warn when running on elixir 1.12 and otp 24

Elixir 1.12 has broken support for OTP 24 typespec AST
elixir-lang/elixir#11158 (comment)

Author: lukaszsamson

.github/workflows/ci.yml

@@ -20,8 +20,6 @@ jobs:
             otp: 22.x
           - elixir: 1.12.x
             otp: 23.x
-          - elixir: 1.12.x
-            otp: 24.x
           - elixir: 1.13.x
             otp: 22.x
           - elixir: 1.13.x

apps/elixir_ls_utils/lib/minimum_version.ex

@@ -12,7 +12,15 @@ defmodule ElixirLS.Utils.MinimumVersion do
 
   def check_elixir_version do
     if Version.match?(System.version(), ">= 1.12.3") do
-      :ok
+      otp_release = String.to_integer(System.otp_release())
+
+      if Version.match?(System.version(), "< 1.13.0") and otp_release == 24 do
+        # see https://github.com/elixir-lang/elixir/pull/11158#issuecomment-981583298
+        {:error,
+         "Elixir 1.12 is not supported on OTP 24. (Currently running v#{System.version()} on OTP #{otp_release})"}
+      else
+        :ok
+      end
     else
       {:error,
        "Elixir versions below 1.12.3 are not supported. (Currently running v#{System.version()})"}