Nolibc: a minimal C-library replacement shipped with the kernel

In case of multiple files, yes definitely, but most of them are quite small, and multi-file projects relying on something like nolibc are rare.

A few functions had to be exported and we found how to do it by declaring them with the weak attribute (e.g. raise(), memcpy() and a few other ones that libgcc may depend on). In this case it's during the linking stage that the linker decides to keep a single copy of each. That's also how we dealt with errno/environ/etc lately. Eventually we could imagine replacing all static functions with weak ones if it proves to provide any benefit (not convinced at the moment).