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> That said, I don't think there are any direct blog posts about it; Firefox's other code just sees Rust as C code, as far as I know. So it means the compiled

> That said, I don't think there are any direct blog posts about it; Firefox's other code just sees Rust as C code, as far as I know. So it means the compiled binary ends up in a simple compatible C ABI? thats pretty nice, if thats the case. But giving the project is using LLVM, even C++ ABI would be achievable without too much effort (i guess).

burntsushi 9y ago
To clarify, Rust has its own ABI, just like C++ has its own ABI. And just like C++, you can expose a C ABI if you want by defining special functions. In C++, it's an `extern "C" { ... }` block, and in Rust, it's a `extern "C" fn foo() ...` function declaration. You can see an example here: https://github.com/rust-lang/regex/tree/master/regex-capi https://github.com/rust-lang/regex/tree/master/regex-capi Adding C++ ABI support is a significant effort.
- oscargrouch 9y ago
  > To clarify, Rust has its own ABI, just like C++ has its own ABI. And just like C++, you can expose a C ABI if you want by defining special functions. In C++, it's an `extern "C" { ... }` block, and in Rust, it's a `extern "C" fn foo() ...` function declaration. Ohh, Now i got it. But its pretty good thing to have anyway. C ABI is the lingua franca anyway to communicate to any language, even C++. > Adding C++ ABI support is a significant effort. Ok. So if has its own ABI, im sure it would be a pretty hard undertaking to be compatible with C++. I was guessing if maybe Rust had managed to squeeze and reuse the C++ ABI.. but sure, giving Rust is not that much alike C++ this would probably be a bad decision for small gains. Thanks for clarifying.
Manishearth 9y ago
bindgen actually has the option to generate wrappers for C++ methods and other stuff for Rust to call. We don't use this, but we do use its ability to generate templates and stuff. The other way around -- getting Rust to use the C++ abi -- needs compiler changes and also has questionable benefits.
- oscargrouch 9y ago
  > getting Rust to use the C++ abi -- needs compiler changes and also has questionable benefits. Yes.. Im sure is not worthy it overall.
vvanders 9y ago
Yup, with bindgen and rusty-cheddar you can build interfaces both ways that just talk over a C ABI. It's really, really nice. In fact Rust in general is awesome for going to a wide range of platforms. I've got a project right now that runs on MSVC-x64/x86, Linux-x64, OSX-x64, Android-armv7, Android-x86, Linux-armv7 and Emscripten. Single codebase and interacting with various languages(C#, C++, Java) via the C ABI. Rust even cross-compiles my C source via GCC crate so I can use C libraries and build for any of those targets from my host(win32) machine. Also, having just spent a few hours fucking around with linker flags in Qt I can't stress enough how awesome Cargo, Crates.io, Rustup and the sane defaults Rust has. It really is an incredible ecosystem.

burntsushi 9y ago

To clarify, Rust has its own ABI, just like C++ has its own ABI. And just like C++, you can expose a C ABI if you want by defining special functions. In C++, it's an `extern "C" { ... }` block, and in Rust, it's a `extern "C" fn foo() ...` function declaration. You can see an example here: https://github.com/rust-lang/regex/tree/master/regex-capi https://github.com/rust-lang/regex/tree/master/regex-capi Adding C++ ABI support is a significant effort.

oscargrouch 9y ago
> To clarify, Rust has its own ABI, just like C++ has its own ABI. And just like C++, you can expose a C ABI if you want by defining special functions. In C++, it's an `extern "C" { ... }` block, and in Rust, it's a `extern "C" fn foo() ...` function declaration. Ohh, Now i got it. But its pretty good thing to have anyway. C ABI is the lingua franca anyway to communicate to any language, even C++. > Adding C++ ABI support is a significant effort. Ok. So if has its own ABI, im sure it would be a pretty hard undertaking to be compatible with C++. I was guessing if maybe Rust had managed to squeeze and reuse the C++ ABI.. but sure, giving Rust is not that much alike C++ this would probably be a bad decision for small gains. Thanks for clarifying.

Manishearth 9y ago

bindgen actually has the option to generate wrappers for C++ methods and other stuff for Rust to call. We don't use this, but we do use its ability to generate templates and stuff. The other way around -- getting Rust to use the C++ abi -- needs compiler changes and also has questionable benefits.

oscargrouch 9y ago
> getting Rust to use the C++ abi -- needs compiler changes and also has questionable benefits. Yes.. Im sure is not worthy it overall.

vvanders 9y ago

Yup, with bindgen and rusty-cheddar you can build interfaces both ways that just talk over a C ABI. It's really, really nice. In fact Rust in general is awesome for going to a wide range of platforms. I've got a project right now that runs on MSVC-x64/x86, Linux-x64, OSX-x64, Android-armv7, Android-x86, Linux-armv7 and Emscripten. Single codebase and interacting with various languages(C#, C++, Java) via the C ABI. Rust even cross-compiles my C source via GCC crate so I can use C libraries and build for any of those targets from my host(win32) machine. Also, having just spent a few hours fucking around with linker flags in Qt I can't stress enough how awesome Cargo, Crates.io, Rustup and the sane defaults Rust has. It really is an incredible ecosystem.