Fix check-sycl tests by excluding old-spelling from the test

Really we should probably be checking this, but since it is a pattern
that is apparently commonly used, AND is a breaking change, we won't
enforce this rule. The standard doesn't require us to (since it is
pretty silent on mixing attribute types).

Author: Erich Keane

clang/lib/Sema/SemaSYCL.cpp

@@ -3626,6 +3626,13 @@ static void CheckSYCL2020SubGroupSizes(Sema &S, FunctionDecl *SYCLKernel,
 
   // Else this doesn't have an attribute, which can only be caused by this being
   // an undefined SYCL_EXTERNAL, and the kernel has an attribute that conflicts.
+  if (const auto *A = SYCLKernel->getAttr<IntelReqdSubGroupSizeAttr>()) {
+    // Don't diagnose this if the kernel got its size from the 'old' attribute
+    // spelling.
+    if (!A->isSYCL2020Spelling())
+      return;
+  }
+
   assert(KernelAttrLoc.isValid() && "Kernel doesn't have attribute either?");
   S.Diag(FD->getLocation(), diag::err_sycl_mismatch_group_size)
       << /*undefined SYCL_EXTERNAL*/ 1;

clang/test/SemaSYCL/sub-group-size.cpp

@@ -142,3 +142,10 @@ void calls_kernel_5() {
 
   });
 }
+
+// Don't diag with the old sub-group-size.
+void calls_kernel_6() {
+  sycl::kernel_single_task<class Kernel6>([]() [[intel::reqd_sub_group_size(10)]] { // #Kernel6
+    NoAttrExternalNotDefined();
+  });
+}