Package ocaml-option-default-unsafe-string

Failed to find a solution:

no platform:
2025-05-16 18:05.16 [INFO] Solving for ocaml-base-compiler,
                           ocaml-option-default-unsafe-string, constraints ocaml-base-compiler<=5.3.0,
                           ocaml-option-default-unsafe-string=1 using opam_repository_commit cf409d95af00ff822422bd76b657ed213b661401

2025-05-16 18:05.17 [INFO] base: eliminated all possibilities in 0.56 s

2025-05-16 18:05.17 [INFO] = base =

2025-05-16 18:05.17 [INFO] Can't find all required versions.
Selected: base-bigarray.base base-threads.base base-unix.base
          host-arch-x86_64.1 ocaml-config.3
          ocaml-option-default-unsafe-string&ocaml-base-compiler system-mingw
          system-mingw|system-msvc host-arch-x86_64 ocaml-base-compiler
          ocaml-base-compiler
- ocaml -> ocaml.4.14.3
    ocaml-variants 4.14.3+trunk requires = 4.14.3
- ocaml-base-compiler -> (problem)
    User requested <= 5.3.0
    Rejected candidates:
      ocaml-base-compiler.5.3.0: In same conflict class (ocaml-core-compiler) as ocaml-variants
      ocaml-base-compiler.5.3.0~rc1: In same conflict class (ocaml-core-compiler) as ocaml-variants
      ocaml-base-compiler.5.3.0~beta2: In same conflict class (ocaml-core-compiler) as ocaml-variants
      ocaml-base-compiler.5.3.0~beta1: In same conflict class (ocaml-core-compiler) as ocaml-variants
      ocaml-base-compiler.5.3.0~alpha1: In same conflict class (ocaml-core-compiler) as ocaml-variants
      ...
- ocaml-option-default-unsafe-string -> ocaml-option-default-unsafe-string.1
    User requested = 1
- ocaml-variants -> ocaml-variants.4.14.3+trunk
    ocaml-option-default-unsafe-string 1 requires >= 4.12.0~ & < 5.0.0~~
- system-mingw -> (problem)
    No usable implementations:
      system-mingw.1: Availability condition not satisfied