[GHC] #1491: Extension RecordWildCards is broken

[Simon Peyton-Jones]

| It didn't reuse the same Name.  When a C{..} pattern was found it was expanded (very early) in expandDotDot by
| looking up the children of the constructor and making a new RdrName for each field.  No C{..} ever reached
| rnPat.
| But I guess there was something about this you didn't like.

It turned out that the nicest way to look up the extra fields requires the renamer monad.  So the pre-pass must be monadic.  Yes, that's possible but it's terribly inelegant, esp when 99.9% of the time it does nothing.

Can you just use your own patch (which is perhaps good enough for your purposes) for now?

| It does affect me in a day-to-day way.  We rely on this extension, so we have to build our own compiler.
| Given that it takes at least a day of fixing the build system every time I try to build ghc I don't do this very
| often.

Bleat early, bleat often.  It should just work.  If it doesn't, complain.

| But at the moment I can't even download the darcs repo for ghc.  That might be a problem at our end that is
| currupting one of the patches. (We can't download the packed up version of the source tree because .bz2 files
| seem to be blocked in our firewall.)

I don't know how to help you on this one. Simon M did send a msg around about a Darcs bug that gave rise to some mysterious looking stuff with Cmm; but darcs revert sorts it out.  I suppose you could be seeing that.

Simon
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