Summary

Documents the CPython divergence reported in #19144 as a cpydiff/ entry, instead of the code fix proposed in #19148.

On builds configured with MICROPY_LONGINT_IMPL_MPZ (the default for unix and most ports), the 3-argument pow() requires its operands to pass a strict integer type check, which excludes bool:

>>> pow(True, 1, 1)   # base
>>> pow(1, True, 1)   # exponent
>>> pow(1, 1, True)   # modulus
TypeError: pow() with 3 arguments requires integers   # MicroPython (MPZ)
0                                                     # CPython (all three)

Trade-offs and Alternatives

• Alternative: code fix. py/objint_mpz: Accept bool in 3-arg pow(). #19148 took the implementation route. Per reviewer consensus, the size cost was not justified for the rarity of pow(x, y, bool) usage. Closing that PR in favour of this documentation.
• Scope. Only the MPZ path is documented. The non-MPZ 3-arg path (py/modbuiltins.c) already accepts bool via mp_binary_op, so it is not a divergence and is intentionally not mentioned in the entry to keep the user-facing description tight. The cause field names MICROPY_LONGINT_IMPL_MPZ so readers on non-MPZ builds know the entry does not apply to them.
• Categorisation. Filed under Types,int to match the existing types_int_* entries (to_bytes, bit_length, subclassconv); Core,Functions was considered but its existing entries cover function-call mechanics, not per-builtin input-domain quirks. Suggestions for a better category are welcome.

Generative AI

I used generative AI tools when creating this PR, but a human has checked the code and is responsible for the code and the description above.

Fix #19144.