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Does this still happen in HEAD?

import qualified GHC.Generics as GHC
import Generics.SOP
import Generics.SOP.TH
import Data.Proxy

gminbound' :: (Generic a, Code a ~ (xs:xss), All2 Bounded (Code a)) => a
gminbound' = minBound
  & I
  & hcpure (Proxy @Bounded)
  & apInjs_POP
  & head
  & to

Fails but doesn't crash with

$ ghci -ignore-dot-ghci -XTypeApplications -XTypeOperators -XDataKinds -XGADTs -XFlexibleContexts /tmp/tX96.hs 
GHCi, version 8.0.1: http://www.haskell.org/ghc/  :? for help
[1 of 1] Compiling Main             ( /tmp/tX96.hs, interpreted )

/tmp/tX96.hs:8:3: error:
    Variable not in scope: (&) :: t4 -> (a0 -> I a0) -> t3

/tmp/tX96.hs:9:3: error:
    Variable not in scope: (&) :: t3 -> t5 -> t2

/tmp/tX96.hs:10:3: error:
    Variable not in scope:
      (&) :: t2 -> (POP f1 xss0 -> [SOP f1 xss0]) -> t1

/tmp/tX96.hs:11:3: error:
    Variable not in scope: (&) :: t1 -> ([a1] -> a1) -> t0

/tmp/tX96.hs:12:3: error:
    Variable not in scope: (&) :: t0 -> (Rep a2 -> a2) -> a
Failed, modules loaded: none.
Prelude> 

but crashes with -fdefer-typed-holes

$ ghci -ignore-dot-ghci -fdefer-typed-holes -XTypeApplications -XTypeOperators -XDataKinds -XGADTs -XFlexibleContexts /tmp/tX96.hs 
GHCi, version 8.0.1: http://www.haskell.org/ghc/  :? for help
[1 of 1] Compiling Main             ( /tmp/tX96.hs, interpreted )

/tmp/tX96.hs:8:3: warning: [-Wtyped-holes]
    Variable not in scope: (&) :: t4 -> (a0 -> I a0) -> t3

/tmp/tX96.hs:9:3: warning: [-Wtyped-holes]
    Variable not in scope: (&) :: t3 -> t5 -> t2

/tmp/tX96.hs:10:3: warning: [-Wtyped-holes]
    Variable not in scope:
      (&) :: t2 -> (POP f1 xss0 -> [SOP f1 xss0]) -> t1

/tmp/tX96.hs:11:3: warning: [-Wtyped-holes]
    Variable not in scope: (&) :: t1 -> ([a1] -> a1) -> t0

/tmp/tX96.hs:12:3: warning: [-Wtyped-holes]
    Variable not in scope: (&) :: t0 -> (Rep a2 -> a2) -> a
ghc: panic! (the 'impossible' happened)
  (GHC version 8.0.1 for x86_64-unknown-linux):
        opt_univ fell into a hole {aabX}

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

> 

---

More minimal example, still requires generics-sop:

import Generics.SOP

a = minBound
  & hcpure (Proxy @Bounded)

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
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