Re: [Haskell-cafe] Why were datatype contexts removed instead of "fixing them"?

Brandon Allbery writes:

... which means that implementers should be free to "fix" data type contexts however they like, as they are now complier extensions which won't conflict with standard Haskell.

Except that people do build older programs with newer Haskell compilers, and it's bad to "repurpose" a syntax like that because it leads to strange errors.

"Remembering" data type contexts shouldn't break existing code, unless it's semantically broken already. (I'm sure that anyone could come up with a theoretical example of code which would break - but would it break any real-world code?)