From b72ac025515fd4b05e4ef3dbef3ceef5a9b11d8c Mon Sep 17 00:00:00 2001
From: Niki Jiandani <niki.jiandani@shopify.com>
Date: Thu, 18 Apr 2024 10:45:11 -0400
Subject: [PATCH] Add support for method aliases

Co-authored-by: Vinicius Stock <vinistock@users.noreply.github.com>
---
 .../lib/ruby_indexer/declaration_listener.rb  | 54 +++++++++++++++++++
 lib/ruby_indexer/lib/ruby_indexer/entry.rb    | 28 ++++++++++
 lib/ruby_indexer/test/method_test.rb          | 20 +++++++
 lib/ruby_indexer/test/test_case.rb            |  1 +
 4 files changed, 103 insertions(+)

diff --git a/lib/ruby_indexer/lib/ruby_indexer/declaration_listener.rb b/lib/ruby_indexer/lib/ruby_indexer/declaration_listener.rb
index fa503cdde..459e5ab7b 100644
--- a/lib/ruby_indexer/lib/ruby_indexer/declaration_listener.rb
+++ b/lib/ruby_indexer/lib/ruby_indexer/declaration_listener.rb
@@ -52,6 +52,7 @@ def initialize(index, dispatcher, parse_result, file_path)
         :on_instance_variable_operator_write_node_enter,
         :on_instance_variable_or_write_node_enter,
         :on_instance_variable_target_node_enter,
+        :on_alias_method_node_enter,
       )
     end
 
@@ -209,6 +210,8 @@ def on_call_node_enter(node)
         handle_attribute(node, reader: false, writer: true)
       when :attr_accessor
         handle_attribute(node, reader: true, writer: true)
+      when :alias_method
+        handle_alias_method(node)
       when :include, :prepend, :extend
         handle_module_operation(node, message)
       when :public
@@ -338,6 +341,20 @@ def on_instance_variable_target_node_enter(node)
       )
     end
 
+    sig { params(node: Prism::AliasMethodNode).void }
+    def on_alias_method_node_enter(node)
+      method_name = node.new_name.slice
+      comments = collect_comments(node)
+      @index << Entry::UnresolvedMethodAlias.new(
+        method_name,
+        node.old_name.slice,
+        @owner_stack.last,
+        @file_path,
+        node.new_name.location,
+        comments,
+      )
+    end
+
     private
 
     sig { params(node: Prism::CallNode).void }
@@ -365,6 +382,43 @@ def handle_private_constant(node)
       entries&.each { |entry| entry.visibility = Entry::Visibility::PRIVATE }
     end
 
+    sig { params(node: Prism::CallNode).void }
+    def handle_alias_method(node)
+      arguments = node.arguments&.arguments
+      return unless arguments
+
+      new_name, old_name = arguments
+      return unless new_name && old_name
+
+      new_name_value = case new_name
+      when Prism::StringNode
+        new_name.content
+      when Prism::SymbolNode
+        new_name.value
+      end
+
+      return unless new_name_value
+
+      old_name_value = case old_name
+      when Prism::StringNode
+        old_name.content
+      when Prism::SymbolNode
+        old_name.value
+      end
+
+      return unless old_name_value
+
+      comments = collect_comments(node)
+      @index << Entry::UnresolvedMethodAlias.new(
+        new_name_value,
+        old_name_value,
+        @owner_stack.last,
+        @file_path,
+        new_name.location,
+        comments,
+      )
+    end
+
     sig do
       params(
         node: T.any(
diff --git a/lib/ruby_indexer/lib/ruby_indexer/entry.rb b/lib/ruby_indexer/lib/ruby_indexer/entry.rb
index 5a3ace7f3..8ae271712 100644
--- a/lib/ruby_indexer/lib/ruby_indexer/entry.rb
+++ b/lib/ruby_indexer/lib/ruby_indexer/entry.rb
@@ -469,5 +469,33 @@ def initialize(name, file_path, location, comments, owner)
         @owner = owner
       end
     end
+
+    class UnresolvedMethodAlias < Entry
+      extend T::Sig
+
+      sig { returns(String) }
+      attr_reader :new_name, :old_name
+
+      sig { returns(T.nilable(Entry::Namespace)) }
+      attr_reader :owner
+
+      sig do
+        params(
+          new_name: String,
+          old_name: String,
+          owner: T.nilable(Entry::Namespace),
+          file_path: String,
+          location: Prism::Location,
+          comments: T::Array[String],
+        ).void
+      end
+      def initialize(new_name, old_name, owner, file_path, location, comments) # rubocop:disable Metrics/ParameterLists
+        super(new_name, file_path, location, comments)
+
+        @new_name = new_name
+        @old_name = old_name
+        @owner = owner
+      end
+    end
   end
 end
diff --git a/lib/ruby_indexer/test/method_test.rb b/lib/ruby_indexer/test/method_test.rb
index 4565bcb2a..852924cc9 100644
--- a/lib/ruby_indexer/test/method_test.rb
+++ b/lib/ruby_indexer/test/method_test.rb
@@ -378,5 +378,25 @@ def third; end
       entry = T.must(@index["third"]&.first)
       assert_equal("Foo", T.must(entry.owner).name)
     end
+
+    def test_keeps_track_of_aliases
+      index(<<~RUBY)
+        class Foo
+          alias whatever to_s
+          alias_method :foo, :to_a
+          alias_method "bar", "to_a"
+
+          # These two are not indexed because they are dynamic or incomplete
+          alias_method baz, :to_a
+          alias_method :baz
+        end
+      RUBY
+
+      assert_entry("whatever", Entry::UnresolvedMethodAlias, "/fake/path/foo.rb:1-8:1-16")
+      assert_entry("foo", Entry::UnresolvedMethodAlias, "/fake/path/foo.rb:2-15:2-19")
+      assert_entry("bar", Entry::UnresolvedMethodAlias, "/fake/path/foo.rb:3-15:3-20")
+      # Foo plus 3 valid aliases
+      assert_equal(4, @index.instance_variable_get(:@entries).length)
+    end
   end
 end
diff --git a/lib/ruby_indexer/test/test_case.rb b/lib/ruby_indexer/test/test_case.rb
index 61708495d..aa4ee4ba2 100644
--- a/lib/ruby_indexer/test/test_case.rb
+++ b/lib/ruby_indexer/test/test_case.rb
@@ -17,6 +17,7 @@ def index(source)
 
     def assert_entry(expected_name, type, expected_location, visibility: nil)
       entries = @index[expected_name]
+      refute_nil(entries, "Expected #{expected_name} to be indexed")
       refute_empty(entries, "Expected #{expected_name} to be indexed")
 
       entry = entries.first