gh-153392: Raise TOMLDecodeError for over-long integers in tomllib

The number branch of tomllib's value parser called match_to_number
without wrapping ValueError, so an integer with more digits than the
interpreter's integer string conversion limit escaped as a bare
ValueError. The date and time branch already wraps ValueError into
TOMLDecodeError; do the same for the number branch so tomllib only
raises TOMLDecodeError on a malformed document.

Author: tonghuaroot

Lib/test/test_tomllib/test_error.py

@@ -34,6 +34,16 @@ def test_missing_value(self):
             tomllib.loads("\n\nfwfw=")
         self.assertEqual(str(exc_info.exception), "Invalid value (at end of document)")
 
+    def test_overlong_integer(self):
+        # An integer with more digits than the int-to-str conversion limit
+        # must raise TOMLDecodeError, not the bare ValueError from int().
+        from test.support import adjust_int_max_str_digits
+        with adjust_int_max_str_digits(1000):
+            digits = "9" * 1001
+            for src in (f"x = {digits}", f"x = -{digits}"):
+                with self.assertRaises(tomllib.TOMLDecodeError):
+                    tomllib.loads(src)
+
     def test_invalid_char_quotes(self):
         with self.assertRaises(tomllib.TOMLDecodeError) as exc_info:
             tomllib.loads("v = '\n'")

Lib/tomllib/_parser.py

@@ -738,7 +738,11 @@ def parse_value(
     # char, so needs to be located after handling of dates and times.
     number_match = RE_NUMBER.match(src, pos)
     if number_match:
-        return number_match.end(), match_to_number(number_match, parse_float)
+        try:
+            number = match_to_number(number_match, parse_float)
+        except ValueError as e:
+            raise TOMLDecodeError("Invalid number", src, pos) from e
+        return number_match.end(), number
 
     # Special floats
     first_three = src[pos : pos + 3]

Misc/NEWS.d/next/Library/2026-07-09-12-30-00.gh-issue-153392.Tm1Num.rst

@@ -0,0 +1,3 @@
+:func:`tomllib.loads` now raises :exc:`tomllib.TOMLDecodeError` instead of
+:exc:`ValueError` when a document contains an integer with more digits than the
+interpreter's integer string conversion limit.