[BUG] Self-referencing struct makes mojo build crash

[gabrieldemarmiesse]

Bug description

My small snippet made the compiler crash. Even if I did a mistake, the compiler should never crash and should give me an helpful error message instead.

Steps to reproduce

from utils import Variant

struct JsonHolder(CollectionElement):
    var value: Variant[List[JsonHolder], Int]
    
    fn __init__(out self, value: None):
        self.value = value

    fn __copyinit__(out self, other: JsonHolder):
        self.value = other.value
    
    fn __moveinit__(out self, owned other: JsonHolder):
        self.value = other.value

def main():
    var a = JsonHolder(None)

magic run mojo build trying_stuff.mojo
[6371:6371:20250124,201157.422165:ERROR elf_dynamic_array_reader.h:64] tag not found
[6371:6371:20250124,201157.423867:ERROR file_io_posix.cc:144] open /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq: No such file or directory (2)
[6371:6371:20250124,201157.423896:ERROR file_io_posix.cc:144] open /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq: No such file or directory (2)
Please submit a bug report to https://github.com/modularml/mojo/issues and include the crash backtrace along with all the relevant source codes.

System information

magic --version
magic 0.6.2 - (based on pixi 0.40.0)
magic run mojo -v
mojo 25.1.0.dev2025012205 (53d8b341)


     Magic version: 0.6.2
System
------------
       Pixi version: 0.40.0
           Platform: linux-64
   Virtual packages: __unix=0=0
                   : __linux=5.10.102.1=0
                   : __glibc=2.35=0
                   : __cuda=12.5=0
                   : __archspec=1=skylake
          Cache dir: /root/.cache/rattler/cache
       Auth storage: /root/.rattler/credentials.json
   Config locations: No config files found

Global
------------
            Bin dir: /root/.modular/bin
    Environment dir: /root/.modular/envs
       Manifest dir: /root/.modular/manifests/pixi-global.toml

Project
------------
               Name: mojo-simdjson
            Version: 0.1.0
      Manifest file: /projects/open_source/mojo-simdjson/mojoproject.toml
       Last updated: 24-01-2025 19:14:10

Environments
------------
        Environment: default
           Features: default
           Channels: conda-forge, https://conda.modular.com/max-nightly
   Dependency count: 1
       Dependencies: max
   Target platforms: linux-64