   line: UInt = #line
 ) {
   do {
-    let (found, _) = try _firstMatch(
+    let found = try _firstMatch(
       regex,
       input: input,
       validateOptimizations: validateOptimizations,
-      syntax: syntax)
+      syntax: syntax)?.0
 
     if xfail {
       XCTAssertNotEqual(found, match, file: file, line: line)

      ("baabc", nil),
      ("bb", nil))
    
    // XFAIL'd versions of the above
    firstMatchTests(
      "a{2,4}+a",
      ("baaabc", nil),
      xfail: true)
    firstMatchTests(
      "a{,4}+a",
      ("babc", nil),
      ("baabc", nil),
      ("baaabc", nil),
      xfail: true)
    firstMatchTests(
      "a{2,}+a",
      ("baaabc", nil),
      ("baaaaabc", nil),
      ("baaaaaaaabc", nil),
      xfail: true)

    // XFAIL'd possessive tests
    firstMatchTests(

      XCTAssertEqual(found, match, file: file, line: line)
    }
  } catch {
    if !xfail {
      XCTFail("\(error)", file: file, line: line)
    }
    return
