#16127: Panic: piResultTys1 in compiler/types/Type.hs:1022:5 -------------------------------------+------------------------------------- Reporter: _deepfire | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.6.1 checker) | Resolution: | Keywords: 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 _deepfire: Old description:
I apologize in advance for a non-minimised repro.
The panic (with a small `-ddump-tc-trace` excerpt, but full log also attached):
{{{ tcPolyExprNC Check{Vocab * (k_a4TNy[tau:2] -> Constraint) i_a4TNv[tau:2] (Present * k_a4TNy[tau:2] i_a4TNv[tau:2])} tcSkolemise tcInferId voc_a4TB2 :: Vocab i_a4TMf[sk:1] (Present * * i_a4TMf[sk:1]) tcCheckId voc_a4TB2 Vocab i_a4TMf[sk:1] (Present * * i_a4TMf[sk:1]) Check{Vocab * (k_a4TNy[tau:2] -> Constraint) i_a4TNv[tau:2] (Present * k_a4TNy[tau:2] i_a4TNv[tau:2])} tcWrapResult Actual: Vocab i_a4TMf[sk:1] (Present * * i_a4TMf[sk:1]) Expected: Check{Vocab * (k_a4TNy[tau:2] -> Constraint) i_a4TNv[tau:2] (Present * k_a4TNy[tau:2] i_a4TNv[tau:2])} tc_sub_type_ds ty_actual = Vocab i_a4TMf[sk:1] (Present * * i_a4TMf[sk:1]) ty_expected = Vocab * (k_a4TNy[tau:2] -> Constraint) i_a4TNv[tau:2] (Present * k_a4TNy[tau:2] i_a4TNv[tau:2]) deeply_instantiate final subst origin: arising from a use of ‘voc_a4TB2’ type: Vocab i_a4TMf[sk:1] (Present * * i_a4TMf[sk:1]) new type: Vocab i_a4TMf[sk:1] (Present * * i_a4TMf[sk:1]) subst: [TCvSubst In scope: InScope {i_a4TMf} Type env: [] Co env: []] u_tys tclvl 2 Vocab i_a4TMf[sk:1] (Present * * i_a4TMf[sk:1]) ~ Vocab * (k_a4TNy[tau:2] -> Constraint) i_a4TNv[tau:2] (Present * k_a4TNy[tau:2] i_a4TNv[tau:2]) arising from a type equality Vocab i_a4TMf[sk:1] (Present * * i_a4TMf[sk:1]) ~ Vocab * (k_a4TNy[tau:2] -> Constraint) i_a4TNv[tau:2] (Present * k_a4TNy[tau:2] i_a4TNv[tau:2])
<no location info>: error: ghc: panic! (the 'impossible' happened) (GHC version 8.6.1 for x86_64-unknown-linux): piResultTys1 * [i_a4TNv[tau:2], Present * k_a4TNy[tau:2] i_a4TNv[tau:2]] Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1160:37 in ghc:Outputable pprPanic, called at compiler/types/Type.hs:1022:5 in ghc:Type
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}}
Repro (requires Nix & some download time, provides hard repro guarantees in return):
{{{ $ git clone https://github.com/deepfire/holotype $ cd holotype $ git reset --hard 7e9f5099eea2080f57205267291eeec50ae4b68a $ nix-shell [nix-shell:~/holotype]$ make }}}
New description: I apologize in advance for a non-minimised repro. The panic (with a small `-ddump-tc-trace` excerpt, but full log also attached -- https://ghc.haskell.org/trac/ghc/attachment/ticket/16127/ghc.out.xz): {{{ tcPolyExprNC Check{Vocab * (k_a4TNy[tau:2] -> Constraint) i_a4TNv[tau:2] (Present * k_a4TNy[tau:2] i_a4TNv[tau:2])} tcSkolemise tcInferId voc_a4TB2 :: Vocab i_a4TMf[sk:1] (Present * * i_a4TMf[sk:1]) tcCheckId voc_a4TB2 Vocab i_a4TMf[sk:1] (Present * * i_a4TMf[sk:1]) Check{Vocab * (k_a4TNy[tau:2] -> Constraint) i_a4TNv[tau:2] (Present * k_a4TNy[tau:2] i_a4TNv[tau:2])} tcWrapResult Actual: Vocab i_a4TMf[sk:1] (Present * * i_a4TMf[sk:1]) Expected: Check{Vocab * (k_a4TNy[tau:2] -> Constraint) i_a4TNv[tau:2] (Present * k_a4TNy[tau:2] i_a4TNv[tau:2])} tc_sub_type_ds ty_actual = Vocab i_a4TMf[sk:1] (Present * * i_a4TMf[sk:1]) ty_expected = Vocab * (k_a4TNy[tau:2] -> Constraint) i_a4TNv[tau:2] (Present * k_a4TNy[tau:2] i_a4TNv[tau:2]) deeply_instantiate final subst origin: arising from a use of ‘voc_a4TB2’ type: Vocab i_a4TMf[sk:1] (Present * * i_a4TMf[sk:1]) new type: Vocab i_a4TMf[sk:1] (Present * * i_a4TMf[sk:1]) subst: [TCvSubst In scope: InScope {i_a4TMf} Type env: [] Co env: []] u_tys tclvl 2 Vocab i_a4TMf[sk:1] (Present * * i_a4TMf[sk:1]) ~ Vocab * (k_a4TNy[tau:2] -> Constraint) i_a4TNv[tau:2] (Present * k_a4TNy[tau:2] i_a4TNv[tau:2]) arising from a type equality Vocab i_a4TMf[sk:1] (Present * * i_a4TMf[sk:1]) ~ Vocab * (k_a4TNy[tau:2] -> Constraint) i_a4TNv[tau:2] (Present * k_a4TNy[tau:2] i_a4TNv[tau:2]) <no location info>: error: ghc: panic! (the 'impossible' happened) (GHC version 8.6.1 for x86_64-unknown-linux): piResultTys1 * [i_a4TNv[tau:2], Present * k_a4TNy[tau:2] i_a4TNv[tau:2]] Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1160:37 in ghc:Outputable pprPanic, called at compiler/types/Type.hs:1022:5 in ghc:Type Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} Repro (requires Nix & some download time, provides hard repro guarantees in return): {{{ $ git clone https://github.com/deepfire/holotype $ cd holotype $ git reset --hard 7e9f5099eea2080f57205267291eeec50ae4b68a $ nix-shell [nix-shell:~/holotype]$ make }}} -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16127#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler