Analysis of extern "C" functions and all reachable types

[shepmaster]

One of our clients was exposing a C API from Rust. That C API would then be consumed via languages such as JavaScript or C#. The creation of such an API is very mechanical and fiddly, requiring that the exposed Rust information match exactly to the C / JS / C# definitions.

To reduce failure points, I wanted to analyze the code to find all extern "C" functions and then find all types referenced in the function signature. This data could be dumped to a file for further processing.

cbindgen helps with creating a C or C++ header file from Rust code, but does not help much for the bindings for other languages. My envisioned use case would allow more user flexibility.