Unexpected [Lint/UselessAssign] Useless assignment to variable

[zw963]

Following is a code example:

# 1.cr

require "option_parser"

module Translater
  target_language : String? = nil

  OptionParser.parse do |parser|
    parser.banner = <<-USAGE
Usage: translater <option> content
USAGE

    parser.on(
      "-t TARGET",
      "--target=TARGET",
      "Specify target language, support zh-CN|en for now.
default is translate English to Chinese.
Youdao don't support this option.
"
    ) do |target|
      case target
      when "zh-CN"
        target_language = "Chinese"
      when "en"
        target_language = "English"
      else
        STDERR.puts "Supported options: -t zh-CN|en"
        exit
      end
    end
  end

  p target_language
end

When run with ameba 1.cr, get following unexpected message:

1.cr:21:9
[W] Lint/UselessAssign: Useless assignment to variable `target_language`
> target_language = "Chinese"
  ^-------------^

1.cr:23:9
[W] Lint/UselessAssign: Useless assignment to variable `target_language`
> target_language = "English"
  ^-------------^

But, this is wrong, if move all code out of module Translater, ameba is fine, but it is same for those two cases.

[Sija]

That's expected since you're inside the module scope, so the variable defined is not really local.

[veelenga]

While the code looks semantically bad, we still need to handle this edge case in Ameba (low priority)

[straight-shoota]

That's expected since you're inside the module scope, so the variable defined is not really local.

target_language is actually a local variable defined in the top-level scope.

There are no type-level scopes for local variables.

module Translater
  target_language : String? = "foo"
end

target_language # => "foo"