[ANN] opam 2.4.0 is out!

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Hi everyone,

We are extremely happy to announce the release of opam 2.4.0 and encourage all users to upgrade.

What’s new? Some highlights:

  • :dragon_face: On opam init the compiler chosen for the default switch will no longer be ocaml-system (#3509)
    This was done because the system compiler (as-is your ocaml installed system wide, e.g. /usr/bin/ocaml) is known to be under-tested and prone to a variety of bugs and configuration issues.
    Removing it from the default compiler allows new-comers a more smooth experience.
    Note: if you wish to use it anyway, you are always able to do it explicitly using opam init --compiler=ocaml-system

  • :dragon: In the same vein, opam switch create [name] <version> will not include compiler packages flagged with avoid-version/deprecated in the generated invariant anymore, unless compiler flagged avoid-version/deprecated are the only ones available (#6494)
    Note: if you wish to use ocaml-system, you can simply say it explicitly using opam switch create [name] ocaml-system

  • :yarn: opam install --deps-only no longer requires unicity of package version between the request and the installed packages. In other words, if you have pkg.1 installed, installing the dependencies of pkg.2 no longer removes pkg.1 if the installed packages are compatible. This also allows to install dependencies of conflicting packages when their dependencies are compliant. (#6520)

  • :camel: GNU patch and the diff command are no longer runtime dependencies. Instead the OCaml patch library is used (#6019, #6052, #3782, ocaml/setup-ocaml#933)
    Doing this we’ve removed some rarely used features of GNU Patch such as the support of Context diffs.
    The new implementation only supports Unified diffs including the git extended headers, however file permission changes via said extended headers have no effect.

  • :snowflake: Add Nix support for external dependencies (depexts) by adding support for stateless package managers (#5982). Thanks to @RyanGibb for this contribution

  • :cockroach: Fix opam install <local_dir> with and without options like --deps-only or --show-action having unexpected behaviours (#6248, #5567) such as:

    • reporting Nothing to do despite dependencies or package not being up-to-date
    • asking to install the wrong dependencies

  • :window: The prebuilt Windows binary now includes Cygwin’s setup-x86_64.exe in the binary itself as fallback in case cygwin.com is inaccessible (#6538). Opam will also no longer fail if cygwin.com is inaccessible when checking for upgrades of setup-x86_64.exe (#6495, #6474)

  • :ocean: Many more UI additions and improvements, bug fixes, …

:open_book: You can read our blog post for the full list of important changes, and for even more details you can take a look at the release note or the changelog.

Try it!

The upgrade instructions are unchanged:

For Unix systems

bash -c "sh <(curl -fsSL https://opam.ocaml.org/install.sh) --version 2.4.0"

or from PowerShell for Windows systems

Invoke-Expression "& { $(Invoke-RestMethod https://opam.ocaml.org/install.ps1) } -Version 2.4.0"

Please report any issues to the bug-tracker.

Happy hacking,
<> <> The opam team <> <> :camel:

I’d also like to personally give a special thanks to the whole haematology department of the NHS Greater Glasgow for making my continued existence and this release – in the state that it is – possible. Fighting cancer is not easy but it is much more bearable with great people <3

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[NOTE] We have had reports of a regression in some cases when using pin-depends. We have a fix and we’re planning to have 2.4.1 out in a couple days.

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