1. Singletonish things like global allocators, rayon-core, etc

2. You may have made a package static safe to mutate with a mutex, but it could be a bad thing to have different versions of that mutex.

3. Compile time computed tables (unicode table, perfect hashes, etc) could be imported multiple times ballooning the binary.

4. ABI/type compatibility with any reexported types

Yeah, go has a magic function `func init()` which gets called before main. (You can actually have as many init's as you want, and they all get called.)

Probably evil, though so far it hasn't hurt me in the same way as, e.g., c++ constructors have. Maybe because it's more explicit and thus you're less likely to use it in practice.