From 929fecff68dca6d5d72281146c59cdfa323f312a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pawe=C5=82=20=C5=9Awi=C4=85tkowski?= <katafrakt@vivaldi.net>
Date: Sun, 23 Nov 2025 12:23:09 +0100
Subject: [PATCH] feat(engine): support go to definition when function is
 called via __MODULE__

This wasn't working, as __MODULE__ is recognized as :var, not as
:module in AST. What was needed is to add a special handling of it in
`expand_alias` function.

Recognizing __MODULE__ as :var, while semantically incorrect, does not
seem to be a problem in scope of definition finding. It's not strictly a
module either, so to be super-correct, we would need to add a special
handling just for it.
---
 .../lib/engine/code_intelligence/entity.ex    |  4 ++
 .../code_intelligence/definition_test.exs     | 44 +++++++++++++++++++
 2 files changed, 48 insertions(+)

diff --git a/apps/engine/lib/engine/code_intelligence/entity.ex b/apps/engine/lib/engine/code_intelligence/entity.ex
index 5ca52c8f..515836b9 100644
--- a/apps/engine/lib/engine/code_intelligence/entity.ex
+++ b/apps/engine/lib/engine/code_intelligence/entity.ex
@@ -346,6 +346,10 @@ defmodule Engine.CodeIntelligence.Entity do
     String.upcase(first_char) == first_char
   end
 
+  defp expand_alias({:var, ~c"__MODULE__"}, analysis, %Position{} = position) do
+    Engine.Analyzer.current_module(analysis, position)
+  end
+
   defp expand_alias({:alias, {:local_or_var, prefix}, charlist}, analysis, %Position{} = position) do
     expand_alias(prefix ++ [?.] ++ charlist, analysis, position)
   end
diff --git a/apps/expert/test/engine/code_intelligence/definition_test.exs b/apps/expert/test/engine/code_intelligence/definition_test.exs
index 3b44b964..c42a30dd 100644
--- a/apps/expert/test/engine/code_intelligence/definition_test.exs
+++ b/apps/expert/test/engine/code_intelligence/definition_test.exs
@@ -336,6 +336,50 @@ defmodule Expert.Engine.CodeIntelligence.DefinitionTest do
       assert referenced_uri == subject_uri
     end
 
+    test "find the function definition when referenced via __MODULE__", %{
+      project: project,
+      subject_uri: subject_uri
+    } do
+      subject_module = ~q[
+        defmodule UsesOwnFunction do
+          def greet do
+          end
+
+          def uses_greet do
+            __MODULE__.gree|t()
+          end
+        end
+      ]
+
+      {:ok, referenced_uri, definition_line} = definition(project, subject_module, subject_uri)
+
+      assert definition_line == ~S[  def «greet» do]
+      assert referenced_uri =~ "navigations/lib/my_module.ex"
+    end
+
+    test "find the function definition when alias __MODULE__ is used", %{
+      project: project,
+      subject_uri: subject_uri
+    } do
+      subject_module = ~q[
+        defmodule MyApp.UsesOwnFunction do
+          alias __MODULE__
+
+          def greet do
+          end
+
+          def uses_greet do
+            UsesOwnFunction.gree|t()
+          end
+        end
+      ]
+
+      {:ok, referenced_uri, definition_line} = definition(project, subject_module, subject_uri)
+
+      assert definition_line == ~S[  def «greet» do]
+      assert referenced_uri =~ "navigations/lib/my_module.ex"
+    end
+
     test "find the attribute", %{project: project, subject_uri: subject_uri} do
       subject_module = ~q[
         defmodule UsesAttribute do