Better naming convention for build directories

[snowleopard]

The old build system used a variety of different names for build directories: dist, dist-boot, dist-install, stage1, etc.

Proposal: always use stageN as the build directory when using stageN compiler. This will simplify the build system considerably.

One potential inconvenience: in the old build system, ghc-stage2 executable lived in stage2 directory. Under this proposal ghc-stage2 will live in stage1 directory, because it is built by stage1 compiler. Admittedly this may be confusing for the long-time users of the old build system, however I think this is logically consistent.

[snowleopard]

I'll give it a try today. Please shout if you have any concerns about this proposal.

[hvr]

This sounds intriguing

Under this proposal ghc-stage2 will live in stage1 directory, because it is built by stage1 compiler.

...and where will ghc-stage1 then be located? :-) (and what will be found in /stage2 then?)

/cc @thomie

PS: This would have the effect that for (non-canadian) cross-compilers, the stage0/ folder would countain binaries and object-code runnable on the build-host, while stage1/ would contain binaries and object-code compiled for the target-arch. That appears to be nicely consistent

[snowleopard]

...and where will ghc-stage1 then be located? :-)

Well, in /stage0 :-) The bootstrapping compiler is referred to as Ghc Stage0 in the new build system. Does this make sense?

...the stage0/ folder would countain binaries and object-code runnable on the build-host, while stage1/ would contain binaries and object-code compiled for the target-arch. That appears to be nicely consistent

Indeed! That's another bonus I didn't think about.

[snowleopard]

I've implemented this and it works smoothly so far: 52ecf6c.

It's possible to rollback to the old naming convention without much difficulty if need be (please reopen the issue in this case).