[clang] [SYCL] Basic diagnostics for the sycl_kernel_entry_point attribute. (PR #120327)

[Tom Honermann via cfe-commits]

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@@ -12408,6 +12408,29 @@ def err_sycl_special_type_num_init_method : Error<
   "types with 'sycl_special_class' attribute must have one and only one '__init' "
   "method defined">;
 
+// SYCL kernel entry point diagnostics
+def err_sycl_entry_point_invalid : Error<
+  "'sycl_kernel_entry_point' attribute cannot be applied to a"
+  " %select{non-static member|variadic|deleted|defaulted|constexpr|consteval|"
+           "noreturn|coroutine}0 function">;
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tahonermann wrote:

Done. I avoided the additional `%select` by duplicating " function" for the relevant cases. I also changed the wording for the noreturn case from "no return function" to "function declared with the 'noreturn' attribute".

https://github.com/llvm/llvm-project/pull/120327