Gradle Android-Arm-Clang plugin

This Gradle plugin integrates the Android NDK toolchain (ARM, Clang-based) into Gradle to cross-compile C/C++ code. The standalone toolchain must be installed separately, please refer to the Android documentation for instructions.

How?

buildscript {
    repositories {
        maven {
            url "https://sgeb.github.io/maven_repo/"
        }
    }

    dependencies {
        classpath "me.sgeb.gradle.plugins:gradle-android-arm-clang-plugin:0.1.0"
    }
}

apply plugin: 'cpp'
apply plugin: 'android-arm-clang'

executables {
    main {}
}

model {
    platforms {
        "android-arm" {
            operatingSystem "linux"
            architecture "arm"
        }
    }
}

Make sure you have arm-linux-androideabi-clang++ from the Android toolchain in your PATH.

There is an annoyance in the bin directory of the Android toolchain: it contains binaries called clang and clang++. In order for these not to override you system-wide compiler, add the toolchain bin directory at the end of PATH.

Gradle does not know any OS called android and we must stick to linux in the platform definition (which is technically correct). But the Android toolchain cannot cross-compile to any arbitrary linux-arm platform, only to a platform running the androideabi. The plugin checks the following to make sure it only builds for the correct platform:

• operatingSystem must be linux
• architecture must be arm
• platform name (android-arm in this example) must contain the string android

Multiple platforms in peaceful co-existence

The following example defines multiple platforms. They can be (cross-)compiled using the same build folder and the same code base.

executables {
    main {}
}

model {
    platforms {
        "osx-x64" {
            operatingSystem "mac os x"
            architecture "x86_64"
        }
        "android-arm" {
            operatingSystem "linux"
            architecture "arm"
        }
    }
}

task build {
    description "Build all binaries on all possible platforms."
    dependsOn binaries.matching { it.buildable }
}

The tasks --all command shows which platforms can be built with the configured toolchains and the compilers found in the PATH.

> ./gradlew tasks --all
[...]
build - Build all binaries on all possible platforms. [android-armMainExecutable, osx-x64MainExecutable]

The same command without the Android toolchain in the PATH:

> ./gradlew tasks --all
[...]
build - Build all binaries on all possible platforms. [osx-x64MainExecutable]

If a platform/binary combination cannot be fulfilled, Gradle will explain why:

> ./gradlew android-armMainExecutable
[...]
:compileAndroid-armMainExecutableMainCpp FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':compileAndroid-armMainExecutableMainCpp'.
> No tool chain is available to build for platform 'android-arm':
    - Tool chain 'visualCpp' (Visual Studio): Visual Studio is not available on this operating system.
    - Tool chain 'gcc' (GNU GCC): XCode g++ is a wrapper around Clang. Treating it as Clang and not GCC.
    - Tool chain 'clang' (Clang): Don't know how to build for platform 'android-arm'.
    - Tool chain 'androidArmClang' (AndroidArmClang): Could not find C++ compiler 'arm-linux-androideabi-clang++' in system path.

BUILD FAILED

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request