Error Dealing with Unboxed Types and Type Families

changed weight to 5

Attached file Unbox.hs ($1261).

The relevant code

Can you explain how to provoke the error? I tried

ghc -c T13244.hs

and all was well. (But I may not have used exactly the version that you did..)

Probably a dup of #12242 (closed)

Attached file lint-errors.txt (download).

lint errors from "stack build --ghc-options -dcore-lint

I'm using stack with resolver lts-7.19 which uses ghc 8.0.1. I ran stack build --ghc-options -dcore-lint and got quite the atrocious output which I will attach to the issue. The error I got originally was from a dup of #12242 (closed) almost certainly, but could the -dcore-lint errors have been caused by that?

Could you provoke it with an invocation of GHC, not via stack? One less indirection.

Yes, here is the relevant session:

samuel@computer:~/Documents/lower/Data$ ghc Unbox.hs -XMagicHash -XDataKinds -XTypeInType -XTypeFamilies
[1 of 1] Compiling Data.Unbox       ( Unbox.hs, Unbox.o )
ghc: panic! (the 'impossible' happened)
  (GHC version 8.0.2 for x86_64-unknown-linux):
	kindPrimRep.go Rep Int

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

Behaviors to note: if I set "box = undefined", the code will compile but still have type errors when run with -dcore-lint, whereas if I set "unbox = undefined" the message is still the same.

OK I can reproduce this. It fails with a Lint error in the GHC 8.0 branch:

*** Core Lint errors : in result of Tidy Core ***
<no location info>: warning:
    In the type ‘Unboxed x_aws[sk] -> x_aws[sk]’
    Ill-kinded argument
      in type or kind ‘Unboxed x_aws[sk] -> x_aws[sk]’
    type or kind ‘Unboxed x_aws[sk] -> x_aws[sk]’ kind: TYPE
                                                          (Rep x_aws[sk])
<no location info>: warning:
    In the type ‘Unboxed x_aws[sk] -> x_aws[sk]’
    Ill-kinded argument
      in type or kind ‘Unboxed x_aws[sk] -> x_aws[sk]’
    type or kind ‘Unboxed x_aws[sk] -> x_aws[sk]’ kind: TYPE
                                                          (Rep x_aws[sk])
<no location info>: warning:
    In the type ‘Unboxed x_aws[sk] -> x_aws[sk]’
    Ill-kinded argument
      in type or kind ‘Unboxed x_aws[sk] -> x_aws[sk]’
    type or kind ‘Unboxed x_aws[sk] -> x_aws[sk]’ kind: TYPE
                                                          (Rep x_aws[sk])
<no location info>: warning:
    In the type ‘forall x_aws[sk].
                 Unbox x_aws[sk] =>
                 Unboxed x_aws[sk] -> x_aws[sk]’
    Ill-kinded argument
      in type or kind ‘Unboxed x_aws[sk] -> x_aws[sk]’
    type or kind ‘Unboxed x_aws[sk] -> x_aws[sk]’ kind: TYPE
                                                          (Rep x_aws[sk])
*** Offending Program ***

But the recent round of improvements to levity polymorphism make this OK in HEAD (and hence in 8.2). I'll add a regression test.

mentioned in commit fed7136c

closed

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedFixed
Test case	- → indexed-types/should_compile/T13244

added Pnormal label

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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Error Dealing with Unboxed Types and Type Families

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