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

As of 088a15c, lineno is None instead
of -1 if there is no line number.

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

Author: FFY00

Lib/test/test_traceback.py

@@ -1204,6 +1204,10 @@ def test_lazy_lines(self):
             '"""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)

Lib/traceback.py

@@ -310,6 +310,8 @@ def _original_line(self):
     @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()
 

Misc/NEWS.d/next/Library/2021-06-17-22-39-34.bpo-44446.qwdRic.rst

@@ -0,0 +1 @@
+Take into account that ``lineno`` might be ``None`` in :class:`traceback.FrameSummary`.