rebuild project if tracing databases are not found

Author: lukaszsamson

apps/language_server/lib/language_server/server.ex

@@ -1120,6 +1120,7 @@ defmodule ElixirLS.LanguageServer.Server do
       |> set_dialyzer_enabled(enable_dialyzer)
       |> add_watched_extensions(additional_watched_extensions)
 
+    maybe_rebuild(state)
     state = create_gitignore(state)
     Tracer.set_project_dir(state.project_dir)
     trigger_build(%{state | settings: settings})
@@ -1298,4 +1299,12 @@ defmodule ElixirLS.LanguageServer.Server do
       _ -> false
     end)
   end
+
+  defp maybe_rebuild(state = %__MODULE__{}) do
+    # detect if we are opening a project that has been compiled without a tracer
+    if is_binary(state.project_dir) and state.mix_project and File.dir?(Path.join([project_dir, ".elixir_ls"])) and not Tracer.has_databases?(project_dir) do
+      Logger.info("DETS databases rebuild will be rebuilt")
+      Build.clean(true)
+    end
+  end
 end

apps/language_server/lib/language_server/tracer.ex

@@ -95,6 +95,10 @@ defmodule ElixirLS.LanguageServer.Tracer do
     :ok
   end
 
+  def has_databases?(project_dir) do
+    File.exists?(dets_path(project_dir, hd(@tables)))
+  end
+
   defp dets_path(project_dir, table) do
     Path.join([project_dir, ".elixir_ls", "#{table}.dets"])
   end