Don't transform dataclass ClassVars (#914)

Co-authored-by: Pierre Sassoulas <pierre.sassoulas@gmail.com>

ChangeLog

@@ -11,6 +11,8 @@ Release Date: TBA
 
   Closes #895 #899
 
+* Don't transform dataclass ClassVars
+
 * Improve typing.TypedDict inference
 
 

astroid/brain/brain_dataclasses.py

@@ -30,6 +30,18 @@ def dataclass_transform(node):
         if not isinstance(assign_node, (astroid.AnnAssign, astroid.Assign)):
             continue
 
+        if (
+            isinstance(assign_node, astroid.AnnAssign)
+            and isinstance(assign_node.annotation, astroid.Subscript)
+            and (
+                isinstance(assign_node.annotation.value, astroid.Name)
+                and assign_node.annotation.value.name == "ClassVar"
+                or isinstance(assign_node.annotation.value, astroid.Attribute)
+                and assign_node.annotation.value.attrname == "ClassVar"
+            )
+        ):
+            continue
+
         targets = (
             assign_node.targets
             if hasattr(assign_node, "targets")

tests/unittest_brain.py

@@ -2108,6 +2108,8 @@ def test_dataclasses():
     code = """
     import dataclasses
     from dataclasses import dataclass
+    import typing
+    from typing import ClassVar
 
     @dataclass
     class InventoryItem:
@@ -2117,6 +2119,8 @@ class InventoryItem:
     @dataclasses.dataclass
     class Other:
         name: str
+        CONST_1: ClassVar[int] = 42
+        CONST_2: typing.ClassVar[int] = 42
     """
 
     module = astroid.parse(code)
@@ -2135,6 +2139,14 @@ class Other:
     assert len(name) == 1
     assert isinstance(name[0], astroid.Unknown)
 
+    const_1 = second.getattr("CONST_1")
+    assert len(const_1) == 1
+    assert isinstance(const_1[0], astroid.AssignName)
+
+    const_2 = second.getattr("CONST_2")
+    assert len(const_2) == 1
+    assert isinstance(const_2[0], astroid.AssignName)
+
 
 @pytest.mark.parametrize(
     "code,expected_class,expected_value",