C traceback code

python · iritkatriel · Nov 5, 2021 · Oct 5, 2021 · Oct 8, 2021 · Oct 24, 2021
commit 42bed01c31e03432873955bd66303054a2fa2483
diff --git a/Include/cpython/traceback.h b/Include/cpython/traceback.h
@@ -10,5 +10,5 @@ typedef struct _traceback {
     int tb_lineno;
 } PyTracebackObject;
 
-PyAPI_FUNC(int) _Py_DisplaySourceLine(PyObject *, PyObject *, int, int, int *, PyObject **);
+PyAPI_FUNC(int) _Py_DisplaySourceLine(PyObject *, PyObject *, int, int, int, char, int *, PyObject **);
 PyAPI_FUNC(void) _PyTraceback_Add(const char *, const char *, int);
diff --git a/Include/traceback.h b/Include/traceback.h
@@ -9,6 +9,10 @@ extern "C" {
 PyAPI_FUNC(int) PyTraceBack_Here(PyFrameObject *);
 PyAPI_FUNC(int) PyTraceBack_Print(PyObject *, PyObject *);
 
+int PyTraceBack_Print_Indented(PyObject *, int, char, PyObject *);
+int _Py_WriteIndentedMargin(int, char, PyObject *);
+int _Py_WriteIndent(int, PyObject *);
+
 /* Reveal traceback type so we can typecheck traceback objects */
 PyAPI_DATA(PyTypeObject) PyTraceBack_Type;
 #define PyTraceBack_Check(v) Py_IS_TYPE(v, &PyTraceBack_Type)

diff --git a/Lib/test/test_traceback.py b/Lib/test/test_traceback.py
@@ -995,9 +995,12 @@ def __eq__(self, other):
     "\nDuring handling of the above exception, "
     "another exception occurred:\n\n")
 
-boundaries = re.compile(
-    '(%s|%s)' % (re.escape(cause_message), re.escape(context_message)))
+nested_exception_header_re = r'[\+-]?\+[-{4} ]+[ \d\.?]+[ -{4}]+'
 
+boundaries = re.compile(
+    '(%s|%s|%s)' % (re.escape(cause_message),
+                    re.escape(context_message),
+                    nested_exception_header_re))
 
 class BaseExceptionReportingTests:
 
@@ -1263,6 +1266,171 @@ def get_report(self, e):
             exception_print(e)
         return s.getvalue()
 
+    # TODO: once traceback.py supports this format, move the
+    #       following tests to the superclass
+
+    def check_exception_group(self, exc_func, expected):
+        report = self.get_report(exc_func)
+        blocks = boundaries.split(report)
+        self.assertEqual(len(blocks), len(expected))
+
+        for i, block in enumerate(blocks):
+            for line in expected[i]:
+                self.assertIn(f"{line}", block)
+                # check indentation
+                self.assertNotIn(f" {line}", block)
+
+        for line in report:
+            # at most one margin char per line
+            self.assertLessEqual(line.count('|'), 1)
+
+    @cpython_only
+    def test_exception_group_basic(self):
+        def exc():
+            raise ExceptionGroup("eg", [ValueError(1), TypeError(2)])
+
+        expected = [
+            ['  |     raise ExceptionGroup("eg", [ValueError(1), TypeError(2)])',
+             '  | ExceptionGroup: eg',
+             '  |  with 2 sub-exceptions:'
+            ],
+            ['-+---------------- 1 ----------------'],
+            ['    | ValueError: 1'],
+            ['+---------------- 2 ----------------'],
+            ['    | TypeError: 2'],
+        ]
+
+        self.check_exception_group(exc, expected)
+
+    @cpython_only
+    def test_exception_group_context(self):
+        def exc():
+            try:
+                raise ExceptionGroup("eg1", [ValueError(1), TypeError(2)])
+            except:
+                raise ExceptionGroup("eg2", [ValueError(3), TypeError(4)])
+
+        expected = [
+            ['  |     raise ExceptionGroup("eg1", [ValueError(1), TypeError(2)])',
+             '  | ExceptionGroup: eg1',
+             '  |  with 2 sub-exceptions:'
+            ],
+            ['-+---------------- 1 ----------------'],
+            ['    | ValueError: 1'],
+            ['+---------------- 2 ----------------'],
+            ['    | TypeError: 2'],
+            [ context_message ],
+            ['  |     raise ExceptionGroup("eg2", [ValueError(3), TypeError(4)])',
+             '  | ExceptionGroup: eg2',
+             '  |  with 2 sub-exceptions:'
+            ],
+            ['-+---------------- 1 ----------------'],
+            ['    | ValueError: 3'],
+            ['+---------------- 2 ----------------'],
+            ['    | TypeError: 4'],
+        ]
+        self.check_exception_group(exc, expected)
+
+    @cpython_only
+    def test_exception_group_context(self):
+        def exc():
+            EG = ExceptionGroup
+            try:
+                raise EG("eg1", [ValueError(1), TypeError(2)])
+            except:
+                raise EG("eg2", [ValueError(3), TypeError(4)])
+
+        expected = [
+            ['  |     raise EG("eg1", [ValueError(1), TypeError(2)])',
+             '  | ExceptionGroup: eg1',
+             '  |  with 2 sub-exceptions:'
+            ],
+            ['-+---------------- context.1 ----------------'],
+            ['    | ValueError: 1'],
+            ['+---------------- context.2 ----------------'],
+            ['    | TypeError: 2'],
+            [ context_message ],
+            ['  |     raise EG("eg2", [ValueError(3), TypeError(4)])',
+             '  | ExceptionGroup: eg2',
+             '  |  with 2 sub-exceptions:'
+            ],
+            ['-+---------------- 1 ----------------'],
+            ['    | ValueError: 3'],
+            ['+---------------- 2 ----------------'],
+            ['    | TypeError: 4'],
+        ]
+        self.check_exception_group(exc, expected)
+
+    def test_exception_group_cause(self):
+        def exc():
+            EG = ExceptionGroup
+            try:
+                raise EG("eg1", [ValueError(1), TypeError(2)])
+            except Exception as e:
+                raise EG("eg2", [ValueError(3), TypeError(4)]) from e
+
+        expected = [
+            ['  |     raise EG("eg1", [ValueError(1), TypeError(2)])',
+             '  | ExceptionGroup: eg1',
+             '  |  with 2 sub-exceptions:'
+            ],
+            ['-+---------------- cause.1 ----------------'],
+            ['    | ValueError: 1'],
+            ['+---------------- cause.2 ----------------'],
+            ['    | TypeError: 2'],
+            [ cause_message ],
+            ['  |     raise EG("eg2", [ValueError(3), TypeError(4)])',
+             '  | ExceptionGroup: eg2',
+             '  |  with 2 sub-exceptions:'
+            ],
+            ['-+---------------- 1 ----------------'],
+            ['    | ValueError: 3'],
+            ['+---------------- 2 ----------------'],
+            ['    | TypeError: 4'],
+        ]
+        self.check_exception_group(exc, expected)
+
+    @cpython_only
+    def test_exception_group_nested(self):
+        def exc():
+            EG = ExceptionGroup
+            VE = ValueError
+            TE = TypeError
+            try:
+                try:
+                    raise EG("nested", [TE(2), TE(3)])
+                except Exception as e:
+                    exc = e
+                raise EG("eg", [VE(1), exc, VE(4)])
+            except:
+                raise EG("top", [VE(5)])
+
+        expected = [
+            ['  |     raise EG("eg", [VE(1), exc, VE(4)])',
+             '  | ExceptionGroup: eg',
+             '  |  with 3 sub-exceptions:'
+            ],
+            ['-+---------------- context.1 ----------------'],
+            ['    | ValueError: 1'],
+            ['+---------------- context.2 ----------------'],
+            ['    | ExceptionGroup: nested',
+             '    |  with 2 sub-exceptions'
+            ],
+            ['-+---------------- context.2.1 ----------------'],
+            ['      | TypeError: 2'],
+            ['+---------------- context.2.2 ----------------'],
+            ['      | TypeError: 3'],
+            ['+---------------- context.3 ----------------'],
+            ['    | ValueError: 4'],
+            [ context_message ],
+            ['  |     raise EG("top", [VE(5)])',
+             '  | ExceptionGroup: top'
+            ],
+            ['-+---------------- 1 ----------------'],
+            ['    | ValueError: 5']
+        ]
+        self.check_exception_group(exc, expected)
+
 
 class LimitTests(unittest.TestCase):
 

diff --git a/Python/_warnings.c b/Python/_warnings.c
@@ -544,7 +544,7 @@ show_warning(PyObject *filename, int lineno, PyObject *text,
         PyFile_WriteString("\n", f_stderr);
     }
     else {
-        _Py_DisplaySourceLine(f_stderr, filename, lineno, 2, NULL, NULL);
+        _Py_DisplaySourceLine(f_stderr, filename, lineno, 2, 0, '\0', NULL, NULL);
     }
 
 error:
-Original file line number
+Diff line change
@@ Expand Up @@
             PyFile_WriteString("\n", f_stderr);
         }
         else {
-            _Py_DisplaySourceLine(f_stderr, filename, lineno, 2, NULL, NULL);
+            _Py_DisplaySourceLine(f_stderr, filename, lineno, 2, 0, '\0', NULL, NULL);
         }
     error:
@@ Expand Down @@