[mypyc] fix IntEnum attributes not treated as final values

[elbehery95]

Fixes mypyc/mypyc#721

Generated __native.c will not compile when mypyc is invoked against the following example.py:

from enum import IntEnum

class Color(IntEnum):
    GREEN = 1

assert Color.GREEN == 1

Error

...
build/__native.c: In function ‘CPyDef___top_level__’:
build/__native.c:358:17: error: ‘CPyStatic_Color___GREEN’ undeclared (first use in this function)
  358 |     cpy_r_r74 = CPyStatic_Color___GREEN;
...

Previously code only treated enum.Enum attributes as Final, I switched to using TypeInfo.is_enum instead of checking type full name against hard-coded string

Your feedback is appreciated

[elbehery95]

Not sure why this is failing against 3.8 but passing against 3.7 and 3.9 !
probably related to the info in this commit python/cpython@8a4f085 and python/cpython#26654 (comment)

As per my understanding this seems to be an issue in cpython implementation that was fixed in later releases, but could not be backported to 3.8 as it was back then allowing security fixes only.

[ichard26]

Hey thanks for filing a PR. I'm a new reviewer so this in no way counts as a full review, but here's some initial feedback:

• Typically we prefix commits and PRs focused on mypyc with [mypyc]. For example ...
  • #14747
• Could you test the function based syntax for IntEnum?
  • Color = IntEnum("Color", ["GREEN"])
• Add Fixes mypyc/mypyc#721 somewhere in your PR description so GitHub will automatically close the related bug report once this PR is merged.

[elbehery95]

Thanks so much @ichard26
I have updated the commit as well as the description.

Regarding the functional based syntax, I think it is not working correctly for both Enum and IntEnum for example the following code will not compile with mypy 1.0.1

import enum
FunctionalColor = enum.Enum("FunctionalColor", ["RED", "BLUE"])
assert FunctionalColor.BLUE == 2

Probably would require a separate patch

[ichard26]

Looks good except from the tests.

It's probably a good idea to also test Flag enums, although I'm not sure whether mypyc still supports Python 3.5 as a compilation target. You may have to version guard this one too.

StrEnum and IntFlag would be nice to test too, but those are new in Python 3.11 so I won't complain if you don't add them in.

[elbehery95]

Thanks so much @ichard26 for the feedback,

I have added fix for StrEnum build error.

And after trying to understand test structure more, I have added tests for StrEnum, Flag and IntFlag

Should title change to reflect `StrEnum fix as well?

---

I recall StrEnum was broken (even after applying this patch locally) so probably would require a separate fix.

E.g.

from enum import StrEnum
class ColorFlag(StrEnum):
    RED = "red"

Reports

build/__native.c: In function ‘CPyDef___top_level__’:
build/__native.c:524:18: error: ‘CPyModule_typing’ undeclared (first use in this function); did you mean ‘CPyModule_sys’?
  524 |     cpy_r_r107 = CPyModule_typing;
      |                  ^~~~~~~~~~~~~~~~
      |                  CPyModule_sys

Regarding Flag and IntFlag they seem to be working when using CLI, but for some reason tests report the following error

class ColorFlag(Flag):
    RED = auto()
    GREEN = auto()
    BLUE = auto()

purple = ColorFlag.RED | ColorFlag.BLUE
assert ColorFlag.RED in purple

Reports

E   mypy.errors.CompileError: native.py:42: error: Unsupported right operand type for in ("ColorFlag")  [operator]

I am not sure if tests invoke mypyc with special arguments that trigger this error or not

[elbehery95]

should docstring change in this case ?

[elbehery95]

My thoughts about this change are as the following:

1. is_extension_class will return False for StrEnum as metaclass_type is set to enum.EnumMeta

   mypy/mypyc/irbuild/util.py

   Line 130 in 284142d

   if cdef.info.metaclass_type and cdef.info.metaclass_type.type.fullname not in (

2. transform_class_def mentioned explicitly in comments that classes inheriting from enum will have non-extension class object created for them

   mypy/mypyc/irbuild/classdef.py

   Line 107 in 284142d

   # decorated or inherit from Enum. Classes decorated with @trait do not

3. For some reason populate_non_ext_bases is explicitly checking for named tuple though any class inheriting say str or have a typing.Sequence in mro it will cause the error currently seen in building code with StrEnum

   mypy/mypyc/irbuild/classdef.py

   Line 475 in 284142d

   if is_named_tuple and cls.fullname in (

Not really sure if checking against both Enums and Named tuples is generic enough or not.

[ichard26]

Hey, I know that I've been away for too long, but you don't need to close your PR. Unfortunately, PR reviews are scarce around here. Things don't always move quickly or even at a decent pace. I'm sorry about all of this, your work is appreciated. You're welcome to reopen this, or if you'd prefer it, I'm happy to file a new PR with your commits (attributed to you only!) and try to get it landed eventually.

[Dreamsorcerer]

@ichard26 Did you end up reviving this PR?

[ichard26]

Nope. I've also stepped back from contributing to mypyc as reviews were few and far between. Sorry.