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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"`json.loads` ignores `sys.int_max_str_digits` (decodes an over-long int instead of raising `ValueError`)","articleBody":"## Feature\n\n`json.loads` should honor the interpreter's integer string-conversion limit (`sys.set_int_max_str_digits`, PEP 651). RustPython's native `_json` scanner (the Rust-implemented accelerated module, RustPython's analog of CPython's C `_json`) decodes an over-long integer literal instead of raising `ValueError`. The pure-Python decoder already honors the limit (its int conversion goes through `int(str)`); only the native `_json` scanner diverges.\n\nSurfaced by running CPython's own stdlib test suite under RustPython — `test_json.test_decode::TestCDecode.test_limit_int` fails. The minimal standalone reproduction:\n\n### Reproduction\n\n```python\nimport sys, json\nsys.set_int_max_str_digits(5000)\njson.loads('1' * 5001)\n```\n\n**CPython 3.14:**\n\n```\nValueError: Exceeds the limit (5000 digits) for integer string conversion: value has 5001 digits\n```\n\n**RustPython:**\n\n```\n(returns the 5001-digit integer — no error)\n```\n\n## Python Documentation or reference to CPython source code\n\n- Limit / API: [`sys.set_int_max_str_digits`](https://docs.python.org/3/library/stdtypes.html#integer-string-conversion-length-limitation) (PEP 651).\n- CPython enforces it in [`_match_number_unicode`](https://github.com/python/cpython/blob/v3.14.3/Modules/_json.c), which builds the int via `PyLong_FromString` (limit-aware).\n- RustPython diverges in [`JsonScanner::parse_number`](https://github.com/RustPython/RustPython/blob/8e35cc9e72ea243df2705acb2cfb1a63fb8fbe0b/crates/stdlib/src/json.rs#L190), which builds the integer with `BigInt::from_str(buf)` and never consults `sys.int_max_str_digits`.\n\n### Suggested fix\n\nRoute the integer construction through `rustpython_common::int::bytes_to_int` with the live `vm.state.int_max_str_digits` (the same path the `int()` builtin uses), so the limit is read per-call and `sys.set_int_max_str_digits` / `adjust_int_max_str_digits` take effect. Float parsing is unaffected. This also unblocks `test_json.test_decode::TestCDecode.test_limit_int`.\n\n---\n*Investigated and drafted with AI assistance (Claude Code), reviewed by a human before filing, per RustPython's AI policy.*\n","author":{"url":"https://github.com/myers","@type":"Person","name":"myers"},"datePublished":"2026-06-05T16:17:50.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/8051/RustPython/issues/8051"}