A deferred type error inferferes with the monomorphism restriction
Here is a fairly simple program:
{-# OPTIONS_GHC -fdefer-type-errors #-}
module Bug where
other = ['a', True]
x = 5
The monomorphism restriction is in effect, and note that the two definitions do not refer to each other.
GHC embarrassingly infers the type Any for x, affected by the presence of the ill-typed other.