[Haskell-beginners] What does 'impossible happened' mean?

[Baa]

Hello, David.
Something new :) So,

1. How to report such bug?
2. How to upgrade to 8.2.2 and to new LTS?
I tried to change "resolve: lts-XX" to "resolve: ghc-8.2.2" in
stack.yaml but hit many errors.


> And I should say, you might try a newer ghc, they fix things all the
> time. Stack is still on ghc 8.0.2, but newer snapshots are on 8.2.2.
> 
> On Mon, Dec 11, 2017 at 11:43 AM, David McBride <toad3k at gmail.com>
> wrote:
> 
> > It may be a bug in ghc.  It may be a bug in stack.  Not much you
> > can do about it other than to report it.
> >
> > On Mon, Dec 11, 2017 at 11:39 AM, Baa <aquagnu at gmail.com> wrote:
> >  
> >> Hello, List. I hit error:
> >>
> >>     ghc: panic! (the 'impossible' happened)
> >>       (GHC version 8.0.2 for x86_64-unknown-linux):
> >>         initTc: unsolved constraints
> >>       WC {wc_insol = [W] spec_a86e :: t_a86d[tau:1] (CHoleCan:
> >> spec)}
> >>
> >>     Please report this as a GHC bug:
> >> http://www.haskell.org/ghc/rep ortabug
> >>
> >> what does it mean and how to fix it?
> >>
> >> PS. I only added template Haskell "call" in my test suite like
> >>
> >>   $(blahBlah something)
> >>
> >> The same call works fine in other modules and in GHCI. "stack
> >> build" works too, but tests - no (last stack 1.6.1)
> >>
> >> ===
> >> Best regards, Paul
> >> _______________________________________________
> >> Beginners mailing list
> >> Beginners at haskell.org
> >> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
> >>  
> >
> >