Description of problem: As time goes by, there is occasional build dependency bitrot. It would be neat if RPM during the build tracked what was accessed, and warns if a build dependency was never accessed at all during the build. Version-Release number of selected component (if applicable): rpm-current
Keeping track of what the build actually does is far out of the scope of rpm. The way to solve this is to build the package without the build deps and check if there is no error.