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

[David McBride]

It is all detailed in the error message.
http://www.haskell.org/ghc/reportabug

On Mon, Dec 11, 2017 at 12:15 PM, Baa <aquagnu at gmail.com> wrote:

> 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
> > >>
> > >
> > >
>
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