[galangalalgol]

Posted elsewhere but The default hello world stripped with one codegen unit and panic=abort was 342kB both nightly and stable. Adding lto dropped it 42kB in stable and 40kB in nightly. Adding build-std and only building core did not reduce it any further in size.

[surajrmal]

I agree, but if you use more of the std library it will contribute more to the final image. I can write a 100 line rust file that ends up being 1MiB (even after lto) because I maximize as much code from the standard library as possible. This is not a knock on rust, but your statements can be a misleading as well. In practice most folks ignore the majority of the standard library so only a few hundred kib of std library end up in their binary.

[galangalalgol]

Bit late, but I made a small program that did network and file io as well as using a variety of containers and running system commands. I couldn't get the default release over 650kB. Using a single codegen unit lto strip and panic=abort got that down to 432kB. Using build-std didn't get it any smaller still. When I added optimization for size was the only way I got build-std to shrink things any further than the other options alone, and that only got me 10kB. My conclusion is that build-std is not a substantial contributor. Using std seems to add 300kB-500kB depending on how much you use. That seems like a lot to me because I am old, but elf binaries add several kB of header so maybe I should stop worrying so much.

[surajrmal]

If you build the standard library as a shared library it will be 4+MiB. The portion of that which you end up using is variable but there are ways to accomplish large usage without a great deal if code. I can get a 1.5 MiB binary down to 500KiB by dynamically linking the shared library. It's a net fun because I have many such binaries so it saves size in aggregate. It really does come down to what subset you use though.