[3.12] pythongh-129843: fix pure Python implementation of warnings.warn_explicit (pythonGH-129848) (python#131350)

pythongh-129843: fix pure Python implementation of `warnings.warn_explicit` (pythonGH-129848)

The pure Python implementation of `warnings.warn_explicit` constructs a `WarningMessage`
with an incorrect source (it incorrectly sets the WarningMessage's line to the given `source`).
(cherry picked from commit 80e00ec)

Co-authored-by: Srinivas Reddy Thatiparthy (తాటిపర్తి శ్రీనివాస్  రెడ్డి) <[email protected]>

Author: miss-islington

Lib/warnings.py

@@ -409,7 +409,7 @@ def warn_explicit(message, category, filename, lineno,
               "Unrecognized action (%r) in warnings.filters:\n %s" %
               (action, item))
     # Print message and context
-    msg = WarningMessage(message, category, filename, lineno, source)
+    msg = WarningMessage(message, category, filename, lineno, source=source)
     _showwarnmsg(msg)
 
 

Misc/NEWS.d/next/Library/2025-03-17-15-45-36.gh-issue-129843.NPdpXL.rst

@@ -0,0 +1 @@
+Fix incorrect argument passing in :func:`warnings.warn_explicit`.