Version 56 (modified by igloo, 6 years ago) (diff)


NOTE: The below is not fully updated yet.

Video: Getting and Building, layout of the source tree, how to set up (23'43")

Getting the GHC Sources

There are two ways to get sources to GHC: download a source distribution, or get the sources directly from our repository using git.

Source distributions

A source distribution is a file like ghc-6.12.2-src.tar.bz2, which contains a complete snapshot of the source tree for a particular version of GHC. Source distributions for all versions of GHC are available from the download page.

In addition to fixed releases of GHC, source distributions are also made each night from the current source repository, for both the HEAD and STABLE branches. To download these snapshots, head over to the download page.

Source distributions are easier to build, because we also include the output from running certain external tools like Happy, so you don't need to install these tools. See Building/Preparation for details.

Getting a GHC repository using git

The first thing to do is install git.

A source tree consists of more than one repository: at the top level there is the main GHC repository, and certain subdirectories contain separate git repositories (the full list of git repositories relating to GHC is at Repositories). To get a complete repository tree using darcs:

  $ git clone
  $ cd ghc
  $ chmod +x sync-all
  $ ./sync-all --testsuite get

Making a local branch

Branches in darcs are just separate repositories, although internally they share most of their files so are cheap to make. Once you have a local GHC repository, branching it is easy: just

 $ 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 as before to branch the rest of the repositories. You can then use sync-all -r <path> to push and pull patches between your two local repository trees.

Getting a branch

The above instructions will get the HEAD - the main trunk of GHC development. There are also branches, from which stable releases are made. The active branches are listed on Repositories.

To get a branch, add the branch name after For example, to get the ghc-7.2 branch, you would first say

  $ git clone

and then use sync-all as above to get the rest of the repositories.

Pulling new patches

The sync-all script makes it easy to pull new patches. For example, sync-all pull will pull all new patches from the original repository into the repository tree in the current directory.

Getting a complete repository tarball

Sometimes it's easier to download the entire set of repositories, complete with history, as a tarball and unpack it onto your system. These bundles are on usually in three files of the form

  • ghc-HEAD-2007-08-29-ghc-corelibs-testsuite.tar.bz2 (100Mbytes)
  • ghc-HEAD-2007-08-29-ghc-corelibs.tar.bz2 (90 Mbytes)
  • ghc-HEAD-2007-08-29-ghc.tar.bz2 (60 Mbytes)

Each of these is a subset of the previous one; pick the smallest one that has what you need. Of course, the dates may vary.

Here's how to use the bundles:

  1. Unpack the bundle, which will create a directory called ghc. You can rename this directory freely.
  2. Change into the new directory, and pull patches from the main GHC repository:
       $ cd ghc
       $ darcs pull -a
  3. Some core libraries might have been added to HEAD which were not in the last tarball. This means that after doing the last pull (which updates the list of core libraries) we need to do this to get any new libraries:
       $ chmod +x darcs-all
       $ ./darcs-all get
  4. Now use the darcs-all script to pull patches from all the library repositories that came in the tarball, and the testsuite repository:
       $ ./darcs-all pull -a
    The command darcs-all automates the fetching of the repositories for the libraries.

If you omit step (3), then darcs-all will pull patches into the GHC repository too. If one of those patches modifies the darcs-all script itself, then bizarre things can happen (or at least: in the past, they could happen.) The safe thing to do is to get your main ghc repo up to date (step 3) and then run the script.

If you see any of the following error messages on Windows (the filename varies)

Warning: ./compiler/main/DynFlags.hs-0: renameFile: permission denied (Permission denied)
darcs failed:  Error applying hunk to file ./compiler/main/DynFlags.hs
Error applying patch to the working directory.
darcs failed:  ./ renameFile: permission denied (Permission denied)
Your repository is now in an inconsistent state.
This must be fixed by running darcs repair.

after doing darcs pull -a, then use newest darcs. Version 2.0.2 is broken, version 2.3.1 works.


Note, on Windows you may have to change git's line-ending behaviour first:

git config --global core.autocrlf false

since this is a global setting, you probably want to change it back after cloning ghc, and then set it locally for the GHC repo(s).