gh-152502: Detect optional curses functions with configure probes (GH-152504)

Some curses functions were called unconditionally or gated only by the
ncurses-specific NCURSES_EXT_FUNCS macro, which broke building the module
against other curses implementations (narrow ncurses, NetBSD curses) even
when they provided the function.  Detect each with a configure capability
probe and gate on HAVE_CURSES_*.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: serhiy-storchaka

Lib/test/test_curses.py

@@ -1563,7 +1563,8 @@ def test_env_queries(self):
         self.assertIsInstance(curses.has_ic(), bool)
         self.assertIsInstance(curses.has_il(), bool)
         self.assertIsInstance(curses.termattrs(), int)
-        self.assertIsInstance(curses.term_attrs(), int)
+        if hasattr(curses, 'term_attrs'):
+            self.assertIsInstance(curses.term_attrs(), int)
 
         c = curses.killchar()
         self.assertIsInstance(c, bytes)

Misc/NEWS.d/next/Build/2026-06-28-16-17-55.gh-issue-152502.6SNqMg.rst

@@ -0,0 +1,4 @@
+The :mod:`curses` module now detects its optional functions with
+:program:`configure` capability probes instead of assuming ncurses, so it
+builds against narrow (non-wide) ncurses and other curses implementations such
+as NetBSD curses, exposing exactly the functions they provide.

Modules/_cursesmodule.c

@@ -5960,6 +5960,7 @@ _curses_getwin(PyObject *module, PyObject *file)
     return res;
 }
 
+#ifdef HAVE_CURSES_SCR_DUMP
 /*[clinic input]
 _curses.scr_dump
 
@@ -6030,6 +6031,7 @@ static PyObject *
 _curses_scr_set(PyObject *module, PyObject *filename)
 /*[clinic end generated code: output=6056fdec12c5935f input=d248c20543cc289b]*/
 ScreenDumpFunctionBody(scr_set)
+#endif /* HAVE_CURSES_SCR_DUMP */
 
 /*[clinic input]
 _curses.halfdelay
@@ -6108,7 +6110,7 @@ _curses_has_key_impl(PyObject *module, int key)
 }
 #endif
 
-#if defined(NCURSES_EXT_FUNCS) && NCURSES_EXT_FUNCS
+#ifdef HAVE_CURSES_DEFINE_KEY
 /*[clinic input]
 _curses.define_key
 
@@ -6134,7 +6136,9 @@ _curses_define_key_impl(PyObject *module, const char *definition,
     return curses_check_err(module, define_key(definition, keycode),
                             "define_key", NULL);
 }
+#endif /* HAVE_CURSES_DEFINE_KEY */
 
+#ifdef HAVE_CURSES_KEY_DEFINED
 /*[clinic input]
 _curses.key_defined
 
@@ -6156,7 +6160,9 @@ _curses_key_defined_impl(PyObject *module, const char *definition)
 
     return PyLong_FromLong(key_defined(definition));
 }
+#endif /* HAVE_CURSES_KEY_DEFINED */
 
+#ifdef HAVE_CURSES_KEYOK
 /*[clinic input]
 _curses.keyok
 
@@ -6177,7 +6183,7 @@ _curses_keyok_impl(PyObject *module, int keycode, int enable)
 
     return curses_check_err(module, keyok(keycode, enable), "keyok", NULL);
 }
-#endif
+#endif /* HAVE_CURSES_KEYOK */
 
 /*[clinic input]
 _curses.init_color
@@ -6778,9 +6784,7 @@ _curses_new_prescr_impl(PyObject *module)
 }
 #endif /* HAVE_CURSES_NEW_PRESCR */
 
-#if defined(NCURSES_EXT_FUNCS) && NCURSES_EXT_FUNCS >= 20081102
-// https://invisible-island.net/ncurses/NEWS.html#index-t20080119
-
+#ifdef HAVE_CURSES_ESCDELAY
 /*[clinic input]
 _curses.get_escdelay
 
@@ -6797,6 +6801,9 @@ _curses_get_escdelay_impl(PyObject *module)
 {
     return PyLong_FromLong(ESCDELAY);
 }
+#endif /* HAVE_CURSES_ESCDELAY */
+
+#ifdef HAVE_CURSES_SET_ESCDELAY
 /*[clinic input]
 _curses.set_escdelay
     ms: int
@@ -6821,7 +6828,9 @@ _curses_set_escdelay_impl(PyObject *module, int ms)
 
     return curses_check_err(module, set_escdelay(ms), "set_escdelay", NULL);
 }
+#endif /* HAVE_CURSES_SET_ESCDELAY */
 
+#ifdef HAVE_CURSES_TABSIZE
 /*[clinic input]
 _curses.get_tabsize
 
@@ -6837,6 +6846,9 @@ _curses_get_tabsize_impl(PyObject *module)
 {
     return PyLong_FromLong(TABSIZE);
 }
+#endif /* HAVE_CURSES_TABSIZE */
+
+#ifdef HAVE_CURSES_SET_TABSIZE
 /*[clinic input]
 _curses.set_tabsize
     size: int
@@ -6860,7 +6872,7 @@ _curses_set_tabsize_impl(PyObject *module, int size)
 
     return curses_check_err(module, set_tabsize(size), "set_tabsize", NULL);
 }
-#endif
+#endif /* HAVE_CURSES_SET_TABSIZE */
 
 /*[clinic input]
 _curses.intrflush
@@ -7686,6 +7698,7 @@ _curses_termattrs_impl(PyObject *module)
 /*[clinic end generated code: output=b06f437fce1b6fc4 input=0559882a04f84d1d]*/
 NoArgReturnIntFunctionBody(termattrs)
 
+#ifdef HAVE_CURSES_TERM_ATTRS
 /*[clinic input]
 _curses.term_attrs
 
@@ -7703,6 +7716,7 @@ _curses_term_attrs_impl(PyObject *module)
 
     return PyLong_FromUnsignedLong(term_attrs());
 }
+#endif /* HAVE_CURSES_TERM_ATTRS */
 
 /*[clinic input]
 @permit_long_summary
@@ -8301,10 +8315,8 @@ static PyMethodDef cursesmodule_methods[] = {
     _CURSES_SCR_INIT_METHODDEF
     _CURSES_SCR_RESTORE_METHODDEF
     _CURSES_SCR_SET_METHODDEF
-#if defined(NCURSES_EXT_FUNCS) && NCURSES_EXT_FUNCS >= 20081102
     _CURSES_GET_ESCDELAY_METHODDEF
     _CURSES_SET_ESCDELAY_METHODDEF
-#endif
     _CURSES_GET_TABSIZE_METHODDEF
     _CURSES_SET_TABSIZE_METHODDEF
     _CURSES_SET_TERM_METHODDEF