bpo-44446: support lineno being None in traceback.FrameSummary (GH-26781)

As of 088a15c49d99ecb4c3bef93f8f40dd513c6cae3b, lineno is None instead
of -1 if there is no line number.

Signed-off-by: Filipe Laíns <lains@riseup.net>

2 files changed, 6 insertions, 0 deletions

diff --git a/Lib/test/test_traceback.py b/Lib/test/test_traceback.py
index 5681dfa..50ebcce 100644
--- a/Lib/test/test_traceback.py
+++ b/Lib/test/test_traceback.py
@@ -1204,6 +1204,10 @@ class TestFrame(unittest.TestCase):
             '"""Test cases for traceback module"""',
             f.line)
 
+    def test_no_line(self):
+        f = traceback.FrameSummary("f", None, "dummy")
+        self.assertEqual(f.line, None)
+
     def test_explicit_line(self):
         f = traceback.FrameSummary("f", 1, "dummy", line="line")
         self.assertEqual("line", f.line)
diff --git a/Lib/traceback.py b/Lib/traceback.py
index cf1ba2a..7cb1241 100644
--- a/Lib/traceback.py
+++ b/Lib/traceback.py
@@ -310,6 +310,8 @@ class FrameSummary:
     @property
     def line(self):
         if self._line is None:
+            if self.lineno is None:
+                return None
             self._line = linecache.getline(self.filename, self.lineno)
         return self._line.strip()