gh-102192: Replace PyErr_Fetch/Restore etc by more efficient alternatives in tkinter module (#102319)

Modules/_tkinter.c

@@ -321,8 +321,6 @@ static PyObject *Tkinter_TclError;
 static int quitMainLoop = 0;
 static int errorInCmd = 0;
 static PyObject *excInCmd;
-static PyObject *valInCmd;
-static PyObject *trbInCmd;
 
 #ifdef TKINTER_PROTECT_LOADTK
 static int tk_load_failed = 0;
@@ -1222,7 +1220,7 @@ typedef struct Tkapp_CallEvent {
     PyObject *args;
     int flags;
     PyObject **res;
-    PyObject **exc_type, **exc_value, **exc_tb;
+    PyObject **exc;
     Tcl_Condition *done;
 } Tkapp_CallEvent;
 
@@ -1339,7 +1337,7 @@ Tkapp_CallProc(Tkapp_CallEvent *e, int flags)
     ENTER_PYTHON
     objv = Tkapp_CallArgs(e->args, objStore, &objc);
     if (!objv) {
-        PyErr_Fetch(e->exc_type, e->exc_value, e->exc_tb);
+        *(e->exc) = PyErr_GetRaisedException();
         *(e->res) = NULL;
     }
     LEAVE_PYTHON
@@ -1354,7 +1352,7 @@ Tkapp_CallProc(Tkapp_CallEvent *e, int flags)
         *(e->res) = Tkapp_ObjectResult(e->self);
     }
     if (*(e->res) == NULL) {
-        PyErr_Fetch(e->exc_type, e->exc_value, e->exc_tb);
+        *(e->exc) = PyErr_GetRaisedException();
     }
     LEAVE_PYTHON
 
@@ -1401,7 +1399,7 @@ Tkapp_Call(PyObject *selfptr, PyObject *args)
            marshal the parameters to the interpreter thread. */
         Tkapp_CallEvent *ev;
         Tcl_Condition cond = NULL;
-        PyObject *exc_type, *exc_value, *exc_tb;
+        PyObject *exc;
         if (!WaitForMainloop(self))
             return NULL;
         ev = (Tkapp_CallEvent*)attemptckalloc(sizeof(Tkapp_CallEvent));
@@ -1413,18 +1411,18 @@ Tkapp_Call(PyObject *selfptr, PyObject *args)
         ev->self = self;
         ev->args = args;
         ev->res = &res;
-        ev->exc_type = &exc_type;
-        ev->exc_value = &exc_value;
-        ev->exc_tb = &exc_tb;
+        ev->exc = &exc;
         ev->done = &cond;
 
         Tkapp_ThreadSend(self, (Tcl_Event*)ev, &cond, &call_mutex);
 
         if (res == NULL) {
-            if (exc_type)
-                PyErr_Restore(exc_type, exc_value, exc_tb);
-            else
-                PyErr_SetObject(Tkinter_TclError, exc_value);
+            if (exc) {
+                PyErr_SetRaisedException(exc);
+            }
+            else {
+                PyErr_SetObject(Tkinter_TclError, exc);
+            }
         }
         Tcl_ConditionFinalize(&cond);
     }
@@ -1578,8 +1576,7 @@ typedef struct VarEvent {
     int flags;
     EventFunc func;
     PyObject **res;
-    PyObject **exc_type;
-    PyObject **exc_val;
+    PyObject **exc;
     Tcl_Condition *cond;
 } VarEvent;
 
@@ -1643,12 +1640,7 @@ var_perform(VarEvent *ev)
 {
     *(ev->res) = ev->func(ev->self, ev->args, ev->flags);
     if (!*(ev->res)) {
-        PyObject *exc, *val, *tb;
-        PyErr_Fetch(&exc, &val, &tb);
-        PyErr_NormalizeException(&exc, &val, &tb);
-        *(ev->exc_type) = exc;
-        *(ev->exc_val) = val;
-        Py_XDECREF(tb);
+        *(ev->exc) = PyErr_GetRaisedException();;
     }
 
 }
@@ -1672,7 +1664,7 @@ var_invoke(EventFunc func, PyObject *selfptr, PyObject *args, int flags)
     TkappObject *self = (TkappObject*)selfptr;
     if (self->threaded && self->thread_id != Tcl_GetCurrentThread()) {
         VarEvent *ev;
-        PyObject *res, *exc_type, *exc_val;
+        PyObject *res, *exc;
         Tcl_Condition cond = NULL;
 
         /* The current thread is not the interpreter thread.  Marshal
@@ -1691,16 +1683,14 @@ var_invoke(EventFunc func, PyObject *selfptr, PyObject *args, int flags)
         ev->flags = flags;
         ev->func = func;
         ev->res = &res;
-        ev->exc_type = &exc_type;
-        ev->exc_val = &exc_val;
+        ev->exc = &exc;
         ev->cond = &cond;
         ev->ev.proc = (Tcl_EventProc*)var_proc;
         Tkapp_ThreadSend(self, (Tcl_Event*)ev, &cond, &var_mutex);
         Tcl_ConditionFinalize(&cond);
         if (!res) {
-            PyErr_SetObject(exc_type, exc_val);
-            Py_DECREF(exc_type);
-            Py_DECREF(exc_val);
+            PyErr_SetObject((PyObject*)Py_TYPE(exc), exc);
+            Py_DECREF(exc);
             return NULL;
         }
         return res;
@@ -2188,7 +2178,7 @@ static int
 PythonCmd_Error(Tcl_Interp *interp)
 {
     errorInCmd = 1;
-    PyErr_Fetch(&excInCmd, &valInCmd, &trbInCmd);
+    excInCmd = PyErr_GetRaisedException();
     LEAVE_PYTHON
     return TCL_ERROR;
 }
@@ -2458,7 +2448,7 @@ FileHandler(ClientData clientData, int mask)
     res = PyObject_CallFunction(func, "Oi", file, mask);
     if (res == NULL) {
         errorInCmd = 1;
-        PyErr_Fetch(&excInCmd, &valInCmd, &trbInCmd);
+        excInCmd = PyErr_GetRaisedException();
     }
     Py_XDECREF(res);
     LEAVE_PYTHON
@@ -2628,7 +2618,7 @@ TimerHandler(ClientData clientData)
 
     if (res == NULL) {
         errorInCmd = 1;
-        PyErr_Fetch(&excInCmd, &valInCmd, &trbInCmd);
+        excInCmd = PyErr_GetRaisedException();
     }
     else
         Py_DECREF(res);
@@ -2725,8 +2715,8 @@ _tkinter_tkapp_mainloop_impl(TkappObject *self, int threshold)
 
     if (errorInCmd) {
         errorInCmd = 0;
-        PyErr_Restore(excInCmd, valInCmd, trbInCmd);
-        excInCmd = valInCmd = trbInCmd = NULL;
+        PyErr_SetRaisedException(excInCmd);
+        excInCmd = NULL;
         return NULL;
     }
     Py_RETURN_NONE;
@@ -3187,8 +3177,8 @@ EventHook(void)
 #endif
     if (errorInCmd) {
         errorInCmd = 0;
-        PyErr_Restore(excInCmd, valInCmd, trbInCmd);
-        excInCmd = valInCmd = trbInCmd = NULL;
+        PyErr_SetRaisedException(excInCmd);
+        excInCmd = NULL;
         PyErr_Print();
     }
     PyEval_SaveThread();