Rebuilding ghc

[Simon Peyton-Jones]

| Where do I put -fno-ds-multi-tyvar so that the build system knows to use
| it? I'm going to try build.mk.
|
| Ok that didn't work and I couldn't find anything about
| -fno-ds-multi-tyvar in the documentation.

Yes, in GhcLibHcOpts in build.mk is a good place.  The flag isn't documented because it's a debug-only flag that I threw in so that I can measure the effect of this particular desugaring change.  It's not really intended for users -- hard to explain just what it does.

In any case I'm just about to push a patch which fixes the original problem and makes the flag unnecessary for your purposes.

| The reason I'm compiling rather than installing is because I want to use
| NDP.

Great!  I'm copying Roman, Gabi, and Manuel so they know you're doing this.

Much of GHC is very stable but NDP emphatically isn't.  We're working hard on it, the code is changing a lot, so you may well get short-lived build difficulties.  So do have a go, but show us your code, and keep us in touch with what happens.

Simon