Random data will make builds unreproducible and must be avoided.

If random-like input is required, the solution is to use a predetermined value to seed a pseudo-random number generator. This value can be read from some file, a changelog or the version control system.

When Link-Time Optimizations are turned on, GCC users will write random identifiers to binary objects they create. Using -frandom-seed can be used for this particular case. As it will hash arbitrary data, passing the file name should work in most cases.

Some compilation tools will write intermediate temporary files. This might lead to reproducibility issues if paths get embedded in the final output. There’s no general solutions for such cases, better fix the code directly. One way is to use the .file assembler directive like it has been done in O’Caml.