From eeba30f1524ae8fb507a15b81bc0fb60a0a39ce9 Mon Sep 17 00:00:00 2001
From: Max Murin <maxmurin@dropbox.com>
Date: Thu, 24 Aug 2023 17:57:48 -0700
Subject: [PATCH] Revert "Add support for `attrs.fields` (#15021)"

This reverts commit 391ed853f7857222d7eb209ecdc48f0a130f70d7.
---
 mypy/plugins/attrs.py                      | 48 ++----------------
 mypy/plugins/default.py                    |  3 --
 test-data/unit/check-plugin-attrs.test     | 57 ----------------------
 test-data/unit/lib-stub/attr/__init__.pyi  |  2 -
 test-data/unit/lib-stub/attrs/__init__.pyi |  2 -
 5 files changed, 3 insertions(+), 109 deletions(-)

diff --git a/mypy/plugins/attrs.py b/mypy/plugins/attrs.py
index d444c18852dd..088a6b7e7240 100644
--- a/mypy/plugins/attrs.py
+++ b/mypy/plugins/attrs.py
@@ -68,7 +68,6 @@
     TupleType,
     Type,
     TypeOfAny,
-    TypeType,
     TypeVarType,
     UninhabitedType,
     UnionType,
@@ -952,7 +951,7 @@ def add_method(
 
 def _get_attrs_init_type(typ: Instance) -> CallableType | None:
     """
-    If `typ` refers to an attrs class, get the type of its initializer method.
+    If `typ` refers to an attrs class, gets the type of its initializer method.
     """
     magic_attr = typ.type.get(MAGIC_ATTR_NAME)
     if magic_attr is None or not magic_attr.plugin_generated:
@@ -1026,7 +1025,7 @@ def _get_expanded_attr_types(
 
 def _meet_fields(types: list[Mapping[str, Type]]) -> Mapping[str, Type]:
     """
-    "Meet" the fields of a list of attrs classes, i.e. for each field, its new type will be the lower bound.
+    "Meets" the fields of a list of attrs classes, i.e. for each field, its new type will be the lower bound.
     """
     field_to_types = defaultdict(list)
     for fields in types:
@@ -1043,7 +1042,7 @@ def _meet_fields(types: list[Mapping[str, Type]]) -> Mapping[str, Type]:
 
 def evolve_function_sig_callback(ctx: mypy.plugin.FunctionSigContext) -> CallableType:
     """
-    Generate a signature for the 'attr.evolve' function that's specific to the call site
+    Generates a signature for the 'attr.evolve' function that's specific to the call site
     and dependent on the type of the first argument.
     """
     if len(ctx.args) != 2:
@@ -1071,44 +1070,3 @@ def evolve_function_sig_callback(ctx: mypy.plugin.FunctionSigContext) -> Callabl
         fallback=ctx.default_signature.fallback,
         name=f"{ctx.default_signature.name} of {inst_type_str}",
     )
-
-
-def fields_function_sig_callback(ctx: mypy.plugin.FunctionSigContext) -> CallableType:
-    """Provide the signature for `attrs.fields`."""
-    if len(ctx.args) != 1 or len(ctx.args[0]) != 1:
-        return ctx.default_signature
-
-    proper_type = get_proper_type(ctx.api.get_expression_type(ctx.args[0][0]))
-
-    # fields(Any) -> Any, fields(type[Any]) -> Any
-    if (
-        isinstance(proper_type, AnyType)
-        or isinstance(proper_type, TypeType)
-        and isinstance(proper_type.item, AnyType)
-    ):
-        return ctx.default_signature
-
-    cls = None
-    arg_types = ctx.default_signature.arg_types
-
-    if isinstance(proper_type, TypeVarType):
-        inner = get_proper_type(proper_type.upper_bound)
-        if isinstance(inner, Instance):
-            # We need to work arg_types to compensate for the attrs stubs.
-            arg_types = [proper_type]
-            cls = inner.type
-    elif isinstance(proper_type, CallableType):
-        cls = proper_type.type_object()
-
-    if cls is not None and MAGIC_ATTR_NAME in cls.names:
-        # This is a proper attrs class.
-        ret_type = cls.names[MAGIC_ATTR_NAME].type
-        assert ret_type is not None
-        return ctx.default_signature.copy_modified(arg_types=arg_types, ret_type=ret_type)
-
-    ctx.api.fail(
-        f'Argument 1 to "fields" has incompatible type "{format_type_bare(proper_type, ctx.api.options)}"; expected an attrs class',
-        ctx.context,
-    )
-
-    return ctx.default_signature
diff --git a/mypy/plugins/default.py b/mypy/plugins/default.py
index b60fc3873c04..692bec206f34 100644
--- a/mypy/plugins/default.py
+++ b/mypy/plugins/default.py
@@ -47,7 +47,6 @@ def get_function_hook(self, fullname: str) -> Callable[[FunctionContext], Type]
             return ctypes.array_constructor_callback
         elif fullname == "functools.singledispatch":
             return singledispatch.create_singledispatch_function_callback
-
         return None
 
     def get_function_signature_hook(
@@ -57,8 +56,6 @@ def get_function_signature_hook(
 
         if fullname in ("attr.evolve", "attrs.evolve", "attr.assoc", "attrs.assoc"):
             return attrs.evolve_function_sig_callback
-        elif fullname in ("attr.fields", "attrs.fields"):
-            return attrs.fields_function_sig_callback
         elif fullname == "dataclasses.replace":
             return dataclasses.replace_function_sig_callback
         return None
diff --git a/test-data/unit/check-plugin-attrs.test b/test-data/unit/check-plugin-attrs.test
index 7580531bebc9..2d77222e193d 100644
--- a/test-data/unit/check-plugin-attrs.test
+++ b/test-data/unit/check-plugin-attrs.test
@@ -1554,63 +1554,6 @@ takes_attrs_cls(A(1, ""))  # E: Argument 1 to "takes_attrs_cls" has incompatible
 takes_attrs_instance(A)  # E: Argument 1 to "takes_attrs_instance" has incompatible type "Type[A]"; expected "AttrsInstance" # N: ClassVar protocol member AttrsInstance.__attrs_attrs__ can never be matched by a class object
 [builtins fixtures/plugin_attrs.pyi]
 
-[case testAttrsFields]
-import attr
-from attrs import fields as f  # Common usage.
-
-@attr.define
-class A:
-    b: int
-    c: str
-
-reveal_type(f(A))  # N: Revealed type is "Tuple[attr.Attribute[builtins.int], attr.Attribute[builtins.str], fallback=__main__.A.____main___A_AttrsAttributes__]"
-reveal_type(f(A)[0])  # N: Revealed type is "attr.Attribute[builtins.int]"
-reveal_type(f(A).b)  # N: Revealed type is "attr.Attribute[builtins.int]"
-f(A).x  # E: "____main___A_AttrsAttributes__" has no attribute "x"
-
-for ff in f(A):
-    reveal_type(ff)  # N: Revealed type is "attr.Attribute[Any]"
-
-[builtins fixtures/plugin_attrs.pyi]
-
-[case testAttrsGenericFields]
-from typing import TypeVar
-
-import attr
-from attrs import fields
-
-@attr.define
-class A:
-    b: int
-    c: str
-
-TA = TypeVar('TA', bound=A)
-
-def f(t: TA) -> None:
-    reveal_type(fields(t))  # N: Revealed type is "Tuple[attr.Attribute[builtins.int], attr.Attribute[builtins.str], fallback=__main__.A.____main___A_AttrsAttributes__]"
-    reveal_type(fields(t)[0])  # N: Revealed type is "attr.Attribute[builtins.int]"
-    reveal_type(fields(t).b)  # N: Revealed type is "attr.Attribute[builtins.int]"
-    fields(t).x  # E: "____main___A_AttrsAttributes__" has no attribute "x"
-
-
-[builtins fixtures/plugin_attrs.pyi]
-
-[case testNonattrsFields]
-# flags: --no-strict-optional
-from typing import Any, cast, Type
-from attrs import fields
-
-class A:
-    b: int
-    c: str
-
-fields(A)  # E: Argument 1 to "fields" has incompatible type "Type[A]"; expected an attrs class
-fields(None)  # E: Argument 1 to "fields" has incompatible type "None"; expected an attrs class
-fields(cast(Any, 42))
-fields(cast(Type[Any], 43))
-
-[builtins fixtures/plugin_attrs.pyi]
-
 [case testAttrsInitMethodAlwaysGenerates]
 from typing import Tuple
 import attr
diff --git a/test-data/unit/lib-stub/attr/__init__.pyi b/test-data/unit/lib-stub/attr/__init__.pyi
index 24ffc0f3f275..1a3838aa3ab1 100644
--- a/test-data/unit/lib-stub/attr/__init__.pyi
+++ b/test-data/unit/lib-stub/attr/__init__.pyi
@@ -247,5 +247,3 @@ def field(
 
 def evolve(inst: _T, **changes: Any) -> _T: ...
 def assoc(inst: _T, **changes: Any) -> _T: ...
-
-def fields(cls: type) -> Any: ...
diff --git a/test-data/unit/lib-stub/attrs/__init__.pyi b/test-data/unit/lib-stub/attrs/__init__.pyi
index a575f97da9bc..bf31274b3eb9 100644
--- a/test-data/unit/lib-stub/attrs/__init__.pyi
+++ b/test-data/unit/lib-stub/attrs/__init__.pyi
@@ -131,5 +131,3 @@ def field(
 
 def evolve(inst: _T, **changes: Any) -> _T: ...
 def assoc(inst: _T, **changes: Any) -> _T: ...
-
-def fields(cls: type) -> Any: ...