I have some experience getting several non-trivial projects to build with a small C compiler [1]. Generally, the more a toolchain resemblance, say GCC, the more GCC specific stuff build scripts will feed to it, this may send you down a rabbit hole of recreating GCC behavior distracting from the intended topic. There are simply too many varying factors in the internal messages between a toolchain's sub-fuctions: versioning, target system, the specific installation's default configuration etc. I have no idea what the author's intended modification are, but it may be actually simpler, and more reliable, to modify a compiler at source level than to provide a drop in injection of a certain stage.
[1] https://github.com/fuhsnn/widcc?tab=readme-ov-file#building-...