Nested recursive fn compilation error

[diyessi]

Bug Description

I defined:

fn fact(n : Int) -> Int:
    fn factint(p : Int, m : Int) -> Int:
        if m == 0:
            return p
        return factint(p*m, m-1)
    return factint(1, n)

and got the compilation error:

error: Expression [6]:5:1: cyclic reference between expressions defining and using parameters
fn fact(n : Int) -> Int:
^

Expression [6]:6:5: parameter "factint($Int::Int,$Int::Int)" is defined here, which references itself
    fn factint(p : Int, m : Int) -> Int:
    ^

A simpler recursive fact without the tail-recursive helper does compile, and a top-level factint compiles, so the problem seems to be related to factint being internal to fact.

Context

11:blkio:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-podfeaac2d5_a246_41df_9300_b56906cac38e.slice/cri-containerd-c1fa9d6cdf96a39b653a771aca2c6190bba02cf664ccb2525e5543afa25f80c2.scope
10:devices:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-podfeaac2d5_a246_41df_9300_b56906cac38e.slice/cri-containerd-c1fa9d6cdf96a39b653a771aca2c6190bba02cf664ccb2525e5543afa25f80c2.scope
9:cpuset:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-podfeaac2d5_a246_41df_9300_b56906cac38e.slice/cri-containerd-c1fa9d6cdf96a39b653a771aca2c6190bba02cf664ccb2525e5543afa25f80c2.scope
8:freezer:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-podfeaac2d5_a246_41df_9300_b56906cac38e.slice/cri-containerd-c1fa9d6cdf96a39b653a771aca2c6190bba02cf664ccb2525e5543afa25f80c2.scope
7:cpu,cpuacct:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-podfeaac2d5_a246_41df_9300_b56906cac38e.slice/cri-containerd-c1fa9d6cdf96a39b653a771aca2c6190bba02cf664ccb2525e5543afa25f80c2.scope
6:memory:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-podfeaac2d5_a246_41df_9300_b56906cac38e.slice/cri-containerd-c1fa9d6cdf96a39b653a771aca2c6190bba02cf664ccb2525e5543afa25f80c2.scope
5:hugetlb:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-podfeaac2d5_a246_41df_9300_b56906cac38e.slice/cri-containerd-c1fa9d6cdf96a39b653a771aca2c6190bba02cf664ccb2525e5543afa25f80c2.scope
4:pids:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-podfeaac2d5_a246_41df_9300_b56906cac38e.slice/cri-containerd-c1fa9d6cdf96a39b653a771aca2c6190bba02cf664ccb2525e5543afa25f80c2.scope
3:perf_event:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-podfeaac2d5_a246_41df_9300_b56906cac38e.slice/cri-containerd-c1fa9d6cdf96a39b653a771aca2c6190bba02cf664ccb2525e5543afa25f80c2.scope
2:net_cls,net_prio:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-podfeaac2d5_a246_41df_9300_b56906cac38e.slice/cri-containerd-c1fa9d6cdf96a39b653a771aca2c6190bba02cf664ccb2525e5543afa25f80c2.scope
1:name=systemd:/kubepods.slice/kubepods-burstable.slice/kubepods-burstable-podfeaac2d5_a246_41df_9300_b56906cac38e.slice/cri-containerd-c1fa9d6cdf96a39b653a771aca2c6190bba02cf664ccb2525e5543afa25f80c2.scope
0::/

[hoxha-saber]

I believe it is related to this defined in the Mojo docs:

Nested functions (any function that is not a top-level function) cannot be recursive in any way. Nested functions are considered “parameters”, and although parameter values do not have to obey lexical order, their uses and definitions cannot form a cycle. Current limitations in Mojo mean that nested functions, which are considered parameter values, cannot be cyclic.

[diyessi]

That would do it.