OPAM 1.2.2 Released

Authors: Louis Gesbert
Date: 2015-05-07
Category: Tooling
Tags: opam

OPAM 1.2.2 has just been released. This fixes a few issues over 1.2.1 and brings a couple of improvements, in particular better use of the solver to keep the installation as up-to-date as possible even when the latest version of a package can not be installed.

Upgrade from 1.2.1 (or earlier)

See the normal installation instructions: you should generally pick up the packages from the same origin as you did for the last version -- possibly switching from the official repository packages to the ones we provide for your distribution, in case the former are lagging behind.

There are no changes in repository format, and you can roll back to earlier versions in the 1.2 branch if needed.


  • Conflict messages now report the original version constraints without translation, and they have been made more concise in some cases
  • Some new opam lint checks, opam lint now numbers its warnings and may provide script-friendly output
  • Feature to automatically install plugins, e.g. opam depext will prompt to install depext if available and not already installed
  • Priority to newer versions even when the latest can't be installed (with a recent solver only. Before, all non-latest versions were equivalent to the solver)
  • Added opam list --resolve to list a consistent installation scenario
  • Be cool by default on errors in OPAM files, these don't concern end-users and packagers and CI now have opam lint to check them.


  • OSX: state cache got broken in 1.2.1, which could induce longer startup times. This is now fixed
  • opam config report has been fixed to report the external solver properly
  • --dry-run --verbose properly outputs all commands that would be run again
  • Providing a simple path to an aspcud executable as external solver (through options or environment) works again, for backwards-compatibility
  • Fixed a fd leak on solver calls (thanks Ivan Gotovchits)
  • opam list now returns 0 when no packages match but no pattern was supplied, which is more helpful in scripts relying on it to check dependencies.

About OCamlPro:

OCamlPro is a R&D lab founded in 2011, with the mission to help industrial users benefit from experts with a state-of-the-art knowledge of programming languages theory and practice.

  • We provide audit, support, custom developer tools and training for both the most modern languages, such as Rust, Wasm and OCaml, and for legacy languages, such as COBOL or even home-made domain-specific languages;
  • We design, create and implement software with great added-value for our clients. High complexity is not a problem for our PhD-level experts. For example, we helped the French Income Tax Administration re-adapt and improve their internally kept M language, we designed a DSL to model and express revenue streams in the Cinema Industry, codename Niagara, and we also developed the prototype of the Tezos proof-of-stake blockchain from 2014 to 2018.
  • We have a long history of creating open-source projects, such as the Opam package manager, the LearnOCaml web platform, and contributing to other ones, such as the Flambda optimizing compiler, or the GnuCOBOL compiler.
  • We are also experts of Formal Methods, developing tools such as our SMT Solver Alt-Ergo (check our Alt-Ergo Users' Club) and using them to prove safety or security properties of programs.

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