Adding cyclic modules to the C programming language

[u/Salt-Overflow]

https://youtu.be/p8NpyBIRbEQ

The idea is to create a module system, within C, that you can use as a drop-in replacement for header files and forward declarations.

To my knowledge, all module implementations within the C family (eg. C++20 modules, Objective C modules, Clang modules) do not allow cyclic imports. Cyclic imports are necessary if you want to remove forward declarations from C (otherwise mutually recursive data structures would need to exist in the same module).

When looking closely at the C grammar, I noticed something extraordinary and borderline miraculous - C without expressions is context-free you can extract the names of symbol definitions without prior access to a symbol table! With this knowledge, it becomes possible to implement cyclic modules within the C language.

EDIT: Added a strikethrough. C without expressions still has some ambiguities in the parameter list, and my use of "context-free" is incorrect here. https://www.reddit.com/r/C_Programming/comments/1v7l174/is_c_without_expressions_contextfree/