Replying to an earlier post

C/C++ compilers are non deterministic due to support of super macros that change run to run, non-deterministic optimisation strategies or ordering due to parallelism, and linkers often produce different outputs every time they are run where subtle bugs can cause crashes when addresses don’t line up how you expect. And that’s without mentioning projects that use a configuration step.

It’s actually a big problem in producing reproducible builds for security.