Alphanumeric sort of lists / object keys

[wyardley]

Introduction

Similar to #783, but for list values / object keys

Proposal

When a data structure like a list or object is used, we often like to have the elements sorted alphanumerically. It would be nice to have an optional (and not enabled by default) linter rule to enforce this. Open to suggestions about, for example, if all unquoted values are first or last, but overall, should work like a naïve alphnumeric sort that factors in numeric values

For example:

passes

  bar = {
    groups = [
      var.bar.email,
      var.foo.email,
      "xyz",
    ]
    service_accounts = [data.terraform_remote_state.foo.outputs.xyz, "foo"]
  }
  foo = [0, 1, 2, 3, 100, "foo", "bar"]

generates errors

  bar = {
    groups = [
      var.foo.email,
      "xyz",
      var.bar.email,
    ]
    service_accounts = ["foo", data.terraform_remote_state.foo.outputs.xyz]
  }
  foo = [0, 3, 1, 100, 2, "bar", "foo"]

References

[bendrucker]

FYI, this would not meet the criteria for inclusion in https://github.com/terraform-linters/tflint-ruleset-terraform, which since my comment on #783 we've clarified as enforcing officially documented recommendations (a finite set) rather than user-specific style preferences (unbounded). Since you're describing the latter, this would be a good candidate for publishing a custom ruleset of your own.