vulkan: Re-add option to build Vulkan-Loader statically

Upstream removed the option in KhronosGroup/Vulkan-Loader#260, which
breaks our current use case.
This commit reverts KhronosGroup/Vulkan-Loader#260 is our vendored
loader.

We may need to re-evaluate how we link the loader, but until then,
reverting this PR fixes Windows support after the upgrade to a recent
SDK version in #36932.

1 files changed, 16 insertions, 0 deletions

diff --git a/thirdparty/vulkan/loader/vk_loader_platform.h b/thirdparty/vulkan/loader/vk_loader_platform.h
index 7824e35d6b..62e8e3ae09 100644
--- a/thirdparty/vulkan/loader/vk_loader_platform.h
+++ b/thirdparty/vulkan/loader/vk_loader_platform.h
@@ -330,9 +330,25 @@ typedef HANDLE loader_platform_thread;
 // The once init functionality is not used when building a DLL on Windows. This is because there is no way to clean up the
 // resources allocated by anything allocated by once init. This isn't a problem for static libraries, but it is for dynamic
 // ones. When building a DLL, we use DllMain() instead to allow properly cleaning up resources.
+#if defined(LOADER_DYNAMIC_LIB)
 #define LOADER_PLATFORM_THREAD_ONCE_DECLARATION(var)
 #define LOADER_PLATFORM_THREAD_ONCE_DEFINITION(var)
 #define LOADER_PLATFORM_THREAD_ONCE(ctl, func)
+#else
+#define LOADER_PLATFORM_THREAD_ONCE_DECLARATION(var) INIT_ONCE var = INIT_ONCE_STATIC_INIT;
+#define LOADER_PLATFORM_THREAD_ONCE_DEFINITION(var) INIT_ONCE var;
+#define LOADER_PLATFORM_THREAD_ONCE(ctl, func) loader_platform_thread_once_fn(ctl, func)
+static BOOL CALLBACK InitFuncWrapper(PINIT_ONCE InitOnce, PVOID Parameter, PVOID *Context) {
+    void (*func)(void) = (void (*)(void))Parameter;
+    func();
+    return TRUE;
+}
+static void loader_platform_thread_once_fn(void *ctl, void (*func)(void)) {
+    assert(func != NULL);
+    assert(ctl != NULL);
+    InitOnceExecuteOnce((PINIT_ONCE)ctl, InitFuncWrapper, (void *)func, NULL);
+}
+#endif
 
 // Thread IDs:
 typedef DWORD loader_platform_thread_id;