Parse error with case in where

The following code produces a peculiar parse error:

subtype = 0
  where (x, y) = case (1, 2) of
    (a, b) -> (3, 4)

parse_error.hs:3:5: parse error on input ‘(’

Trac metadata

Trac field	Value
Version	7.10.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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