[GHC] #10934: Iface type variable out of scope

[GHC]

#10934: Iface type variable out of scope
-------------------------------------+-------------------------------------
           Reporter:  mjmrotek       |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  7.10.2
           Keywords:  interface      |  Operating System:  Linux
       Architecture:                 |   Type of failure:  Compile-time
  Unknown/Multiple                   |  crash
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |
-------------------------------------+-------------------------------------
 I'm sorry for spamming code and not providing a distilled example, but
 honestly I have no idea how to even begin pinpointing this.

 I'm writing a library and hosting it on Github:
 https://github.com/marcinmrotek/pipes-key-value-csv which compiles fine,
 but when I try to compile the test suite, GHC crashes with this error
 message:
 {{{
 /home/marcin/haskell/pipes-key-value-csv/.stack-
 work/dist/x86_64-linux/Cabal-1.22.4.0/build/Pipes/KeyValueCsv/Internal/KeyValue.hi
 Declaration for $fFromKeyValuesf:3:
   Iface type variable out of scope:  k
 Cannot continue after interface file error
 }}}
 when I uncomment the
 {{{#!hs
 . KV.foldHeader
 }}}
 line in https://github.com/marcinmrotek/pipes-key-value-
 csv/blob/master/test/Test/KeyValue.hs

 The thing is, this function does not even use the "FromKeyValues" type
 class mentioned - https://github.com/marcinmrotek/pipes-key-value-
 csv/blob/master/src/Pipes/KeyValueCsv/Internal/KeyValue.hs

 KV.parseLine, which does, compiles fine (the test suite runs and fails
 with "Prelude: undefined". They're both defined here:
 https://github.com/marcinmrotek/pipes-key-value-
 csv/blob/master/src/Pipes/KeyValueCsv/KeyValue.hs

 I've tried "stack clean", reinstalling both GHC and stack, installing my
 package globally with cabal-install (although I had to fix the
 validation-0.5.1 package by removing the Safe pragma; I've tried to use
 stack again, pointing it to the exact same code for validation-0.5.1, to
 no avail), the result is always the same - the library compiles, the test
 suite doesn't.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10934>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler