The swig binary stored at https://github.com/SketchUp/ruby-c-extension-examples/blob/main/ThirdParty/bin/win32/swig/swig.exe has version number 2.0 which is not C++17 compliant.
SWIG documentation indicates that version 4.0 is required to produce C++17 code: https://www.swig.org/Doc4.1/CPlusPlus17.html#CPlusPlus17
The swig binary stored at https://github.com/SketchUp/ruby-c-extension-examples/blob/main/ThirdParty/bin/win32/swig/swig.exe has version number 2.0 which is not C++17 compliant.
SWIG documentation indicates that version 4.0 is required to produce C++17 code: https://www.swig.org/Doc4.1/CPlusPlus17.html#CPlusPlus17