The option currently applies to only dependency version constraints according to the man page:
--ignore-constraints-on[=PACKAGES] (default=)
Forces opam to ignore version constraints on all dependencies to
the listed packages. This can be used to test compatibility, but
expect builds to break when using this. Note that version
constraints on optional dependencies and conflicts are unaffected.
This is equivalent to setting $OPAMIGNORECONSTRAINTS.
However the option name itself sounds more general, so it could also apply to package available constraints. In particular, it could further help with compatibility testing when the package currently has been made unavailable on certain OS-s, architectures, etc.
The option currently applies to only dependency version constraints according to the man page:
However the option name itself sounds more general, so it could also apply to package
availableconstraints. In particular, it could further help with compatibility testing when the package currently has been made unavailable on certain OS-s, architectures, etc.