dev meeting 2025 03 05

Agenda

• Solution for (package (name x) (deps)? Do we want users to have it or do we support the opam file deps when no deps available?
• Dune needs ocamlc to be able to load the default context in Dune. What should we do about it because some packages don't rely on it.
  • Delay ocaml loading until necessary?
  • For package management, the toolchain requires ocaml to be there by default?

Meeting notes

Attendes: @Leonidas-from-XIV @gridbugs @maiste @art-w @jason h.

@gridbugs: dune pkg is currently using the dependencies from the dune-project files and not using the opam files. Many projects have more uptodate opam files (at least if we read them from the opam-repo). Change the default to read from opam if dune-project declares no dependencies? At least add a warning that there are no dependencies in the dune file?

• @Leonidas: why would opam files be more uptodate? maybe because or, not, dependency constraints were not supported before? "deprecated package name" could explain empty packages?
• @shym: would like an error if there are any difference between dune-project and .opam dependencies, to help converging on the same metadata; Warning message could be "Will be using .opam file dependencies because ..." to at least tell the user which file lists the dependencies
• @gridbugs: makes sense to remove ambiguity on which dependencies will be used, but as a warning and not an error to avoid breaking workflows

@gridbugs: It's possible to install dune without having OCaml installed. Running dune build then fails because it can't find an installed version of ocaml.

• @Leonidas: dune is to eager to call ocamlc for its config. Can we delay? @gridbugs: it's not obvious because there's too much to wrap in Memo to defer the call to ocaml config.
• @maiste: can we enforce that ocaml is always a dependency for dune projects? then dune pkg lock will install a compiler and dune build would work
• @Leonidas & @maiste https://packages.debian.org/bookworm/ocaml-dune Debian's dune doesn't depend on ocaml
• @Leonidas: we can't assume that ocaml was previously installed
• @gridbugs: it's almost possible to use dune without having installed ocaml before, but then there are subtle issues with running tooling where suddenly ocaml might be missing?
• @maiste: uv asks the user if it can install python when it's missing
• @gridbugs & @art-w: can we make up a fake ocaml config if ocamlc is missing? (as we expect it'll not be used) @maiste: this might be dangerous later on? it sounds bad to use fake values for arch etc.
• @gridbugs: is in favor of obtaining more system informations without having to depend on ocamlc, even if that may not be sufficient to fix this issue fully