gh-137477: Extend regex pattern check in inspect.findsource

Lib/inspect.py

@@ -1002,6 +1002,15 @@ def findsource(object):
         lnum = object.co_firstlineno - 1
         if lnum >= len(lines):
             raise OSError('lineno is out of bounds')
+        pat = re.compile(r'^(\s*def\s)|(\s*class\s)|(\s*async\s+def\s)|(.*(?<!\w)lambda(:|\s))|^(\s*@)')
+        while lnum > 0:
+            try:
+                line = lines[lnum]
+            except IndexError:
+                raise OSError('lineno is out of bounds')
+            if pat.match(line):
+                break
+            lnum = lnum - 1
         return lines, lnum
     raise OSError('could not find code object')
 

Lib/test/test_inspect/inspect_fodder2.py

@@ -369,3 +369,11 @@ class dc364:
 # line 369
 dc370 = dataclasses.make_dataclass('dc370', (('x', int), ('y', int)))
 dc371 = dataclasses.make_dataclass('dc370', (('x', int), ('y', int)), module=__name__)
+
+# line 373
+from inspect import currentframe
+def generator_frame():
+    loops = (
+        currentframe() for _ in [0]
+    )
+    return list(loops)[0]

Lib/test/test_inspect/test_inspect.py

@@ -1195,6 +1195,11 @@ def test_class_definition_same_name_diff_methods(self):
         self.assertSourceEqual(mod2.cls296, 296, 298)
         self.assertSourceEqual(mod2.cls310, 310, 312)
 
+    def test_generator_frame(self):
+        frame = mod2.generator_frame()
+        assert frame is not None
+        self.assertSourceEqual(frame, 375, 379)
+
 class TestNoEOL(GetSourceBase):
     def setUp(self):
         self.tempdir = TESTFN + '_dir'