bpo-40612: Fix SyntaxError edge cases in traceback formatting (GH-20072)
This fixes both the traceback.py module and the C code for formatting syntax errors (in Python/pythonrun.c). They now both consistently do the following:
- Suppress caret if it points left of text
- Allow caret pointing just past end of line
- If caret points past end of line, clip to *just* past end of line
The syntax error formatting code in traceback.py was mostly rewritten; small, subtle changes were applied to the C code in pythonrun.c.
There's still a difference when the text contains embedded newlines. Neither handles these very well, and I don't think the case occurs in practice.
Automerge-Triggered-By: @gvanrossum
diff --git a/Lib/test/test_traceback.py b/Lib/test/test_traceback.py
index 7361d09..f9a5f2f 100644
--- a/Lib/test/test_traceback.py
+++ b/Lib/test/test_traceback.py
@@ -58,13 +58,13 @@
SyntaxError)
self.assertIn("^", err[2]) # third line has caret
self.assertEqual(err[2].count('\n'), 1) # and no additional newline
- self.assertEqual(err[1].find("+"), err[2].find("^")) # in the right place
+ self.assertEqual(err[1].find("+") + 1, err[2].find("^")) # in the right place
err = self.get_exception_format(self.syntax_error_with_caret_non_ascii,
SyntaxError)
self.assertIn("^", err[2]) # third line has caret
self.assertEqual(err[2].count('\n'), 1) # and no additional newline
- self.assertEqual(err[1].find("+"), err[2].find("^")) # in the right place
+ self.assertEqual(err[1].find("+") + 1, err[2].find("^")) # in the right place
def test_nocaret(self):
exc = SyntaxError("error", ("x.py", 23, None, "bad syntax"))
@@ -78,14 +78,13 @@
self.assertEqual(len(err), 4)
self.assertEqual(err[1].strip(), "print(2)")
self.assertIn("^", err[2])
- self.assertEqual(err[1].find(")"), err[2].find("^"))
+ self.assertEqual(err[1].find(")") + 1, err[2].find("^"))
+ # No caret for "unexpected indent"
err = self.get_exception_format(self.syntax_error_bad_indentation2,
IndentationError)
- self.assertEqual(len(err), 4)
+ self.assertEqual(len(err), 3)
self.assertEqual(err[1].strip(), "print(2)")
- self.assertIn("^", err[2])
- self.assertEqual(err[1].find("p"), err[2].find("^"))
def test_base_exception(self):
# Test that exceptions derived from BaseException are formatted right
@@ -656,7 +655,7 @@
self.assertIn('inner_raise() # Marker', blocks[2])
self.check_zero_div(blocks[2])
- @support.skip_if_new_parser("Pegen is arguably better here, so no need to fix this")
+ @unittest.skipIf(support.use_old_parser(), "Pegen is arguably better here, so no need to fix this")
def test_syntax_error_offset_at_eol(self):
# See #10186.
def e():
@@ -666,7 +665,7 @@
def e():
exec("x = 5 | 4 |")
msg = self.get_report(e).splitlines()
- self.assertEqual(msg[-2], ' ^')
+ self.assertEqual(msg[-2], ' ^')
def test_message_none(self):
# A message that looks like "None" should not be treated specially
@@ -679,6 +678,25 @@
err = self.get_report(Exception(''))
self.assertIn('Exception\n', err)
+ def test_syntax_error_various_offsets(self):
+ for offset in range(-5, 10):
+ for add in [0, 2]:
+ text = " "*add + "text%d" % offset
+ expected = [' File "file.py", line 1']
+ if offset < 1:
+ expected.append(" %s" % text.lstrip())
+ elif offset <= 6:
+ expected.append(" %s" % text.lstrip())
+ expected.append(" %s^" % (" "*(offset-1)))
+ else:
+ expected.append(" %s" % text.lstrip())
+ expected.append(" %s^" % (" "*5))
+ expected.append("SyntaxError: msg")
+ expected.append("")
+ err = self.get_report(SyntaxError("msg", ("file.py", 1, offset+add, text)))
+ exp = "\n".join(expected)
+ self.assertEqual(exp, err)
+
class PyExcReportingTests(BaseExceptionReportingTests, unittest.TestCase):
#