Should this be a valid program?

[Jens]

The following program compiles:

struct S {
    static func f() -> Int { return S.c }
    static let c = S.f()
}
print(S.c)

When running it, there will be a runtime error:

Thread 1: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0)

at this line:

    static let c = S.f()

---

Should this program compile (like it currently does), or should there be a compile time error?

[John_McCall]

It's impossible to statically detect every case of infinite recursion without imposing some pretty heavy constraints on code. Of course we could do a better job of trying to catch it in the common case, though.

[Chris_Lattner3 (Chris Lattner)]

We should also produce a better error at runtime when it is detected.

[John_McCall]

Definitely.