Fix stack StackLevelError during self referential constant resolution

Author: pkondzior

lib/ruby_indexer/lib/ruby_indexer/index.rb

@@ -903,10 +903,12 @@ def resolve_alias(entry, seen_names)
       return entry if seen_names.include?(alias_name)
 
       seen_names << alias_name
-
       target = resolve(entry.target, entry.nesting, seen_names)
       return entry unless target
 
+      # Self referential alias can be unresolved we should bail out from resolving
+      return entry if target.first == entry
+
       target_name = target.first #: as !nil
         .name
       resolved_alias = Entry::ConstantAlias.new(target_name, entry)

lib/ruby_indexer/test/constant_test.rb

@@ -318,6 +318,28 @@ module A
       assert_instance_of(Entry::Constant, constant)
     end
 
+    def test_self_referential_constant_alias
+      index(<<~RUBY)
+        module RealClass
+          CONSTANT = {}
+        end
+
+        module Foo
+          SomeClass = ::SomeClass
+          RealClass = ::RealClass
+
+          UNRESOLVED = SomeClass::CONSTANT
+          CONSTANT = RealClass::CONSTANT
+        end
+      RUBY
+
+      assert_entry("RealClass", Entry::Module, "/fake/path/foo.rb:0-0:2-3")
+      assert_no_entry("SomeClass")
+      assert_entry("Foo", Entry::Module, "/fake/path/foo.rb:4-0:10-3")
+      assert_entry("RealClass::CONSTANT", Entry::Constant, "/fake/path/foo.rb:1-2:1-15")
+      assert_entry("Foo::UNRESOLVED", Entry::UnresolvedConstantAlias, "/fake/path/foo.rb:8-2:8-34")
+    end
+
     def test_indexing_or_and_operator_nodes
       index(<<~RUBY)
         A ||= 1