Re: [GHC] #13474: GHC HEAD regression: Prelude.!!: index too large

#13474: GHC HEAD regression: Prelude.!!: index too large -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.2.1 Component: Compiler | Version: 8.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * cc: bgamari (added) Comment: The commit that caused this regression is somewhat surprising. It's d2f48495ebe79b5ef5808a4891b3d03dfd297d35: {{{ From d2f48495ebe79b5ef5808a4891b3d03dfd297d35 Mon Sep 17 00:00:00 2001 From: Ben Gamari Date: Sun, 26 Feb 2017 15:33:54 -0500 Subject: [PATCH] Coercion: Try dropping constraintIsLifted axiom While working through the FunCo patch I encountered some lint issues which suggested that `Constraint` wasn't being considered equal to `TYPE 'LiftedRep`. Consequently I introduced this axiom and associated messy ball of logic to explicitly coerce `Constraint`. However, as @goldfire points out on D3208 this really shouldn't be necessary. Indeed, I tried ripping out the axiom and things appear to just work. I suspect the issue motivating the axiom was a bug elsewhere in the FunCo branch that I fixed during development. }}} Thoughts, Ben? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13474#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler