[SYCL] annotated_ptr API fixes part 3 (#10936)

Deprecate implicit constructor by marking constructor explicit and
adding new deprecated implicit constructor.

This is separate because it won't be included in 2024.0.

Author: rolandschulz

sycl/doc/extensions/experimental/sycl_ext_oneapi_annotated_ptr.asciidoc

@@ -262,9 +262,9 @@ class annotated_ptr {
     using reference = annotated_ref<T, PropertyListT>;
 
     annotated_ptr() noexcept;
-    annotated_ptr(T *Ptr, const PropertyListT &P = properties{}) noexcept;
+    explicit annotated_ptr(T *Ptr, const PropertyListT &P = properties{}) noexcept;
     template<typename... PropertyValueTs>
-    annotated_ptr(T *Ptr, PropertyValueTs... props) noexcept;
+    explicit annotated_ptr(T *Ptr, PropertyValueTs... props) noexcept;
 
     template <typename T2, typename P> explicit annotated_ptr(
       const annotated_ptr<T2, P>&) noexcept;

sycl/include/sycl/ext/oneapi/experimental/annotated_ptr/annotated_ptr.hpp

@@ -205,15 +205,16 @@ __SYCL_TYPE(annotated_ptr) annotated_ptr<T, detail::properties_t<Props...>> {
   annotated_ptr(const annotated_ptr &) = default;
   annotated_ptr &operator=(const annotated_ptr &) = default;
 
-  annotated_ptr(T *Ptr, const property_list_t & = properties{}) noexcept
+  explicit annotated_ptr(T *Ptr,
+                         const property_list_t & = properties{}) noexcept
       : m_Ptr(global_pointer_t(Ptr)) {}
 
   // Constructs an annotated_ptr object from a raw pointer and variadic
   // properties. The new property set contains all properties of the input
   // variadic properties. The same property in `Props...` and
   // `PropertyValueTs...` must have the same property value.
   template <typename... PropertyValueTs>
-  annotated_ptr(T *Ptr, const PropertyValueTs &...props) noexcept
+  explicit annotated_ptr(T *Ptr, const PropertyValueTs &...props) noexcept
       : m_Ptr(global_pointer_t(Ptr)) {
     static_assert(
         std::is_same<

sycl/test/extensions/annotated_arg/annotated_ptr.cpp

@@ -1,5 +1,4 @@
 // RUN: %clangxx -fsycl -fsycl-targets=%sycl_triple -fsyntax-only -Xclang -verify -Xclang -verify-ignore-unexpected=note %s
-// expected-no-diagnostics
 
 #include "sycl/sycl.hpp"
 #include <sycl/ext/intel/fpga_extensions.hpp>
@@ -110,7 +109,9 @@ void TestVectorAddWithAnnotatedMMHosts() {
   // annotated_ptr<int, decltype(properties{dwidth<32>})> arg24(tmp21,
   // properties{dwidth<32>});   // ERR
 
-  // Implicit conversion
+  // Removed
+  // Assignment / implicit conversion
+  // expected-error@+1 {{no viable overloaded '='}}
   a1 = raw;
 
   // Property merge