I think the -B or --buildpkgonly option is not enough, as there might be case, where you'd like to build a package, which conflicts with another one. Example: I have mozilla-firebird-bin installed, and I'm going to build the source as a package. Emerge suggests to uninstall the bin first, and then emerge the source-ebuild. Problem: You won't have a browser during that time. Solution: Some kind of ignore&buildpkgonly option would be nice. Another solution would be to ignore the conflicts. I haven't seen this as a feature yet... Maybe in future? Reproducible: Always Steps to Reproduce:
emerge --nodeps --buildpkgonly should work