From e47698cc4110aac41a610160bd9b7d8af8f7f7b9 Mon Sep 17 00:00:00 2001
From: Ilya Konstantinov <ilya.konstantinov@gmail.com>
Date: Wed, 25 Jan 2023 23:07:09 -0500
Subject: [PATCH] wip

---
 mypy/plugins/attrs.py                      | 16 +++++++++++++++
 mypy/plugins/default.py                    | 12 ++++++++++-
 test-data/unit/check-attr.test             | 24 +++++++++++++++++++++-
 test-data/unit/lib-stub/attr/__init__.pyi  |  2 ++
 test-data/unit/lib-stub/attrs/__init__.pyi |  1 +
 5 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/mypy/plugins/attrs.py b/mypy/plugins/attrs.py
index 16e8891e5f575..1ae737eeec16d 100644
--- a/mypy/plugins/attrs.py
+++ b/mypy/plugins/attrs.py
@@ -883,3 +883,19 @@ def add_method(
         """
         self_type = self_type if self_type is not None else self.self_type
         add_method(self.ctx, method_name, args, ret_type, self_type, tvd)
+
+
+def evolve_callback(ctx: mypy.plugin.FunctionSigContext) -> FunctionLike:
+    """Callback to provide an accurate signature for attrs.evolve."""
+    md = ctx.args[0][0].node.type.type.metadata
+
+    args = {
+        md_attribute['name']: ctx.api.named_generic_type(md_attribute['init_type'], args=[])
+        for md_attribute in md.get('attrs', {}).get('attributes', [])
+    }
+
+    return ctx.default_signature.copy_modified(
+        arg_kinds=ctx.default_signature.arg_kinds[:1] + [ARG_NAMED_OPT] * len(args),
+        arg_names=ctx.default_signature.arg_names[:1] + list(args.keys()),
+        arg_types=ctx.default_signature.arg_types[:1] + list(args.values()),
+    )
diff --git a/mypy/plugins/default.py b/mypy/plugins/default.py
index 04971868e8f41..26ecbd8e39fb8 100644
--- a/mypy/plugins/default.py
+++ b/mypy/plugins/default.py
@@ -13,6 +13,8 @@
     MethodSigContext,
     Plugin,
 )
+from mypy.plugin import FunctionSigContext
+from mypy.plugins import attrs
 from mypy.plugins.common import try_getting_str_literals
 from mypy.subtypes import is_subtype
 from mypy.typeops import is_literal_type_like, make_simplified_union
@@ -45,10 +47,18 @@ def get_function_hook(self, fullname: str) -> Callable[[FunctionContext], Type]
             return singledispatch.create_singledispatch_function_callback
         return None
 
+    def get_function_signature_hook(
+        self, fullname: str
+    ) -> Callable[[FunctionSigContext], FunctionLike] | None:
+        if fullname == "attr.evolve":
+            return attrs.evolve_callback
+        return None
+
+
     def get_method_signature_hook(
         self, fullname: str
     ) -> Callable[[MethodSigContext], FunctionLike] | None:
-        from mypy.plugins import ctypes, singledispatch
+        from mypy.plugins import attrs, ctypes, singledispatch
 
         if fullname == "typing.Mapping.get":
             return typed_dict_get_signature_callback
diff --git a/test-data/unit/check-attr.test b/test-data/unit/check-attr.test
index f555f2ea70111..7fd0b15aac18d 100644
--- a/test-data/unit/check-attr.test
+++ b/test-data/unit/check-attr.test
@@ -1866,4 +1866,26 @@ reveal_type(D) # N: Revealed type is "def (a: builtins.int, b: builtins.str) ->
 D(1, "").a = 2 # E: Cannot assign to final attribute "a"
 D(1, "").b = "2" # E: Cannot assign to final attribute "b"
 
-[builtins fixtures/property.pyi]
\ No newline at end of file
+[builtins fixtures/property.pyi]
+
+[case testEvolve]
+import attr
+
+@attr.s(auto_attribs=True)
+class C:
+    name: str
+
+c = C(name='foo')
+attr.evolve(c)
+attr.evolve(c, name='bar')
+attr.evolve(
+    c,
+    name=42,  # type: ignore[arg-type]
+)
+attr.evolve(
+    c,
+    age=42,  # type: ignore[call-arg]
+)
+
+[builtins fixtures/dict.pyi]
+[typing fixtures/typing-medium.pyi]
diff --git a/test-data/unit/lib-stub/attr/__init__.pyi b/test-data/unit/lib-stub/attr/__init__.pyi
index 795e5d3f4f697..06b321244f506 100644
--- a/test-data/unit/lib-stub/attr/__init__.pyi
+++ b/test-data/unit/lib-stub/attr/__init__.pyi
@@ -244,3 +244,5 @@ def field(
     order: Optional[bool] = ...,
     on_setattr: Optional[object] = ...,
 ) -> Any: ...
+
+def evolve(inst: _T, **changes: Any) -> _T: ...
diff --git a/test-data/unit/lib-stub/attrs/__init__.pyi b/test-data/unit/lib-stub/attrs/__init__.pyi
index d257740451324..cdd23dc1d747d 100644
--- a/test-data/unit/lib-stub/attrs/__init__.pyi
+++ b/test-data/unit/lib-stub/attrs/__init__.pyi
@@ -126,3 +126,4 @@ def field(
     order: Optional[bool] = ...,
     on_setattr: Optional[object] = ...,
 ) -> Any: ...
+