[SILGen] NFC: Make sure that passing inout/Array argument to variadic pointer parameter is safe

Author: xedin

test/SILGen/pointer_conversion.swift

@@ -481,3 +481,21 @@ public struct RefObj {
 public func objectFieldToPointer(rc: RefObj) {
   takeObjectPointer(&rc.o.object)
 }
+
+// CHECK-LABEL: sil [ossa] @$s18pointer_conversion21testVariadicParameter1aySaySiGz_tF : $@convention(thin) (@inout Array<Int>) -> ()
+// CHECK: [[ARRAY_REF:%.*]] = begin_access [modify] [unknown] %0 : $*Array<Int>
+// CHECK: [[CONVERT_ARRAY_TO_POINTER:%.*]] = function_ref @$ss37_convertMutableArrayToPointerArgumentyyXlSg_q_tSayxGzs01_E0R_r0_lF
+// CHECK: apply [[CONVERT_ARRAY_TO_POINTER]]<Int, UnsafeMutableRawPointer>({{.*}}, [[ARRAY_REF]])
+// CHECK: [[V_REF:%.*]] = begin_access [modify] [unknown] %28 : $*Double
+// CHECK: [[DOUBLE_AS_PTR:%.*]] = address_to_pointer [stack_protection] [[V_REF]] : $*Double to $Builtin.RawPointer
+// CHECK: [[INOUT_TO_PTR:%.*]] = function_ref @$ss30_convertInOutToPointerArgumentyxBps01_E0RzlF
+// CHECK: apply [[INOUT_TO_PTR]]<UnsafeMutableRawPointer>(%39, [[DOUBLE_AS_PTR]])
+// CHECK: } // end sil function '$s18pointer_conversion21testVariadicParameter1aySaySiGz_tF'
+public func testVariadicParameter(a: inout [Int]) {
+  func test(_ : UnsafeMutableRawPointer?...) {}
+
+  test(&a)
+
+  var v: Double
+  test(&v)
+}