hadrian/build.sh clean continues building Hadrian, instead of cleaning stuff up

[thomie]

make clean or hadrian/build.sh clean should preferably finish in a few seconds.

Scenario: a user has second-thoughts about starting their Hadrian-powered ghc build, or wants to still tweak some settings and start over.

The clean target should perhaps be implemented in a script.

[snowleopard]

A related issue: at the moment we are not cleaning the Hadrian executable (it cannot delete itself).

Once the move of all build results to buildRootPath is complete (#113) cleaning will be as simple as deleting the build directory.

[ndmitchell]

Is the goal of this to avoid compiling Hadrian itself? If so, I disagree - having the first clean take 1 min to compile Hadrian is no big deal, but having two sources of information or duplicating command line parsing is inadvisable.

[thomie]

Is the goal of this to avoid compiling Hadrian itself?

yes

having the first clean take 1 min to compile Hadrian is no big deal

it was a small annoyance to me

Priority lowest.

[snowleopard]

Just to record here that there may be more complexity to clean than I previously thought:

Build system is IMO awful. It works fine, after a fresh clone ./boot && ./configure && ./make just works. But you can't:

• Clean only stage2.
• Clean only libraries.
• Build only stage1/2 from the top level.
• Build only the libraries.
• Uninstall GHC.

Hopefully with new Shake-based build system I can at least implement these myself.

(From this reddit thread: https://www.reddit.com/r/haskell/comments/4isua9/ghc_development_outsidein/. The emphasis is mine.)

Cleaning only specific stages or only specific package(s) may be useful and easy implement in Hadrian, but I think it would be next to impossible to support this from within a script.

A script for cleaning everything (just by deleting _build) can be easily written by the user in their favourite script language. I don't think it is really worth to ship this trivial script together with the build system.

[izgzhen]

@snowleopard I guess this is a wontfix?

[snowleopard]

@izgzhen Let's keep this open for now. I've marked it low priority. Perhaps this will become more important when we have more Hadrian users.

[alpmestan]

A lot of this should be significantly easier with the new build-dir structure though, right?

[snowleopard]

Yes, clean up is pretty easy now.

A special script even feels superfluous, since it's going to be just something like rm -rf _build.

[alpmestan]

Right. Except for those files created by boot and configure, which still live in the source tree.

[snowleopard]

True, we need to keep track of files produced by boot and configure, which is a bit annoying.

[angerman]

If you really want to take care of boot and configure, I think the best option is to just invoke git clean -xfd. That of course requires a git checkout.

Maybe the question "What does one want to achieve with that clean step?" needs to be answered first.

[alpmestan]

Yeah, it should be answered first, because git clean -xdf would remove e.g new files that you have not yet registered in git.

[snowleopard]

I believe this issue is out of date, so closing.