fix(narrowing): preserve reassigned facet types across branches

[rexledesma]

Summary

Fixes #5259.

Preserve reassigned attribute and subscript types when merging branches. An unchanged root name does not imply its facets were only narrowed; when a branch widens a facet's type, merge it as a reassignment instead of simplifying back to the earlier type.

AI-assisted implementation and description.

Test Plan

• Regression cases fail before the fix and pass afterward, covering optional attributes, nested attributes, and TypedDict keys.
• Library suite: 9,223 passed, 3 ignored. The existing deep_phi_chain_term_expr test overflows the default stack before and after the fix; it passes separately with PYREFLY_STACK_SIZE=67108864.
• Formatting and linting: python3 test.py --no-test --no-tensor-shapes --no-conformance --no-jsonschema --no-extension.

[meta-codesync]

This pull request has been imported. If you are a Meta employee, you can view this in D125865538. (Because this pull request was imported automatically, there will not be any future comments.)

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

============================================================
SUMMARY
============================================================
Total: +32 new errors, -52 fixed errors
By preset: +16/-37 (default), +16/-37 (strict)

Projects with changes (15):
  pip: +2 -2
  cloud-init: +0 -1
  cwltool: +2 -2
  urllib3: +1 -1
  scikit-learn: +3 -3
  setuptools: +0 -1
  pwndbg: +3 -3
  apprise: +2 -2
  yarl: +1 -1
  meson: +0 -1
  core: +2 -2
  xarray: +0 -1
  spack: +14 -7
  pydantic: +0 -23
  discord.py: +2 -2
============================================================

FULL DIFF DETAILS
------------------------------------------------------------

pip (https://github.com/pypa/pip)
- ERROR src/pip/_internal/network/auth.py:555:12-37: Implicit conversion of `None` to `bool` is not allowed [implicit-bool]
+ ERROR src/pip/_internal/network/auth.py:555:12-37: Implicit conversion of `Credentials | None` to `bool` is not allowed [implicit-bool]
- ERROR src/pip/_vendor/urllib3/response.py:778:36-46: Implicit conversion of `None` to `bool` is not allowed [implicit-bool]
+ ERROR src/pip/_vendor/urllib3/response.py:778:36-46: Implicit conversion of `bytes | str | None` to `bool` is not allowed [implicit-bool]

cloud-init (https://github.com/canonical/cloud-init)
- ERROR cloudinit/sources/DataSourceSmartOS.py:672:12-27: Implicit conversion of `Unknown | None` to `bool` is not allowed [implicit-bool]

cwltool (https://github.com/common-workflow-language/cwltool)
- ERROR cwltool/software_requirements.py:68:12-36: Implicit conversion of `None` to `bool` is not allowed [implicit-bool]
+ ERROR cwltool/software_requirements.py:68:12-36: Implicit conversion of `str | Any | None` to `bool` is not allowed [implicit-bool]
- ERROR cwltool/software_requirements.py:68:12-85: Implicit conversion of `None` to `bool` is not allowed [implicit-bool]
+ ERROR cwltool/software_requirements.py:68:12-85: Implicit conversion of `Literal[''] | bool | Any | None` to `bool` is not allowed [implicit-bool]

urllib3 (https://github.com/urllib3/urllib3)
- ERROR src/urllib3/response.py:816:36-46: Implicit conversion of `None` to `bool` is not allowed [implicit-bool]
+ ERROR src/urllib3/response.py:816:36-46: Implicit conversion of `bytes | str | None` to `bool` is not allowed [implicit-bool]

scikit-learn (https://github.com/scikit-learn/scikit-learn)
- ERROR sklearn/gaussian_process/_gpc.py:767:9-39: Result of call expression is of type `_BinaryGaussianProcessClassifierLaplace` and is not used; assign to `_` if this is intentional [unused-call-result]
+ ERROR sklearn/gaussian_process/_gpc.py:767:9-39: Result of call expression is of type `_BinaryGaussianProcessClassifierLaplace | Unknown` and is not used; assign to `_` if this is intentional [unused-call-result]
+ ERROR sklearn/gaussian_process/_gpc.py:778:17-61: Object of type `OneVsOneClassifier | OneVsRestClassifier | _BinaryGaussianProcessClassifierLaplace` has no attribute `log_marginal_likelihood` [missing-attribute]
+ ERROR sklearn/gaussian_process/_gpc.py:888:25-55: The type of attribute `log_marginal_likelihood_value_` is unknown because it comes from an error [unknown-from-error]
- ERROR sklearn/gaussian_process/tests/test_gpc.py:185:12-187:51: `>=` is not supported between `float` and `tuple[float | Unknown, ndarray[Unknown]]` [unsupported-operation]
- ERROR sklearn/gaussian_process/tests/test_gpc.py:185:12-187:51: `>=` is not supported between `tuple[float | Unknown, ndarray[Unknown]]` and `float` [unsupported-operation]

setuptools (https://github.com/pypa/setuptools)
- ERROR setuptools/_distutils/command/bdist.py:131:56-81: `+` is not supported between `Literal['bdist.']` and `None` [unsupported-operation]

pwndbg (https://github.com/pwndbg/pwndbg)
- ERROR pwndbg/aglib/heap/glibc.py:1254:24-45: Implicit conversion of `Literal[0] | None` to `bool` is not allowed [implicit-bool]
+ ERROR pwndbg/aglib/heap/glibc.py:1254:24-45: Implicit conversion of `int | Unknown | None` to `bool` is not allowed [implicit-bool]
- ERROR pwndbg/aglib/heap/glibc.py:1263:52-73: Argument `int | None` is not assignable to parameter `address` with type `int` in function `pwndbg.aglib.memory.is_readable_address` [bad-argument-type]
+ ERROR pwndbg/aglib/heap/glibc.py:1263:52-73: Argument `int | Unknown | None` is not assignable to parameter `address` with type `int` in function `pwndbg.aglib.memory.is_readable_address` [bad-argument-type]
- ERROR pwndbg/aglib/heap/glibc.py:1264:38-59: Argument `int | None` is not assignable to parameter `addr` with type `int` in function `Arena.__init__` [bad-argument-type]
+ ERROR pwndbg/aglib/heap/glibc.py:1264:38-59: Argument `int | Unknown | None` is not assignable to parameter `addr` with type `int` in function `Arena.__init__` [bad-argument-type]

apprise (https://github.com/caronc/apprise)
- ERROR apprise/plugins/email/base.py:425:20-37: Implicit conversion of `bool | str` to `bool` is not allowed [implicit-bool]
+ ERROR apprise/plugins/email/base.py:425:20-37: Implicit conversion of `bool | str | Any` to `bool` is not allowed [implicit-bool]
- ERROR apprise/plugins/simplepush.py:285:24-34: Implicit conversion of `None` to `bool` is not allowed [implicit-bool]
+ ERROR apprise/plugins/simplepush.py:285:24-34: Implicit conversion of `bytes | None` to `bool` is not allowed [implicit-bool]

yarl (https://github.com/aio-libs/yarl)
- ERROR yarl/_url.py:1176:12-50: Implicit conversion of `Literal[0] | str` to `bool` is not allowed [implicit-bool]
+ ERROR yarl/_url.py:1176:12-50: Implicit conversion of `Literal[0, 1] | str` to `bool` is not allowed [implicit-bool]

meson (https://github.com/mesonbuild/meson)
- ERROR mesonbuild/modules/gnome.py:298:16-40: Returned type `str | None` is not assignable to declared return type `str` [bad-return]

core (https://github.com/home-assistant/core)
- ERROR homeassistant/components/fibaro/binary_sensor.py:69:12-36: Implicit conversion of `None` to `bool` is not allowed [implicit-bool]
+ ERROR homeassistant/components/fibaro/binary_sensor.py:69:12-36: Implicit conversion of `Literal['com.fibaro.FGMS001', 'com.fibaro.accelerometer', 'com.fibaro.doorSensor', 'com.fibaro.floodSensor', 'com.fibaro.heatDetector', 'com.fibaro.motionSensor', 'com.fibaro.smokeSensor', 'com.fibaro.windowSensor'] | None` to `bool` is not allowed [implicit-bool]
- ERROR homeassistant/components/panasonic_viera/__init__.py:211:12-28: Implicit conversion of `list[str] | None` to `bool` is not allowed [implicit-bool]
+ ERROR homeassistant/components/panasonic_viera/__init__.py:211:12-28: Implicit conversion of `list[str] | Unknown` to `bool` is not allowed [implicit-bool]

xarray (https://github.com/pydata/xarray)
- ERROR xarray/groupers.py:234:16-36: Returned type `Index | None` is not assignable to declared return type `Index` [bad-return]

spack (https://github.com/spack/spack)
+ ERROR lib/spack/spack/environment/environment.py:229:5-51: Object of class `object` has no attribute `env_path` [missing-attribute]
- ERROR lib/spack/spack/environment/environment.py:269:13-32: Object of class `NoneType` has no attribute `disable` [missing-attribute]
+ ERROR lib/spack/spack/environment/environment.py:269:13-32: Object of type `object | Unknown | None` has no attribute `disable` [missing-attribute]
+ ERROR lib/spack/spack/main.py:701:30-45: The type of this argument is unknown [unknown-argument-type]
- ERROR lib/spack/spack/repo.py:2290:37-51: Object of class `NoneType` has no attribute `repos` [missing-attribute]
+ ERROR lib/spack/spack/repo.py:2290:37-51: Object of type `object | Unknown | None` has no attribute `repos` [missing-attribute]
- ERROR lib/spack/spack/repo.py:2299:5-21: Object of class `NoneType` has no attribute `disable` [missing-attribute]
+ ERROR lib/spack/spack/repo.py:2299:5-21: Object of type `object | Unknown | None` has no attribute `disable` [missing-attribute]
- ERROR lib/spack/spack/repo.py:2306:21-29: Argument `Unknown | None` is not assignable to parameter `repo_path` with type `RepoPath` in function `enable_repo` [bad-argument-type]
+ ERROR lib/spack/spack/repo.py:2306:21-29: Argument `object | Unknown | None` is not assignable to parameter `repo_path` with type `RepoPath` in function `enable_repo` [bad-argument-type]
+ ERROR lib/spack/spack/repo.py:2370:28-50: `object | Unknown | None` is not assignable to variable `repo` with type `Repo | RepoPath | str | None` [bad-assignment]
- ERROR lib/spack/spack/subprocess_context.py:129:31-42: `Unknown | None` is not assignable to attribute `CONFIG` with type `Configuration` [bad-assignment]
+ ERROR lib/spack/spack/subprocess_context.py:129:31-42: `object | Unknown | None` is not assignable to attribute `CONFIG` with type `Configuration` [bad-assignment]
- ERROR lib/spack/spack/subprocess_context.py:130:64-75: Argument `Unknown | None` is not assignable to parameter `config` with type `Configuration` in function `spack.repo.RepoPath.from_config` [bad-argument-type]
+ ERROR lib/spack/spack/subprocess_context.py:130:64-75: Argument `object | Unknown | None` is not assignable to parameter `config` with type `Configuration` in function `spack.repo.RepoPath.from_config` [bad-argument-type]
+ ERROR lib/spack/spack/test/env.py:2296:81-94: Argument `object | Unknown | None` is not assignable to parameter `config` with type `Configuration | None` in function `spack.config.canonicalize_path` [bad-argument-type]
+ ERROR lib/spack/spack/util/lang.py:706:16-35: Cannot index into `object` [bad-index]
+ ERROR lib/spack/spack/util/lang.py:709:16-40: `in` is not supported between `Unknown` and `object` [not-iterable]
+ ERROR lib/spack/spack/util/lang.py:712:16-29: Expected a callable, got `object` [not-callable]
- ERROR lib/spack/spack/util/lang.py:715:20-35: No matching overload found for function `iter` called with arguments: (Unknown | None) [no-matching-overload]
+ ERROR lib/spack/spack/util/lang.py:715:20-35: No matching overload found for function `iter` called with arguments: (object | Unknown | None) [no-matching-overload]

pydantic (https://github.com/pydantic/pydantic)
- ERROR pydantic/v1/fields.py:607:30-40: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `type_` with type `type[Any]` in function `pydantic.v1.typing.is_literal_type` [bad-argument-type]
- ERROR pydantic/v1/fields.py:609:27-37: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `type_` with type `type[Any]` in function `pydantic.v1.typing.is_typeddict` [bad-argument-type]
- ERROR pydantic/v1/fields.py:612:24-34: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `ann_type` with type `type[Any]` in function `pydantic.v1.typing.is_finalvar` [bad-argument-type]
- ERROR pydantic/v1/fields.py:618:39-49: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_args` [bad-argument-type]
- ERROR pydantic/v1/fields.py:623:29-39: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_origin` [bad-argument-type]
- ERROR pydantic/v1/fields.py:626:35-45: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_args` [bad-argument-type]
- ERROR pydantic/v1/fields.py:644:35-45: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_args` [bad-argument-type]
- ERROR pydantic/v1/fields.py:668:29-39: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_args` [bad-argument-type]
- ERROR pydantic/v1/fields.py:692:35-45: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_args` [bad-argument-type]
- ERROR pydantic/v1/fields.py:702:35-45: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_args` [bad-argument-type]
- ERROR pydantic/v1/fields.py:712:35-45: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_args` [bad-argument-type]
- ERROR pydantic/v1/fields.py:715:35-45: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_args` [bad-argument-type]
- ERROR pydantic/v1/fields.py:718:35-45: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_args` [bad-argument-type]
- ERROR pydantic/v1/fields.py:722:61-71: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_args` [bad-argument-type]
- ERROR pydantic/v1/fields.py:723:35-45: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_args` [bad-argument-type]
- ERROR pydantic/v1/fields.py:726:61-71: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_args` [bad-argument-type]
- ERROR pydantic/v1/fields.py:727:35-45: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_args` [bad-argument-type]
- ERROR pydantic/v1/fields.py:730:61-71: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_args` [bad-argument-type]
- ERROR pydantic/v1/fields.py:734:61-71: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_args` [bad-argument-type]
- ERROR pydantic/v1/fields.py:735:35-45: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_args` [bad-argument-type]
- ERROR pydantic/v1/fields.py:740:35-45: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_args` [bad-argument-type]
- ERROR pydantic/v1/fields.py:749:108-118: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `tp` with type `type[Any]` in function `pydantic.v1.typing.get_args` [bad-argument-type]
- ERROR pydantic/v1/fields.py:756:50-60: Argument `type[Any] | TypeVar | Any` is not assignable to parameter `type_` with type `type[Any]` in function `ModelField._create_sub_type` [bad-argument-type]

discord.py (https://github.com/Rapptz/discord.py)
- ERROR discord/ext/commands/core.py:1646:12-46: Implicit conversion of `Literal[''] | None` to `bool` is not allowed [implicit-bool]
+ ERROR discord/ext/commands/core.py:1646:12-46: Implicit conversion of `Literal[''] | Command[CogT, ..., Any] | None` to `bool` is not allowed [implicit-bool]
- ERROR discord/ext/commands/core.py:1686:12-46: Implicit conversion of `Literal[''] | None` to `bool` is not allowed [implicit-bool]
+ ERROR discord/ext/commands/core.py:1686:12-46: Implicit conversion of `Literal[''] | Command[CogT, ..., Any] | None` to `bool` is not allowed [implicit-bool]