Sycl improve code coverage multi ptr

[dklochkov-emb]

This PR adds unit and e2e tests to check multi_ptr class. One bug is fixed: sycl 2020 specification tells that constructor multi_ptr(local_accessor<ElementType, dimensions> Accessor) should be available only in if

Available only when: (Space == access::address_space::local_space || Space == access::address_space::generic_space) && (std::is_void_v || std::is_same_v<std::remove_const_t, std::remove_const_t>) && (std::is_const_v || !std::is_const_v).

See 4.7.7.1 of the sycl 2020 spec.

[Copilot]

Pull request overview

This PR expands SYCL multi_ptr validation by adding a dedicated unit-test suite plus new compile-only and e2e tests, and fixes multi_ptr’s legacy local_accessor constructor availability to match the SYCL 2020 spec’s address-space restrictions.

Changes:

• Add new sycl/unittests/multi_ptr test suite covering constructors, operators, conversions (including void specialization), and accessor-related construction.
• Add compile-only negative/restricted conversion coverage (-verify) and an e2e test exercising multi_ptr::prefetch.
• Restrict the legacy multi_ptr(local_accessor<...>) constructor to only participate for local_space / generic_space.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 10 comments.

Show a summary per file

File	Description
sycl/include/sycl/multi_ptr.hpp	Restricts legacy local_accessor constructor via SFINAE to local/generic spaces.
sycl/unittests/CMakeLists.txt	Adds the new multi_ptr unit-test subdirectory to the SYCL unit tests build.
sycl/unittests/multi_ptr/CMakeLists.txt	Defines the new MultiPtrTests unit-test target and sources.
sycl/unittests/multi_ptr/Constructors.cpp	Unit tests for multi_ptr construction and converting construction.
sycl/unittests/multi_ptr/Operators.cpp	Unit tests for pointer-like operators and comparisons.
sycl/unittests/multi_ptr/Conversion.cpp	Unit tests for cross-decoration, void, const, and address-space conversion behavior.
sycl/unittests/multi_ptr/Accessors.cpp	Unit tests for construction from accessors/local_accessors and address_space_cast.
sycl/unittests/multi_ptr/NegativeConversions.cpp	Unit tests asserting conversions are rejected where required.
sycl/unittests/multi_ptr/VoidSpecialization.cpp	Unit tests focused on multi_ptr<void> / multi_ptr<const void> behavior.
sycl/test/multi_ptr/restricted_conversions.cpp	-verify test for diagnostics/warnings around restricted conversions.
sycl/test-e2e/multi_ptr/prefetch.cpp	E2E test for multi_ptr::prefetch in several scenarios.