Add comment to the regression suite test case, put it into unnamed-lambda.cpp instead as @AlexeySachkov requested offline

Author: Erich Keane

sycl/test/regression/unnamed-lambda-split-order.cpp

@@ -33,3 +33,15 @@ void bar(cl::sycl::queue queue) {
     cgh.parallel_for<class K2>(cl::sycl::range<2>{1024,768}, f);
   });
 }
+
+// This validates the case where using a lambda in a kernel in a different order
+// than the lexical order of the lambdas. In a previous implemetation of
+// __builtin_sycl_unique_stable_name this would result in the value of the
+// builtin being invalidated, causing a compile error. The redesigned
+// implementation should no longer have a problem with this pattern.
+void out_of_order_decls() {
+  auto w = [](auto i) {};
+  sycl::queue q;
+  q.parallel_for(10, [](auto i) {});
+  q.parallel_for(10, w);
+}