How Build works ?

1. Codegen.cmake :

• Installs Caffe2 header files (this has nothing to do with code generation)
• Configures caffe2/core/macros.h
• Creates an ATen target for its generated C++ files and adds it as a dependency

2. Caffe2CmakeLists.txt This file does all the important stuff for codegen and build setup. Example: https://github.com/pytorch/pytorch/blob/3f72bcfcaacadfbbfb40e1cc32fc15fdec26bca5/caffe2/CMakeLists.txt#L299

This line generates all the Python bindings for templates.