[BUG] Use of unknown declaration in a for loop elif block

[bpo217]

Bug description

All the code

src/colcat.mojo

import sys
import sys.arg as cli
import tag


trait CliEventHandler:
    fn toggle_hyphenate(inout self) raises:
        ...


@value
struct App(CliEventHandler):
    var hyphenate: Bool

    fn toggle_hyphenate(inout self) raises:
        if self.hyphenate:
            raise Error("You passed `--hyphenate` twice.")
        else:
            self.hyphenate = True
        

fn base_arg[T: CliEventHandler](
    inout app: T, 
    borrowed arg: String,
) raises -> Int:
    if arg == "--col-width":
        return tag.parse_col_width
    elif arg == "--hyphenate":
        try:
            app.toggle_hyphenate() 
        except e:
            print(e, file=sys.stderr)
        return tag.stop
    else:
        raise Error("The argument `" + arg + "` is undefined.")
     

fn main():
    var app = App(hyphenate=False)
    var state: Int = tag.skip
    for arg in cli.argv():
        if state == tag.do_base_arg:
            try:
                state = base_arg(app, arg)
            except e:
                print(e, file=sys.stderr)
                return
        elif state == tag.stop:
            return
        elif state == tag.skip:
            state = tag.do_base_arg
            continue
        else:
            print("OMG")
            return

src/tag/__init.mojo

"""
Implements the tag package.
The tag package represents the app's events in its timeline as tags.
"""
from .constants import do_base_arg, parse_col_width, print_help, stop, skip

src/tag/constants.mojo

alias do_base_arg = 0
alias parse_col_width = 1
alias print_help = 2
alias stop = 3
alias skip = 4

Steps to reproduce

1. Create a mojo project with mojo init --format mojoproject.
2. Write some code like I provided.

System information

System: Macbook Air M2 2023 on Sonoma 14.5
mojo --version: `mojo 24.4.0 (2cb57382)`
magic -V: `magic 0.4.0 - (based on pixi 0.33.0)`
magic info:

     Magic version: 0.4.0
System
------------
      Pixi version: 0.33.0
          Platform: osx-arm64
  Virtual packages: __unix=0=0
                  : __osx=14.5=0
                  : __archspec=1=m2
         Cache dir: /Users/bpo/Library/Caches/rattler/cache
      Auth storage: /Users/bpo/.rattler/credentials.json
  Config locations: No config files found

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

Project
------------
              Name: colcat-mojo
           Version: 0.1.0
     Manifest file: /Users/bpo/Projects/colcat-mojo/mojoproject.toml
      Last updated: 23-10-2024 19:24:21

Environments
------------
       Environment: default
          Features: default
          Channels: conda-forge, https://conda.modular.com/max
  Dependency count: 0
  Target platforms: osx-arm64

[soraros]

We can further reduce the repro.

# bug.mojo

import tag

fn main():
    state = tag.A

# tag.mojo

alias A = 0

[bpo217]

We can further reduce the repro.

# bug.mojo

import tag

fn main():
    state = tag.A

# tag.mojo

alias A = 0

Actually, because I assumed it so my bad. This is not the same bug. I thought in a fn declaration mojo var is required. So this isn't the same thing. What would be the same thing is this:

# bug.mojo
import tag

fn main():
    var state = tag.A
    state = tag.B

# tag.mojo
alias A = 0
alias B = 1

Don't you think? Also this way does indeed reproduce the correct error that I was seeing.