platform = native
Native development platform is intended to be used for desktop OS. This platform uses built-in toolchains (preferable based on GCC), frameworks, libs from particular OS where it will be run.
For more detailed information please visit vendor site.
Examples are listed from Native development platform repository:
You can switch between stable releases of Native development platform and the latest upstream version using platform option as described below:
; Custom stable version
[env:stable]
platform =native@x.y.z
board = ...
...
; The latest upstream/development version
[env:upstream]
platform = https://github.com/platformio/platform-native.git
board = ...
...