[SYCL] Fix handler::require() to accept a non-placeholder arg (#7786)

Author: KornevNikita

sycl/include/sycl/handler.hpp

@@ -1469,18 +1469,18 @@ class __SYCL_EXPORT handler {
   use_kernel_bundle(const kernel_bundle<bundle_state::executable> &ExecBundle);
 
   /// Requires access to the memory object associated with the placeholder
-  /// accessor.
+  /// accessor. Calling this function with a non-placeholder accessor has no
+  /// effect.
   ///
   /// The command group has a requirement to gain access to the given memory
   /// object before executing.
   ///
   /// \param Acc is a SYCL accessor describing required memory region.
   template <typename DataT, int Dims, access::mode AccMode,
-            access::target AccTarget>
-  void
-  require(accessor<DataT, Dims, AccMode, AccTarget, access::placeholder::true_t>
-              Acc) {
-    associateWithHandler(&Acc, AccTarget);
+            access::target AccTarget, access::placeholder isPlaceholder>
+  void require(accessor<DataT, Dims, AccMode, AccTarget, isPlaceholder> Acc) {
+    if (Acc.is_placeholder())
+      associateWithHandler(&Acc, AccTarget);
   }
 
   /// Registers event dependencies on this command group.

sycl/unittests/handler/CMakeLists.txt

@@ -1,3 +1,4 @@
 add_sycl_unittest(HandlerTests OBJECT
   SetArgForLocalAccessor.cpp
+  require.cpp
 )

sycl/unittests/handler/require.cpp

@@ -0,0 +1,19 @@
+#include <gtest/gtest.h>
+#include <helpers/PiMock.hpp>
+
+#include <sycl/sycl.hpp>
+
+TEST(Require, RequireWithNonPlaceholderAccessor) {
+  sycl::unittest::PiMock Mock;
+  sycl::queue Q;
+  int data = 5;
+  {
+    sycl::buffer<int, 1> buf(&data, 1);
+    Q.submit([&](sycl::handler &h) {
+      auto acc = buf.get_access<sycl::access::mode::read_write>(h);
+      // It should be compilable and does nothing according to the spec
+      h.require(acc);
+    });
+    Q.wait();
+  }
+}