Summary

Two CPython parity gaps in compile() argument validation, both in crates/vm/src/stdlib/builtins.rs.

1. optimize validation gap (real bug)

CPython accepts optimize ∈ {-1, 0, 1, 2} only; anything else raises ValueError("compile(): invalid optimize value") (Python/bltinmodule.c::builtin_compile_impl).

The previous logic only validated through i32::try_into::<u8>(), which silently accepts every value in [0, 255]. So optimize=3, optimize=99, etc. were silently truncated to a u8 instead of being rejected.

>>> compile('x = 1', '<x>', 'exec', optimize=3)
# CPython 3.14.4: ValueError: compile(): invalid optimize value
# RustPython main: <code object ...>  ❌

2. flags error wording (wording-only)

CPython uses British "unrecognised" with a colon separator: compile(): unrecognised flags. The previous wording was American "unrecognized" without the colon.

Fix

Replace the cast-based optimize validation with a range pattern, and align the flags wording with CPython's.

let optimize: u8 = match optimize {
    -1 => vm.state.config.settings.optimize,
    0..=2 => optimize as u8,
    _ => return Err(vm.new_value_error("compile(): invalid optimize value")),
};

The optimize=1 << 1000 boundary still raises OverflowError via the ArgPrimitiveIndex<i32> conversion layer before this check (preserves Lib/test/test_compile.py:668).

Verification (CPython 3.14.4)

cargo run --release -- -m test test_compile test_builtin test_compileall test_codeop test_ast — 703 tests pass, 0 regressions. All 189 extra_tests/snippets/*.py pass under the CI feature set. A new builtin_compile.py adds regression coverage for both wordings.

Summary by CodeRabbit

• Bug Fixes

  • Enhanced the compile() function's parameter validation with clearer error messages for invalid optimize values and unrecognized compile flags.

• Tests

  • Added comprehensive test coverage for the compile() function, validating accepted parameter values and ensuring proper error handling across different scenarios.