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by almostgotcaught 335 days ago
> LLVM into their runtime

they're not embedding LLVM - they're embedding clang. if you look at my comment below, you'll see LLVM is not currently sufficient.

> [C++] is a royal pain in the ass to target for a dynamic FFI because of that

name mangling is by the easiest part of cpp FFI - the hard part is the rest of the ABI. anyone curious can start here

https://github.com/rust-lang/rust-bindgen/issues/778
2 comments
Jeaye 335 days ago
To be fair, jank embeds both Clang and LLVM. We use Clang for C++ interop and JIT C++ compilation. We use LLVM for IR generation and jank's compiler back-end.
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johnnyjeans 335 days ago
> they're not embedding LLVM - they're embedding clang

They're embedding both, according to the article. But it's also just sloppy semantics on my part; when I say LLVM, I don't make a distinction of the frontend or any other part of it. I'm fully relying on context to include all relevant bits of software being used. In the same way I might use "Windows" to refer to any part of the Windows operating system like dwm.exe, explorer.exe, command.com, ps.exe, etc. LLVM a generic catch-all for me, I don't say "LLI" I say "the LLVM VM", for example. I can't really consider clang to be distinct from that ecosystem, though I know it's a discrete piece of software.

> name mangling is by the easiest part of cpp FFI

And it still requires a lot of work, and increases in effort when you have multiple compilers, and if you're on a tiny code team that's already understaffed, it's not really something you can worry about.

https://en.m.wikiversity.org/wiki/Visual_C%2B%2B_name_mangli...

You're right, writing platform specific code to handle this is more than possible. But it takes manhours that might just be better spent elsewhere. And that's before we get to the part where embedding a C++ compiler is extremely inappropriate when you just want a symbol name and an ABI.

But this is besides the point: The fact that it's not a problem solved by the gargantuan standard is awful. I also consider the ABI to be the exact same issue, that being absolutely awful support of runtime code loading, linking and interoperation. There's also no real reason for it, other than the standards committee being incompetent.

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