#14450: GHCi spins forever -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: high | Milestone: 8.4.1 Component: Compiler | Version: 8.2.1 Resolution: | Keywords: TypeInType, | PolyKinds Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Simon Peyton Jones <simonpj@…>): In [changeset:"0a85190312a1de3d300912051309b94589c08683/ghc" 0a851903/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="0a85190312a1de3d300912051309b94589c08683" Fix a TyVar bug in the flattener A year ago I gave up on trying to rigorously separate TyVars from TcTyVars, and instead allowed TyVars to appear rather more freely in types examined by the constraint solver: commit 18d0bdd3848201882bae167e3b15fd797d217e93 Author: Simon Peyton Jones <simonpj@microsoft.com> Date: Wed Nov 23 16:00:00 2016 +0000 Allow TyVars in TcTypes See Note [TcTyVars in the typechecker] in TcType. However, TcFlatten.flatten_tyvar1 turned out to treat a TyVar specially, and implicitly assumed that it could not have an equality constraint in the inert set. Wrong! This caused Trac #14450. Fortunately it is easily fixed, by deleting code. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14450#comment:7> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler