Swift: Crash on device when enum parameter has associated struct value

Originator:thephatmann
Number:rdar://19579256 Date Originated:23-Jan-2015 11:38 AM
Status:Duplicate of 19792160 Resolved:
Product:Developer Tools Product Version:Xcode 6.1.1
Classification:Crash/Hang/Data Loss Reproducible:Always
 
Summary:
If an enum with an associated struct value is passed as a parameter to a function, in certain circumstances the compiler will incorrectly pop the parameter off the stack, leading a to a Bad Access crash.

Steps to Reproduce:
Run the attached project on an iPhone 5S with iOS 8.1.2.

Expected Results:
App should show blank screen.

Actual Results:
App crashes when the function “f” is called.

Regression:
The crash does not happen in the simulator. I did not test other devices or different iOS versions.

Notes:
The crash will not occur if one of the following is changed:
  * use associated class value instead of struct
  * function “f” returns Void instead of a tuple
  * enum has only one associated value
  * struct only has one property

So it is a very fragile combination of events that causes the crash. In my app, I changed the structs to classes as a workaround.

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