gh-89770: Implement PEP-678 - Exception notes (GH-31317)

1 files changed, 57 insertions, 24 deletions

diff --git a/Python/pythonrun.c b/Python/pythonrun.c
index e086f0f..769c34e 100644
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -1129,7 +1129,7 @@ error:
 }
 
 static int
-print_exception_note(struct exception_print_context *ctx, PyObject *value)
+print_exception_notes(struct exception_print_context *ctx, PyObject *value)
 {
     PyObject *f = ctx->file;
 
@@ -1137,41 +1137,74 @@ print_exception_note(struct exception_print_context *ctx, PyObject *value)
         return 0;
     }
 
-    PyObject *note = PyObject_GetAttr(value, &_Py_ID(__note__));
-    if (note == NULL) {
+    if (!PyObject_HasAttr(value, &_Py_ID(__notes__))) {
+        return 0;
+    }
+    PyObject *notes = PyObject_GetAttr(value, &_Py_ID(__notes__));
+    if (notes == NULL) {
         return -1;
     }
-    if (!PyUnicode_Check(note)) {
-        Py_DECREF(note);
-        return 0;
+    if (!PySequence_Check(notes)) {
+        int res = 0;
+        if (write_indented_margin(ctx, f) < 0) {
+            res = -1;
+        }
+        PyObject *s = PyObject_Repr(notes);
+        if (s == NULL) {
+            PyErr_Clear();
+            res = PyFile_WriteString("<__notes__ repr() failed>", f);
+        }
+        else {
+            res = PyFile_WriteObject(s, f, Py_PRINT_RAW);
+            Py_DECREF(s);
+        }
+        Py_DECREF(notes);
+        return res;
     }
+    Py_ssize_t num_notes = PySequence_Length(notes);
+    PyObject *lines = NULL;
+    for (Py_ssize_t ni = 0; ni < num_notes; ni++) {
+        PyObject *note = PySequence_GetItem(notes, ni);
+        PyObject *note_str = PyObject_Str(note);
+        Py_DECREF(note);
 
-    PyObject *lines = PyUnicode_Splitlines(note, 1);
-    Py_DECREF(note);
+        if (note_str == NULL) {
+            PyErr_Clear();
+            if (PyFile_WriteString("<note str() failed>", f) < 0) {
+                goto error;
+            }
+        }
+        else {
+            lines = PyUnicode_Splitlines(note_str, 1);
+            Py_DECREF(note_str);
 
-    if (lines == NULL) {
-        return -1;
-    }
+            if (lines == NULL) {
+                goto error;
+            }
 
-    Py_ssize_t n = PyList_GET_SIZE(lines);
-    for (Py_ssize_t i = 0; i < n; i++) {
-        PyObject *line = PyList_GET_ITEM(lines, i);
-        assert(PyUnicode_Check(line));
-        if (write_indented_margin(ctx, f) < 0) {
-            goto error;
+            Py_ssize_t n = PyList_GET_SIZE(lines);
+            for (Py_ssize_t i = 0; i < n; i++) {
+                PyObject *line = PyList_GET_ITEM(lines, i);
+                assert(PyUnicode_Check(line));
+                if (write_indented_margin(ctx, f) < 0) {
+                    goto error;
+                }
+                if (PyFile_WriteObject(line, f, Py_PRINT_RAW) < 0) {
+                    goto error;
+                }
+            }
+            Py_CLEAR(lines);
         }
-        if (PyFile_WriteObject(line, f, Py_PRINT_RAW) < 0) {
+        if (PyFile_WriteString("\n", f) < 0) {
             goto error;
         }
     }
-    if (PyFile_WriteString("\n", f) < 0) {
-        goto error;
-    }
 
-    Py_DECREF(lines);
+    Py_DECREF(notes);
     return 0;
 error:
-    Py_DECREF(lines);
+    Py_XDECREF(lines);
+    Py_DECREF(notes);
     return -1;
 }
 
@@ -1206,7 +1239,7 @@ print_exception(struct exception_print_context *ctx, PyObject *value)
     if (PyFile_WriteString("\n", f) < 0) {
         goto error;
     }
-    if (print_exception_note(ctx, value) < 0) {
+    if (print_exception_notes(ctx, value) < 0) {
         goto error;
     }