[3.12] gh-117535: Ignore made up file name "sys" for warnings (#118014)

Author: gaogaotiantian

Lib/warnings.py

@@ -36,7 +36,9 @@ def _formatwarnmsg_impl(msg):
     category = msg.category.__name__
     s =  f"{msg.filename}:{msg.lineno}: {category}: {msg.message}\n"
 
-    if msg.line is None:
+    # "sys" is a made up file name when we are not able to get the frame
+    # so do not try to get the source line
+    if msg.line is None and msg.filename != "sys":
         try:
             import linecache
             line = linecache.getline(msg.filename, msg.lineno)

Misc/NEWS.d/next/Library/2024-04-17-23-38-06.gh-issue-117535.4Fgjlq.rst

@@ -0,0 +1 @@
+Do not try to get the source line for made up file name "sys" in :mod:`warnings`.