Front end crashes when importing RankNTypes
When importing the module RankNTypes from the front-end test suite, the front end crashes. E.g., if Test.curry contains
import RankNTypes
main = 42
the compilation of this file returns an error:
> :l Test
[1 of 3] Skipping Prelude ( /net/medoc/home/mh/pakcs2.5/lib/Prelude.curry, /net/medoc/home/mh/pakcs2.5/lib/.curry/Prelude.fcy )
[2 of 3] Skipping RankNTypes ( RankNTypes.curry, .curry/RankNTypes.fcy )
[3 of 3] Compiling Test ( Test.curry, .curry/Test.fcy )
pakcs-frontend: Internal error: Checks.InterfaceSyntaxCheck.checkClosed
CallStack (from HasCallStack):
error, called at src/Base/Messages.hs:78:21 in main:Base.Messages