pip install face_recognition giving error
I ran into this issue as well. I am using windows and have a python environment that I am installing the requirements to.
I ran pip install cmake , and then pip install dlib. I no longer received the error and successfully installed dlib.
RuntimeError:

CMake must be installed to build the following extensions: dlib


Failed building wheel for dlib
  Running setup.py clean for dlib
Failed to build dlib