D.4. Platform-Specific Macro Definitions in vk_platform.h

## D.4. Platform-Specific Macro Definitions in `vk_platform.h`

Additional platform-specific macros and interfaces are defined using the included `vk_platform.h` file. These macros are used to control platform-dependent behavior, and their exact definitions are under the control of specific platforms and Vulkan implementations.

### D.4.1. Platform-Specific Calling Conventions

On many platforms the following macros are empty strings, causing platform- and compiler-specific default calling conventions to be used.

`VKAPI_ATTR` is a macro placed before the return type in Vulkan API function declarations. This macro controls calling conventions for C++11 and GCC/Clang-style compilers.

`VKAPI_CALL` is a macro placed after the return type in Vulkan API function declarations. This macro controls calling conventions for MSVC-style compilers.

`VKAPI_PTR` is a macro placed between the ( and * in Vulkan API function pointer declarations. This macro also controls calling conventions, and typically has the same definition as `VKAPI_ATTR` or `VKAPI_CALL`, depending on the compiler.

### D.4.2. Platform-Specific Header Control

If the `VK_NO_STDINT_H` macro is defined by the application at compile time, extended integer types used by `vulkan.h`, such as `uint8_t`, must also be defined by the application. Otherwise, `vulkan.h` will not compile. If `VK_NO_STDINT_H` is not defined, the system `<stdint.h>` is used to define these types, or there is a fallback path when Microsoft Visual Studio version 2008 and earlier versions are detected at compile time.

### D.4.3. Window System-Specific Header Control

To use a Vulkan extension supporting a platform-specific window system, header files for that window systems must be included at compile time. The Vulkan header files cannot determine whether or not an external header is available at compile time, so applications wishing to use such an extension must #define a macro causing such headers to be included. If this is not done, the corresponding extension interfaces will not be defined and they will be unusable.

The extensions, required compile time symbols to enable them, window systems they correspond to, and external header files that are included when the macro is #defined are shown in the following table.

Table D.1. Window System Extensions and Required Compile Time Symbol Definitions

Extension Name | Required Compile Time Symbol | Window System Name | External Header Files Used
--- | --- | --- | ---
`VK_KHR_android_surface` | `VK_USE_PLATFORM_ANDROID_KHR` | Android Native | `<android/native_window.h>`
`VK_KHR_mir_surface` | `VK_USE_PLATFORM_MIR_KHR` | Mir | `<mir_toolkit/client_types.h>`
`VK_KHR_wayland_surface` | `VK_USE_PLATFORM_WAYLAND_KHR` | Wayland | `<wayland-client.h>`
`VK_KHR_win32_surface` | `VK_USE_PLATFORM_WIN32_KHR` | Microsoft Windows | `<windows.h>`
`VK_KHR_xcb_surface` | `VK_USE_PLATFORM_XCB_KHR` | X Window System Xcb library | `<xcb/xcb.h>`
`VK_KHR_xlib_surface` | `VK_USE_PLATFORM_XLIB_KHR` | X Window System Xlib library | `<X11/Xlib.h>`