#12027: ghc 8.0rc4 treats INLINE pragmas for methods with default (implicit) definitions as errors -------------------------------------+------------------------------------- Reporter: carter | Owner: Type: bug | Status: closed Priority: high | Milestone: Component: Compiler | Version: 8.0.1 Resolution: invalid | 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: | -------------------------------------+------------------------------------- Changes (by bgamari): * status: new => closed * resolution: => invalid Comment: Right, because, just as the error says, that INLINE doesn't correspond to any particular in-scope binding. However, you should not need an INLINE here; instead just place one on the default definition. You can test this yourself with the following, {{{#!hs module Class where class AClass a where aList :: a -> [Int] aList _ = [1,2,3] {-# INLINE aList #-} }}} {{{#!hs module Instance where import Class instance AClass Int where }}} {{{#!hs module Use where import Class import Instance n :: Int n = 42 main :: IO () main = print (aList n) }}} If you build `Use` with `-O -ddump-simpl` you will see that the RHS of `aList` has been inlined. I suspect the real bug here is the fact that this wasn't warned about previously. I'll try to draw attention to this change in the release notes. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12027#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler