Platform Support

GPBT detects the target platform at configure time and sets GPBT_CURRENT_PLATFORM to a consistent token string. That token is used internally for thirdparty package matching and is available for platform-conditional logic in your own CMakeLists.txt files.

Supported platforms

Platform	GPBT_CURRENT_PLATFORM	Detection condition
Windows	Windows	WIN32 is set
Android	Android	CMAKE_SYSTEM_NAME == "Android"
iOS	iOS	CMAKE_SYSTEM_NAME == "iOS"
macOS	macOS	APPLE is set (and not iOS)
FreeBSD	FreeBSD	CMAKE_SYSTEM_NAME == "FreeBSD"
Linux	Linux	UNIX is set (and not Apple, Android, or FreeBSD)

Detection follows a priority order. Android is checked before the more general UNIX check; iOS is checked before APPLE. This matters for cross-compiled targets, an Android build on a macOS host is identified as Android, not macOS.

Platform-specific CMakeLists.txt behaviour

You can use GPBT_CURRENT_PLATFORM or standard CMake conditions in any CMakeLists.txt:

gpStartModule("platform/window")
  if(WIN32)
    gpAddCompileDefinition(PRIVATE GP_WINDOW_WIN32)
    gpAddDependency(PRIVATE gp::thirdparty::d3d12)
  elseif(APPLE)
    gpAddCompileDefinition(PRIVATE GP_WINDOW_COCOA)
    gpAddDependency(PRIVATE gp::thirdparty::metal)
  else()
    gpAddCompileDefinition(PRIVATE GP_WINDOW_X11)
  endif()
gpEndModule()

Platform policy files

Each platform has a corresponding policy file under source/gp-build-tool/platforms/. These files are included automatically at configure time and can add platform-specific compiler definitions, linker flags, or feature detection logic.

The platform policy files are currently stubs. Planned additions include automatic WINVER and _WIN32_WINNT definitions on Windows, and framework search path configuration on macOS and iOS.

Thirdparty platform gating

Platform tokens are used directly in thirdparty package descriptors to restrict which packages are resolved on which platforms:

gpThirdpartyRequiresPlatforms(Windows)   # package only resolved on Windows
gpThirdpartyRequiresPlatforms(macOS iOS) # package only resolved on Apple platforms

Packages that do not match the current platform are skipped silently during configuration.