Linkers are such weird pieces of software.
So intricate that they're a huge endeavor, so fundamental every developer needs one, but so obscure there's very few of them. There's more production-quality assemblers and web servers than linkers, but neither will ever work without a linker.
Such a strange corner of computer technology.
Anyone nerdy enough writes their own compiler. Lots of people have written their own compressor or archiver; it's still an area of active research.
But linkers? It's kinda a solved problem, and so uninteresting (?). But it's a very large and fiddly problem, and so hard to toy around casually.
Heck, there's way, way more people writing their own *operating system* than their own linker. Or C compiler. Or basically anything you can think of.
@icefox I don't think this is actually true Link time optimization is relatively recent and something the LLVM people have been working on.
And a lot of the limitations of C++ come from it having to be compatible with the C linker. I think things like Rust and Haskell, say, implicitly have their own linker but also use the standard system linker to link with C libraries for foreign calls.
@Azure Rust uses the system linker. Using llvm's code generation to do link-time code optimization (equivalent to what the Java/Clojure people call tree shaking?) is still an unstable feature.
I know this because Windows link.exe does this automatically and someone euphoniously titled WindowsBunny likes to brag about it.
@Azure a combination of tree shake, inlining and then optimization based on the IR resulting of the inlining? I am fuzzy on the details.
@Azure Iirc most C compilers stop at function-level tree shake, which is Often Good Enough for technology to mostly stop there since the late 90s.
@icefox Tree shaking just gets rid of everything that isn't used. Lisp systems do it when distributing standalone executables. Stalin uses it as a prequel to partially specializing the heck out of everything.
Link time optimization is (or should be) way more than just a tree shake.