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Comment by mgaunard | Hacker News Reader

There are two paths towards building small binaries:

- build all of your dependencies yourself (including standard libs) and ensure they're built with LTO, and link everything statically. Everything you don't actually need will be removed.

- link everything dynamically. The total image size is huge, but technically it's not part of your binary, and can be shared with other binaries as well.

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That's actually one thing that I really like about Rust, since everything is static linkage by default it's easy to make pretty sweeping changes, on nightly you can even recompile the stdlib with different configurations(I.E. Oz/Os) if you want.

Static linkage is not there only by default but it is actually the only option because Rust doesn't have a stable ABI. I personally don't consider this as an advantage and in C++ you can also statically link against the standard library if you wish to. I don't see many valid reasons to do so but the option is there.

in practice ABI compatibility is holding back libstdc++ more than anything.

I haven't yet found convincing arguments other than cargo cult programming ones. But I'd be glad to hear concrete examples if you have some and I'll be happy to discuss.

See Carbon.

I did. And?

They're making the argument that it is, abd even holding back C++ itself, which is why they started their own C++ fork.

LTO without Os/z will increase your binary size, since more things get inlined

Why would most things get inlined when you're optimizing for size rather than speed?

if you don't optimize for size, more things get inlined. LTO creates more inlining opportunities, so plain LTO will increase your binary size. A complicating factor is small functions often inline smaller than leaving them outlined, since you no longer need call and return infrastructure.

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