Background

CPython's compile() (Python/Python-ast.c) accepts any object with __index__ for the flags and optimize arguments — not just exact int. RustPython's CompileArgs typed both fields as OptionalArg<PyIntRef>, so a class with only __index__ raised TypeError: Expected type 'int' but '<X>' found. during arg binding.

bpo-36907's regression test (test_call.test_fastcall_clearing_dict) exercises exactly this: an IntWithDict.__index__ that mutates self.kwargs mid-call. CPython parses both args via __index__, doesn't crash even when the kwargs dict is cleared between binding and use.

Repro

import gc
class IntWithDict:
    __slots__ = ['kwargs']
    def __init__(self, **kwargs): self.kwargs = kwargs
    def __index__(self):
        self.kwargs.clear()
        gc.collect()
        return 0

x = IntWithDict(optimize=IntWithDict())
compile("pass", "", "exec", x, **x.kwargs)
# CPython 3.14: succeeds
# RustPython:   TypeError: Expected type 'int' but 'IntWithDict' found.   (before this PR)

Fix

Change flags and optimize in CompileArgs from OptionalArg<PyIntRef> to OptionalArg<ArgPrimitiveIndex<i32>>. ArgPrimitiveIndex (already used by range, slice, bytes.__mul__, hex, oct, ...) calls __index__ then converts to the primitive in one step. Three call sites simplify from .map_or(Ok(default), |v| v.try_to_primitive(vm))? to .map_or(default, |v| v.value).

Tests unmasked

• test_call.FastCallTests.test_fastcall_clearing_dict

Verification

• CPython 3.14.4 byte-identical for the bpo-36907 repro
• Normal cases unchanged: compile("...", "<t>", "eval", 0), compile(..., flags=0), compile(..., optimize=1)
• Non-int, non-__index__ objects still raise TypeError (now from try_index instead of strict PyIntRef check)
• No regressions across test_call, test_compile, test_int, test_index, test_descr, test_typing, test_ast (~1,571 tests)
• Cross-module grep for the same TODO marker text — test_termios.py has 4 instances of Expected type 'int' but 'FileIO' found., but those are a different fix path (file-descriptor protocol via fileno(), not __index__); out of scope.

Summary by CodeRabbit

• Refactor
  • Improved compile() function's argument handling to accept a broader range of numeric types, enhancing compatibility with Python conventions.