gh-108082: Use PyErr_FormatUnraisable() (GH-111580)

Replace most of calls of _PyErr_WriteUnraisableMsg() and some
calls of PyErr_WriteUnraisable(NULL) with PyErr_FormatUnraisable().

Co-authored-by: Victor Stinner <vstinner@python.org>

5 files changed, 19 insertions, 51 deletions

diff --git a/Objects/codeobject.c b/Objects/codeobject.c
index f662b8e..48ff5b8 100644
--- a/Objects/codeobject.c
+++ b/Objects/codeobject.c
@@ -12,8 +12,6 @@
 #include "pycore_tuple.h"         // _PyTuple_ITEMS()
 #include "clinic/codeobject.c.h"
 
-static PyObject* code_repr(PyCodeObject *co);
-
 static const char *
 code_event_name(PyCodeEvent event) {
     switch (event) {
@@ -41,21 +39,9 @@ notify_code_watchers(PyCodeEvent event, PyCodeObject *co)
             // callback must be non-null if the watcher bit is set
             assert(cb != NULL);
             if (cb(event, co) < 0) {
-                // Don't risk resurrecting the object if an unraisablehook keeps
-                // a reference; pass a string as context.
-                PyObject *context = NULL;
-                PyObject *repr = code_repr(co);
-                if (repr) {
-                    context = PyUnicode_FromFormat(
-                        "%s watcher callback for %U",
-                        code_event_name(event), repr);
-                    Py_DECREF(repr);
-                }
-                if (context == NULL) {
-                    context = Py_NewRef(Py_None);
-                }
-                PyErr_WriteUnraisable(context);
-                Py_DECREF(context);
+                PyErr_FormatUnraisable(
+                    "Exception ignored in %s watcher callback for %R",
+                    code_event_name(event), co);
             }
         }
         i++;
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index 361f8e9..5aa2c0d 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -5912,14 +5912,9 @@ _PyDict_SendEvent(int watcher_bits,
                 // unraisablehook keep a reference to it, so we don't pass the
                 // dict as context, just an informative string message.  Dict
                 // repr can call arbitrary code, so we invent a simpler version.
-                PyObject *context = PyUnicode_FromFormat(
-                    "%s watcher callback for <dict at %p>",
+                PyErr_FormatUnraisable(
+                    "Exception ignored in %s watcher callback for <dict at %p>",
                     dict_event_name(event), mp);
-                if (context == NULL) {
-                    context = Py_NewRef(Py_None);
-                }
-                PyErr_WriteUnraisable(context);
-                Py_DECREF(context);
             }
         }
         watcher_bits >>= 1;
diff --git a/Objects/funcobject.c b/Objects/funcobject.c
index 56c5af6..8ce1bff 100644
--- a/Objects/funcobject.c
+++ b/Objects/funcobject.c
@@ -8,8 +8,6 @@
 #include "pycore_pyerrors.h"      // _PyErr_Occurred()
 
 
-static PyObject* func_repr(PyFunctionObject *op);
-
 static const char *
 func_event_name(PyFunction_WatchEvent event) {
     switch (event) {
@@ -35,21 +33,9 @@ notify_func_watchers(PyInterpreterState *interp, PyFunction_WatchEvent event,
             // callback must be non-null if the watcher bit is set
             assert(cb != NULL);
             if (cb(event, func, new_value) < 0) {
-                // Don't risk resurrecting the func if an unraisablehook keeps a
-                // reference; pass a string as context.
-                PyObject *context = NULL;
-                PyObject *repr = func_repr(func);
-                if (repr != NULL) {
-                    context = PyUnicode_FromFormat(
-                        "%s watcher callback for %U",
-                        func_event_name(event), repr);
-                    Py_DECREF(repr);
-                }
-                if (context == NULL) {
-                    context = Py_NewRef(Py_None);
-                }
-                PyErr_WriteUnraisable(context);
-                Py_DECREF(context);
+                PyErr_FormatUnraisable(
+                    "Exception ignored in %s watcher callback for function %U at %p",
+                    func_event_name(event), func->func_qualname, func);
             }
         }
         i++;
diff --git a/Objects/moduleobject.c b/Objects/moduleobject.c
index 5b9f74d..a3d55b7 100644
--- a/Objects/moduleobject.c
+++ b/Objects/moduleobject.c
@@ -647,7 +647,7 @@ _PyModule_ClearDict(PyObject *d)
                         PyErr_Clear();
                 }
                 if (PyDict_SetItem(d, key, Py_None) != 0) {
-                    PyErr_WriteUnraisable(NULL);
+                    PyErr_FormatUnraisable("Exception ignored on clearing module dict");
                 }
             }
         }
@@ -668,7 +668,7 @@ _PyModule_ClearDict(PyObject *d)
                         PyErr_Clear();
                 }
                 if (PyDict_SetItem(d, key, Py_None) != 0) {
-                    PyErr_WriteUnraisable(NULL);
+                    PyErr_FormatUnraisable("Exception ignored on clearing module dict");
                 }
             }
         }
@@ -902,10 +902,9 @@ module_clear(PyModuleObject *m)
     {
         int res = m->md_def->m_clear((PyObject*)m);
         if (PyErr_Occurred()) {
-            PySys_FormatStderr("Exception ignored in m_clear of module%s%V\n",
-                               m->md_name ? " " : "",
-                               m->md_name, "");
-            PyErr_WriteUnraisable(NULL);
+            PyErr_FormatUnraisable("Exception ignored in m_clear of module%s%V",
+                                   m->md_name ? " " : "",
+                                   m->md_name, "");
         }
         if (res)
             return res;
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 2508569..f44e30c 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -828,7 +828,9 @@ PyType_Modified(PyTypeObject *type)
             if (bits & 1) {
                 PyType_WatchCallback cb = interp->type_watchers[i];
                 if (cb && (cb(type) < 0)) {
-                    PyErr_WriteUnraisable((PyObject *)type);
+                    PyErr_FormatUnraisable(
+                        "Exception ignored in type watcher callback #%d for %R",
+                        i, type);
                 }
             }
             i++;
@@ -9291,7 +9293,7 @@ releasebuffer_call_python(PyObject *self, Py_buffer *buffer)
         // from a Python __buffer__ function.
         mv = PyMemoryView_FromBuffer(buffer);
         if (mv == NULL) {
-            PyErr_WriteUnraisable(self);
+            PyErr_FormatUnraisable("Exception ignored in bf_releasebuffer of %s", Py_TYPE(self)->tp_name);
             goto end;
         }
         // Set the memoryview to restricted mode, which forbids
@@ -9304,7 +9306,7 @@ releasebuffer_call_python(PyObject *self, Py_buffer *buffer)
     PyObject *stack[2] = {self, mv};
     PyObject *ret = vectorcall_method(&_Py_ID(__release_buffer__), stack, 2);
     if (ret == NULL) {
-        PyErr_WriteUnraisable(self);
+        PyErr_FormatUnraisable("Exception ignored in __release_buffer__ of %s", Py_TYPE(self)->tp_name);
     }
     else {
         Py_DECREF(ret);
@@ -9312,7 +9314,7 @@ releasebuffer_call_python(PyObject *self, Py_buffer *buffer)
     if (!is_buffer_wrapper) {
         PyObject *res = PyObject_CallMethodNoArgs(mv, &_Py_ID(release));
         if (res == NULL) {
-            PyErr_WriteUnraisable(self);
+            PyErr_FormatUnraisable("Exception ignored in bf_releasebuffer of %s", Py_TYPE(self)->tp_name);
         }
         else {
             Py_DECREF(res);