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

Calculating dependencies ...

!!! Problem resolving dependencies for =dev-ada/gpr-24.0.0-r3
 done!
Dependency resolution took 0.84 s (backtrack: 0/20).


!!! The ebuild selected to satisfy "=dev-ada/gpr-24.0.0-r3" has unmet requirements.
- dev-ada/gpr-24.0.0-r3::gentoo USE="shared -static-libs -static-pic" ADA_TARGET="gcc_15 -gcc_12 -gcc_13 -gcc_14 (-gcc_16)"

  The following REQUIRED_USE flag constraints are unsatisfied:
    exactly-one-of ( ada_target_gcc_12 ada_target_gcc_13 ada_target_gcc_14 )

  The above constraints are a subset of the following complete expression:
    any-of ( shared static-libs static-pic ) exactly-one-of ( ada_target_gcc_12 ada_target_gcc_13 ada_target_gcc_14 )