Some generated clauses can never match

[wodow]

Compiling the library results in ~40 warnings like:

warning: this clause cannot match because a previous clause at line 109 always matches
  lib/domainatrex.ex:88

warning: this clause cannot match because a previous clause at line 109 always matches
  lib/domainatrex.ex:88

warning: this clause cannot match because a previous clause at line 109 always matches
  lib/domainatrex.ex:88

I'm not yet sure how to determine which entries in the PSL cause these or whether it's a problem.

[yssoe]

Having the same problem, bit annoying in the CI/CD pipeline, is there a quick fix for this? thanks

[axelson]

I took a look at this. Here's a minimal example of the issue:

defmodule Demo do
  @doc """
      iex> my_match(["com", "customer-oci"])
      :match2plus
      iex> my_match(["com", "customer-oci", "a"])
      :match3
      iex> my_match(["com", "customer-oci", "a", "b"])
      :match4
      iex> my_match(["com", "customer-oci", "a", "b", "c"])
      :match2plus

      iex> my_match(["com", "customer-oci"])
      :match2plus
      iex> my_match(["com", "customer-oci", "oci"])
      :match3
      iex> my_match(["com", "customer-oci", "oci", "b"])
      :match4
      iex> my_match(["com", "customer-oci", "oci", "b", "c"])
      :match2plus

      iex> my_match(["com", "customer-oci"])
      :match2plus
      iex> my_match(["com", "customer-oci", "ocp"])
      :match3
      iex> my_match(["com", "customer-oci", "ocp", "b"])
      :match4
      iex> my_match(["com", "customer-oci", "ocp", "b", "c"])
      :match2plus
  """
  for suffix <- [
        ["com", "customer-oci", "oci", "*"],
        ["com", "customer-oci", "ocp", "*"]
      ] do
    # matches list of length 3
    def my_match([unquote(Enum.at(suffix, 0)), unquote(Enum.at(suffix, 1)), _a]) do
      :match3
    end

    # matches list of length 4
    def my_match([unquote(Enum.at(suffix, 0)), unquote(Enum.at(suffix, 1)), _a, _b]) do
      :match4
    end

    # matches list of length 2+
    def my_match([unquote(Enum.at(suffix, 0)), unquote(Enum.at(suffix, 1)) | _] = _args) do
      :match2plus
    end
  end
end

The problem is that the "same" function head is being defined multiple times (e.g. since only the first two parts of the suffix are used in the match).