   .skip(.custom(
     { _isFastAssertConfiguration() },
     reason: "this trap is not guaranteed to happen in -Ounchecked"))
-  .crashOutputMatches(_isDebugAssertConfiguration() ?
-    "Fatal access conflict detected." : "")
+  .crashOutputMatches(
+    !_isDebugAssertConfiguration() ? ""
+    : hasBackdeployedConcurrencyRuntime() ? "inout rules were violated"
+    : "Fatal access conflict detected."
+  )
   .code {
   let v = ViolateInoutSafetyNeedElementTypeCheck()
   expectCrashLater()

  let da = ba as! [Derived]
  expectCrashLater()
  _ = da[2]
}

var ArraySemanticOptzns = TestSuite("ArraySemanticOptzns" + testSuiteSuffix)

  .skip(.custom(
    { _isFastAssertConfiguration() },
    reason: "this trap is not guaranteed to happen in -Ounchecked"))
  .crashOutputMatches(
    !_isDebugAssertConfiguration() ? ""
    : hasBackdeployedConcurrencyRuntime() ? "inout rules were violated"
    : "Fatal access conflict detected."
  )
  .code {
  let v = ViolateInoutSafetySwitchToObjcBuffer()
  expectCrashLater()
