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Upgrading 7-Zip

When installing GHC or MSYS2 on Windows, Stack will also install 7-Zip. 7-Zip is a file archiver and is used by Stack to extract files from archives. This section explains the steps required to upgrade the 7-Zip version used by Stack. The 7-Zip functionality used by Stack is mature and stable. It is anticipated that the Stack-supplied 7-Zip will not need to be updated frequently. On 10 September 2022, it was updated from 7-Zip 9.20 (released on 18 November 2010) to 7-Zip 22.01 (released on 15 July 2022).

  1. Download the latest installer for 64-bit x64 Windows from 7-Zip's website.

  2. Run the installer and install to the default location (C:\C:\Program Files\7-Zip). The four relevant files from those installed will be:

    7z.exe  # 7-Zip Console
    7z.dll  # 7-Zip Engine
    license.txt  # 7-Zip License
    readme.txt  # 7-Zip Overview
  3. In the commercialhaskell/stackage-content GitHub repository, create a new draft release tagged and named 7z-XX.YY, where XX.YY is the 7-Zip version number.

  4. Upload the four relevant files in step 2 above into the draft release.

  5. Provide a description for the release. For example:

    7-Zip 22.01 (2022-07-15) for Windows 64-bit x64.
  6. Publish the release.

  7. Changes need to be made to the stackage-content/stack/stack-setup-2.yaml file, to switch over to using the newly uploaded files. For example (extract):

        url: ""
        content-length: 545280
        sha256: 254cf6411d38903b2440819f7e0a847f0cfee7f8096cfad9e90fea62f42b0c23
        url: ""
        content-length: 1814016
        sha256: 73578f14d50f747efa82527a503f1ad542f9db170e2901eddb54d6bce93fc00e

    The content-length: key's value is the size of the file in bytes. It can be obtained from the Length field of the dir command. The sha256: key's value can be obtained from the commands (in PowerShell):

    (Get-FileHash 7z.exe -Algorithm SHA256).Hash.ToLower()
    (Get-FileHash 7z.dll -Algorithm SHA256).Hash.ToLower()

    The sha256: key only accepts lowercase hash results as values.

  8. The changed stack-setup-2.yaml file should be tested locally. This can be done by:

    • temporarily disabling the existing local copy of 7-Zip by changing the name of the 7z.exe and 7z.dll files in the stack path --programs directory;

    • identifying a version of GHC not already installed in the stack path --programs directory; and

    • executing the command:

      stack --snapshot <snapshot> setup --setup-info-yaml <path to local copy of stack-setup-2.yaml>

    where <snapshot> requires the missing version of GHC.

    If all is well, the command should proceed to download the missing version of GHC, download the 7z.exe and 7z.dll files, and use the 7-Zip version to extract files from the GHC archive.

  9. Raise a pull request on commercialhaskell/stackage-contents for the changes to the locally-tested stack-setup-2.yaml file.