Package eio

Failed to find a solution:

no platform:
2026-02-04 14:54.43 [INFO] Solving for ocaml-base-compiler,
                           eio, constraints ocaml-base-compiler<=5.4.0,
                           eio=0.5 using opam_repository_commit 45c04602c2fc908af6d1b17ba39c7517d58cb274

2026-02-04 14:54.44 [INFO] base: eliminated all possibilities in 0.23 s

2026-02-04 14:54.44 [INFO] = base =

2026-02-04 14:54.44 [INFO] Can't find all required versions.
Selected: base-threads.base base-unix.base bigstringaf.0.10.0 csexp.1.5.2
          cstruct.6.2.0 dune.3.21.0 dune-configurator.3.21.0 fmt.0.11.0
          hmap.0.8.1 lwt-dllist.1.1.0 mtime.2.1.0 ocaml.5.6.0
          ocamlbuild.0.16.1 ocamlfind.1.9.8 optint.0.3.0 psq.0.2.1 seq.base
          topkg.1.1.1 eio&ocaml-base-compiler ocaml-base-compiler
- eio -> eio.0.5
    User requested = 0.5
- ocaml-base-compiler -> (problem)
    User requested <= 5.4.0
    eio 0.5 requires not(>= 5.0.0~beta1)
    Rejected candidates:
      ocaml-base-compiler.5.4.0: Incompatible with restriction: not(>= 5.0.0~beta1)
      ocaml-base-compiler.5.4.0~rc1: Incompatible with restriction: not(>= 5.0.0~beta1)
      ocaml-base-compiler.5.4.0~beta2: Incompatible with restriction: not(>= 5.0.0~beta1)
      ocaml-base-compiler.5.4.0~beta1: Incompatible with restriction: not(>= 5.0.0~beta1)
      ocaml-base-compiler.5.4.0~alpha1: Incompatible with restriction: not(>= 5.0.0~beta1)
      ...
- odoc -> (problem)
    dune 3.21.0 requires not(< 2.0.1)
    Rejected candidates:
      odoc.3.1.0: Requires ocaml >= 4.08.0 & < 5.5
      odoc.3.0.0: Requires ocaml >= 4.02.0 & < 5.4
      odoc.2.1.1: Requires ocaml >= 4.02.0 & < 5.1
      odoc.1.5.3: Incompatible with restriction: not(< 2.0.1)