Re: [GHC] #15757: Coercion Variable Almost Devoid Checking in ForAllCo

#15757: Coercion Variable Almost Devoid Checking in ForAllCo -------------------------------------+------------------------------------- Reporter: ningning | Owner: ningning Type: task | Status: new Priority: normal | Milestone: Component: Compiler | Version: Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #15497 | Differential Rev(s): Phab:D5231 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Ningning Xie ): In [changeset:"879db5595208fb665ff1a0a2b12b9921d3efae0e/ghc" 879db559/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="879db5595208fb665ff1a0a2b12b9921d3efae0e" Adding almost devoid check for covar in ForAllCo Summary: For the sake of consistency of the dependent core, there is a restriction on where a coercion variable can appear in ForAllCo: the coercion variable can appear nowhere except in coherence coercions. Currently this restriction is missing in Core. The goal of this patch is to add the missing restriction. After discussion, we decide: coercion variables can appear nowhere except in `GRefl` and `Refl`. Relaxing the restriction to include `Refl` should not break consistency, we premuse. Test Plan: ./validate Reviewers: goldfire, simonpj, bgamari Reviewed By: goldfire Subscribers: rwbarton, carter GHC Trac Issues: #15757 Differential Revision: https://phabricator.haskell.org/D5231 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15757#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler