On ResourceWarning, log traceback where the object was allocated

Issue #26567:

* Add a new function PyErr_ResourceWarning() function to pass the destroyed
  object
* Add a source attribute to warnings.WarningMessage
* Add warnings._showwarnmsg() which uses tracemalloc to get the traceback where
  source object was allocated.

1 files changed, 7 insertions, 1 deletions

diff --git a/Doc/library/warnings.rst b/Doc/library/warnings.rst
index 8a538ad..4ce88ab 100644
--- a/Doc/library/warnings.rst
+++ b/Doc/library/warnings.rst
@@ -319,7 +319,7 @@ Available Functions
    of the warning message).
 
 
-.. function:: warn_explicit(message, category, filename, lineno, module=None, registry=None, module_globals=None)
+.. function:: warn_explicit(message, category, filename, lineno, module=None, registry=None, module_globals=None, source=None)
 
    This is a low-level interface to the functionality of :func:`warn`, passing in
    explicitly the message, category, filename and line number, and optionally the
@@ -335,6 +335,12 @@ Available Functions
    source for modules found in zipfiles or other non-filesystem import
    sources).
 
+   *source*, if supplied, is the destroyed object which emitted a
+   :exc:`ResourceWarning`.
+
+   .. versionchanged:: 3.6
+      Add the *source* parameter.
+
 
 .. function:: showwarning(message, category, filename, lineno, file=None, line=None)