{-# LANGUAGE RecordWildCards #-}
data A = A Int Int deriving Show
main = let f1 = 0
　　　　　　　f2 = 0 in print A{..}

[1 of 1] Compiling Main ( *.hs, *.o )
Linking *.exe ...

*.exe: rec.hs:7:14-18: Missing field in record construction

RecordWildCards危なすぎだろ……