[3.12] gh-107810: Improve DeprecationWarning for metaclasses with custom tp_new (GH-107834) (#107864)

miss-islington · cdce8p · Eclips4 · web-flow · commit 431ce239d2a9 · 2023-08-11T16:12:50.000+02:00
gh-107810: Improve DeprecationWarning for metaclasses with custom tp_new (GH-107834) (cherry picked from commit 16dcce2) Co-authored-by: Marc Mueller <30130371+cdce8p@users.noreply.github.com> Co-authored-by: Kirill Podoprigora <kirill.bast9@mail.ru>
diff --git a/Lib/test/test_capi/test_misc.py b/Lib/test/test_capi/test_misc.py
@@ -740,7 +740,7 @@ class Base(metaclass=metaclass):
 
         # Class creation from C
         with warnings_helper.check_warnings(
-                ('.*custom tp_new.*in Python 3.14.*', DeprecationWarning),
+                ('.* _testcapi.Subclass .* custom tp_new.*in Python 3.14.*', DeprecationWarning),
                 ):
             sub = _testcapi.make_type_with_base(Base)
         self.assertTrue(issubclass(sub, Base))
diff --git a/Misc/NEWS.d/next/C API/2023-08-10-11-12-25.gh-issue-107810.oJ40Qx.rst b/Misc/NEWS.d/next/C API/2023-08-10-11-12-25.gh-issue-107810.oJ40Qx.rst
@@ -0,0 +1 @@
+Improve :exc:`DeprecationWarning` for uses of :c:type:`PyType_Spec` with metaclasses that have custom ``tp_new``.
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
@@ -4242,9 +4242,9 @@ _PyType_FromMetaclass_impl(
         if (_allow_tp_new) {
             if (PyErr_WarnFormat(
                     PyExc_DeprecationWarning, 1,
-                    "Using PyType_Spec with metaclasses that have custom "
-                    "tp_new is deprecated and will no longer be allowed in "
-                    "Python 3.14.") < 0) {
+                    "Type %s uses PyType_Spec with a metaclass that has custom "
+                    "tp_new. This is deprecated and will no longer be allowed in "
+                    "Python 3.14.", spec->name) < 0) {
                 goto finally;
             }
         }

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	+Improve :exc:`DeprecationWarning` for uses of :c:type:`PyType_Spec` with metaclasses that have custom ``tp_new``.
Original file line number	Diff line number	Diff line change
`@@ -4242,9 +4242,9 @@ _PyType_FromMetaclass_impl(`
`4242`	`4242`	`if (_allow_tp_new) {`
`4243`	`4243`	`if (PyErr_WarnFormat(`
`4244`	`4244`	`PyExc_DeprecationWarning, 1,`
`4245`		`- "Using PyType_Spec with metaclasses that have custom "`
`4246`		`- "tp_new is deprecated and will no longer be allowed in "`
`4247`		`- "Python 3.14.") < 0) {`
	`4245`	`+ "Type %s uses PyType_Spec with a metaclass that has custom "`
	`4246`	`+ "tp_new. This is deprecated and will no longer be allowed in "`
	`4247`	`+ "Python 3.14.", spec->name) < 0) {`
`4248`	`4248`	`goto finally;`
`4249`	`4249`	`}`
`4250`	`4250`	`}`