Check irb_require loaded files against the load path

lib/irb/command/load.rb

@@ -45,8 +45,7 @@ def execute(arg)
       def execute_internal(file_name = nil)
         raise_cmd_argument_error unless file_name
 
-        rex = Regexp.new("(?:\\A|/)#{Regexp.escape(file_name)}(?:\\.o|\\.rb)?\\z")
-        return false if $".find{|f| f =~ rex}
+        return false if already_loaded?(file_name)
 
         case file_name
         when /\.rb$/
@@ -69,6 +68,19 @@ def execute_internal(file_name = nil)
           require(file_name)
         end
       end
+
+      private
+
+      # $" holds the names irb_require pushed and the absolute paths that
+      # Kernel#require loaded from a $LOAD_PATH directory.
+      def already_loaded?(file_name)
+        names = [file_name, "#{file_name}.rb", "#{file_name}.o"]
+        paths = $LOAD_PATH.flat_map do |dir|
+          dir = dir.to_s
+          names.map { |name| File.expand_path(File.join(dir, name)) }
+        end
+        $".any? { |f| names.include?(f) || paths.include?(f) }
+      end
     end
 
     class Source < LoaderCommand

test/irb/test_command.rb

@@ -495,6 +495,21 @@ def test_irb_require_skips_file_already_loaded_by_require
       assert_match(/prefix_loaded/, out)
     end
 
+    def test_irb_require_loads_file_with_same_name_as_loaded_file_in_other_directory
+      Dir.mkdir("#{@tmpdir}/sub")
+      File.write("#{@tmpdir}/sub/irb_require_same.rb", "$irb_require_same_sub = true\n")
+      File.write("#{@tmpdir}/irb_require_same.rb", "'top_loaded'\n")
+
+      out, err = execute_lines(
+        "$LOAD_PATH.unshift '#{@tmpdir}'\n",
+        "require 'sub/irb_require_same'\n",
+        "irb_require 'irb_require_same'\n",
+      )
+
+      assert_empty(err)
+      assert_match(/top_loaded/, out)
+    end
+
     def test_irb_require_falls_back_to_kernel_require_when_not_in_load_path
       code = <<~RUBY
         p 'fallback_loaded'