> One explaination for that would be stripping "out of scope" macros that the sublibrary depends on but wishes to avoid including.

Another explaination would be the original source being multi-file, with the single-file variant being generated. E.g. duktape ( https://github.com/svaarala/duktape ) generates src-custom/duktape.c from src-input/*/*.c ( https://github.com/svaarala/duktape/tree/master/src-input ) via python script, as documented in the Readme:

https://github.com/svaarala/duktape/tree/master?tab=readme-o...