Re: [GHC] #11248: Ambiguous Types with Constraint Synonyms

#11248: Ambiguous Types with Constraint Synonyms -------------------------------------+------------------------------------- Reporter: crockeea | Owner: Type: bug | Status: new Priority: high | Milestone: 8.0.1 Component: Compiler | Version: 7.10.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: GHC rejects | Test Case: valid program | polykinds/T11248 Blocked By: | Blocking: Related Tickets: #11330 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Simon Peyton Jones ): In [changeset:"3c060f36f6eb4d359f252168e2f97b573d017080/ghc" 3c060f36/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="3c060f36f6eb4d359f252168e2f97b573d017080" Fix exprIsHNF (Trac #11248) Blimey! CoreUtils.exprIsHNFlike had not one but two bugs. * is_hnf_like treated coercion args like type args (result: exprIsHNF might wrongly say True) * app_is_value treated type args like value args (result: exprIsHNF might wrongly say False) Bizarre. This goes back to at least 2012. It's amazing that it hasn't caused more trouble. It was discovered by a Lint error when compiling Trac #11248 with -O. }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11248#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler