Something odd about protocol get-only static property: why is it `var`, not `let`, and very surprising: it can be re-assigned!

[sjavora (Šimon Javora)]

@Nevin

3. I believe I have seen it mentioned that a static computed property is more efficient than a static stored property, but I don’t have a citation at hand.

I found this some time ago:

@cukr

For a proof that there's no difference in this specific case see https://godbolt.org/z/6iLNSc
Both compile to the same code when optimizations are enabled.

static output.S.c.getter : Swift.Int:
        push    rbp
        mov     rbp, rsp
        mov     eax, 1234
        pop     rbp
        ret

static output.S.d.getter : Swift.Int:
        push    rbp
        mov     rbp, rsp
        mov     eax, 1234
        pop     rbp
        ret