[SYCL] Print default arguments of templates when printing kernel names for lambdas/functors in integration header

clang/lib/Sema/SemaSYCL.cpp

@@ -7691,6 +7691,8 @@ void SYCLIntegrationHeader::emit(raw_ostream &O) {
       OutputStableNameInChars(O, K.StableName);
       O << "> {\n";
     } else {
+      Policy.SuppressDefaultTemplateArgs = false;
+      Policy.EnforceDefaultTemplateArgs = true;
       O << "template <> struct KernelInfo<";
       SYCLKernelNameTypePrinter Printer(O, Policy);
       Printer.Visit(K.NameType);

clang/test/CodeGenSYCL/int_header_func_pointer_template_arg.cpp

@@ -4,32 +4,45 @@
 #include "sycl.hpp"
 // Test to ensure that the integration header properly prints class template specializations that contain
 // function pointers to free function kernels as template arguments. 
-// Also check that the forward declarations for free function kernels appear first in the integration header.
+// Check that the forward declarations for free function kernels appear first in the integration header.
+// Also check that default template arguments are printed properly when printing the name of a lambda/functor
+// kernel in KernelInfo struct.
+
 
 // CHECK: Forward declarations of kernel and its argument types:
 // CHECK: void bar();
 
 // CHECK: Forward declarations of kernel and its argument types:
 // CHECK: template <typename T> void foo(T);
 
-// CHECK: template <> struct KernelInfo<::Kernel<&foo<int>>> {
+// CHECK: template <> struct KernelInfo<::Kernel<&foo<int>, int>> {
+
+// CHECK: template <> struct KernelInfo<::Kernel<&bar, int>> {
 
-// CHECK: template <> struct KernelInfo<::Kernel<&bar>> {
+// CHECK: template <> struct KernelInfo<::Kernel<&foo<int>, ::X<int, int>>> {
+
+// CHECK: template <> struct KernelInfo<::Kernel<&foo<float>, ::X<float, float>>> {
+
+template <typename T, typename = int>
+struct X;
 
 template<typename T>
 [[__sycl_detail__::add_ir_attributes_function("sycl-single-task-kernel", 2)]] 
 void foo(T arg) {}
 
-
 [[__sycl_detail__::add_ir_attributes_function("sycl-single-task-kernel", 2)]] 
 void bar() {}
 
-template<auto *Func>
+template<auto *Func, typename Arg = int>
 struct Kernel;
 
 void foo() {
   using kernel_name1 = Kernel<&foo<int>>;
   using kernel_name2 = Kernel<&bar>;
+  using kernel_name3 = Kernel<&foo<int>, X<int>>;
+  using kernel_name4 = Kernel<&foo<float>, X<float, float>>;
   sycl::kernel_single_task<kernel_name1>([](){});
   sycl::kernel_single_task<kernel_name2>([](){});
+  sycl::kernel_single_task<kernel_name3>([](){});
+  sycl::kernel_single_task<kernel_name4>([](){});
 }