Poll: Error message spans

Hi all, Currently, when GHC reports an error it only gives a source position, not a source span. For example, with this module: main = print (f (const 'x' 'x') 'y') f xs y = xs ++ [y] you get an error starting: u.hs:1:18: Couldn't match expected type `[a]' against inferred type `Char' There's a (probably little-known) flag -ferror-spans with which you get this error instead: u.hs:1:18-30: Couldn't match expected type `[a]' against inferred type `Char' i.e. rather than just giving the start column number 18, it gives you the span 18-30 (the "const 'x' 'x'"). Would you find the extra information useful, or just noise? i.e. should we show error spans by default? Thanks Ian