[SYCL][clang] Clarify warning message for potential property conflicts (#20572)

The compiler currently warns when properties are used in conjunction
with SYCL 2020 properties, warning about potentially ignored conflicting
properties. This commit makes the warning messages a little clearer to
help users understand what particular properties may be of concern.

---------

Signed-off-by: Larsen, Steffen <[email protected]>

Author: steffenlarsen

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -13425,8 +13425,9 @@ def err_sycl_add_ir_attribute_invalid_filter : Error<
   "initializer list in the first argument of %0 must contain only string "
   "literals">;
 def warn_sycl_old_and_new_kernel_attributes : Warning<
-  "kernel has both attribute %0 and kernel properties; conflicting properties "
-  "are ignored">, InGroup<IgnoredAttributes>;
+  "kernel has both attribute %0 and kernel properties; if the kernel "
+  "properties contains the property \"%1\" it will be ignored">,
+  InGroup<IgnoredAttributes>;
 def err_attribute_argument_is_not_valid : Error<
   "%0 attribute requires integer constant value 0 or 1">;
 

clang/lib/Sema/SemaSYCLDeclAttr.cpp

@@ -3256,14 +3256,19 @@ void SemaSYCL::checkSYCLAddIRAttributesFunctionAttrConflicts(Decl *D) {
   }
 
   // If there are potentially conflicting attributes, we issue a warning.
-  for (const auto *Attr : std::vector<AttributeCommonInfo *>{
-           D->getAttr<SYCLReqdWorkGroupSizeAttr>(),
-           D->getAttr<IntelReqdSubGroupSizeAttr>(),
-           D->getAttr<SYCLWorkGroupSizeHintAttr>(),
-           D->getAttr<SYCLDeviceHasAttr>()})
+  for (const auto [Attr, PotentialConflictProp] :
+       std::vector<std::pair<AttributeCommonInfo *, StringRef>>{
+           {D->getAttr<SYCLReqdWorkGroupSizeAttr>(),
+            "sycl::ext::oneapi::experimental::work_group_size"},
+           {D->getAttr<IntelReqdSubGroupSizeAttr>(),
+            "sycl::ext::oneapi::experimental::sub_group_size"},
+           {D->getAttr<SYCLWorkGroupSizeHintAttr>(),
+            "sycl::ext::oneapi::experimental::work_group_size_hint"},
+           {D->getAttr<SYCLDeviceHasAttr>(),
+            "sycl::ext::oneapi::experimental::device_has"}})
     if (Attr)
       Diag(Attr->getLoc(), diag::warn_sycl_old_and_new_kernel_attributes)
-          << Attr;
+          << Attr << PotentialConflictProp;
 }
 
 void SemaSYCL::handleSYCLRegisteredKernels(Decl *D, const ParsedAttr &A) {