#15825: Core Lint error from Explicit Foralls Proposal -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): This is fixed on GHC HEAD as of commit 5e45ad10ffca1ad175b10f6ef3327e1ed8ba25f3 (Finish fix for #14880.). It now gives a proper error message: {{{ $ ghc2/inplace/bin/ghc-stage2 --interactive Bug.hs -fprint-explicit-kinds GHCi, version 8.7.20181029: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Main ( Bug.hs, interpreted ) Bug.hs:12:29: error: • Illegal type synonym family application ‘GHC.Types.Any k’ in instance: X (a (GHC.Types.Any k)) • In the instance declaration for ‘X (a :: *)’ | 12 | instance forall (a :: C k). X (a :: *) | ^^^^^^^^^^ }}} TODO: Check this program in as a test case. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15825#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler