Re: [GHC] #11882: Use coercionKind instread of zonkTcType in TcFlatten.flatten_tyvar

#11882: Use coercionKind instread of zonkTcType in TcFlatten.flatten_tyvar -------------------------------------+------------------------------------- Reporter: simonpj | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Resolution: fixed | 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: | -------------------------------------+------------------------------------- Changes (by simonpj): * status: new => closed * resolution: => fixed Comment: Done by this commit; stupidly failed to mention it in the commit message. {{{ commit a7ee2d4c4229b27af324ebac93081f692835365d Author: Simon Peyton Jones Date: Fri Apr 15 16:17:54 2016 +0100 Improve TcFlatten.flattenTyVar This patch tides up the structure, simplifying FlattenTvResult. It also replaces a use of zonkTcType (which I hated) with coercionKind, in that same function. Happily, the result is little faster, maybe even a percentage point or two, which is a lot for a compiler. This also removes the line || not (map binderVisibility bndrs1 == map binderVisibility bndrs2) from TcCanonical.can_eq_nc', in the ForAllTy/ForAllTy case. Why? Becuase I can't see why binder-visiblity should matter, and when we use coercionKind instead of zonkTcType in flattenTyVar, this case pops up and rejects a program that should pass. I did discuss this with Richard. }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11882#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler