Getting the GHC Sources (GHC 7.8 or earlier)

These instructions refer to GHC 7.8 or earlier. For more recent GHC versions, see Building/GettingTheSources

Getting a branch

It is best to check out the desired branch directly in a fresh clone, as follows:

  $ git clone -b ghc-7.8 git://git.haskell.org/ghc.git ghc-7.8
  $ cd ghc-7.8
  $ ./sync-all get -b ghc-7.8

Getting a tag

Each release is tagged in the git repository, making it possible to check out an old version of GHC by tag. To see all available tags, run git tag in the GHC repository.

To check out a specific version of GHC, run

  $ git clone http://git.haskell.org/ghc.git
  $ cd ghc
  $ git checkout <tag>
  $ ./sync-all get

For checking out a tag after you have already done ./sync-all [OPTIONS] get

  $ shopt -s extglob
  $ rm -rf !(.git)
  $ git checkout -f <tag>
  $ ./sync-all get

Getting a GHC repository from GitHub

  $ git clone git://github.com/ghc/ghc
  $ cd ghc
  $ ./sync-all get

If you want to clone your own fork instead, add an argument to sync-all to tell it where it can find the other repositories it needs.

  $ git clone <your preferred github.com GHC fork URL> ghc
  $ cd ghc
  $ ./sync-all -r git://github.com/ghc get

Making a local clone

You can make a local clone of a GHC tree with

 $ git clone ~/ghc ~/ghc-branch

where ~/ghc is the repository you want to branch and ~/ghc-branch is where you want to put the branch. Then use sync-all (see Building/SyncAll) to clone the rest of the repositories. Note that the origin for the local clone will point back to the repository that it was cloned from - if you want origin to point back to the main GHC repo then do this:

  $ ./sync-all -r git://git.haskell.org remote set-url origin

Tracking the full repository state (pre-March 2014, e.g., the 7.8.* branches)

Since db19c665e/ghc, all used repositories are submodules, so this is only relevant to track older states, e.g., for GHC 7.8.*.

The full state of a GHC repository includes the current state of the repositories for all of the GHC boot libraries that are used to to build GHC (list of boot libraries). For GHC 7.8.* the repositories for these libraries are fetched and updated by the sync-all script. To record the full repository state (including boot libraries), git submodules can be used starting from March 2014, but for 7.8.* they are not fully usable, so fingerprints are provided instead in annotated & gpg-signed release tags, such as http://git.haskell.org/ghc.git/tag/refs/tags/ghc-7.8.3-release. That way you're able to restore via the fingerprint for a given release, as in:

$ ./utils/fingerprint/fingerprint.py restore -f <(git show ghc-7.8.3-release | grep -F '|')

Here is how such fingerprints are created. The fingerprint.py script in utils/fingerprint/ can create a "fingerprint" to uniquely identify a GHC repository state by recording the current commits of the GHC and boot library repositories. This fingerprint can be used later to restore the state of all repositories to the state captured by the fingerprint.

To create a new fingerprint, run the create command in the top level ghc repo. The fingerprint can also be created from a Builder log that contains the appropriate output from the sync-all command by passing the log file to the create command with the -l flag.

$ ./utils/fingerprint/fingerprint.py create 
$ ./utils/fingerprint/fingerprint.py create -l builder.log 

This command will create a new fingerprint, which is just pairs of repositories and commits.

To restore a fingerprint use the restore command and pass either a fingerprint file with the -f flag or a builder log file with the -l flag.

$ ./utils/fingerprint/fingerprint.py restore -f 2011-05-23.fp 
$ ./utils/fingerprint/fingerprint.py restore -l builder.log 

This command will read the fingerprint and perform a checkout of the appropriate commit for each repository found in the fingerprint. By default, the restore command will create a new branch in the top level ghc repository and add an entry to git config that sets the new branch's remote to origin. The config options are added so that future sync-all commands will work as expected. Passing the -n flag will cause the fingerprint script not to create a new branch. To "unrestore" a fingerprint, simply use sync-all to checkout the master branch in each repository

$ ./sync-all checkout master 

To make the best use of fingerprinting, you need to collect fingerprints for the states you may wish to restore. To ease the automatic collection of fingerprints, the fingerprint.py script allows a -d DIR option that will output a fingerprint to the directory DIR with the current time stamp as a file name. The -g DIR option tells the script to run in the ghc repository pointed to by DIR. These options can be useful for collecting fingerprints as a cron job or on a post-commit hook.

To restore the repository state as of a particular date, you can grab a fingerprint emitted by one of the nightly builds. The nightly build emails are sent to the ghc-builds mailing list, and have subjects like "[nightly] 06-Oct-2012 build of HEAD on x86_64-unknown-linux (cam-04-unx)". Copy and paste the fingerprint section, which looks something like this:

Respository hashes: 
.|4a138b708463a99a1087ce2d8a70239de3aa04e4 
ghc-tarballs|18e0c37f8023abf469af991e2fc2d3b024319c27 
libraries/Cabal|31c3f404dceb221d7281467a66bf68cc166fc2d9 
libraries/Win32|21335a30161c099da79ae9619c9782e5e32e4644 
libraries/array|e4b800af700cd7a5d42286086f17713ec98698a0 
libraries/base|219ea0e539aca217fe1819baf02d4cdd1d670f51 
... and so on 

Put it in a file, and run ./utils/fingerprint.py restore -f <file> to restore your repository tree to that state.