It's some kind of Berberis. Berberis are all edible, though Berberis buxifolia (known locally as calafate in Arg/Chile) is probably the best eating.

You'll probably find that the birds eat it all before the acidity falls to levels suitable for human eating, though maybe you can pick it sooner and use it for cooking. Also most kinds are rather seedy, so may need straining. I have a large bush of Berberis darwinii and never managed to get anything worthwhile before the birds get to it. I recently planted a B buxifolia but its still small.