[clang] [clang][Sema] Split SYCLKernel back into its own attribute (PR #162868)

[Nick Sarnie via cfe-commits]

================
@@ -1599,8 +1599,15 @@ def CUDAShared : InheritableAttr {
 }
 def : MutualExclusions<[CUDAConstant, CUDAShared, HIPManaged]>;
 
+def SYCLKernel : InheritableAttr {
+  let Spellings = [Clang<"sycl_kernel">];
+  let Subjects = SubjectList<[FunctionTmpl]>;
+  let LangOpts = [SYCLDevice];
----------------
sarnex wrote:

Just tried and it seems yes:

```
 "/llvm/build/bin/clang-22" -cc1 -triple x86_64-unknown-linux-gnu -fsycl-is-host -sycl-std=2020 -emit-obj -dumpdir a- -disable-free -clear-ast-before-backend -main-file-name foo.cpp -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -v -resource-dir /llvm/build/lib/clang/22 -internal-isystem /usr/lib/gcc/x86_64-redhat-linux/11/../../../../include/c++/11 -internal-isystem /usr/lib/gcc/x86_64-redhat-linux/11/../../../../include/c++/11/x86_64-redhat-linux -internal-isystem /usr/lib/gcc/x86_64-redhat-linux/11/../../../../include/c++/11/backward -internal-isystem /usr/lib/gcc/x86_64-redhat-linux/11/../../../../include/c++/11 -internal-isystem /usr/lib/gcc/x86_64-redhat-linux/11/../../../../include/c++/11/x86_64-redhat-linux -internal-isystem /usr/lib/gcc/x86_64-redhat-linux/11/../../../../include/c++/11/backward -internal-isystem /llvm/build/lib/clang/22/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-redhat-linux/11/../../../../x86_64-redhat-linux/include -internal-externc-isystem /include -internal-externc-isystem /usr/include -internal-isystem /llvm/build/lib/clang/22/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-redhat-linux/11/../../../../x86_64-redhat-linux/include -internal-externc-isystem /include -internal-externc-isystem /usr/include -fdeprecated-macro -ferror-limit 19 -fmessage-length=262 -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fcxx-exceptions -fexceptions -fcolor-diagnostics -fembed-offload-object=/tmp/foo-b73420.out -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/foo-053756.o -x c++ foo.cpp
clang -cc1 version 22.0.0git based upon LLVM 22.0.0git default target x86_64-unknown-linux-gnu
ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/11/../../../../x86_64-redhat-linux/include"
ignoring nonexistent directory "/include"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/11/../../../../x86_64-redhat-linux/include"
ignoring nonexistent directory "/include"
ignoring duplicate directory "/usr/lib/gcc/x86_64-redhat-linux/11/../../../../include/c++/11"
ignoring duplicate directory "/usr/lib/gcc/x86_64-redhat-linux/11/../../../../include/c++/11/x86_64-redhat-linux"
ignoring duplicate directory "/usr/lib/gcc/x86_64-redhat-linux/11/../../../../include/c++/11/backward"
ignoring duplicate directory "/llvm/build/lib/clang/22/include"
ignoring duplicate directory "/usr/local/include"
ignoring duplicate directory "/usr/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/lib/gcc/x86_64-redhat-linux/11/../../../../include/c++/11
 /usr/lib/gcc/x86_64-redhat-linux/11/../../../../include/c++/11/x86_64-redhat-linux
 /usr/lib/gcc/x86_64-redhat-linux/11/../../../../include/c++/11/backward
 /llvm/build/lib/clang/22/include
 /usr/local/include
 /usr/include
End of search list.
foo.cpp:2:3: warning: 'clang::sycl_kernel' attribute ignored [-Wignored-attributes]
    2 | [[clang::sycl_kernel]]


```

No warning for the device compile.

https://github.com/llvm/llvm-project/pull/162868