Each Python version uses a specific compiler version. In most cases, you should use the same compiler version for building python extensions.
| Visual C++ | CPython |
|---|---|
| 2015, 2017 | 3.7 |
| 2015 | 3.5,3.6 |
| 2010 | 3.3,3.4 |
| 2008 | 2.6, 2.7, 3.0, 3.1, 3.2 |
Currently, the official ONNXRuntime Python wheel (v1.3.0 onwards) hosted on PyPi requires Visual C++ 2019 runtime installed on the target machine.
If the Python wheel is built from source using the build toolset provided with Visual Studio 2017, it will work with the Visual C++ 2017 runtime.
CPython 3.7 is distributed with a VC++ 2017 runtime. Unlike the earlier VC++ version, VC++ 2017 Runtime is binary backward compatible with VC++ 2015. Which means you could build your application with VC++ 2015 then run it with VC++ 2017 runtime.