Open Radar

 
Summary:
Swift doesn’t let you define recursive local functions ( ಠ_ಠ — seriously grumpymaking), and if you try to trick it, it crashes.


Steps to Reproduce:
1. Compile this elaborate code!

func f() {
	func g() {
		{ g() }()
	}
}


Expected Results:
I expected it to allow me to capture g, or at least to shout at me with the usual “local functions cannot reference themselves” error.


Actual Results:
Swift noticed my subterfuge and crashed just to spite me.


Regression:
If you don’t use the closure it just says:

./spurious-local-nested-function-error-of-doom.swift:5:3: error: local functions cannot reference themselves

You can get a variation on this crash by returning the function from the closure instead of calling it and binding that to a constant, but it has a pretty similar stack trace. For completeness’ sake, the code:

func f() {
	func g() {
		let h = { g }()
	}
}


Notes:
I was delighted to encounter this one in the reduction of a spurious compiler error rather than in my actual code ✨