Hello, On Tue, Sep 18, 2012 at 1:25 PM, Ian Lynagh wrote:

Why do you want to build 7.6 but not 7.6.1, OOI?

I was trying to build a different branch which is a fork of 7.6---I

wanted to play around with the profiling suite described in the "Core Diving" talk from the Haskell Implementors workshop.

More generally, I run into this problem all the time with people trying to

...

build the branch I work on, so it really would be nice if we started using sub-modules to keep track of this dependency. I talked to folks at ICFP about this, and one idea was that we could check in the "fingerprint" for a branch into the repo, and track the dependencies this way, but this is

See

http://hackage.haskell.org/trac/ghc/wiki/Building/GettingTheSources#Tracking...

The nightly build logs include a fingerprint.

Where are the nightly build logs?

exactly what git's submodule machinery does, so it seems pointless to

...

implement the functionality which is already there with a standard interface. Thoughts?

http://hackage.haskell.org/trac/ghc/wiki/DarcsConversion#Theperspectiveonsub...

I have seen this. Our custom "fingerprint" solution has the exact same drawbacks (because it does the exact same thing as sub-modules), and in addition it has the drawback of 1. being a custom non-standard solution, 2. it is not obvious where to find the "fingerprint" associated with a particular branch (which is what lead to my question in the first place). -Iavor

Well, it doesn't quite have the same drawbacks as submodules, because our solution places a burden only on someone who wants to recover a particular repository state, rather than on everyone doing development.

I think it's worth keeping an eye on submodules in case they fix the gotchas in the UI, but at the moment it looks like we'd have a lot of confused developers, lost work and accidental breakages due to people not understanding how submodules work or forgetting to jump through the correct hoops.

I'm not saying fingerprints are a good solution, obviously they only solve a part of the problem, but the current tooling for submodules leaves a lot to be desired.

Since you already have fingerprinting in place, have you looked into 'git subtree' for the remaining functionality? Used to be an addon module, has recently been merged into git (contrib/). http://apenwarr.ca/log/?m=200904#02 https://github.com/gitster/git/blob/634392b26275fe5436c0ea131bc89b46476aa4ae... https://github.com/apenwarr/git-subtree I don't have further information or recommendations, just wanted to pass on this alternative - it tends to come up when googling for 'git submodule' issues, and most reports on it have been favorable (no idea whether it would work for the size and complexity of the ghc&friends repo landscape). Claus

On 20/09/2012 16:25, Iavor Diatchki wrote:

perhaps we should have a well-defined place in the repo where we keep the finger-prints associated with tags and branches in the main repo? This would make it a lot easier to get to a fully defined previous/different state.

We do have tags for releases, so you can say ./sync-all checkout ghc-7.6.1-release and get the exact 7.6.1 sources. I wouldn't object to also having fingerprints in the repo too though. Cheers, Simon

On this note, could someone send the link to the 7.6 fingerprint? Ian said that it is somewhere in the nightly build logs but I don't where to look.

-Iavor

On Thu, Sep 20, 2012 at 7:20 AM, Simon Marlow mailto:marlowsd@gmail.com> wrote:

On 19/09/2012 02:15, Iavor Diatchki wrote:

> exactly what git's submodule machinery does, so it seems pointless to

> implement the functionality which is already there with a standard > interface. Thoughts?

http://hackage.haskell.org/__trac/ghc/wiki/DarcsConversion#__Theperspectiveo... http://hackage.haskell.org/trac/ghc/wiki/DarcsConversion#Theperspectiveonsub...

I have seen this. Our custom "fingerprint" solution has the exact same drawbacks (because it does the exact same thing as sub-modules), and in addition it has the drawback of 1. being a custom non-standard solution, 2. it is not obvious where to find the "fingerprint" associated with a particular branch (which is what lead to my question in the first place).

Well, it doesn't quite have the same drawbacks as submodules, because our solution places a burden only on someone who wants to recover a particular repository state, rather than on everyone doing development.

I think it's worth keeping an eye on submodules in case they fix the gotchas in the UI, but at the moment it looks like we'd have a lot of confused developers, lost work and accidental breakages due to people not understanding how submodules work or forgetting to jump through the correct hoops.

I'm not saying fingerprints are a good solution, obviously they only solve a part of the problem, but the current tooling for submodules leaves a lot to be desired.

Cheers, Simon