[GHC] #1491: Extension RecordWildCards is broken

[Augustsson, Lennart]

I will try my own fix again when/if I manage to get a new repository.
(But I suspect it will need reworking since now you've made part of the changes.)

Believe me I've tried to keep up with ghc.  But when you have local changes darcs just falls over every so often and I have to start from a new repo.  And then fix this and that to make it compile.  And I do complain every time I find something that falls over in the build system, but I only complain once per bug.

  -- Lennart

-----Original Message-----
From: Simon Peyton-Jones [mailto:simonpj at microsoft.com] 
Sent: Thursday, July 05, 2007 9:41 AM
To: Augustsson, Lennart; 'glasgow-haskell-bugs at haskell.org'
Subject: RE: [GHC] #1491: Extension RecordWildCards is broken

| 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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