 }
 
 CStringTests.test("String.validatingUTF8.with.Array.input") {
+  guard #available(SwiftStdlib 5.7, *) else { return }
   do {
     let (u8p, dealloc) = getASCIIUTF8()
     defer { dealloc() }

}

CStringTests.test("String.cString.with.inout.CChar.conversion") {
  var c = CChar.zero
  var str = String(cString: &c)
  expectTrue(str.isEmpty)

}

CStringTests.test("String.decodeCString.with.String.input") {
  guard #available(SwiftStdlib 5.7, *) else { return }
  let (u8p, dealloc) = getASCIIUTF8()
  defer { dealloc() }
  var result = String.decodeCString(
