Corey Feldman just got awesome news -- Richard Donner told us he's making a sequel to " The Goonies " ... and wants to bring back the entire cast.

Donner was signing autographs in Bev Hills when he dropped the bombshell ... genuinely surprising our photog.

What Donner didn't say ... whether he'll recast the main characters and bring in Corey, Josh Brolin, Sean Astin and Data for cameos, or if these guys will actually play the same roles 28 years later. A gnarly but interesting thought.