[3.12] gh-113781: Silence AttributeError in warning module during Python finalization (GH-113813) (GH-113873)

The tracemalloc module can already be cleared.
(cherry picked from commit 0297418)

Co-authored-by: Serhiy Storchaka <[email protected]>

Author: miss-islington

Lib/warnings.py

@@ -58,15 +58,16 @@ def _formatwarnmsg_impl(msg):
         # catch Exception, not only ImportError and RecursionError.
         except Exception:
             # don't suggest to enable tracemalloc if it's not available
-            tracing = True
+            suggest_tracemalloc = False
             tb = None
         else:
-            tracing = tracemalloc.is_tracing()
             try:
+                suggest_tracemalloc = not tracemalloc.is_tracing()
                 tb = tracemalloc.get_object_traceback(msg.source)
             except Exception:
                 # When a warning is logged during Python shutdown, tracemalloc
                 # and the import machinery don't work anymore
+                suggest_tracemalloc = False
                 tb = None
 
         if tb is not None:
@@ -85,7 +86,7 @@ def _formatwarnmsg_impl(msg):
                 if line:
                     line = line.strip()
                     s += '    %s\n' % line
-        elif not tracing:
+        elif suggest_tracemalloc:
             s += (f'{category}: Enable tracemalloc to get the object '
                   f'allocation traceback\n')
     return s

Misc/NEWS.d/next/Library/2024-01-08-14-57-09.gh-issue-113781.IoTnwi.rst

@@ -0,0 +1,2 @@
+Silence unraisable AttributeError when warnings are emitted during Python
+finalization.