Target.'cfg(target_os="android") or IOS doesn't work

help
1

I had two projects for IOS and Android, that shared same logic, I decided yo merge them with cfg
macro, but it doesn't seem to be working.

In toll: (doesn't work)

[target.'cfg(target_os="android")'.dependencies]
[target.'cfg(target_os="ios")'.build-dependencies]
[target.'cfg(target_os="android")'.build-dependencies]

in build.rs: (doesn't work)

//IOS
#[cfg(target_os = "ios")]
use cbindgen::Language::C;
//Android
#[cfg(target_os = "android")]
use rust_swig::{JavaConfig, LanguageConfig};

And methods like this:

//We have custom setup for IOS and Android, otherwise do nothing.
#[cfg(any(not(target_os = "android"), not(target_os = "ios")))] (doesn't work)
fn setup() {
    println!("Build: default setup");
}

#[cfg(target_os = "ios")]
fn setup() {
    println!("Build: IOS setup");
}

#[cfg(target_os = "android")]
fn setup() {
    println!("Build: Android setup");
}

I build Android with:

CC=aarch64-linux-android21-clang cargo build --target aarch64-linux-android --release
CC=armv7a-linux-androideabi21-clang cargo build --target armv7-linux-androideabi --release
CC=i686-linux-android21-clang cargo build --target i686-linux-android --release

IOS:

cargo lipo --release

Reference:
https://doc.rust-lang.org/reference/conditional-compilation.html

1 Like
2

I think you need the default to be all(not(x), not(y)) or not(any(x, y)).

3

I tried to add print in build.rs ;

fn main() {
    println!("cargo:warning=Build started");
    let target_os = env::var("CARGO_CFG_TARGET_OS");
    match target_os.as_ref().map(|x| &**x) {
        Ok(tos) => println!("cargo:warning=target os {:?}", tos),
        Err(err)=> println!("cargo:warning=os not defined {:?}!", err)
    }
    setup();
}

I changed default setup to:

//#[cfg(all(not(target_os = "android"), not(target_os = "ios")))]
#[cfg(target_os = "macos")]
fn setup() {
    println!("cargo:warning=Build: default setup");
}

And still, when I execute, I see next:

warning: Build started
warning: target os "android"!
warning: Build: default setup

This method is not executed:

#[cfg(target_os = "android")]
fn setup() {
    println!("cargo:warning=Build: Android setup");
}
4

I tired to move one dependency in cargo.toml to "macos" target and now build for android is failing.

[target.'cfg(target_os = "macos")'.dependencies]
serde = { version = "*", features = ["derive"] }

Seems cfg(target_os = "android") is not recognized at all?

5

As well when I added configuration for different lib types:

[target.'cfg(target_os = "android")'.lib]
name = "swapi_core"
crate-type = ["dylib"]

[target.'cfg(target_os = "ios")'.lib]
name = "swapi_core"
crate-type = ["staticlib", "cdylib"]

I got warning in logs:

warning: unused manifest key: target.cfg(target_os = "android").lib
warning: unused manifest key: target.cfg(target_os = "ios").lib
6

Your build.rs is built and executed for the host, thus target_os in there is your host system, not the target you're building your crate for.

target.lib can't be configured per target, as the warnings indicate.

7

So target is only host not a target of the build? I totally misunderstood it...
If there a way to implement what I want, for a target of build?

In toml. it also target host or build target?

8

It's the target the program is being build for. As the build.rs is a program that needs to run on your current running machine during the build process of the whole thing it is your host's system, yes.

You've already shown yourself the answer: branch on the environment variable CARGO_CFG_TARGET_OS if you need to know it in your build script.

For normal dependencies it picks the target of your final program.

2 Likes
9

Got it. But I have some build dependencies that I need only for a specific platform, example:

About toml I think there is a problem with android and ios keyword then.
Because if I put macos and run on my laptop - I see my dependencies are compiled, when I change it to android and build for it - it is not compiled

10

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.