#16347: GHC HEAD regression: piResultTys1 -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: Component: Compiler (Type | Version: 8.7 checker) | Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by RyanGlScott: Old description:

The following program typechecks on GHC 8.0.2 through 8.6.3, but panics on HEAD:

{{{#!hs {-# LANGUAGE GADTs #-} {-# LANGUAGE TypeInType #-} module Bug where

import Data.Kind import Data.Proxy

data T f :: f Type -> Type where MkT :: T f a }}} {{{ $ ~/Software/ghc4/inplace/bin/ghc-stage2 Bug.hs [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.7.20190219 for x86_64-unknown-linux): piResultTys1 k_a10k[tau:1] [*] Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1159:37 in ghc:Outputable pprPanic, called at compiler/types/Type.hs:1063:5 in ghc:Type }}}

New description: The following program typechecks on GHC 8.0.2 through 8.6.3, but panics on HEAD: {{{#!hs {-# LANGUAGE GADTs #-} {-# LANGUAGE TypeInType #-} module Bug where import Data.Kind data T f :: f Type -> Type where MkT :: T f a }}} {{{ $ ~/Software/ghc4/inplace/bin/ghc-stage2 Bug.hs [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.7.20190219 for x86_64-unknown-linux): piResultTys1 k_a10k[tau:1] [*] Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1159:37 in ghc:Outputable pprPanic, called at compiler/types/Type.hs:1063:5 in ghc:Type }}} -- -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16347#comment:1> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

#16347: GHC HEAD regression: piResultTys1 -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: Component: Compiler (Type | Version: 8.7 checker) | Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): Interestingly this is a consequence of the broken-ness described in #16344. Fixing the latter fixes this ticket too. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16347#comment:3> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

#16347: GHC HEAD regression: piResultTys1 -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: Component: Compiler (Type | Version: 8.7 checker) | Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Marge Bot <ben+marge-bot@…>): In [changeset:"4db9bdd91549b4eada5324cd7452e7e74ada28f5/ghc" 4db9bdd9/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="4db9bdd91549b4eada5324cd7452e7e74ada28f5" Add regression test for #16347 Commit 1f5cc9dc8aeeafa439d6d12c3c4565ada524b926 ended up fixing #16347. Let's add a regression test to ensure that it stays fixed. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16347#comment:5> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler