// RUN: %target-swift-emit-silgen -enable-experimental-feature Extern %s | %FileCheck %s

// REQUIRES: swift_feature_Extern

// CHECK-DAG: sil hidden_external @my_c_name : $@convention(c) (Int) -> Int
@_extern(c, "my_c_name")
func withCName(_ x: Int) -> Int

// CHECK-DAG: sil hidden_external @take_c_func_ptr : $@convention(c) (@convention(c) (Int) -> Int) -> ()
@_extern(c, "take_c_func_ptr")
func takeCFuncPtr(_ f: @convention(c) (Int) -> Int)

// CHECK-DAG: sil @public_visible : $@convention(c) (Int) -> Int
@_extern(c, "public_visible")
public func publicVisibility(_ x: Int) -> Int

// CHECK-DAG: sil @private_visible : $@convention(c) (Int) -> Int
@_extern(c, "private_visible")
private func privateVisibility(_ x: Int) -> Int

// CHECK-DAG: sil hidden_external @withoutCName : $@convention(c) () -> Int
@_extern(c)
func withoutCName() -> Int

// CHECK-DAG: sil hidden [ossa] @$s8extern_c10defaultArgyySiFfA_ : $@convention(thin) () -> Int {
// CHECK-DAG: sil hidden_external @default_arg : $@convention(c) (Int) -> ()
@_extern(c, "default_arg")
func defaultArg(_ x: Int = 42)

func main() {
  // CHECK-DAG: [[F1:%.+]] = function_ref @my_c_name : $@convention(c) (Int) -> Int
  // CHECK-DAG: [[F2:%.+]] = function_ref @take_c_func_ptr : $@convention(c) (@convention(c) (Int) -> Int) -> ()
  // CHECK-DAG: apply [[F2]]([[F1]]) : $@convention(c) (@convention(c) (Int) -> Int) -> ()
  takeCFuncPtr(withCName)
  // CHECK-DAG: [[F3:%.+]] = function_ref @public_visible : $@convention(c) (Int) -> Int
  // CHECK-DAG: apply [[F3]]({{.*}}) : $@convention(c) (Int) -> Int
  _ = publicVisibility(42)
  // CHECK-DAG: [[F4:%.+]] = function_ref @private_visible : $@convention(c) (Int) -> Int
  // CHECK-DAG: apply [[F4]]({{.*}}) : $@convention(c) (Int) -> Int
  _ = privateVisibility(24)
  // CHECK-DAG: [[F5:%.+]] = function_ref @withoutCName : $@convention(c) () -> Int
  // CHECK-DAG: apply [[F5]]() : $@convention(c) () -> Int
  _ = withoutCName()
  // CHECK-DAG: [[F6:%.+]] = function_ref @$s8extern_c10defaultArgyySiFfA_ : $@convention(thin) () -> Int
  // CHECK-DAG: [[DEFAULT_V:%.+]] = apply [[F6]]() : $@convention(thin) () -> Int
  // CHECK-DAG: [[F7:%.+]] = function_ref @default_arg : $@convention(c) (Int) -> ()
  // CHECK-DAG: apply [[F7]]([[DEFAULT_V]]) : $@convention(c) (Int) -> ()
  defaultArg()
}

main()