python
diff --git a/‎mypy/plugins/attrs.py
Lines changed: 30 additions & 11 deletions b/‎mypy/plugins/attrs.py
Lines changed: 30 additions & 11 deletions
diff --git a/‎test-data/unit/check-attr.test
Lines changed: 12 additions & 4 deletions b/‎test-data/unit/check-attr.test
Lines changed: 12 additions & 4 deletions
@@ -967,18 +967,37 @@ def evolve_function_sig_callback(ctx: mypy.plugin.FunctionSigContext) -> Callabl
         return ctx.default_signature  # evolve(Any, ....) -> Any
     # We stringify it first, so that TypeVars maintain their name.
     inst_type_str = format_type_bare(inst_type)
-    upper_bound = inst_type.upper_bound if isinstance(inst_type, TypeVarType) else inst_type
-    if not (
-        isinstance(upper_bound, Instance)
-        and (attrs_init_type := _get_attrs_init_type(upper_bound))
-    ):
-        ctx.api.fail(
-            f'Argument 1 to "evolve" has incompatible type "{inst_type_str}"; expected an attrs class',
-            ctx.context,
-        )
-        return ctx.default_signature
+    if isinstance(inst_type, TypeVarType):
+        attrs_type = inst_type.upper_bound
+        if not isinstance(attrs_type, Instance):
+            ctx.api.fail(
+                f'Argument 1 to "evolve" has a variable type "{inst_type_str}" with unexpected upper bounds',
+                ctx.context,
+            )
+            return ctx.default_signature  # TODO: is this possible?
+        attrs_init_type = _get_attrs_init_type(attrs_type)
+        if attrs_init_type is None:
+            ctx.api.fail(
+                f'Argument 1 to "evolve" has a variable type "{inst_type_str}" not bound to an attrs class',
+                ctx.context,
+            )
+            return ctx.default_signature
+    else:
+        attrs_type = inst_type
+        if not isinstance(attrs_type, Instance):
+            ctx.api.fail(
+                f'Argument 1 to "evolve" has incompatible type "{inst_type_str}"', ctx.context
+            )
+            return ctx.default_signature  # TODO: is this possible?
+        attrs_init_type = _get_attrs_init_type(attrs_type)
+        if attrs_init_type is None:
+            ctx.api.fail(
+                f'Argument 1 to "evolve" has incompatible type "{inst_type_str}"; expected an attrs class',
+                ctx.context,
+            )
+            return ctx.default_signature  # TODO: is this possible?
 
-    attrs_init_type = expand_type_by_instance(attrs_init_type, upper_bound)
+    attrs_init_type = expand_type_by_instance(attrs_init_type, attrs_type)
 
     # AttrClass.__init__ has the following signature (or similar, if having kw-only & defaults):
     #   def __init__(self, attr1: Type1, attr2: Type2) -> None:
 
@@ -2006,18 +2006,26 @@ class B(A):
     pass
 
 
-T = TypeVar('T', bound=A)
+TA = TypeVar('TA', bound=A)
+TInt = TypeVar('TInt', bound=int)
+TAny = TypeVar('TAny')
 
 
-def f(t: T) -> T:
+def f(t: TA) -> TA:
     t2 = attrs.evolve(t, x=42)
-    reveal_type(t2)  # N: Revealed type is "T`-1"
-    t3 = attrs.evolve(t, x='42')  # E: Argument "x" to "evolve" of "T" has incompatible type "str"; expected "int"
+    reveal_type(t2)  # N: Revealed type is "TA`-1"
+    t3 = attrs.evolve(t, x='42')  # E: Argument "x" to "evolve" of "TA" has incompatible type "str"; expected "int"
     return t2
 
 f(A(x=42))
 f(B(x=42))
 
+def g(t: TInt) -> None:
+    _ = attrs.evolve(t, x=42)  # E: Argument 1 to "evolve" has a variable type "TInt" not bound to an attrs class
+
+def h(t: TAny) -> None:
+    _ = attrs.evolve(t, x=42)  # E: Argument 1 to "evolve" has a variable type "TAny" not bound to an attrs class
+
 [builtins fixtures/attr.pyi]
 [typing fixtures/typing-medium.pyi]