gh-107810: Improve DeprecationWarning for metaclasses with custom tp_new (GH-107834)

cdce8p · Eclips4 · web-flow · commit 16dcce21768b · 2023-08-10T15:55:47.000Z
Co-authored-by: Kirill Podoprigora &lt;kirill.bast9@mail.ru&gt;
diff --git a/Lib/test/test_capi/test_misc.py b/Lib/test/test_capi/test_misc.py
@@ -611,7 +611,7 @@ 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
@@ -4264,9 +4264,9 @@ _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
`@@ -4264,9 +4264,9 @@ _PyType_FromMetaclass_impl(`
`4264`	`4264`	`if (_allow_tp_new) {`
`4265`	`4265`	`if (PyErr_WarnFormat(`
`4266`	`4266`	`PyExc_DeprecationWarning, 1,`
`4267`		`- "Using PyType_Spec with metaclasses that have custom "`
`4268`		`- "tp_new is deprecated and will no longer be allowed in "`
`4269`		`- "Python 3.14.") < 0) {`
	`4267`	`+ "Type %s uses PyType_Spec with a metaclass that has custom "`
	`4268`	`+ "tp_new. This is deprecated and will no longer be allowed in "`
	`4269`	`+ "Python 3.14.", spec->name) < 0) {`
`4270`	`4270`	`goto finally;`
`4271`	`4271`	`}`
`4272`	`4272`	`}`