These are the packages that would be merged, in order:

Calculating dependencies ...

!!! Problem resolving dependencies for =dev-vcs/mercurial-6.7.4-r2
 done!
Dependency resolution took 0.83 s (backtrack: 0/20).


!!! The ebuild selected to satisfy "=dev-vcs/mercurial-6.7.4-r2" has unmet requirements.
- dev-vcs/mercurial-6.7.4-r2::gentoo USE="chg gpg -debug -emacs -rust -test -tk" PYTHON_TARGETS="-python3_12"

  The following REQUIRED_USE flag constraints are unsatisfied:
    python_targets_python3_12

  The above constraints are a subset of the following complete expression:
    rust? ( !python_targets_python3_12 ) any-of ( python_targets_python3_12 )