include: Added `\threadsafety` notes to about 60 more functions.

Reference Issue #7140.

(cherry picked from commit 28e42699159ece63b2b8fc8673fc0296488740a9)

include/SDL3/SDL_asyncio.h

@@ -213,6 +213,8 @@ typedef struct SDL_AsyncIOQueue SDL_AsyncIOQueue;
  * \returns a pointer to the SDL_AsyncIO structure that is created or NULL on
  *          failure; call SDL_GetError() for more information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_CloseAsyncIO
@@ -531,6 +533,8 @@ extern SDL_DECLSPEC void SDLCALL SDL_SignalAsyncIOQueue(SDL_AsyncIOQueue *queue)
  * \returns true on success or false on failure; call SDL_GetError() for more
  *          information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_LoadFile_IO

include/SDL3/SDL_init.h

@@ -224,6 +224,8 @@ typedef void (SDLCALL *SDL_AppQuit_func)(void *appstate, SDL_AppResult result);
  * \returns true on success or false on failure; call SDL_GetError() for more
  *          information.
  *
+ * \threadsafety This function should only be called on the main thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_SetAppMetadata
@@ -244,6 +246,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_Init(SDL_InitFlags flags);
  * \returns true on success or false on failure; call SDL_GetError() for more
  *          information.
  *
+ * \threadsafety This function should only be called on the main thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_Init
@@ -260,6 +264,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_InitSubSystem(SDL_InitFlags flags);
  *
  * \param flags any of the flags used by SDL_Init(); see SDL_Init for details.
  *
+ * \threadsafety This function is not thread safe.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_InitSubSystem
@@ -274,6 +280,8 @@ extern SDL_DECLSPEC void SDLCALL SDL_QuitSubSystem(SDL_InitFlags flags);
  * \returns a mask of all initialized subsystems if `flags` is 0, otherwise it
  *          returns the initialization status of the specified subsystems.
  *
+ * \threadsafety This function is not thread safe.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_Init
@@ -292,6 +300,8 @@ extern SDL_DECLSPEC SDL_InitFlags SDLCALL SDL_WasInit(SDL_InitFlags flags);
  * application is shutdown, but it is not wise to do this from a library or
  * other dynamically loaded code.
  *
+ * \threadsafety This function should only be called on the main thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_Init

include/SDL3/SDL_main.h

@@ -333,6 +333,8 @@ extern "C" {
  * \returns SDL_APP_FAILURE to terminate with an error, SDL_APP_SUCCESS to
  *          terminate with success, SDL_APP_CONTINUE to continue.
  *
+ * \threadsafety This function is called once by SDL, at startup, on a single thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_AppIterate
@@ -537,6 +539,8 @@ extern SDLMAIN_DECLSPEC int SDLCALL SDL_main(int argc, char *argv[]);
  * will not be changed it is necessary to define SDL_MAIN_HANDLED before
  * including SDL.h.
  *
+ * \threadsafety This function is not thread safe.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_Init
@@ -629,6 +633,8 @@ extern SDL_DECLSPEC int SDLCALL SDL_EnterAppMainCallbacks(int argc, char *argv[]
  * \returns true on success or false on failure; call SDL_GetError() for more
  *          information.
  *
+ * \threadsafety This function is not thread safe.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC bool SDLCALL SDL_RegisterApp(const char *name, Uint32 style, void *hInst);
@@ -646,6 +652,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_RegisterApp(const char *name, Uint32 style,
  * deregistered when the registration counter in SDL_RegisterApp decrements to
  * zero through calls to this function.
  *
+ * \threadsafety This function is not thread safe.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC void SDLCALL SDL_UnregisterApp(void);
@@ -658,6 +666,8 @@ extern SDL_DECLSPEC void SDLCALL SDL_UnregisterApp(void);
  * This function is only needed for Xbox GDK support; all other platforms will
  * do nothing and set an "unsupported" error message.
  *
+ * \threadsafety This function is not thread safe.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC void SDLCALL SDL_GDKSuspendComplete(void);

include/SDL3/SDL_mutex.h

@@ -308,6 +308,8 @@ typedef struct SDL_Mutex SDL_Mutex;
  * \returns the initialized and unlocked mutex or NULL on failure; call
  *          SDL_GetError() for more information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_DestroyMutex
@@ -334,6 +336,8 @@ extern SDL_DECLSPEC SDL_Mutex * SDLCALL SDL_CreateMutex(void);
  *
  * \param mutex the mutex to lock.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_TryLockMutex
@@ -355,6 +359,8 @@ extern SDL_DECLSPEC void SDLCALL SDL_LockMutex(SDL_Mutex *mutex) SDL_ACQUIRE(mut
  * \param mutex the mutex to try to lock.
  * \returns true on success, false if the mutex would block.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_LockMutex
@@ -374,6 +380,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_TryLockMutex(SDL_Mutex *mutex) SDL_TRY_ACQU
  *
  * \param mutex the mutex to unlock.
  *
+ * \threadsafety This call must be paired with a previous locking call on the same thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_LockMutex
@@ -392,6 +400,8 @@ extern SDL_DECLSPEC void SDLCALL SDL_UnlockMutex(SDL_Mutex *mutex) SDL_RELEASE(m
  *
  * \param mutex the mutex to destroy.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_CreateMutex
@@ -457,6 +467,8 @@ typedef struct SDL_RWLock SDL_RWLock;
  * \returns the initialized and unlocked read/write lock or NULL on failure;
  *          call SDL_GetError() for more information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_DestroyRWLock
@@ -497,6 +509,8 @@ extern SDL_DECLSPEC SDL_RWLock * SDLCALL SDL_CreateRWLock(void);
  *
  * \param rwlock the read/write lock to lock.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_LockRWLockForWriting
@@ -528,6 +542,8 @@ extern SDL_DECLSPEC void SDLCALL SDL_LockRWLockForReading(SDL_RWLock *rwlock) SD
  *
  * \param rwlock the read/write lock to lock.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_LockRWLockForReading
@@ -553,6 +569,8 @@ extern SDL_DECLSPEC void SDLCALL SDL_LockRWLockForWriting(SDL_RWLock *rwlock) SD
  * \param rwlock the rwlock to try to lock.
  * \returns true on success, false if the lock would block.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_LockRWLockForReading
@@ -583,6 +601,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_TryLockRWLockForReading(SDL_RWLock *rwlock)
  * \param rwlock the rwlock to try to lock.
  * \returns true on success, false if the lock would block.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_LockRWLockForWriting
@@ -607,6 +627,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_TryLockRWLockForWriting(SDL_RWLock *rwlock)
  *
  * \param rwlock the rwlock to unlock.
  *
+ * \threadsafety This call must be paired with a previous locking call on the same thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_LockRWLockForReading
@@ -627,6 +649,8 @@ extern SDL_DECLSPEC void SDLCALL SDL_UnlockRWLock(SDL_RWLock *rwlock) SDL_RELEAS
  *
  * \param rwlock the rwlock to destroy.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_CreateRWLock
@@ -670,6 +694,8 @@ typedef struct SDL_Semaphore SDL_Semaphore;
  * \returns a new semaphore or NULL on failure; call SDL_GetError() for more
  *          information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_DestroySemaphore
@@ -689,6 +715,8 @@ extern SDL_DECLSPEC SDL_Semaphore * SDLCALL SDL_CreateSemaphore(Uint32 initial_v
  *
  * \param sem the semaphore to destroy.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_CreateSemaphore
@@ -707,6 +735,8 @@ extern SDL_DECLSPEC void SDLCALL SDL_DestroySemaphore(SDL_Semaphore *sem);
  *
  * \param sem the semaphore wait on.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_SignalSemaphore
@@ -726,6 +756,8 @@ extern SDL_DECLSPEC void SDLCALL SDL_WaitSemaphore(SDL_Semaphore *sem);
  * \param sem the semaphore to wait on.
  * \returns true if the wait succeeds, false if the wait would block.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_SignalSemaphore
@@ -746,6 +778,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_TryWaitSemaphore(SDL_Semaphore *sem);
  *                  indefinitely.
  * \returns true if the wait succeeds or false if the wait times out.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_SignalSemaphore
@@ -759,6 +793,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_WaitSemaphoreTimeout(SDL_Semaphore *sem, Si
  *
  * \param sem the semaphore to increment.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_TryWaitSemaphore
@@ -773,6 +809,8 @@ extern SDL_DECLSPEC void SDLCALL SDL_SignalSemaphore(SDL_Semaphore *sem);
  * \param sem the semaphore to query.
  * \returns the current value of the semaphore.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC Uint32 SDLCALL SDL_GetSemaphoreValue(SDL_Semaphore *sem);
@@ -806,6 +844,8 @@ typedef struct SDL_Condition SDL_Condition;
  * \returns a new condition variable or NULL on failure; call SDL_GetError()
  *          for more information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_BroadcastCondition
@@ -821,6 +861,8 @@ extern SDL_DECLSPEC SDL_Condition * SDLCALL SDL_CreateCondition(void);
  *
  * \param cond the condition variable to destroy.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_CreateCondition

include/SDL3/SDL_platform.h

@@ -51,6 +51,8 @@ extern "C" {
  * \returns the name of the platform. If the correct platform name is not
  *          available, returns a string beginning with the text "Unknown".
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC const char * SDLCALL SDL_GetPlatform(void);

include/SDL3/SDL_properties.h

@@ -111,6 +111,8 @@ typedef enum SDL_PropertyType
  * \returns a valid property ID on success or 0 on failure; call
  *          SDL_GetError() for more information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC SDL_PropertiesID SDLCALL SDL_GetGlobalProperties(void);

include/SDL3/SDL_rect.h

@@ -237,6 +237,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_HasRectIntersection(const SDL_Rect *A, cons
  *               rectangles `A` and `B`.
  * \returns true if there is an intersection, false otherwise.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_HasRectIntersection
@@ -253,6 +255,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_GetRectIntersection(const SDL_Rect *A, cons
  * \returns true on success or false on failure; call SDL_GetError() for more
  *          information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC bool SDLCALL SDL_GetRectUnion(const SDL_Rect *A, const SDL_Rect *B, SDL_Rect *result);
@@ -272,6 +276,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_GetRectUnion(const SDL_Rect *A, const SDL_R
  * \returns true if any points were enclosed or false if all the points were
  *          outside of the clipping rectangle.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC bool SDLCALL SDL_GetRectEnclosingPoints(const SDL_Point *points, int count, const SDL_Rect *clip, SDL_Rect *result);
@@ -292,6 +298,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_GetRectEnclosingPoints(const SDL_Point *poi
  * \param Y2 a pointer to the ending Y-coordinate of the line.
  * \returns true if there is an intersection, false otherwise.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC bool SDLCALL SDL_GetRectAndLineIntersection(const SDL_Rect *rect, int *X1, int *Y1, int *X2, int *Y2);
@@ -423,6 +431,8 @@ SDL_FORCE_INLINE bool SDL_RectsEqualFloat(const SDL_FRect *a, const SDL_FRect *b
  * \param B an SDL_FRect structure representing the second rectangle.
  * \returns true if there is an intersection, false otherwise.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_GetRectIntersection
@@ -440,6 +450,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_HasRectIntersectionFloat(const SDL_FRect *A
  *               rectangles `A` and `B`.
  * \returns true if there is an intersection, false otherwise.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_HasRectIntersectionFloat
@@ -456,6 +468,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_GetRectIntersectionFloat(const SDL_FRect *A
  * \returns true on success or false on failure; call SDL_GetError() for more
  *          information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC bool SDLCALL SDL_GetRectUnionFloat(const SDL_FRect *A, const SDL_FRect *B, SDL_FRect *result);
@@ -476,6 +490,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_GetRectUnionFloat(const SDL_FRect *A, const
  * \returns true if any points were enclosed or false if all the points were
  *          outside of the clipping rectangle.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC bool SDLCALL SDL_GetRectEnclosingPointsFloat(const SDL_FPoint *points, int count, const SDL_FRect *clip, SDL_FRect *result);
@@ -497,6 +513,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_GetRectEnclosingPointsFloat(const SDL_FPoin
  * \param Y2 a pointer to the ending Y-coordinate of the line.
  * \returns true if there is an intersection, false otherwise.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC bool SDLCALL SDL_GetRectAndLineIntersectionFloat(const SDL_FRect *rect, float *X1, float *Y1, float *X2, float *Y2);

include/SDL3/SDL_system.h

@@ -370,6 +370,8 @@ extern SDL_DECLSPEC void * SDLCALL SDL_GetAndroidActivity(void);
  *
  * \returns the Android API level.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC int SDLCALL SDL_GetAndroidSDKVersion(void);
@@ -379,6 +381,8 @@ extern SDL_DECLSPEC int SDLCALL SDL_GetAndroidSDKVersion(void);
  *
  * \returns true if this is a Chromebook, false otherwise.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC bool SDLCALL SDL_IsChromebook(void);
@@ -388,6 +392,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_IsChromebook(void);
  *
  * \returns true if this is a DeX docking station, false otherwise.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC bool SDLCALL SDL_IsDeXMode(void);
@@ -605,6 +611,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_SendAndroidMessage(Uint32 command, int para
  *
  * \returns true if the device is a tablet, false otherwise.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC bool SDLCALL SDL_IsTablet(void);
@@ -616,6 +624,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_IsTablet(void);
  *
  * \returns true if the device is a TV, false otherwise.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC bool SDLCALL SDL_IsTV(void);

include/SDL3/SDL_thread.h

@@ -208,6 +208,8 @@ typedef int (SDLCALL *SDL_ThreadFunction) (void *data);
  *          new thread could not be created; call SDL_GetError() for more
  *          information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_CreateThreadWithProperties
@@ -274,6 +276,8 @@ extern SDL_DECLSPEC SDL_Thread * SDLCALL SDL_CreateThread(SDL_ThreadFunction fn,
  *          new thread could not be created; call SDL_GetError() for more
  *          information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_CreateThread
@@ -329,6 +333,8 @@ extern SDL_DECLSPEC SDL_Thread * SDLCALL SDL_CreateThreadWithProperties(SDL_Prop
  *          new thread could not be created; call SDL_GetError() for more
  *          information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC SDL_Thread * SDLCALL SDL_CreateThreadRuntime(SDL_ThreadFunction fn, const char *name, void *data, SDL_FunctionPointer pfnBeginThread, SDL_FunctionPointer pfnEndThread);
@@ -343,6 +349,8 @@ extern SDL_DECLSPEC SDL_Thread * SDLCALL SDL_CreateThreadRuntime(SDL_ThreadFunct
  *          new thread could not be created; call SDL_GetError() for more
  *          information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC SDL_Thread * SDLCALL SDL_CreateThreadWithPropertiesRuntime(SDL_PropertiesID props, SDL_FunctionPointer pfnBeginThread, SDL_FunctionPointer pfnEndThread);
@@ -363,6 +371,8 @@ extern SDL_DECLSPEC SDL_Thread * SDLCALL SDL_CreateThreadWithPropertiesRuntime(S
  * \returns a pointer to a UTF-8 string that names the specified thread, or
  *          NULL if it doesn't have a name.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC const char * SDLCALL SDL_GetThreadName(SDL_Thread *thread);
@@ -379,6 +389,8 @@ extern SDL_DECLSPEC const char * SDLCALL SDL_GetThreadName(SDL_Thread *thread);
  *
  * \returns the ID of the current thread.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_GetThreadID
@@ -396,6 +408,8 @@ extern SDL_DECLSPEC SDL_ThreadID SDLCALL SDL_GetCurrentThreadID(void);
  * \returns the ID of the specified thread, or the ID of the current thread if
  *          `thread` is NULL.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_GetCurrentThreadID
@@ -413,6 +427,8 @@ extern SDL_DECLSPEC SDL_ThreadID SDLCALL SDL_GetThreadID(SDL_Thread *thread);
  * \returns true on success or false on failure; call SDL_GetError() for more
  *          information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC bool SDLCALL SDL_SetCurrentThreadPriority(SDL_ThreadPriority priority);
@@ -445,6 +461,9 @@ extern SDL_DECLSPEC bool SDLCALL SDL_SetCurrentThreadPriority(SDL_ThreadPriority
  *               function by its 'return', or -1 if the thread has been
  *               detached or isn't valid, may be NULL.
  *
+ * \threadsafety It is safe to call this function from any thread, but only
+ *               a single thread can wait any specific thread to finish.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_CreateThread
@@ -459,6 +478,8 @@ extern SDL_DECLSPEC void SDLCALL SDL_WaitThread(SDL_Thread *thread, int *status)
  * \returns the current state of a thread, or SDL_THREAD_UNKNOWN if the thread
  *          isn't valid.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_ThreadState
@@ -491,6 +512,8 @@ extern SDL_DECLSPEC SDL_ThreadState SDLCALL SDL_GetThreadState(SDL_Thread *threa
  *
  * It is safe to pass NULL to this function; it is a no-op.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \param thread the SDL_Thread pointer that was returned from the
  *               SDL_CreateThread() call that started this thread.
  *

include/SDL3/SDL_time.h

@@ -106,6 +106,8 @@ typedef enum SDL_TimeFormat
  * \returns true on success or false on failure; call SDL_GetError() for more
  *          information.
  *
+ * \threadsafety This function is not thread safe.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC bool SDLCALL SDL_GetDateTimeLocalePreferences(SDL_DateFormat *dateFormat, SDL_TimeFormat *timeFormat);
@@ -118,6 +120,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_GetDateTimeLocalePreferences(SDL_DateFormat
  * \returns true on success or false on failure; call SDL_GetError() for more
  *          information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC bool SDLCALL SDL_GetCurrentTime(SDL_Time *ticks);
@@ -134,6 +138,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_GetCurrentTime(SDL_Time *ticks);
  * \returns true on success or false on failure; call SDL_GetError() for more
  *          information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC bool SDLCALL SDL_TimeToDateTime(SDL_Time ticks, SDL_DateTime *dt, bool localTime);
@@ -149,6 +155,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_TimeToDateTime(SDL_Time ticks, SDL_DateTime
  * \returns true on success or false on failure; call SDL_GetError() for more
  *          information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC bool SDLCALL SDL_DateTimeToTime(const SDL_DateTime *dt, SDL_Time *ticks);
@@ -165,6 +173,8 @@ extern SDL_DECLSPEC bool SDLCALL SDL_DateTimeToTime(const SDL_DateTime *dt, SDL_
  * \param dwHighDateTime a pointer filled in with the high portion of the
  *                       Windows FILETIME value.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC void SDLCALL SDL_TimeToWindows(SDL_Time ticks, Uint32 *dwLowDateTime, Uint32 *dwHighDateTime);
@@ -180,6 +190,8 @@ extern SDL_DECLSPEC void SDLCALL SDL_TimeToWindows(SDL_Time ticks, Uint32 *dwLow
  * \param dwHighDateTime the high portion of the Windows FILETIME value.
  * \returns the converted SDL time.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC SDL_Time SDLCALL SDL_TimeFromWindows(Uint32 dwLowDateTime, Uint32 dwHighDateTime);
@@ -192,6 +204,8 @@ extern SDL_DECLSPEC SDL_Time SDLCALL SDL_TimeFromWindows(Uint32 dwLowDateTime, U
  * \returns the number of days in the requested month or -1 on failure; call
  *          SDL_GetError() for more information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC int SDLCALL SDL_GetDaysInMonth(int year, int month);
@@ -205,6 +219,8 @@ extern SDL_DECLSPEC int SDLCALL SDL_GetDaysInMonth(int year, int month);
  * \returns the day of year [0-365] if the date is valid or -1 on failure;
  *          call SDL_GetError() for more information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC int SDLCALL SDL_GetDayOfYear(int year, int month, int day);
@@ -218,6 +234,8 @@ extern SDL_DECLSPEC int SDLCALL SDL_GetDayOfYear(int year, int month, int day);
  * \returns a value between 0 and 6 (0 being Sunday) if the date is valid or
  *          -1 on failure; call SDL_GetError() for more information.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  */
 extern SDL_DECLSPEC int SDLCALL SDL_GetDayOfWeek(int year, int month, int day);

include/SDL3/SDL_version.h

@@ -85,6 +85,8 @@ extern "C" {
  *
  * \param version the version number.
  *
+ * \threadsafety It is safe to call this macro from any thread.
+ *
  * \since This macro is available since SDL 3.2.0.
  */
 #define SDL_VERSIONNUM_MAJOR(version) ((version) / 1000000)
@@ -96,6 +98,8 @@ extern "C" {
  *
  * \param version the version number.
  *
+ * \threadsafety It is safe to call this macro from any thread.
+ *
  * \since This macro is available since SDL 3.2.0.
  */
 #define SDL_VERSIONNUM_MINOR(version) (((version) / 1000) % 1000)
@@ -107,6 +111,8 @@ extern "C" {
  *
  * \param version the version number.
  *
+ * \threadsafety It is safe to call this macro from any thread.
+ *
  * \since This macro is available since SDL 3.2.0.
  */
 #define SDL_VERSIONNUM_MICRO(version) ((version) % 1000)
@@ -114,6 +120,8 @@ extern "C" {
 /**
  * This is the version number macro for the current SDL version.
  *
+ * \threadsafety It is safe to call this macro from any thread.
+ *
  * \since This macro is available since SDL 3.2.0.
  *
  * \sa SDL_GetVersion
@@ -124,6 +132,8 @@ extern "C" {
 /**
  * This macro will evaluate to true if compiled with SDL at least X.Y.Z.
  *
+ * \threadsafety It is safe to call this macro from any thread.
+ *
  * \since This macro is available since SDL 3.2.0.
  */
 #define SDL_VERSION_ATLEAST(X, Y, Z) \
@@ -141,6 +151,8 @@ extern "C" {
  *
  * \returns the version of the linked library.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_GetRevision
@@ -168,6 +180,8 @@ extern SDL_DECLSPEC int SDLCALL SDL_GetVersion(void);
  * \returns an arbitrary string, uniquely identifying the exact revision of
  *          the SDL library in use.
  *
+ * \threadsafety It is safe to call this function from any thread.
+ *
  * \since This function is available since SDL 3.2.0.
  *
  * \sa SDL_GetVersion

src/time/SDL_time.c

@@ -32,7 +32,6 @@
  */
 Sint64 SDL_CivilToDays(int year, int month, int day, int *day_of_week, int *day_of_year)
 {
-
     year -= month <= 2;
     const int era = (year >= 0 ? year : year - 399) / 400;
     const unsigned yoe = (unsigned)(year - era * 400);                                  // [0, 399]