#12768: 8.0.2 derives invalid code when class method is constrained by itself -------------------------------------+------------------------------------- Reporter: jophish | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.2 Component: Compiler | Version: 8.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Ryan Scott <ryan.gl.scott@…>): In [changeset:"ead83db8a7db772a9f248af9767a4283218a5c9f/ghc" ead83db/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="ead83db8a7db772a9f248af9767a4283218a5c9f" Describe symptoms of (and the cure for) #12768 in 8.0.2 release notes GHC 8.0.2 introduced a bugfix involving GeneralizedNewtypeDeriving in 96d451450923a80b043b5314c5eaaa9d0eab7c56. This made typechecking of GND-produced code a bit stricter, and an unfortunate side effect of this was that there were a couple of corner-case programs that stopped compiling when transitioning from GHC 8.0.1 to 8.0.2. Since the number of affected programs seems quite small, and since the fix is so straightforward, we opt to simply note this discrepancy in the 8.0.2 release notes. Resolves #12768. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12768#comment:9> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler