Address reviews

Author: vstinner

Doc/c-api/unicode.rst

@@ -1423,7 +1423,9 @@ They all return ``NULL`` or ``-1`` if an exception occurs.
    This function returns ``-1`` upon failure, so one should call
    :c:func:`PyErr_Occurred` to check for errors.
 
-   See also :c:func:`PyUnicode_Equal`.
+   .. seealso::
+
+      The :c:func:`PyUnicode_Equal` function.
 
 
 .. c:function:: int PyUnicode_Equal(PyObject *a, PyObject *b)
@@ -1433,11 +1435,13 @@ They all return ``NULL`` or ``-1`` if an exception occurs.
    * Return ``1`` if *a* is equal to *b*.
    * Return ``0`` if *a* is not equal to *b*.
    * Set a :exc:`TypeError` exception and return ``-1`` if *a* or *b* is not a
-     Python :class:`str` object.
+     :class:`str` object.
 
-   The function always succeed if *a* and *b* are Python :class:`str` objects.
+   The function always succeeds if *a* and *b* are :class:`str` objects.
+
+   .. seealso::
 
-   See also :c:func:`PyUnicode_Compare`.
+      The :c:func:`PyUnicode_Compare` function.
 
    .. versionadded:: 3.14
 

Doc/whatsnew/3.14.rst

@@ -646,7 +646,8 @@ New Features
   <https://peps.python.org/pep-0630/#type-checking>`__ mentioned in :pep:`630`
   (:gh:`124153`).
 
-* Add :c:func:`PyUnicode_Equal` function to test if two strings are equal.
+* Add :c:func:`PyUnicode_Equal` function to the limited C API:
+  test if two strings are equal.
   (Contributed by Victor Stinner in :gh:`124502`.)
 
 

Lib/test/test_capi/test_unicode.py

@@ -1919,6 +1919,12 @@ def copy(text):
         self.assertFalse(unicode_equal("\u20ac", "\u20ad"))
         self.assertFalse(unicode_equal("\U0010ffff", "\U0010fffe"))
 
+        # str subclass
+        self.assertTrue(unicode_equal("abc", Str("abc")))
+        self.assertTrue(unicode_equal(Str("abc"), "abc"))
+        self.assertFalse(unicode_equal("abc", Str("abcd")))
+        self.assertFalse(unicode_equal(Str("abc"), "abcd"))
+
         # invalid type
         for invalid_type in (b'bytes', 123, ("tuple",)):
             with self.subTest(invalid_type=invalid_type):

Misc/NEWS.d/next/C_API/2024-09-25-11-44-02.gh-issue-124502.qWuDjT.rst

@@ -1,2 +1,2 @@
-Add :c:func:`PyUnicode_Equal` function to test if two strings are equal.
-Patch by Victor Stinner.
+Add :c:func:`PyUnicode_Equal` function to the limited C API: test if two
+strings are equal. Patch by Victor Stinner.

Objects/unicodeobject.c

@@ -11012,17 +11012,14 @@ _PyUnicode_Equal(PyObject *str1, PyObject *str2)
 int
 PyUnicode_Equal(PyObject *str1, PyObject *str2)
 {
-    if (!PyUnicode_Check(str1)) {
-        PyErr_Format(PyExc_TypeError,
-                     "first argument must be str, not %T", str1);
-        return -1;
-    }
-    if (!PyUnicode_Check(str2)) {
-        PyErr_Format(PyExc_TypeError,
-                     "second argument must be str, not %T", str2);
-        return -1;
+    if (PyUnicode_Check(str1) && PyUnicode_Check(str2)) {
+        return _PyUnicode_Equal(str1, str2);
     }
-    return _PyUnicode_Equal(str1, str2);
+
+    PyErr_Format(PyExc_TypeError,
+                 "Can't compare %T and %T",
+                 str1, str2);
+    return -1;
 }