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by vvanders 1091 days ago
> like getting a dependency of something not written in rust, or picking features based on some system configuration

I've found that things like this are pretty straightforward with a build.rs and you aren't context switching between a configuration language and your target language since build.rs is just a Rust program that outputs configuration values via println.

> ... very complex applications

That's not always a feature for me, the amount of time it takes me to ramp into a complex CMake configuration vs arbitrary crate is significantly different since the conventions are well established. If you spend any time cross-compiling things the Rust experience(I.E. first-class triple support, cc crate) is miles above anything CMake provides.
1 comments
jenadine 1091 days ago
> I've found that things like this are pretty straightforward with a build.rs

- build.rs can't change the feature set.

- what they usually do to bring dependency is vendor the C files within the crates, but when it comes to configuring to use an installed library and passing the right linker flags, this becomes really tricky.

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vvanders 1091 days ago
> build.rs can't change the feature set.

Can you be more specific here? You can totally do that based on OS, environment vars or even direct feature flags in the Cargo.toml. I've got a number of projects that do this and let downstream consumers decide what features they want. At the end of the day it's just a Rust program that runs ahead of the build and can do anything that you would be able to do in a normal command line program.

> ... but when it comes to configuring to use an installed library and passing the right linker flags, this becomes really tricky.

pkg-config[1] does all of that including returning linker flags. I can't think of a single case where I wasn't able to integrate with an existing library.

I'm not saying there are zero issues(I.E. passing some linker flags as a dependent crate gets annoying) but my experience having used C++ across a number of platforms(Win32, Linux, proprietary systems) before CMake existed and after it started getting wider adoption is that CMake has a significantly higher hurdle and is just harder to get things working correctly, especially under cross-compilation configurations.

[1] https://crates.io/crates/pkg-config

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