Purge project apps on recompile

we rely on application controller being able to return app modules
elixir loads apps only on initial compilation and and without purging we end up with outdated module list
workaround elixir-lang/elixir#13001

Author: lukaszsamson

apps/language_server/lib/language_server/build.ex

@@ -297,6 +297,14 @@ defmodule ElixirLS.LanguageServer.Build do
   end
 
   defp purge_app(app) do
+    Logger.debug("Stopping #{app}")
+
+    case Application.stop(app) do
+      :ok -> :ok
+      {:error, {:not_started, _}} -> :ok
+      {:error, error} -> Logger.warning("Application.stop failed for #{app}: #{inspect(error)}")
+    end
+
     modules =
       case :application.get_key(app, :modules) do
         {:ok, modules} -> modules
@@ -310,31 +318,11 @@ defmodule ElixirLS.LanguageServer.Build do
 
     Logger.debug("Unloading #{app}")
 
-    case Application.stop(app) do
-      :ok -> :ok
-      {:error, :not_started} -> :ok
-      {:error, error} -> Logger.warning("Application.stop failed for #{app}: #{inspect(error)}")
-    end
-
-    lib_dir = :code.lib_dir(app)
-
     case Application.unload(app) do
       :ok -> :ok
+      {:error, {:not_loaded, _}} -> :ok
       {:error, error} -> Logger.warning("Application.unload failed for #{app}: #{inspect(error)}")
     end
-
-    if is_list(lib_dir) do
-      case :code.del_path(:filename.join(lib_dir, ~c"ebin")) do
-        true ->
-          :ok
-
-        false ->
-          :ok
-
-        {:error, reason} ->
-          Logger.warning("Unable to clean code path for #{app}: #{inspect(reason)}")
-      end
-    end
   end
 
   defp get_deps_by_app(deps), do: get_deps_by_app(deps, %{})
@@ -396,16 +384,46 @@ defmodule ElixirLS.LanguageServer.Build do
     cached_deps_by_app = get_deps_by_app(cached_deps)
     removed_apps = Map.keys(cached_deps_by_app) -- Map.keys(current_deps_by_app)
 
-    removed_deps = cached_deps_by_app |> Map.take(removed_apps)
+    removed_deps =
+      cached_deps_by_app
+      |> Map.take(removed_apps)
+      |> Enum.flat_map(&elem(&1, 1))
+      |> Enum.uniq()
 
-    for {_app, deps} <- removed_deps,
-        dep <- deps do
+    # purge removed dependencies
+    for dep <- removed_deps do
       purge_dep(dep)
     end
 
+    # purge current dependencies in invalid state
     for dep <- current_deps do
       maybe_purge_dep(dep)
     end
+
+    mix_project_apps =
+      if Mix.Project.umbrella?() do
+        Mix.Project.apps_paths() |> Enum.map(&elem(&1, 0))
+      else
+        # in umbrella Mix.Project.apps_paths() returns nil
+        # get app from config instead
+        [Mix.Project.config()[:app]]
+      end
+
+    mix_project_apps_deps =
+      current_deps_by_app
+      |> Map.take(mix_project_apps)
+      |> Enum.flat_map(&elem(&1, 1))
+      |> Enum.uniq()
+
+    # purge mix project apps
+    # elixir compiler loads apps only on initial compilation
+    # on subsequent ones it does not update application controller state
+    # if we don't purge the apps we end up with invalid state
+    # e.g. :application.get_key(app, :modules) returns outdated module list
+    # see https://github.com/elixir-lang/elixir/issues/13001
+    for dep <- mix_project_apps_deps do
+      purge_dep(dep)
+    end
   end
 
   defp fetch_deps(current_deps) do
@@ -462,7 +480,6 @@ defmodule ElixirLS.LanguageServer.Build do
     options =
       if Version.match?(System.version(), ">= 1.14.0") do
         Keyword.merge(options,
-          # we are running the server with consolidated protocols
           # this disables warnings `X has already been consolidated`
           # when running `compile` task
           ignore_already_consolidated: true

apps/language_server/lib/language_server/doc_links.ex

@@ -32,23 +32,29 @@ defmodule ElixirLS.LanguageServer.DocLinks do
     case get_app(module) do
       {app, vsn} ->
         "#{@hex_base_url}/#{app}/#{vsn}/#{inspect(module)}.html"
-      nil -> nil
+
+      nil ->
+        nil
     end
   end
 
   def hex_docs_function_link(module, function, arity) do
     case get_app(module) do
       {app, vsn} ->
         "#{@hex_base_url}/#{app}/#{vsn}/#{inspect(module)}.html##{function}/#{arity}"
-      nil -> nil
+
+      nil ->
+        nil
     end
   end
 
   def hex_docs_type_link(module, type, arity) do
     case get_app(module) do
       {app, vsn} ->
         "#{@hex_base_url}/#{app}/#{vsn}/#{inspect(module)}.html#t:#{type}/#{arity}"
-      nil -> nil
+
+      nil ->
+        nil
     end
   end
 end

apps/language_server/lib/language_server/providers/hover.ex

@@ -53,6 +53,7 @@ defmodule ElixirLS.LanguageServer.Providers.Hover do
   defp build_module_link(module) do
     if ElixirSense.Core.Introspection.elixir_module?(module) do
       url = DocLinks.hex_docs_module_link(module)
+
       if url do
         "[View on hexdocs](#{url})\n\n"
       else
@@ -66,6 +67,7 @@ defmodule ElixirLS.LanguageServer.Providers.Hover do
   defp build_function_link(module, function, arity) do
     if ElixirSense.Core.Introspection.elixir_module?(module) do
       url = DocLinks.hex_docs_function_link(module, function, arity)
+
       if url do
         "[View on hexdocs](#{url})\n\n"
       else
@@ -79,6 +81,7 @@ defmodule ElixirLS.LanguageServer.Providers.Hover do
   defp build_type_link(module, type, arity) do
     if module != nil and ElixirSense.Core.Introspection.elixir_module?(module) do
       url = DocLinks.hex_docs_type_link(module, type, arity)
+
       if url do
         "[View on hexdocs](#{url})\n\n"
       else