#10009: type inference regression when faking injective type families -------------------------------------+------------------------------------- Reporter: aavogt | Owner: Type: bug | Status: new Priority: high | Milestone: 7.10.2 Component: Compiler (Type | Version: 7.10.1-rc1 checker) | Keywords: Resolution: | Architecture: Operating System: Unknown/Multiple | Unknown/Multiple Type of failure: GHC rejects | Test Case: valid program | Blocking: Blocked By: | Differential Revisions: Related Tickets: #10226 | -------------------------------------+------------------------------------- Comment (by simonpj): Thanks for re-highlighting this. I've just been looking at this again, as it happens. The sad story is that it's an unexpected consequence of some refactoring I did to the type-family solver. I can't undo that on the branch; it's quite pervasive. But it showed up a shortcoming in the way we do type inference generally. That is, I exposed an existing bug which happened not to show up before. Fixing that bug is quite non-trivial. I do intend to fix it, probably in the next couple of weeks. Let's see how invasive the fix is. Meanwhile you say "it is affecting code in the wild". Can you be more specific? Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10009#comment:21 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler