[SYCL] Fix KernelNameInfo generated for empty template parameter pack (#1775)

* Fix KernelNameInfo generated in integration header when kernel
name type is a template specialization class with empty template
pack argument.

This commit fixes a bug introduced by commit e7020a1
where an extra comma was printed before empty pack arguments

Signed-off-by: Elizabeth Andrews <[email protected]>

Author: elizabethandrews

clang/lib/Sema/SemaSYCL.cpp

@@ -1906,6 +1906,10 @@ static void printArguments(ASTContext &Ctx, raw_ostream &ArgOS,
   for (unsigned I = 0; I < Args.size(); I++) {
     const TemplateArgument &Arg = Args[I];
 
+    // If argument is an empty pack argument, skip printing comma and argument.
+    if (Arg.getKind() == TemplateArgument::ArgKind::Pack && !Arg.pack_size())
+      continue;
+
     if (I != 0)
       ArgOS << ", ";
 

clang/test/CodeGenSYCL/int_header1.cpp

@@ -12,6 +12,7 @@
 // CHECK:template <> struct KernelInfo<::nm1::KernelName4<KernelName7>> {
 // CHECK:template <> struct KernelInfo<::nm1::KernelName8<::nm1::nm2::C>> {
 // CHECK:template <> struct KernelInfo<::TmplClassInAnonNS<ClassInAnonNS>> {
+// CHECK:template <> struct KernelInfo<::nm1::KernelName9<char>> {
 
 // This test checks if the SYCL device compiler is able to generate correct
 // integration header when the kernel name class is expressed in different
@@ -42,6 +43,9 @@ namespace nm1 {
   template <> class KernelName4<nm1::nm2::KernelName0> {};
   template <> class KernelName4<KernelName1> {};
 
+  template <typename T, typename...>
+  class KernelName9;
+
 } // namespace nm1
 
 namespace {
@@ -128,6 +132,10 @@ struct MyWrapper {
     kernel_single_task<TmplClassInAnonNS<class ClassInAnonNS>>(
       [=]() { acc.use(); });
 
+    // Kernel name type is a templated specialization class with empty template pack argument
+    kernel_single_task<nm1::KernelName9<char>>(
+        [=]() { acc.use(); });
+
     return 0;
   }
 };
@@ -151,5 +159,6 @@ int main() {
   KernelInfo<class nm1::KernelName4<class KernelName7>>::getName();
   KernelInfo<class nm1::KernelName8<nm1::nm2::C>>::getName();
   KernelInfo<class TmplClassInAnonNS<class ClassInAnonNS>>::getName();
+  KernelInfo<class nm1::KernelName9<char>>::getName();
 #endif //__SYCL_DEVICE_ONLY__
 }