Kotlin/Native开发环境搭建

Kotlin/Native is a technology for compiling Kotlin code to native binaries, which can run without a virtual machine. It is an LLVM based backend for the Kotlin compiler and native implementation of the Kotlin standard library.

Kotlin/Native目前虽然是Beta版，但是已经比较稳定，是目前最靠谱的跨平台技术之一。
KN的安装过程非常简单，本文将基于Linux/MacOS环境安装KN的过程做可一个简单的整理，详细步骤如下：

安装JVM

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Kotlin的编译离不开JVM，所以安装JVM是前提条件。JVM的安装想必大家都很清楚，这里就不具体介绍了。

安装Kotlin/Native

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https://github.com/JetBrains/kotlin/releases/latest
从官方下载KN最新版本，下载需要使用wget

mac

$ brew install wget

linux（ubuntu）

$ sudo apt install wget

然后使用wget下载KN

mac

$ wget https://github.com/JetBrains/kotlin/releases/download/v1.3.61/kotlin-native-macos-1.3.61.tar.gz

linux（ubuntu）

$ wget https://github.com/JetBrains/kotlin/releases/download/v1.3.61/kotlin-native-linux-1.3.61.tar.gz

下载完成后，解压并移动到谁当位置，我们选择路径/usr/local/kotlin-native

$ tar xzvf kotlin-native-macos-1.3.61.tar.gz
$ sudo mkdir -p /usr/local/kotlin-native
$ sudo mv kotlin-native-macos-1.3.61/* /usr/local/kotlin-native

配置环境变量，~/.bash_profile中添加如下

$ export PATH=$PATH:/usr/local/kotlin-native/bin/

安装 IntelliJ IDEA

虽然也可以使用别的IDE进行开发，但是同属Jetbrains家族的产品，对KN的支持自然最到位。天然集成gradle也会为我们在开发中对于各种依赖库的管理提供方便。
请到IntelliJ IDEA官网自行下载安装即可，过程非常简单

Hello world

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打开IDEA，写下第一行KN代码

fun main(args: Array<String>) {
    println("Hello, World!")
}

编译

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初次运行时需要下载和安装LLVM所依赖的各个package，会稍微花点时间

$ kotlinc-native hello.kt -o hello

运行

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$ ./hello.kexe
Hello, World!

程序顺利执行！

编译Library

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通过-p参数，可以编译成任意形式的Library

$ kotlinc-native hello.kt -p dynamic

-p 参数	lib类型
program	可执行二进制
static	.a文件
dynamic	Linux下生成.so, macOS下生成.dylib
framework	iOS/macOS所需的framework
library	klib(Kotlin库)
bitcode	bc文件（LLVM的Bitcodebc）

可以通过-h查询KN更多参数的使用方法

$ kotlinc-native -h
Usage: kotlinc-native <options> <source files>
where possible options include:
  -g                         Enable emitting debug information
  -enable-assertions (-ea)   Enable runtime assertions in generated code
  -friend-modules <path>     Paths to friend modules
  -generate-no-exit-test-runner (-trn)
                             Produce a runner for unit tests not forcing exit
  -generate-test-runner (-tr) Produce a runner for unit tests
  -generate-worker-test-runner (-trw)
                             Produce a worker runner for unit tests
  -include-binary (-ib) <path> Pack external binary within the klib
  -library (-l) <path>       Link with the library
  -library-version (-lv) <version>
                             Set library version
  -linker-options <arg>      Pass arguments to linker
  -list-targets              List available hardware targets
  -entry (-e) <name>         Qualified entry point name
  -manifest <path>           Provide a maniferst addend file
  -memory-model <model>      Memory model to use, 'strict' and 'relaxed' are currently supported
  -module-name <name>        Specify a name for the compilation module
  -native-library (-nl) <path> Include the native bitcode library
  -no-default-libs           Don't link the libraries from dist/klib automatically
  -no-endorsed-libs          Don't link the endorsed libraries from dist automatically
  -nomain                    Assume 'main' entry point to be provided by external libraries
  -nopack                    Don't pack the library into a klib file
  -nostdlib                  Don't link with stdlib
  -opt                       Enable optimizations during compilation
  -output (-o) <name>        Output name
  -produce (-p) {program|static|dynamic|framework|library|bitcode}
                             Specify output file kind
  -repo (-r) <path>          Library search path
  -linker-option <arg>       Pass argument to linker
  -target <target>           Set hardware target
  -Werror                    Report an error if there are any warnings
  -api-version <version>     Allow to use declarations only from the specified version of bundled libraries
  -X                         Print a synopsis of advanced options
  -help (-h)                 Print a synopsis of standard options
  -kotlin-home <path>        Path to Kotlin compiler home directory, used for runtime libraries discovery
  -language-version <version> Provide source compatibility with specified language version
  -P plugin:<pluginId>:<optionName>=<value>
                             Pass an option to a plugin
  -progressive               Enable progressive compiler mode.
                             In this mode, deprecations and bug fixes for unstable code take effect immediately,
                             instead of going through a graceful migration cycle.
                             Code written in the progressive mode is backward compatible; however, code written in
                             non-progressive mode may cause compilation errors in the progressive mode.
  -nowarn                    Generate no warnings
  -verbose                   Enable verbose logging output
  -version                   Display compiler version
  @<argfile>                 Read compiler arguments and file paths from the given file

最后

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编译过程感觉有些慢，据说Kotlin1.4对KN的编译有很多优化，值得期待。