Hi, `dev-cpp/sdbus-c++` has been updated to 2.0.0 recently, but the package hypridle-0.1.2 won't compile with `dev-cpp/sdbus-c++-2.*`. This issue has been discussed in hypridle repository issues#95, and fixed in pr#96, which has been included in version 0.1.4.
I just found the hypridle-1.0.4.ebuild already in dev branch... It works for me.