Ensure compile paths are available during compilation, closes elixir-lang#13458

Author: josevalim

lib/mix/lib/mix/tasks/compile.all.ex

@@ -43,7 +43,11 @@ defmodule Mix.Tasks.Compile.All do
       Code.delete_paths(current_paths -- loaded_paths)
     end
 
-    Code.prepend_paths(loaded_paths -- current_paths, cache: true)
+    # Add the current compilation path. compile.elixir and compile.erlang
+    # will also add this path, but only if they run, so we always add it
+    # here too. Furthermore, we don't cache it as we may still write to it.
+    compile_path = to_charlist(Mix.Project.compile_path())
+    Code.prepend_paths([compile_path | loaded_paths -- current_paths], cache: true)
 
     result =
       if "--no-compile" in args do
@@ -62,12 +66,6 @@ defmodule Mix.Tasks.Compile.All do
       Mix.AppLoader.write_cache(app_cache, Map.new(loaded_modules))
     end
 
-    # Add the current compilation path. compile.elixir and compile.erlang
-    # will also add this path, but only if they run, so we always add it
-    # here too. Furthermore, we don't cache it as we may still write to it.
-    compile_path = to_charlist(Mix.Project.compile_path())
-    _ = Code.prepend_path(compile_path)
-
     unless "--no-app-loading" in args do
       app = config[:app]
 

lib/mix/test/mix/tasks/compile.elixir_test.exs

@@ -19,6 +19,14 @@ defmodule Mix.Tasks.Compile.ElixirTest do
 
     in_fixture("no_mixfile", fn ->
       Mix.Project.push(MixTest.Case.Sample)
+
+      File.write!("lib/a.ex", """
+      defmodule A, do: :ok
+
+      # Also make sure that we access the ebin directory during compilation
+      true = to_charlist(Mix.Project.compile_path()) in :code.get_path()
+      """)
+
       Mix.Tasks.Compile.Elixir.run(["--verbose"])
 
       assert File.regular?("_build/shared/lib/sample/ebin/Elixir.A.beam")
@@ -32,6 +40,14 @@ defmodule Mix.Tasks.Compile.ElixirTest do
   test "compiles a project with per environment build" do
     in_fixture("no_mixfile", fn ->
       Mix.Project.push(MixTest.Case.Sample)
+
+      File.write!("lib/a.ex", """
+      defmodule A, do: :ok
+
+      # Also make sure that we access the ebin directory during compilation
+      true = to_charlist(Mix.Project.compile_path()) in :code.get_path()
+      """)
+
       Mix.Tasks.Compile.Elixir.run(["--verbose"])
 
       assert File.regular?("_build/dev/lib/sample/ebin/Elixir.A.beam")
@@ -736,7 +752,7 @@ defmodule Mix.Tasks.Compile.ElixirTest do
     end)
   end
 
-  test "compiles mtime changed files if content changed but not length" do
+  test "recompiles mtime changed files if content changed but not length" do
     in_fixture("no_mixfile", fn ->
       Mix.Project.push(MixTest.Case.Sample)
       assert Mix.Tasks.Compile.Elixir.run(["--verbose"]) == {:ok, []}
@@ -836,7 +852,7 @@ defmodule Mix.Tasks.Compile.ElixirTest do
     end)
   end
 
-  test "compiles size changed files" do
+  test "recompiles size changed files" do
     in_fixture("no_mixfile", fn ->
       Mix.Project.push(MixTest.Case.Sample)
       past = @old_time
@@ -858,7 +874,7 @@ defmodule Mix.Tasks.Compile.ElixirTest do
     end)
   end
 
-  test "compiles dependent changed modules" do
+  test "recompiles dependent changed modules" do
     in_fixture("no_mixfile", fn ->
       Mix.Project.push(MixTest.Case.Sample)
       File.write!("lib/a.ex", "defmodule A, do: B.module_info()")
@@ -878,7 +894,7 @@ defmodule Mix.Tasks.Compile.ElixirTest do
     end)
   end
 
-  test "compiles dependent changed modules without beam files" do
+  test "recompiles dependent changed modules without beam files" do
     in_fixture("no_mixfile", fn ->
       Mix.Project.push(MixTest.Case.Sample)
 
@@ -907,7 +923,7 @@ defmodule Mix.Tasks.Compile.ElixirTest do
     Code.put_compiler_option(:ignore_module_conflict, false)
   end
 
-  test "compiles dependent changed modules even on removal" do
+  test "recompiles dependent changed modules even on removal" do
     in_fixture("no_mixfile", fn ->
       Mix.Project.push(MixTest.Case.Sample)
       File.write!("lib/a.ex", "defmodule A, do: B.module_info()")
@@ -928,7 +944,7 @@ defmodule Mix.Tasks.Compile.ElixirTest do
     end)
   end
 
-  test "compiles dependent changed on conflict" do
+  test "recompiles dependent changed on conflict" do
     in_fixture("no_mixfile", fn ->
       Mix.Project.push(MixTest.Case.Sample)
 
@@ -955,7 +971,7 @@ defmodule Mix.Tasks.Compile.ElixirTest do
     end)
   end
 
-  test "compiles dependent changed external resources" do
+  test "recompiles dependent changed external resources" do
     in_fixture("no_mixfile", fn ->
       Mix.Project.push(MixTest.Case.Sample)
       tmp = tmp_path("c.eex")