#16251: T5515 broken in devel2 flavour -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The `T5515` testcase is broken in the `devel2` build flavour: {{{ --- indexed-types/should_fail/T5515.run/T5515.stderr.normalised 2019-01-27 16:01:12.703091135 +0000 +++ indexed-types/should_fail/T5515.run/T5515.comp.stderr.normalised 2019-01-27 16:01:12.703091135 +0000 @@ -1,24 +1,12 @@ +ghc: panic! (the 'impossible' happened) + (GHC version 8.7.20190127 for x86_64-unknown-linux): + ASSERT failed! + rhs axiom D:R:Argf :: + Arg f = a_asO[sk:1] -- Defined at T5515.hs:15:8 + Call stack: + CallStack (from HasCallStack): + callStackDoc, called at compiler/utils/Outputable.hs:<line>:<column> in <package-id>:Outputable + pprPanic, called at compiler/utils/Outputable.hs:<line>:<column> in <package-id>:Outputable + assertPprPanic, called at compiler/typecheck/FamInst.hs:<line>:<column> in <package-id>:FamInst -T5515.hs:6:16: - Expecting one more argument to ‘ctx’ - Expected a type, but ‘ctx’ has kind ‘* -> Constraint’ - In the first argument of ‘Arg’, namely ‘ctx’ - In the first argument of ‘ctx’, namely ‘(Arg ctx)’ - In the class declaration for ‘Bome’ - -T5515.hs:14:1: - Type variable ‘a’ is mentioned in the RHS, - but not bound on the LHS of the family instance - In the type instance declaration for ‘Arg’ - In the instance declaration for ‘Some f’ - -T5515.hs:14:10: - Could not deduce (C f a0) - from the context: C f a - bound by an instance declaration: - forall f a. C f a => Some f - at T5515.hs:14:10-24 - The type variable ‘a0’ is ambiguous - In the ambiguity check for an instance declaration - To defer the ambiguity check to use sites, enable AllowAmbiguousTypes - In the instance declaration for ‘Some f’ +Please report this as a GHC bug: https://www.haskell.org/ghc/reportabug }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16251 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler