Do not propagate parent config when building archives/escripts

lib/mix/lib/mix/local/installer.ex

@@ -91,17 +91,23 @@ defmodule Mix.Local.Installer do
         end
 
         fetch(dep_spec, fn _ ->
-          local_install(module, module.build(install_spec, opts), opts)
+          local_install(module, build(module, install_spec, opts), opts)
         end)
 
       {path_or_url, src} when path_or_url in [:local, :url] ->
         local_install(module, src, opts)
 
       :project ->
-        local_install(module, module.build(install_spec, opts), opts)
+        local_install(module, build(module, install_spec, opts), opts)
     end
   end
 
+  defp build(module, install_spec, opts) do
+    Mix.Tasks.Loadconfig.preserve_config(fn ->
+      module.build(install_spec, opts)
+    end)
+  end
+
   defp task(module) do
     Mix.Utils.module_name_to_command(module, 2)
   end

lib/mix/lib/mix/state.ex

@@ -45,8 +45,8 @@ defmodule Mix.State do
 
   ## Persistent term cache (persistent, cleared in tests)
 
-  def read_cache(key) do
-    :persistent_term.get({__MODULE__, key}, nil)
+  def read_cache(key, default \\ nil) do
+    :persistent_term.get({__MODULE__, key}, default)
   end
 
   def write_cache(key, value) do

lib/mix/lib/mix/tasks/loadconfig.ex

@@ -51,7 +51,7 @@ defmodule Mix.Tasks.Loadconfig do
 
   @doc false
   def read_compile() do
-    Mix.State.read_cache(__MODULE__) || []
+    Mix.State.read_cache(__MODULE__, [])
   end
 
   @doc false
@@ -70,6 +70,25 @@ defmodule Mix.Tasks.Loadconfig do
     config
   end
 
+  @doc false
+  def preserve_config(fun) do
+    config = read_compile()
+
+    try do
+      delete_all_config(config)
+      fun.()
+    after
+      delete_all_config(read_compile())
+      Application.put_all_env(config, persistent: true)
+    end
+  end
+
+  defp delete_all_config(config) do
+    for {app, kv} <- config, Application.spec(app, :vsn) == nil, {key, _} <- kv do
+      Application.delete_env(app, key, persistent: true)
+    end
+  end
+
   defp hydrate_apps(config) do
     for {app, pairs} <- config do
       hd(Config.Reader.merge([{app, Application.get_all_env(app)}], [{app, pairs}]))

lib/mix/test/fixtures/escript_test/lib/escript_test.ex

@@ -30,6 +30,13 @@ defmodule EscriptTest do
     :erl_prim_loader.list_dir(~c"#{:code.lib_dir(app)}/priv") |> IO.inspect()
   end
 
+  @parent Application.compile_env(:foobar, :parent, "NIL")
+
+  def main(["--config"]) do
+    IO.puts(["VALUE=", Application.get_env(:foobar, :value, "TEST")])
+    IO.puts(["PARENT=", @parent])
+  end
+
   def main(_argv) do
     IO.puts(Application.get_env(:foobar, :value, "TEST"))
   end

lib/mix/test/mix/tasks/escript_test.exs

@@ -83,7 +83,6 @@ defmodule Mix.Tasks.EscriptTest do
   test "generate escript with compile config" do
     in_fixture("escript_test", fn ->
       push_project_with_config(Escript)
-
       File.mkdir_p!("config")
 
       File.write!("config/config.exs", ~S"""
@@ -93,14 +92,14 @@ defmodule Mix.Tasks.EscriptTest do
 
       Mix.Tasks.Escript.Build.run([])
       assert_received {:mix_shell, :info, ["Generated escript escript_test with MIX_ENV=dev"]}
+
       assert System.cmd("escript", ["escript_test"]) == {"COMPILE dev TARGET host\n", 0}
     end)
   end
 
   test "generate escript with runtime config" do
     in_fixture("escript_test", fn ->
       push_project_with_config(Escript)
-
       File.mkdir_p!("config")
 
       File.write!("config/config.exs", """
@@ -127,7 +126,6 @@ defmodule Mix.Tasks.EscriptTest do
   test "generate escript with debug information" do
     in_fixture("escript_test", fn ->
       push_project_with_config(Escript, escript: [main_module: EscriptTest, strip_beams: false])
-
       Mix.Tasks.Escript.Build.run([])
 
       msg = "Generated escript escript_test with MIX_ENV=dev"
@@ -211,7 +209,6 @@ defmodule Mix.Tasks.EscriptTest do
   test "generate escript with Erlang and deps" do
     in_fixture("escript_test", fn ->
       push_project_with_config(EscriptErlangWithDeps)
-
       Mix.Tasks.Escript.Build.run([])
 
       message = "Generated escript escript_test with MIX_ENV=dev"
@@ -261,7 +258,20 @@ defmodule Mix.Tasks.EscriptTest do
   end
 
   test "escript install and uninstall" do
-    File.rm_rf!(tmp_path(".mix/escripts"))
+    escripts = tmp_path(".mix/escripts")
+    File.rm_rf!(escripts)
+
+    # Configuration in the parent should not impact the escript
+    in_tmp("config", fn ->
+      File.mkdir_p!("config")
+
+      File.write!("config/config.exs", ~S"""
+      import Config
+      config :foobar, :parent, "SET_ON_PARENT"
+      """)
+
+      Mix.Tasks.Loadconfig.run([])
+    end)
 
     in_fixture("escript_test", fn ->
       push_project_with_config(Escript)
@@ -274,6 +284,10 @@ defmodule Mix.Tasks.EscriptTest do
       send(self(), {:mix_shell_input, :yes?, true})
       Mix.Tasks.Escript.Install.run([])
 
+      # execute the script
+      assert System.cmd("escript", [Path.join(escripts, "escript_test"), "--config"]) ==
+               {"VALUE=TEST\nPARENT=NIL\n", 0}
+
       # check that it shows in the list
       Mix.Tasks.Escript.run([])
       assert_received {:mix_shell, :info, ["* escript_test"]}
@@ -400,7 +414,7 @@ defmodule Mix.Tasks.EscriptTest do
       end)
     after
       System.delete_env("MIX_OS_DEPS_COMPILE_PARTITION_COUNT")
-      purge([SourceRepo.Escript, SourceRepo.MixProject, Mix.Local.Installer.MixProject])
+      purge([GitRepo, SourceRepo.Escript, SourceRepo.MixProject, Mix.Local.Installer.MixProject])
     end
   end