From 0fd59f04d848a19d446959b0e3a2af5236e6427a Mon Sep 17 00:00:00 2001
From: Thomas Grainger <tagrain@gmail.com>
Date: Tue, 22 Mar 2022 10:07:27 +0000
Subject: [PATCH] handle frame.f_lineno is None in inspect.getframeinfo

---
 Lib/inspect.py                                | 32 ++++++++++++++++---
 .../2022-03-22-10-16-11.bpo-45563.o-oP2m.rst  |  1 +
 2 files changed, 29 insertions(+), 4 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2022-03-22-10-16-11.bpo-45563.o-oP2m.rst

diff --git a/Lib/inspect.py b/Lib/inspect.py
index 9c1283ab3734bfa..00dde27d9027a2e 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -1649,10 +1649,10 @@ def getframeinfo(frame, context=1):
     The optional second argument specifies the number of lines of context
     to return, which are centered around the current line."""
     if istraceback(frame):
-        lineno = frame.tb_lineno
+        lineno = _tblineno(frame)
         frame = frame.tb_frame
     else:
-        lineno = frame.f_lineno
+        lineno = getlineno(frame)
     if not isframe(frame):
         raise TypeError('{!r} is not a frame or traceback object'.format(frame))
 
@@ -1672,10 +1672,34 @@ def getframeinfo(frame, context=1):
 
     return Traceback(filename, lineno, frame.f_code.co_name, lines, index)
 
+
+def _tblineno(tb):
+    tb_lineno = tb.tb_lineno
+    if tb_lineno is not None:
+        return tb_lineno
+
+    return _lasti2lineno(tb.tb_frame.f_code, tb.tb_lasti)
+
+
+def _lasti2lineno(code, lasti):
+    prev_line = code.co_firstlineno
+
+    for start, next_line in dis.findlinestarts(code):
+        if lasti < start:
+            return prev_line
+        prev_line = next_line
+
+    return prev_line
+
 def getlineno(frame):
     """Get the line number from a frame object, allowing for optimization."""
-    # FrameType.f_lineno is now a descriptor that grovels co_lnotab
-    return frame.f_lineno
+    # FrameType.f_lineno is now a descriptor that often grovels co_lnotab
+    f_lineno = frame.f_lineno
+    if f_lineno is not None:
+        return f_lineno
+
+    return _lasti2lineno(frame.f_code, frame.f_lasti)
+
 
 FrameInfo = namedtuple('FrameInfo', ('frame',) + Traceback._fields)
 
diff --git a/Misc/NEWS.d/next/Library/2022-03-22-10-16-11.bpo-45563.o-oP2m.rst b/Misc/NEWS.d/next/Library/2022-03-22-10-16-11.bpo-45563.o-oP2m.rst
new file mode 100644
index 000000000000000..d4e0076be67e11f
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-03-22-10-16-11.bpo-45563.o-oP2m.rst
@@ -0,0 +1 @@
+handle frame.f_lineno is None in inspect.getframeinfo