Allow errors for unsound Self definitions on non-final classes (#2221)

Author: davidhalter

conformance/results/mypy/generics_self_advanced.toml

@@ -7,14 +7,14 @@ Does not retain `Self` when accessing attribute through `type[Self]`.
 """
 output = """
 generics_self_advanced.py:35: error: Expression is of type "ChildB", not "Self"  [assert-type]
-generics_self_advanced.py:38: error: Expression is of type "ChildB", not "Self"  [assert-type]
-generics_self_advanced.py:42: error: Expression is of type "type[ChildB]", not "type[Self]"  [assert-type]
-generics_self_advanced.py:45: error: Expression is of type "ChildB", not "Self"  [assert-type]
+generics_self_advanced.py:41: error: Expression is of type "ChildB", not "Self"  [assert-type]
+generics_self_advanced.py:45: error: Expression is of type "type[ChildB]", not "type[Self]"  [assert-type]
+generics_self_advanced.py:51: error: Expression is of type "ChildB", not "Self"  [assert-type]
 """
 conformance_automated = "Fail"
 errors_diff = """
 Line 35: Unexpected errors ['generics_self_advanced.py:35: error: Expression is of type "ChildB", not "Self"  [assert-type]']
-Line 38: Unexpected errors ['generics_self_advanced.py:38: error: Expression is of type "ChildB", not "Self"  [assert-type]']
-Line 42: Unexpected errors ['generics_self_advanced.py:42: error: Expression is of type "type[ChildB]", not "type[Self]"  [assert-type]']
-Line 45: Unexpected errors ['generics_self_advanced.py:45: error: Expression is of type "ChildB", not "Self"  [assert-type]']
+Line 41: Unexpected errors ['generics_self_advanced.py:41: error: Expression is of type "ChildB", not "Self"  [assert-type]']
+Line 45: Unexpected errors ['generics_self_advanced.py:45: error: Expression is of type "type[ChildB]", not "type[Self]"  [assert-type]']
+Line 51: Unexpected errors ['generics_self_advanced.py:51: error: Expression is of type "ChildB", not "Self"  [assert-type]']
 """

conformance/results/results.html

@@ -345,7 +345,7 @@ <h3>Python Type System Conformance Test Results</h3>
 <tr><th class="column col1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;generics_self_advanced</th>
 <th class="column col2 partially-conformant"><div class="hover-text">Partial<span class="tooltip-text" id="bottom"><p>Does not infer the type of an unannotated `self` parameter to be type `Self`.</p><p>Does not retain `Self` when calling method that returns `Self`.</p><p>Does not infer the type of an unannotated `cls` parameter to be type `type[Self]`.</p><p>Does not retain `Self` when accessing attribute through `type[Self]`.</p></span></div></th>
 <th class="column col2 conformant">Pass</th>
-<th class="column col2 partially-conformant"><div class="hover-text">Partial<span class="tooltip-text" id="bottom"><p>Doesn't allow accessing `Self` in a classmethod</p></span></div></th>
+<th class="column col2 conformant">Pass</th>
 <th class="column col2 conformant"><div class="hover-text">Pass*<span class="tooltip-text" id="bottom"><p>Treats attributes not initialized on the class as instance-only</p></span></div></th>
 <th class="column col2 conformant">Pass</th>
 </tr>

conformance/results/zuban/generics_self_advanced.toml

@@ -1,13 +1,6 @@
-conformant = "Partial"
-notes = """
-Doesn't allow accessing `Self` in a classmethod
-"""
-conformance_automated = "Fail"
+conformance_automated = "Pass"
 errors_diff = """
-Line 43: Unexpected errors ['generics_self_advanced.py:43: error: Access to generic instance variables via class is ambiguous  [misc]']
-Line 44: Unexpected errors ['generics_self_advanced.py:44: error: Access to generic instance variables via class is ambiguous  [misc]']
 """
 output = """
-generics_self_advanced.py:43: error: Access to generic instance variables via class is ambiguous  [misc]
-generics_self_advanced.py:44: error: Access to generic instance variables via class is ambiguous  [misc]
+generics_self_advanced.py:48: error: Access to generic instance variables via class is ambiguous  [misc]
 """

conformance/tests/generics_self_advanced.py

@@ -33,13 +33,19 @@ class ChildB(ParentB):
 
     def method2(self) -> None:
         assert_type(self, Self)
-        assert_type(self.a, list[Self])
-        assert_type(self.a[0], Self)
+        # Allow type checkers to error here, since Self definitions on
+        # non-final classes are unsound.
+        a = self.a  # E?
+        assert_type(a, list[Self])
+        assert_type(a[0], Self)
         assert_type(self.method1(), Self)
 
     @classmethod
     def method3(cls) -> None:
         assert_type(cls, type[Self])
-        assert_type(cls.a, list[Self])
-        assert_type(cls.a[0], Self)
+        # Allow type checkers to error here, since Self definitions on
+        # non-final classes are unsound.
+        a = cls.a  # E?
+        assert_type(a, list[Self])
+        assert_type(a[0], Self)
         assert_type(cls.method1(), Self)