[menaerus]

Ah, I see. Thanks for the example. I think I understand now. In C++ problem of monomorphization, or potential bloat due to excessive template instantiations, is normally handled at the linker level but can be controlled at the code level too through either by rewriting the code with some other type-erasure technique or simply by extracting bits of not-quite-generic-code into smaller non-generic entities (usually a non-templated base class).

Does this mean that the Rust frontend is spitting out the intermediate representation such that it doesn't allow the de-duplication at the linking phase? I see that Rust now has its own linker as of Sep 25' but it still works with normal linkers that are used in C and C++ too - gnu ld, lld, mold, ...

[dminik]

There's no custom rust linker just yet. The change in September was to switch from GNU LD to lld for performance on Linux. There are some rust linker projects (like wild), but these tend to be aimed at speed (and/by incremental linking) rather than executable size.

I'm not sure how useful deduplication at the linker level is in practice. Though I don't think Rust does anything different here than C++. The main issue I imagine is that the types used in generic code have different sizes and layouts. This seems to me like it would prevent deduplication for most functions.