fix(completions): completions inside alias/import/require special forms

Closes #421

Author: mhanberg

Diff for: priv/monkey/_next_ls_private_compiler.ex

@@ -1213,38 +1213,56 @@ if Version.match?(System.version(), ">= 1.17.0-dev") do
       expand({form, meta, [arg, []]}, state, env)
     end
 
-    defp expand({:alias, meta, [arg, opts]}, state, env) do
+    defp expand({:alias, meta, [arg, opts]} = node, state, env) do
       {arg, state, env} = expand(arg, state, env)
       {opts, state, env} = expand_directive_opts(opts, state, env)
 
-      # An actual compiler would raise if the alias fails.
-      case Macro.Env.define_alias(env, meta, arg, [trace: false] ++ opts) do
-        {:ok, env} -> {arg, state, env}
-        {:error, _} -> {arg, state, env}
+      case arg do
+        {:__aliases__, _, _} ->
+          # An actual compiler would raise if the alias fails.
+          case Macro.Env.define_alias(env, meta, arg, [trace: false] ++ opts) do
+            {:ok, env} -> {arg, state, env}
+            {:error, _} -> {arg, state, env}
+          end
+
+        _ ->
+          {node, state, env}
       end
     end
 
-    defp expand({:require, meta, [arg, opts]}, state, env) do
+    defp expand({:require, meta, [arg, opts]} = node, state, env) do
       {arg, state, env} = expand(arg, state, env)
       {opts, state, env} = expand_directive_opts(opts, state, env)
 
-      # An actual compiler would raise if the module is not defined or if the require fails.
-      case Macro.Env.define_require(env, meta, arg, [trace: false] ++ opts) do
-        {:ok, env} -> {arg, state, env}
-        {:error, _} -> {arg, state, env}
+      case arg do
+        {:__aliases__, _, _} ->
+          # An actual compiler would raise if the module is not defined or if the require fails.
+          case Macro.Env.define_require(env, meta, arg, [trace: false] ++ opts) do
+            {:ok, env} -> {arg, state, env}
+            {:error, _} -> {arg, state, env}
+          end
+
+        _ ->
+          {node, state, env}
       end
     end
 
-    defp expand({:import, meta, [arg, opts]}, state, env) do
+    defp expand({:import, meta, [arg, opts]} = node, state, env) do
       {arg, state, env} = expand(arg, state, env)
       {opts, state, env} = expand_directive_opts(opts, state, env)
 
-      # An actual compiler would raise if the module is not defined or if the import fails.
-      with true <- is_atom(arg) and Code.ensure_loaded?(arg),
-           {:ok, env} <- Macro.Env.define_import(env, meta, arg, [trace: false] ++ opts) do
-        {arg, state, env}
-      else
-        _ -> {arg, state, env}
+      case arg do
+        {:__aliases__, _, _} ->
+          # An actual compiler would raise if the module is not defined or if the import fails.
+          with true <- is_atom(arg) and Code.ensure_loaded?(arg),
+               {:ok, env} <- Macro.Env.define_import(env, meta, arg, [trace: false] ++ opts) do
+            {arg, state, env}
+          else
+            _ -> {arg, state, env}
+          end
+
+        _ ->
+          {node, state, env}
       end
     end
 

Diff for: test/next_ls/completions_test.exs

@@ -31,6 +31,16 @@ defmodule NextLS.CompletionsTest do
     end
     """)
 
+    baz = Path.join(cwd, "my_proj/lib/baz.ex")
+
+    File.write!(baz, """
+    defmodule Foo.Bar.Baz do
+      def run() do
+        :ok
+      end
+    end
+    """)
+
     [foo: foo, cwd: cwd]
   end
 
@@ -342,4 +352,37 @@ defmodule NextLS.CompletionsTest do
       }
     ]
   end
+
+  test "inside alias special form", %{client: client, foo: foo} do
+    uri = uri(foo)
+
+    did_open(client, foo, """
+    defmodule Foo do
+      alias Foo.Bar.
+
+      def run() do
+        :ok
+      end
+    end
+    """)
+
+    request client, %{
+      method: "textDocument/completion",
+      id: 2,
+      jsonrpc: "2.0",
+      params: %{
+        textDocument: %{
+          uri: uri
+        },
+        position: %{
+          line: 1,
+          character: 16
+        }
+      }
+    }
+
+    assert_result 2, [
+      %{"data" => _, "documentation" => _, "insertText" => "Baz", "kind" => 9, "label" => "Baz"}
+    ]
+  end
 end