Support RBS signature aliases

lib/ruby_indexer/lib/ruby_indexer/entry.rb

@@ -492,7 +492,7 @@ class UnresolvedMethodAlias < Entry
           old_name: String,
           owner: T.nilable(Entry::Namespace),
           file_path: String,
-          location: Prism::Location,
+          location: T.any(Prism::Location, RubyIndexer::Location),
           comments: T::Array[String],
         ).void
       end

lib/ruby_indexer/lib/ruby_indexer/rbs_indexer.rb

@@ -69,6 +69,8 @@ def handle_class_or_module_declaration(declaration, pathname)
           handle_method(member, entry)
         when RBS::AST::Declarations::Constant
           handle_constant(member, nesting, file_path)
+        when RBS::AST::Members::Alias # NOTE: This is a signature alias, not a Ruby method alias
+          handle_signature_alias(member, entry)
         end
       end
     end
@@ -243,5 +245,22 @@ def handle_constant(declaration, nesting, file_path)
         Array(declaration.comment&.string),
       ))
     end
+
+    sig { params(member: RBS::AST::Members::Alias, owner_entry: Entry::Namespace).void }
+    def handle_signature_alias(member, owner_entry)
+      file_path = member.location.buffer.name
+      comments = Array(member.comment&.string)
+
+      entry = Entry::UnresolvedMethodAlias.new(
+        member.new_name.to_s,
+        member.old_name.to_s,
+        owner_entry,
+        file_path,
+        to_ruby_indexer_location(member.location),
+        comments,
+      )
+
+      @index.add(entry)
+    end
   end
 end

lib/ruby_indexer/test/rbs_indexer_test.rb

@@ -331,6 +331,23 @@ def self?.open: (String name, ?String mode, ?Integer perm) -> IO?
       assert_kind_of(Entry::BlockParameter, parameters[3])
     end
 
+    def test_signature_alias
+      # In RBS, an alias means that two methods have the same signature. It does not mean the same thing as a Ruby
+      # alias.
+      any_entries = @index["any?"]
+
+      assert_equal(["Array", "Enumerable", "Hash"], any_entries.map { _1.owner.name })
+
+      entry = any_entries.find { |entry| entry.owner.name == "Array" }
+
+      assert_kind_of(RubyIndexer::Entry::UnresolvedMethodAlias, entry)
+      assert_equal("any?", entry.name)
+      assert_equal("all?", entry.old_name)
+      assert_equal("Array", entry.owner.name)
+      assert(entry.file_path.end_with?("core/array.rbs"))
+      assert_includes(entry.comments[0], "Returns `true` if any element of `self` meets a given criterion.")
+    end
+
     private
 
     def parse_rbs_methods(rbs, method_name)