Hi Thorkil,
Attached a tar file with what I believe you are asking for. In addition to Package.hcr, multiple1.txt explains in more detail what I did. The remaining files may also be useful.
And I just tried scons build yhc without the type=release, so that the ghc compiles become without -O. And now the correct "Not found" message is produced. So the case leans definitely towards an error in the ghc-6.6 that I am using.
That does look like an error, and it doesn't lean towards an error in the generated core, as the release build goes from the same core. I just downloaded 6.6 on this machine and rebuilt Yhc, and it works perfectly on x86. I guess that points at a GHC bug in the code generator. I've just added some code so it now reads: case (local,res) of ([x], _) -> return x (_, [x]) -> return x ([], []) -> raiseError $ ErrorFileNone noErrPos askMsg file rs (as, bs) -> -- ASSERTION TO DEBUG GHC 6.6 WITHOUT -O CODEGEN ON A MAC! assert (not $ null $ as ++ bs) $ raiseError $ ErrorFileMany noErrPos askMsg file (map anyOne (as ++ bs)) That (to me) looks like an assertion that should always be true, but which appears at first glance to be being violated by GHC 6.6 on a Mac when compiled without -O. Can you try that on your machine, and see if it does raise an assertion? If it does, we can then contact the GHC developers and let them get a minimal test case :) Thanks Neil