patch applied (ghc): Add assertion for arity match (checks Trac #2844)

[Simon Marlow]

Simon Marlow wrote:
> Simon Peyton-Jones wrote:
>> | Hooray for the testsuite and validate: out of 2000+ tests, there was
>> | exactly 1 (ONE) that demonstrated this bug, and it was in a test for 
>> the
>> | System.Random library of all things.  This serves as a reminder to 
>> all of
>> | us: any test failure should be treated as suspicious, even if it 
>> doesn't
>> | look at all related to something you changed, and this is exactly 
>> why we
>> | have to keep validate clean.  I am now a fully paid-up validate 
>> convert!
>>
>> Indeed!
>>
>> On Windows (MSYS) I get several failures that I'm pretty sure have 
>> been there for a while.  They seem to relate to things like 'printf' 
>> not existing.  That makes it harder to interpret a Windows validate run.
>>
>> I wonder if someone (Neil? Ian?) might investigate?
> 
> I see some, but not all of those failures on our buildbots, I'll 
> investigate.  We had zero failures a few days ago, so I think these are 
> new.

Well, on closer inspection we currently have zero failures on the Cygwin 
buildbots, for the fast/validate testsuite.  I don't have an MSYS build set 
up, so could someone else try with that?

Cheers,
	Simon