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

Calculating dependencies ...

!!! Problem resolving dependencies for =dev-cpp/opentelemetry-cpp-1.25.0
 done!
Dependency resolution took 0.83 s (backtrack: 0/20).


!!! The ebuild selected to satisfy "=dev-cpp/opentelemetry-cpp-1.25.0" has unmet requirements.
- dev-cpp/opentelemetry-cpp-1.25.0::gentoo USE="http -elasticsearch -grpc -otlp -prometheus -test"

  The following REQUIRED_USE flag constraints are unsatisfied:
    http? ( otlp )

  The above constraints are a subset of the following complete expression:
    grpc? ( otlp ) http? ( otlp )