[GHC] #16188: GHC HEAD-only panic (buildKindCoercion)

[GHC]

#16188: GHC HEAD-only panic (buildKindCoercion)
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.8.1
       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 RyanGlScott):

 Here's what you get when you compile the program with `-dcore-lint`:

 {{{
 $ ~/Software/ghc4/inplace/bin/ghc-stage2 Bug.hs -dcore-lint
 [1 of 1] Compiling Bug              ( Bug.hs, Bug.o )
 *** Core Lint errors : in result of Desugar (before optimization) ***
 <no location info>: warning:
     [RHS of ds_d1ur :: (Sing Any, Sing (ReNotEmpty re2_a1hm))]
     The type of this binder doesn't match the type of its RHS: ds_d1ur
     Binder's type: (Sing Any, Sing (ReNotEmpty re2_a1hm))
     Rhs type: (Sing (Apply ReNotEmptySym0 re1_a1hl),
                Sing (ReNotEmpty re2_a1hm))
 *** Offending Program ***

 <elided>

 blah :: forall t (re :: RegExp t). Sing re -> ()
 [LclIdX]
 blah
   = \ (@ t_a1hg)
       (@ (re_a1hh :: RegExp t_a1hg))
       (ds_d1uq :: Sing re_a1hh) ->
       let {
         ds_d1vi :: R:SingRegExp t_a1hg re_a1hh
         [LclId]
         ds_d1vi
           = ds_d1uq
             `cast` (D:R:SingRegExp0[0] <t_a1hg>_N <re_a1hh>_N
                     :: Sing re_a1hh ~R# R:SingRegExp t_a1hg re_a1hh) } in
       case ds_d1vi of wild_00
       { SApp @ re1_a1hl @ re2_a1hm co_a1hn sre1_aXI sre2_aXJ ->
       let {
         ds_d1ur :: (Sing Any, Sing (ReNotEmpty re2_a1hm))
         [LclId]
         ds_d1ur
           = (sReNotEmpty @ t_a1hg @ re1_a1hl sre1_aXI,
              (sReNotEmpty @ t_a1hg @ re2_a1hm sre2_aXJ)
              `cast` (Sub (Sym (Sing
                                  <Bool>_N
                                  (Sym
 (D:R:ApplyRegExpBoolReNotEmptySym0r[0]
                                            <t_a1hg>_N <re2_a1hm>_N)))_N)
                      :: Sing (Apply ReNotEmptySym0 re2_a1hm)
                         ~R# Sing (ReNotEmpty re2_a1hm))) } in
       let {
         fail_d1v2 :: Void# -> ()
         [LclId]
         fail_d1v2
           = \ (ds_d1v3 [OS=OneShot] :: Void#) ->
               patError @ 'LiftedRep @ () "Bug.hs:(47,5)-(48,26)|case"# }
 in
       case ds_d1ur of wild_00 { (ds_d1uY, ds_d1uZ) ->
       let {
         ds_d1v0 :: R:SingBool Any
         [LclId]
         ds_d1v0
           = ds_d1uY
             `cast` (D:R:SingBool0[0] <Any>_N
                     :: Sing Any ~R# R:SingBool Any) } in
       case ds_d1v0 of wild_00 {
         __DEFAULT -> fail_d1v2 void#;
         STrue co_a1hA ->
           let {
             ds_d1v1 :: R:SingBool Any
             [LclId]
             ds_d1v1
               = ds_d1uZ
                 `cast` (D:R:SingBool0[0] <Any>_N
                         :: Sing Any ~R# R:SingBool Any) } in
           case ds_d1v1 of wild_00 {
             __DEFAULT -> fail_d1v2 void#;
             STrue co_a1hD -> ()
           }
       }
       }
       }
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16188#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler