testsuite/tests/typecheck/should_fail/tcfail108.stderr


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tcfail108.hs:7:10: error:
    • Variable ‘f’ occurs more often
        in the constraint ‘Eq (f (Rec f))’
        than in the instance head ‘Eq (Rec f)’
      (Use UndecidableInstances to permit this)
    • In the instance declaration for ‘Eq (Rec f)’