Do not chain multiple NotShareableError.

Author: ericsnowcurrently

Python/crossinterp.c

@@ -204,15 +204,15 @@ _set_xid_lookup_failure(PyThreadState *tstate, PyObject *obj, const char *msg,
 {
     if (msg != NULL) {
         assert(obj == NULL);
-        set_notshareableerror(tstate, cause, msg);
+        set_notshareableerror(tstate, cause, 0, msg);
     }
     else if (obj == NULL) {
         msg = "object does not support cross-interpreter data";
-        set_notshareableerror(tstate, cause, msg);
+        set_notshareableerror(tstate, cause, 0, msg);
     }
     else {
-        format_notshareableerror(
-            tstate, cause, "%S does not support cross-interpreter data", obj);
+        msg = "%S does not support cross-interpreter data";
+        format_notshareableerror(tstate, cause, 0, msg, obj);
     }
 }
 
@@ -225,7 +225,7 @@ _PyObject_CheckXIData(PyThreadState *tstate, PyObject *obj)
     }
     xidatafunc getdata = lookup_getdata(&ctx, obj);
     if (getdata == NULL) {
-        if (!PyErr_Occurred()) {
+        if (!_PyErr_Occurred(tstate)) {
             _set_xid_lookup_failure(tstate, obj, NULL, NULL);
         }
         return -1;
@@ -252,14 +252,18 @@ _PyObject_GetXIData(PyThreadState *tstate,
     xidatafunc getdata = lookup_getdata(&ctx, obj);
     if (getdata == NULL) {
         Py_DECREF(obj);
-        if (!PyErr_Occurred()) {
+        if (!_PyErr_Occurred(tstate)) {
             _set_xid_lookup_failure(tstate, obj, NULL, NULL);
         }
         return -1;
     }
     int res = getdata(tstate, obj, data);
     Py_DECREF(obj);
     if (res != 0) {
+        PyObject *cause = _PyErr_GetRaisedException(tstate);
+        assert(cause != NULL);
+        _set_xid_lookup_failure(tstate, obj, NULL, cause);
+        Py_XDECREF(cause);
         return -1;
     }
 
@@ -1067,6 +1071,7 @@ _PyXI_ApplyError(_PyXI_error *error)
     }
     else if (error->code == _PyXI_ERR_NOT_SHAREABLE) {
         // Propagate the exception directly.
+        assert(!_PyErr_Occurred(tstate));
         _set_xid_lookup_failure(tstate, NULL, error->uncaught.msg, NULL);
     }
     else {

Python/crossinterp_data_lookup.h

@@ -73,7 +73,7 @@ void
 _PyXIData_SetNotShareableError(PyThreadState *tstate, const char *msg)
 {
     PyObject *cause = NULL;
-    set_notshareableerror(tstate, cause, msg);
+    set_notshareableerror(tstate, cause, 1, msg);
 }
 
 void
@@ -83,7 +83,7 @@ _PyXIData_FormatNotShareableError(PyThreadState *tstate,
     PyObject *cause = NULL;
     va_list vargs;
     va_start(vargs, format);
-    format_notshareableerror_v(tstate, cause, format, vargs);
+    format_notshareableerror_v(tstate, cause, 1, format, vargs);
     va_end(vargs);
 }
 

Python/crossinterp_exceptions.h

@@ -16,6 +16,7 @@ _ensure_current_cause(PyThreadState *tstate, PyObject *cause)
     }
     assert(PyException_GetCause(exc) == NULL);
     PyException_SetCause(exc, cause);
+    _PyErr_SetRaisedException(tstate, exc);
 }
 
 
@@ -80,41 +81,59 @@ get_notshareableerror_type(PyThreadState *tstate)
 }
 
 static void
-set_notshareableerror(PyThreadState *tstate, PyObject *cause, const char *msg)
+_ensure_notshareableerror(PyThreadState *tstate,
+                          PyObject *cause, int force, PyObject *msgobj)
 {
+    PyObject *ctx = _PyErr_GetRaisedException(tstate);
     PyObject *exctype = get_notshareableerror_type(tstate);
-    if (exctype == NULL) {
+    if (exctype != NULL) {
+        if (!force && ctx != NULL && Py_TYPE(ctx) == (PyTypeObject *)exctype) {
+            // A NotShareableError instance is already set.
+            assert(cause == NULL);
+            _PyErr_SetRaisedException(tstate, ctx);
+        }
+    }
+    else {
         exctype = PyExc_ValueError;
     }
-    // We have to set the context manually since _PyErr_SetObject() won't.
-    PyObject *ctx = _PyErr_GetRaisedException(tstate);
-    _PyErr_SetString(tstate, exctype, msg);
+    _PyErr_SetObject(tstate, exctype, msgobj);
+    // We have to set the context manually since _PyErr_SetObject() doesn't.
     _PyErr_ChainExceptions1Tstate(tstate, ctx);
     _ensure_current_cause(tstate, cause);
 }
 
 static void
-format_notshareableerror_v(PyThreadState *tstate, PyObject *cause,
+set_notshareableerror(PyThreadState *tstate, PyObject *cause, int force, const char *msg)
+{
+    PyObject *msgobj = PyUnicode_FromString(msg);
+    if (msgobj == NULL) {
+        assert(_PyErr_Occurred(tstate));
+    }
+    else {
+        _ensure_notshareableerror(tstate, cause, force, msgobj);
+    }
+}
+
+static void
+format_notshareableerror_v(PyThreadState *tstate, PyObject *cause, int force,
                            const char *format, va_list vargs)
 {
-    PyObject *exctype = get_notshareableerror_type(tstate);
-    if (exctype == NULL) {
-        exctype = PyExc_ValueError;
+    PyObject *msgobj = PyUnicode_FromFormatV(format, vargs);
+    if (msgobj == NULL) {
+        assert(_PyErr_Occurred(tstate));
+    }
+    else {
+        _ensure_notshareableerror(tstate, cause, force, msgobj);
     }
-    // We have to set the context manually since _PyErr_SetObject() won't.
-    PyObject *ctx = _PyErr_GetRaisedException(tstate);
-    _PyErr_FormatV(tstate, exctype, format, vargs);
-    _PyErr_ChainExceptions1Tstate(tstate, ctx);
-    _ensure_current_cause(tstate, cause);
 }
 
 static void
-format_notshareableerror(PyThreadState *tstate, PyObject *cause,
+format_notshareableerror(PyThreadState *tstate, PyObject *cause, int force,
                          const char *format, ...)
 {
     va_list vargs;
     va_start(vargs, format);
-    format_notshareableerror_v(tstate, cause, format, vargs);
+    format_notshareableerror_v(tstate, cause, force, format, vargs);
     va_end(vargs);
 }