#13154: Standalone-derived anyclass instances aren't as permissive as empty instances -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: RyanGlScott Type: bug | Status: patch Priority: normal | Milestone: 8.6.1 Component: Compiler (Type | Version: 8.1 checker) | Resolution: | Keywords: deriving Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4337 Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * status: new => patch * differential: => Phab:D4337 Comment: Phab:D4337 fixes the issue in comment:8. It does //not// fix the entire issue, as there is still the degenerate case of: {{{#!hs {-# LANGUAGE DeriveAnyClass #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE StandaloneDeriving #-} class C a deriving instance C a }}} Which needs further patching to fix. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13154#comment:13 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler