A sample project to demonstrate a Swift/Xcode issue

Having some Swift code in a project that has the same construct as the code in LetsBreakTheDebugger.swift will cause a build error ("Illegal Instruction: 4").

The basic construct is:

• A class B that inherits from a generic class A, and specialises it with another class Y.
• Class B has a nested struct S.
• Class Y also inherits from a generic class X, and specialises it with the struct S.

Changing the Swift Compilation Mode to Whole Module allows the project to build, but if you try to use po in the console, the debugger detaches from the process with the following message output to the console: "Message from debugger: The LLDB RPC server has crashed."

Moving the nested struct S out from being a nested type on B works as a temporary workaround. This now compiles without issue, and debugging works.

There are branches to demonstrate each step.

All with Xcode 11.3.1