KLIB Commonizer

You can use platform-dependent libraries, such as Foundation, UIKit, posix, in source sets shared among several native targets. For each project that has native source sets that depend on a shared native source set, the special tool KLIB Commonizer automatically produces:

• One library in the KLIB format (*.klib) with the common API of the library that includes declarations that are identical among all platforms and expect declarations for the APIs that differ from platform to platform.
• One KLIB for each platform-specific source set that contains the actual declarations and the declarations that are available only on this particular platform.

                    commonMain
                        |
                        |
                     iosMain ----------▶ Foundation (common)
                      /   \              ┌──────────────────┐
                     /     \             │ expect class ... │
         iosArm64Main      iosX64Main    │ expect fun ...   │
                |             |          └──────────────────┘
                |             |
                ▼             ▼
Foundation (ios_arm64)     Foundation (ios_x64)
┌────────────────────┐     ┌──────────────────┐
│ actual class ...   │     │ actual class ... │
│ actual fun ...     │     │ actual fun ...   │
└────────────────────┘     └──────────────────┘

The resulting KLIBs are automatically added to the dependencies of the corresponding shared native and platform-specific source sets.

There are a few limitations in the current version of Klib Commonizer:

• It supports only interop libraries shipped with Kotlin/Native. It doesn’t support KLIBs that are produced from C-interop or Kotlin code.
• It works only for a native source set that is shared among platform-specific source sets and these source sets themselves. It doesn’t work for native source sets shared at higher levels of the source set hierarchy. For example, if you have nativeDarwinMain that includes iosMain with iosArm64Main and iosX64Main, and watchosDeviceMain with watchosArm64Main and watchosArm32Main, the KLIB Commonizer will work for separately iosMain and watchosDeviceMain and won’t work for nativeDarwinMain.

                  commonMain
                      |
                      |
               nativeDarwinMain    <--- Commonizer is NOT applied
                  /       \
                 /         \
          iosMain         watchosDeviceMain  <--- Commonizer is applied
           /   \                /  \
          /     \              ..  ..
iosArm64Main   iosX64Main