From dc4cc3dd16387cd7ff1b9b2b6ebac561221e0691 Mon Sep 17 00:00:00 2001
From: Serhiy Storchaka <storchaka@gmail.com>
Date: Tue, 25 Aug 2026 11:38:56 +0300
Subject: [PATCH] gh-156348: Fix the value of curses.ERR

Setting the module constants with an unsigned conversion, needed for the
chtype constants that can set bits beyond a 32-bit long, turned ERR from -1
into 18446744073709551615.  Set ERR and OK with a signed conversion.
---
 Lib/test/test_curses.py |  5 +++++
 Modules/_cursesmodule.c | 29 ++++++++++++++++++++++-------
 2 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/Lib/test/test_curses.py b/Lib/test/test_curses.py
index 630de544a457f40..dde236a4578f2eb 100644
--- a/Lib/test/test_curses.py
+++ b/Lib/test/test_curses.py
@@ -2967,6 +2967,11 @@ def test_has_extended_color_support(self):
         r = curses.has_extended_color_support()
         self.assertIsInstance(r, bool)
 
+    def test_err_and_ok(self):
+        # ERR is negative; it is not a chtype constant.
+        self.assertEqual(curses.ERR, -1)
+        self.assertEqual(curses.OK, 0)
+
     def test_type_names(self):
         # The curses types report their public module rather than the
         # underscore extension that implements them.
diff --git a/Modules/_cursesmodule.c b/Modules/_cursesmodule.c
index bd13022261c20ea..2ff15dd31d21803 100644
--- a/Modules/_cursesmodule.c
+++ b/Modules/_cursesmodule.c
@@ -6657,11 +6657,10 @@ curses_init_dict(PyObject *module)
     }
     /* This was moved from initcurses() because it core dumped on SGI,
        where they're not defined until you've called initscr() */
-    /* Use long long, not long: a chtype constant (the A_* attributes, ACS_*
-       and key codes) can set bits beyond a 32-bit long, which is what long is
-       on LLP64 platforms such as Windows -- A_DIM (0x80000000) would otherwise
-       be sign-extended to a negative number.  long long is at least 64 bits
-       everywhere and still represents the negative ERR (-1). */
+    /* Use unsigned long long, not long: a chtype constant (the A_* attributes,
+       ACS_* and key codes) can set bits beyond a 32-bit long, which is what
+       long is on LLP64 platforms such as Windows -- A_DIM (0x80000000) would
+       otherwise be sign-extended to a negative number. */
 #define SetDictInt(NAME, VALUE)                                     \
     do {                                                            \
         PyObject *value = PyLong_FromUnsignedLongLong((unsigned long long)(VALUE));  \
@@ -9419,8 +9418,24 @@ cursesmodule_exec(PyObject *module)
         }                                                           \
     } while (0)
 
-    SetDictInt("ERR", ERR);
-    SetDictInt("OK", OK);
+    /* ERR is -1, so it needs a signed conversion, unlike the chtype
+       constants below. */
+#define SetDictSignedInt(NAME, VALUE)                               \
+    do {                                                            \
+        PyObject *value = PyLong_FromLongLong((long long)(VALUE));  \
+        if (value == NULL) {                                        \
+            return -1;                                              \
+        }                                                           \
+        int rc = PyDict_SetItemString(module_dict, (NAME), value);  \
+        Py_DECREF(value);                                           \
+        if (rc < 0) {                                               \
+            return -1;                                              \
+        }                                                           \
+    } while (0)
+
+    SetDictSignedInt("ERR", ERR);
+    SetDictSignedInt("OK", OK);
+#undef SetDictSignedInt
 
     /* Here are some attributes you can add to chars to print */