Support cargo (Rust) libraries

[HappySeaFox]

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Is your feature request related to a problem? Please describe.

Some Rust libraries can be built with cargo tool into a C library with dll+lib files. For example, resvg. It would be great to enable vcpkg to build such libraries.

For example: to compile resvg C binding:

1. Download and run rustup-init.exe from https://www.rust-lang.org/tools/install
2. Compile resvg:

   git clone https://github.com/RazrFalcon/resvg.git
   cd resvg\c-api
   %USERPROFILE%\.cargo\bin\cargo build --release

This creates resvg.dll and resvg.dll.lib.

Proposed solution Add cargo as build tool.

Describe alternatives you've considered -

Additional context -

[JackBoosY]

Can you provide more build documentation for cargo?

[HappySeaFox]

As per the docs https://github.com/rust-lang/cargo, cargo has a recursive build dependency on itself :) Yes, one needs cargo installed to build cargo from sources. I think installing a pre-compiled binary package is the only way to go to install it from scratch.

The pre-compiled package is available for different platforms and compilers. It also allows unattended install with specifying CLI options. Custom installation path can be set with environment variables, see https://github.com/rust-lang/rustup/issues/618#issuecomment-236252290

[JackBoosY]

@HappySeaFox The last question is: are there other libraries that can be compiled with cargo?

[HappySeaFox]

That's a good question. I haven't done any research as resvg is the only Rust lib I need. However, to support cargo, I can say that making C api for a Rust library is rather easy. I mean it's possible to patch a Rust-only library and add it in vcpkg rather easily.

[Be-ing]

This would be neat. I have an odd use case for this which I don't think I'd try to upstream, but it could be a nice hack for our overlay. In Mixxx we use sccache, which is a Rust program, for complier caching on Windows with MSVC. It would be nice if vcpkg could automatically install this as a build tool along with the libraries the application uses.

FWIW there is a Rust crate to do the opposite and integrate vcpkg into Cargo.

[soulmachine]

Rust libraries are can be easily converted to FFI compatible libraries, for example, crypto-crawler-ffi.

If vcpkg supports building cargo projects out-of-box, many rust libraries can be imported to vcpkg.io.

[JackBoosY]

It looks like rustup doesn't provide a full tarball, but uses the built-in management tools to install and manage its dependencies. So we can't easily add it as a tool, we can only follow vcpkg_acquire_msys.

[kLiHz]

I think the question here might not be getting rustup ported to or integrated into vcpkg, since it's a installer that helps users to download and manage pre-built binaries of the Rust toolchain - such as rustc (Rust compiler), rust-std (Rust standard lib) and cargo (a package manager and also a build tool). In my opinion these binaries or the Rust toolchain should be installed by the user, just as they need to install MSVC or GCC C/C++ compiler to use vcpkg.

Although it seems that cargo can be optional, most of the time it's highly tied to Rust projects. So as far as I can see, to support Rust-based libraries, we might need to support cargo in vcpkg. Or maybe these Rust crates which provide C/C++ libraries are somehow different and not relying on cargo so much that we can develop/find something equivalent? It would be nice if someone familiar with Rust can tell me 😃.

And since I'm not quite familiar with vcpkg and how it works now (I saw discussion in #15441 but still not quite clear), I have no idea how Rust support can be added to vcpkg, or how possible/difficult it can be. What I know is that most C/C++ projects uses CMake or Makefile to manage the build, while Rust projects use cargo with Cargo.toml which defines the build.

Anyway I believe it would be nice if some Rust libraries can be brought onto vcpkg, like besides the resvg mentioned above, the quiche project can also be helpful for enabling HTTP/3 support for curl (#32109). 😇

[dg0yt]

Looking at how Debian packages librsvg (no resvg): It has meson, cargo and cargo-c preinstalled. But: The usually small set of Debian changes on top of the orig tarball has all the stuff which is required via Cargo. https://sources.debian.org/src/librsvg/2.58.0%2Bdfsg-1/debian/README.source/ This adds 29 MB "changes" to a 7.7 MB "orig" tarball. https://snapshot.debian.org/package/librsvg/2.58.0%2Bdfsg-1/ And it contributes a lengthy section to the copyright file: https://tracker.debian.org/media/packages/libr/librsvg/copyright-2.58.0dfsg-1 (TLDNR: Apache-2.0, and BSD-2-clause, and BSD-3-clause, and Expat, and Apache-2.0 or Expat or 0BSD, and Apache-2.0 or Boost-1.0, and Apache-2.0 or Expat, and Expat or Unlicense, and MPL-2.0, and Sun-permissive, and zlib)