ghc: panic! (the 'impossible' happened) - piResultTy

Oddly this only happens on our build server, not on my local machine. On compilation, I get:

[187 of 273] Compiling Query.Order      ( Query/Order.hs, dist/build/Query/Order.o )

Query/Order.hs:340:1: warning: [-Wredundant-constraints]
    • Redundant constraint: MonadBaseControl IO m
    • In the type signature for:
           updateOrdersSuccess :: (MonadBaseControl IO m,
                                   MonadTransaction m) =>
                                  m ()
ghc: panic! (the 'impossible' happened)
  (GHC version 8.0.1 for x86_64-unknown-linux):
	piResultTy
  Maybe Int64
  a1_a4WiL

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

The configuration parameters are:

configureFlags: --verbose --prefix=/nix/store/qxfjd5jxr593dn43i3659s86d0rdllyv-circuithub-api-0.0.4 --libdir=$prefix/lib/$compiler --libsubdir=$pkgid --with-gcc=gcc --package-db=/tmp/nix-build-circuithub-api-0.0.4.drv-0/package.conf.d --ghc-option=-j1 --disable-split-objs --disable-library-profiling --disable-profiling --disable-shared --enable-library-vanilla --disable-executable-dynamic --disable-tests

I've attached Query/Order.hs, but you won't be able to compile it stand-alone.

Trac metadata

Trac field	Value
Version	8.0.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture