-fdefer-type-errors doesn't defer errors from `deriving`

When I say

{-# OPTIONS_GHC -fdefer-type-errors #-}

data Foo = MkFoo
data Bar = MkBar Foo
  deriving Show

I get a type error that there is no instance for Show Foo. This error should be deferred.

Using standalone-deriving works just fine, though.

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