gh-142968: Add type checks to token.ISTERMINAL and ISNONTERMINAL

Lib/test/test_token.py

@@ -0,0 +1,17 @@
+import unittest
+import token
+
+class TokenTest(unittest.TestCase):
+    def test_terminal_validations(self):
+        # Regression test for gh-142968
+        self.assertRaises(TypeError, token.ISTERMINAL, 0.5)
+        self.assertRaises(TypeError, token.ISNONTERMINAL, 0.5)
+        self.assertRaises(TypeError, token.ISTERMINAL, "string")
+        self.assertRaises(TypeError, token.ISNONTERMINAL, "string")
+
+        # (sanity check)
+        self.assertIs(token.ISTERMINAL(1), True)
+        self.assertIs(token.ISNONTERMINAL(1), False)
+
+if __name__ == "__main__":
+    unittest.main()

Misc/NEWS.d/next/Library/2026-01-03-14-30-00.gh-issue-142968.manual.rst

@@ -0,0 +1 @@
+Add type checks to :func:`token.ISTERMINAL` and :func:`token.ISNONTERMINAL`.

Tools/build/generate_token.py

@@ -279,9 +279,13 @@ def make_rst(infile, outfile='Doc/library/token-list.inc',
 }
 
 def ISTERMINAL(x: int) -> bool:
+    if not isinstance(x,int):
+        raise TypeError(f"expected integer, got {type(x).__name__}")
     return x < NT_OFFSET
 
 def ISNONTERMINAL(x: int) -> bool:
+    if not isinstance(x,int):
+        raise TypeError(f"expected integer, got {type(x).__name__}")
     return x >= NT_OFFSET
 
 def ISEOF(x: int) -> bool: