/sycl/ext/intel/experimental/fpga_lsu.hpp

@@ -14,9 +14,7 @@
 
 namespace sycl {
 __SYCL_INLINE_VER_NAMESPACE(_V1) {
-namespace ext {
-namespace intel {
-namespace experimental {
+namespace ext::intel::experimental {
 
 constexpr uint8_t BURST_COALESCE = 0x1;
 constexpr uint8_t CACHE = 0x2;
@@ -201,8 +199,6 @@ template <class... _mem_access_params> class lsu final {
 #endif
 };
 
-} // namespace experimental
-} // namespace intel
-} // namespace ext
+} // namespace ext::intel::experimental
 } // __SYCL_INLINE_VER_NAMESPACE(_V1)
 } // namespace sycl

sycl/include/sycl/ext/intel/experimental/online_compiler.hpp

@@ -17,9 +17,7 @@
 
 namespace sycl {
 __SYCL_INLINE_VER_NAMESPACE(_V1) {
-namespace ext {
-namespace intel {
-namespace experimental {
+namespace ext::intel::experimental {
 
 using byte = unsigned char;
 
@@ -222,8 +220,6 @@ online_compiler<source_language::cm>::compile(const std::string &src) {
   return compile(src, std::vector<std::string>{});
 }
 
-} // namespace experimental
-} // namespace intel
-} // namespace ext
+} // namespace ext::intel::experimental
 } // __SYCL_INLINE_VER_NAMESPACE(_V1)
 } // namespace sycl

sycl/include/sycl/ext/intel/experimental/pipes.hpp

@@ -17,9 +17,7 @@
 
 namespace sycl {
 __SYCL_INLINE_VER_NAMESPACE(_V1) {
-namespace ext {
-namespace intel {
-namespace experimental {
+namespace ext::intel::experimental {
 
 template <class _name, class _dataT, int32_t _min_capacity = 0,
           class _propertiesT = decltype(oneapi::experimental::properties{}),
@@ -278,8 +276,6 @@ class pipe<_name, _dataT, _min_capacity, _propertiesT,
 #endif // __SYCL_DEVICE_ONLY__
 };
 
-} // namespace experimental
-} // namespace intel
-} // namespace ext
+} // namespace ext::intel::experimental
 } // __SYCL_INLINE_VER_NAMESPACE(_V1)
 } // namespace sycl