Add runtime platform selection

This adds compile-time support for multiple platforms and runtime
detection of them.  Window system related platform functions are now
called from shared code via the function pointer struct _GLFWplatform.

The timer, thread and module loading platform functions are still called
directly by name and the implementation chosen at link-time.  These
functions are the same for any backend on a given OS, including the Null
backend.

The platforms are now enabled via CMake dependent options following the
GLFW_BUILD_<platform> pattern instead of a mix of automagic and ad-hoc
option names.  There is no longer any option for the Null backend as it
is now always enabled.

Much of the struct stitching work in platform.h was based on an earlier
experimental branch for runtime platform selection by @ronchaine.

Every platform function related to windows, contexts, monitors, input,
event processing and Vulkan have been renamed so that multiple sets of
them can exist without colliding.  Calls to these are now routed through
the _glfw.platform struct member.  These changes makes up most of this
commit.

For Wayland and X11 the client library loading and display creation is
used to detect a running compositor/server.  The XDG_SESSION_TYPE
environment variable is ignored for now, as X11 is still by far the more
complete implementation.

Closes #1655
Closes #1958

src/cocoa_window.m

@@ -105,20 +105,20 @@ static void updateCursorMode(_GLFWwindow* window)
     if (window->cursorMode == GLFW_CURSOR_DISABLED)
     {
         _glfw.ns.disabledCursorWindow = window;
-        _glfwPlatformGetCursorPos(window,
-                                  &_glfw.ns.restoreCursorPosX,
-                                  &_glfw.ns.restoreCursorPosY);
+        _glfwGetCursorPosCocoa(window,
+                               &_glfw.ns.restoreCursorPosX,
+                               &_glfw.ns.restoreCursorPosY);
         _glfwCenterCursorInContentArea(window);
         CGAssociateMouseAndMouseCursorPosition(false);
     }
     else if (_glfw.ns.disabledCursorWindow == window)
     {
         _glfw.ns.disabledCursorWindow = NULL;
-        _glfwPlatformSetCursorPos(window,
-                                  _glfw.ns.restoreCursorPosX,
-                                  _glfw.ns.restoreCursorPosY);
+        _glfwSetCursorPosCocoa(window,
+                               _glfw.ns.restoreCursorPosX,
+                               _glfw.ns.restoreCursorPosY);
         // NOTE: The matching CGAssociateMouseAndMouseCursorPosition call is
-        //       made in _glfwPlatformSetCursorPos as part of a workaround
+        //       made in _glfwSetCursorPosCocoa as part of a workaround
     }
 
     if (cursorInContentArea(window))
@@ -286,7 +286,7 @@ static const NSRange kEmptyRange = { NSNotFound, 0 };
         _glfwCenterCursorInContentArea(window);
 
     int x, y;
-    _glfwPlatformGetWindowPos(window, &x, &y);
+    _glfwGetWindowPosCocoa(window, &x, &y);
     _glfwInputWindowPos(window, x, y);
 }
 
@@ -318,7 +318,7 @@ static const NSRange kEmptyRange = { NSNotFound, 0 };
 - (void)windowDidResignKey:(NSNotification *)notification
 {
     if (window->monitor && window->autoIconify)
-        _glfwPlatformIconifyWindow(window);
+        _glfwIconifyWindowCocoa(window);
 
     _glfwInputWindowFocus(window, GLFW_FALSE);
 }
@@ -803,8 +803,8 @@ static GLFWbool createNativeWindow(_GLFWwindow* window,
         GLFWvidmode mode;
         int xpos, ypos;
 
-        _glfwPlatformGetVideoMode(window->monitor, &mode);
-        _glfwPlatformGetMonitorPos(window->monitor, &xpos, &ypos);
+        _glfwGetVideoModeCocoa(window->monitor, &mode);
+        _glfwGetMonitorPosCocoa(window->monitor, &xpos, &ypos);
 
         contentRect = NSMakeRect(xpos, ypos, mode.width, mode.height);
     }
@@ -872,8 +872,8 @@ static GLFWbool createNativeWindow(_GLFWwindow* window,
         [window->ns.object setTabbingMode:NSWindowTabbingModeDisallowed];
 #endif
 
-    _glfwPlatformGetWindowSize(window, &window->ns.width, &window->ns.height);
-    _glfwPlatformGetFramebufferSize(window, &window->ns.fbWidth, &window->ns.fbHeight);
+    _glfwGetWindowSizeCocoa(window, &window->ns.width, &window->ns.height);
+    _glfwGetFramebufferSizeCocoa(window, &window->ns.fbWidth, &window->ns.fbHeight);
 
     return GLFW_TRUE;
 }
@@ -895,10 +895,10 @@ float _glfwTransformYCocoa(float y)
 //////                       GLFW platform API                      //////
 //////////////////////////////////////////////////////////////////////////
 
-int _glfwPlatformCreateWindow(_GLFWwindow* window,
-                              const _GLFWwndconfig* wndconfig,
-                              const _GLFWctxconfig* ctxconfig,
-                              const _GLFWfbconfig* fbconfig)
+int _glfwCreateWindowCocoa(_GLFWwindow* window,
+                           const _GLFWwndconfig* wndconfig,
+                           const _GLFWctxconfig* ctxconfig,
+                           const _GLFWfbconfig* fbconfig)
 {
     @autoreleasepool {
 
@@ -937,8 +937,8 @@ int _glfwPlatformCreateWindow(_GLFWwindow* window,
 
     if (window->monitor)
     {
-        _glfwPlatformShowWindow(window);
-        _glfwPlatformFocusWindow(window);
+        _glfwShowWindowCocoa(window);
+        _glfwFocusWindowCocoa(window);
         acquireMonitor(window);
     }
 
@@ -947,7 +947,7 @@ int _glfwPlatformCreateWindow(_GLFWwindow* window,
     } // autoreleasepool
 }
 
-void _glfwPlatformDestroyWindow(_GLFWwindow* window)
+void _glfwDestroyWindowCocoa(_GLFWwindow* window)
 {
     @autoreleasepool {
 
@@ -973,12 +973,12 @@ void _glfwPlatformDestroyWindow(_GLFWwindow* window)
     window->ns.object = nil;
 
     // HACK: Allow Cocoa to catch up before returning
-    _glfwPlatformPollEvents();
+    _glfwPollEventsCocoa();
 
     } // autoreleasepool
 }
 
-void _glfwPlatformSetWindowTitle(_GLFWwindow* window, const char* title)
+void _glfwSetWindowTitleCocoa(_GLFWwindow* window, const char* title)
 {
     @autoreleasepool {
     NSString* string = @(title);
@@ -989,14 +989,14 @@ void _glfwPlatformSetWindowTitle(_GLFWwindow* window, const char* title)
     } // autoreleasepool
 }
 
-void _glfwPlatformSetWindowIcon(_GLFWwindow* window,
-                                int count, const GLFWimage* images)
+void _glfwSetWindowIconCocoa(_GLFWwindow* window,
+                             int count, const GLFWimage* images)
 {
     _glfwInputError(GLFW_FEATURE_UNAVAILABLE,
                     "Cocoa: Regular windows do not have icons on macOS");
 }
 
-void _glfwPlatformGetWindowPos(_GLFWwindow* window, int* xpos, int* ypos)
+void _glfwGetWindowPosCocoa(_GLFWwindow* window, int* xpos, int* ypos)
 {
     @autoreleasepool {
 
@@ -1011,7 +1011,7 @@ void _glfwPlatformGetWindowPos(_GLFWwindow* window, int* xpos, int* ypos)
     } // autoreleasepool
 }
 
-void _glfwPlatformSetWindowPos(_GLFWwindow* window, int x, int y)
+void _glfwSetWindowPosCocoa(_GLFWwindow* window, int x, int y)
 {
     @autoreleasepool {
 
@@ -1023,7 +1023,7 @@ void _glfwPlatformSetWindowPos(_GLFWwindow* window, int x, int y)
     } // autoreleasepool
 }
 
-void _glfwPlatformGetWindowSize(_GLFWwindow* window, int* width, int* height)
+void _glfwGetWindowSizeCocoa(_GLFWwindow* window, int* width, int* height)
 {
     @autoreleasepool {
 
@@ -1037,7 +1037,7 @@ void _glfwPlatformGetWindowSize(_GLFWwindow* window, int* width, int* height)
     } // autoreleasepool
 }
 
-void _glfwPlatformSetWindowSize(_GLFWwindow* window, int width, int height)
+void _glfwSetWindowSizeCocoa(_GLFWwindow* window, int width, int height)
 {
     @autoreleasepool {
 
@@ -1059,9 +1059,9 @@ void _glfwPlatformSetWindowSize(_GLFWwindow* window, int width, int height)
     } // autoreleasepool
 }
 
-void _glfwPlatformSetWindowSizeLimits(_GLFWwindow* window,
-                                      int minwidth, int minheight,
-                                      int maxwidth, int maxheight)
+void _glfwSetWindowSizeLimitsCocoa(_GLFWwindow* window,
+                                   int minwidth, int minheight,
+                                   int maxwidth, int maxheight)
 {
     @autoreleasepool {
 
@@ -1078,7 +1078,7 @@ void _glfwPlatformSetWindowSizeLimits(_GLFWwindow* window,
     } // autoreleasepool
 }
 
-void _glfwPlatformSetWindowAspectRatio(_GLFWwindow* window, int numer, int denom)
+void _glfwSetWindowAspectRatioCocoa(_GLFWwindow* window, int numer, int denom)
 {
     @autoreleasepool {
     if (numer == GLFW_DONT_CARE || denom == GLFW_DONT_CARE)
@@ -1088,7 +1088,7 @@ void _glfwPlatformSetWindowAspectRatio(_GLFWwindow* window, int numer, int denom
     } // autoreleasepool
 }
 
-void _glfwPlatformGetFramebufferSize(_GLFWwindow* window, int* width, int* height)
+void _glfwGetFramebufferSizeCocoa(_GLFWwindow* window, int* width, int* height)
 {
     @autoreleasepool {
 
@@ -1103,9 +1103,9 @@ void _glfwPlatformGetFramebufferSize(_GLFWwindow* window, int* width, int* heigh
     } // autoreleasepool
 }
 
-void _glfwPlatformGetWindowFrameSize(_GLFWwindow* window,
-                                     int* left, int* top,
-                                     int* right, int* bottom)
+void _glfwGetWindowFrameSizeCocoa(_GLFWwindow* window,
+                                  int* left, int* top,
+                                  int* right, int* bottom)
 {
     @autoreleasepool {
 
@@ -1126,8 +1126,8 @@ void _glfwPlatformGetWindowFrameSize(_GLFWwindow* window,
     } // autoreleasepool
 }
 
-void _glfwPlatformGetWindowContentScale(_GLFWwindow* window,
-                                        float* xscale, float* yscale)
+void _glfwGetWindowContentScaleCocoa(_GLFWwindow* window,
+                                     float* xscale, float* yscale)
 {
     @autoreleasepool {
 
@@ -1142,14 +1142,14 @@ void _glfwPlatformGetWindowContentScale(_GLFWwindow* window,
     } // autoreleasepool
 }
 
-void _glfwPlatformIconifyWindow(_GLFWwindow* window)
+void _glfwIconifyWindowCocoa(_GLFWwindow* window)
 {
     @autoreleasepool {
     [window->ns.object miniaturize:nil];
     } // autoreleasepool
 }
 
-void _glfwPlatformRestoreWindow(_GLFWwindow* window)
+void _glfwRestoreWindowCocoa(_GLFWwindow* window)
 {
     @autoreleasepool {
     if ([window->ns.object isMiniaturized])
@@ -1159,7 +1159,7 @@ void _glfwPlatformRestoreWindow(_GLFWwindow* window)
     } // autoreleasepool
 }
 
-void _glfwPlatformMaximizeWindow(_GLFWwindow* window)
+void _glfwMaximizeWindowCocoa(_GLFWwindow* window)
 {
     @autoreleasepool {
     if (![window->ns.object isZoomed])
@@ -1167,28 +1167,28 @@ void _glfwPlatformMaximizeWindow(_GLFWwindow* window)
     } // autoreleasepool
 }
 
-void _glfwPlatformShowWindow(_GLFWwindow* window)
+void _glfwShowWindowCocoa(_GLFWwindow* window)
 {
     @autoreleasepool {
     [window->ns.object orderFront:nil];
     } // autoreleasepool
 }
 
-void _glfwPlatformHideWindow(_GLFWwindow* window)
+void _glfwHideWindowCocoa(_GLFWwindow* window)
 {
     @autoreleasepool {
     [window->ns.object orderOut:nil];
     } // autoreleasepool
 }
 
-void _glfwPlatformRequestWindowAttention(_GLFWwindow* window)
+void _glfwRequestWindowAttentionCocoa(_GLFWwindow* window)
 {
     @autoreleasepool {
     [NSApp requestUserAttention:NSInformationalRequest];
     } // autoreleasepool
 }
 
-void _glfwPlatformFocusWindow(_GLFWwindow* window)
+void _glfwFocusWindowCocoa(_GLFWwindow* window)
 {
     @autoreleasepool {
     // Make us the active application
@@ -1200,11 +1200,11 @@ void _glfwPlatformFocusWindow(_GLFWwindow* window)
     } // autoreleasepool
 }
 
-void _glfwPlatformSetWindowMonitor(_GLFWwindow* window,
-                                   _GLFWmonitor* monitor,
-                                   int xpos, int ypos,
-                                   int width, int height,
-                                   int refreshRate)
+void _glfwSetWindowMonitorCocoa(_GLFWwindow* window,
+                                _GLFWmonitor* monitor,
+                                int xpos, int ypos,
+                                int width, int height,
+                                int refreshRate)
 {
     @autoreleasepool {
 
@@ -1236,7 +1236,7 @@ void _glfwPlatformSetWindowMonitor(_GLFWwindow* window,
 
     // HACK: Allow the state cached in Cocoa to catch up to reality
     // TODO: Solve this in a less terrible way
-    _glfwPlatformPollEvents();
+    _glfwPollEventsCocoa();
 
     const NSUInteger styleMask = getStyleMask(window);
     [window->ns.object setStyleMask:styleMask];
@@ -1293,35 +1293,35 @@ void _glfwPlatformSetWindowMonitor(_GLFWwindow* window,
     } // autoreleasepool
 }
 
-int _glfwPlatformWindowFocused(_GLFWwindow* window)
+int _glfwWindowFocusedCocoa(_GLFWwindow* window)
 {
     @autoreleasepool {
     return [window->ns.object isKeyWindow];
     } // autoreleasepool
 }
 
-int _glfwPlatformWindowIconified(_GLFWwindow* window)
+int _glfwWindowIconifiedCocoa(_GLFWwindow* window)
 {
     @autoreleasepool {
     return [window->ns.object isMiniaturized];
     } // autoreleasepool
 }
 
-int _glfwPlatformWindowVisible(_GLFWwindow* window)
+int _glfwWindowVisibleCocoa(_GLFWwindow* window)
 {
     @autoreleasepool {
     return [window->ns.object isVisible];
     } // autoreleasepool
 }
 
-int _glfwPlatformWindowMaximized(_GLFWwindow* window)
+int _glfwWindowMaximizedCocoa(_GLFWwindow* window)
 {
     @autoreleasepool {
     return [window->ns.object isZoomed];
     } // autoreleasepool
 }
 
-int _glfwPlatformWindowHovered(_GLFWwindow* window)
+int _glfwWindowHoveredCocoa(_GLFWwindow* window)
 {
     @autoreleasepool {
 
@@ -1339,21 +1339,21 @@ int _glfwPlatformWindowHovered(_GLFWwindow* window)
     } // autoreleasepool
 }
 
-int _glfwPlatformFramebufferTransparent(_GLFWwindow* window)
+int _glfwFramebufferTransparentCocoa(_GLFWwindow* window)
 {
     @autoreleasepool {
     return ![window->ns.object isOpaque] && ![window->ns.view isOpaque];
     } // autoreleasepool
 }
 
-void _glfwPlatformSetWindowResizable(_GLFWwindow* window, GLFWbool enabled)
+void _glfwSetWindowResizableCocoa(_GLFWwindow* window, GLFWbool enabled)
 {
     @autoreleasepool {
     [window->ns.object setStyleMask:getStyleMask(window)];
     } // autoreleasepool
 }
 
-void _glfwPlatformSetWindowDecorated(_GLFWwindow* window, GLFWbool enabled)
+void _glfwSetWindowDecoratedCocoa(_GLFWwindow* window, GLFWbool enabled)
 {
     @autoreleasepool {
     [window->ns.object setStyleMask:getStyleMask(window)];
@@ -1361,7 +1361,7 @@ void _glfwPlatformSetWindowDecorated(_GLFWwindow* window, GLFWbool enabled)
     } // autoreleasepool
 }
 
-void _glfwPlatformSetWindowFloating(_GLFWwindow* window, GLFWbool enabled)
+void _glfwSetWindowFloatingCocoa(_GLFWwindow* window, GLFWbool enabled)
 {
     @autoreleasepool {
     if (enabled)
@@ -1371,39 +1371,39 @@ void _glfwPlatformSetWindowFloating(_GLFWwindow* window, GLFWbool enabled)
     } // autoreleasepool
 }
 
-void _glfwPlatformSetWindowMousePassthrough(_GLFWwindow* window, GLFWbool enabled)
+void _glfwSetWindowMousePassthroughCocoa(_GLFWwindow* window, GLFWbool enabled)
 {
     @autoreleasepool {
     [window->ns.object setIgnoresMouseEvents:enabled];
     }
 }
 
-float _glfwPlatformGetWindowOpacity(_GLFWwindow* window)
+float _glfwGetWindowOpacityCocoa(_GLFWwindow* window)
 {
     @autoreleasepool {
     return (float) [window->ns.object alphaValue];
     } // autoreleasepool
 }
 
-void _glfwPlatformSetWindowOpacity(_GLFWwindow* window, float opacity)
+void _glfwSetWindowOpacityCocoa(_GLFWwindow* window, float opacity)
 {
     @autoreleasepool {
     [window->ns.object setAlphaValue:opacity];
     } // autoreleasepool
 }
 
-void _glfwPlatformSetRawMouseMotion(_GLFWwindow *window, GLFWbool enabled)
+void _glfwSetRawMouseMotionCocoa(_GLFWwindow *window, GLFWbool enabled)
 {
     _glfwInputError(GLFW_FEATURE_UNIMPLEMENTED,
                     "Cocoa: Raw mouse motion not yet implemented");
 }
 
-GLFWbool _glfwPlatformRawMouseMotionSupported(void)
+GLFWbool _glfwRawMouseMotionSupportedCocoa(void)
 {
     return GLFW_FALSE;
 }
 
-void _glfwPlatformPollEvents(void)
+void _glfwPollEventsCocoa(void)
 {
     @autoreleasepool {
 
@@ -1422,7 +1422,7 @@ void _glfwPlatformPollEvents(void)
     } // autoreleasepool
 }
 
-void _glfwPlatformWaitEvents(void)
+void _glfwWaitEventsCocoa(void)
 {
     @autoreleasepool {
 
@@ -1435,12 +1435,12 @@ void _glfwPlatformWaitEvents(void)
                                           dequeue:YES];
     [NSApp sendEvent:event];
 
-    _glfwPlatformPollEvents();
+    _glfwPollEventsCocoa();
 
     } // autoreleasepool
 }
 
-void _glfwPlatformWaitEventsTimeout(double timeout)
+void _glfwWaitEventsTimeoutCocoa(double timeout)
 {
     @autoreleasepool {
 
@@ -1452,12 +1452,12 @@ void _glfwPlatformWaitEventsTimeout(double timeout)
     if (event)
         [NSApp sendEvent:event];
 
-    _glfwPlatformPollEvents();
+    _glfwPollEventsCocoa();
 
     } // autoreleasepool
 }
 
-void _glfwPlatformPostEmptyEvent(void)
+void _glfwPostEmptyEventCocoa(void)
 {
     @autoreleasepool {
 
@@ -1475,7 +1475,7 @@ void _glfwPlatformPostEmptyEvent(void)
     } // autoreleasepool
 }
 
-void _glfwPlatformGetCursorPos(_GLFWwindow* window, double* xpos, double* ypos)
+void _glfwGetCursorPosCocoa(_GLFWwindow* window, double* xpos, double* ypos)
 {
     @autoreleasepool {
 
@@ -1491,7 +1491,7 @@ void _glfwPlatformGetCursorPos(_GLFWwindow* window, double* xpos, double* ypos)
     } // autoreleasepool
 }
 
-void _glfwPlatformSetCursorPos(_GLFWwindow* window, double x, double y)
+void _glfwSetCursorPosCocoa(_GLFWwindow* window, double x, double y)
 {
     @autoreleasepool {
 
@@ -1527,15 +1527,15 @@ void _glfwPlatformSetCursorPos(_GLFWwindow* window, double x, double y)
     } // autoreleasepool
 }
 
-void _glfwPlatformSetCursorMode(_GLFWwindow* window, int mode)
+void _glfwSetCursorModeCocoa(_GLFWwindow* window, int mode)
 {
     @autoreleasepool {
-    if (_glfwPlatformWindowFocused(window))
+    if (_glfwWindowFocusedCocoa(window))
         updateCursorMode(window);
     } // autoreleasepool
 }
 
-const char* _glfwPlatformGetScancodeName(int scancode)
+const char* _glfwGetScancodeNameCocoa(int scancode)
 {
     @autoreleasepool {
 
@@ -1584,14 +1584,14 @@ const char* _glfwPlatformGetScancodeName(int scancode)
     } // autoreleasepool
 }
 
-int _glfwPlatformGetKeyScancode(int key)
+int _glfwGetKeyScancodeCocoa(int key)
 {
     return _glfw.ns.scancodes[key];
 }
 
-int _glfwPlatformCreateCursor(_GLFWcursor* cursor,
-                              const GLFWimage* image,
-                              int xhot, int yhot)
+int _glfwCreateCursorCocoa(_GLFWcursor* cursor,
+                           const GLFWimage* image,
+                           int xhot, int yhot)
 {
     @autoreleasepool {
 
@@ -1633,7 +1633,7 @@ int _glfwPlatformCreateCursor(_GLFWcursor* cursor,
     } // autoreleasepool
 }
 
-int _glfwPlatformCreateStandardCursor(_GLFWcursor* cursor, int shape)
+int _glfwCreateStandardCursorCocoa(_GLFWcursor* cursor, int shape)
 {
     @autoreleasepool {
 
@@ -1707,7 +1707,7 @@ int _glfwPlatformCreateStandardCursor(_GLFWcursor* cursor, int shape)
     } // autoreleasepool
 }
 
-void _glfwPlatformDestroyCursor(_GLFWcursor* cursor)
+void _glfwDestroyCursorCocoa(_GLFWcursor* cursor)
 {
     @autoreleasepool {
     if (cursor->ns.object)
@@ -1715,7 +1715,7 @@ void _glfwPlatformDestroyCursor(_GLFWcursor* cursor)
     } // autoreleasepool
 }
 
-void _glfwPlatformSetCursor(_GLFWwindow* window, _GLFWcursor* cursor)
+void _glfwSetCursorCocoa(_GLFWwindow* window, _GLFWcursor* cursor)
 {
     @autoreleasepool {
     if (cursorInContentArea(window))
@@ -1723,7 +1723,7 @@ void _glfwPlatformSetCursor(_GLFWwindow* window, _GLFWcursor* cursor)
     } // autoreleasepool
 }
 
-void _glfwPlatformSetClipboardString(const char* string)
+void _glfwSetClipboardStringCocoa(const char* string)
 {
     @autoreleasepool {
     NSPasteboard* pasteboard = [NSPasteboard generalPasteboard];
@@ -1732,7 +1732,7 @@ void _glfwPlatformSetClipboardString(const char* string)
     } // autoreleasepool
 }
 
-const char* _glfwPlatformGetClipboardString(void)
+const char* _glfwGetClipboardStringCocoa(void)
 {
     @autoreleasepool {
 
@@ -1761,7 +1761,7 @@ const char* _glfwPlatformGetClipboardString(void)
     } // autoreleasepool
 }
 
-EGLenum _glfwPlatformGetEGLPlatform(EGLint** attribs)
+EGLenum _glfwGetEGLPlatformCocoa(EGLint** attribs)
 {
     if (_glfw.egl.ANGLE_platform_angle)
     {
@@ -1792,17 +1792,17 @@ EGLenum _glfwPlatformGetEGLPlatform(EGLint** attribs)
     return 0;
 }
 
-EGLNativeDisplayType _glfwPlatformGetEGLNativeDisplay(void)
+EGLNativeDisplayType _glfwGetEGLNativeDisplayCocoa(void)
 {
     return EGL_DEFAULT_DISPLAY;
 }
 
-EGLNativeWindowType _glfwPlatformGetEGLNativeWindow(_GLFWwindow* window)
+EGLNativeWindowType _glfwGetEGLNativeWindowCocoa(_GLFWwindow* window)
 {
     return window->ns.layer;
 }
 
-void _glfwPlatformGetRequiredInstanceExtensions(char** extensions)
+void _glfwGetRequiredInstanceExtensionsCocoa(char** extensions)
 {
     if (_glfw.vk.KHR_surface && _glfw.vk.EXT_metal_surface)
     {
@@ -1816,17 +1816,17 @@ void _glfwPlatformGetRequiredInstanceExtensions(char** extensions)
     }
 }
 
-int _glfwPlatformGetPhysicalDevicePresentationSupport(VkInstance instance,
-                                                      VkPhysicalDevice device,
-                                                      uint32_t queuefamily)
+int _glfwGetPhysicalDevicePresentationSupportCocoa(VkInstance instance,
+                                                   VkPhysicalDevice device,
+                                                   uint32_t queuefamily)
 {
     return GLFW_TRUE;
 }
 
-VkResult _glfwPlatformCreateWindowSurface(VkInstance instance,
-                                          _GLFWwindow* window,
-                                          const VkAllocationCallbacks* allocator,
-                                          VkSurfaceKHR* surface)
+VkResult _glfwCreateWindowSurfaceCocoa(VkInstance instance,
+                                       _GLFWwindow* window,
+                                       const VkAllocationCallbacks* allocator,
+                                       VkSurfaceKHR* surface)
 {
     @autoreleasepool {
 
@@ -1923,6 +1923,14 @@ GLFWAPI id glfwGetCocoaWindow(GLFWwindow* handle)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
     _GLFW_REQUIRE_INIT_OR_RETURN(nil);
+
+    if (_glfw.platform.platformID != GLFW_PLATFORM_COCOA)
+    {
+        _glfwInputError(GLFW_PLATFORM_UNAVAILABLE,
+                        "Cocoa: Platform not initialized");
+        return NULL;
+    }
+
     return window->ns.object;
 }