Ensure that <Never>.x is Never

Author: A5rocks

mypy/checkmember.py

@@ -70,6 +70,7 @@
     TypeVarLikeType,
     TypeVarTupleType,
     TypeVarType,
+    UninhabitedType,
     UnionType,
     get_proper_type,
 )
@@ -253,6 +254,8 @@ def _analyze_member_access(
     elif isinstance(typ, DeletedType):
         mx.msg.deleted_as_rvalue(typ, mx.context)
         return AnyType(TypeOfAny.from_error)
+    elif isinstance(typ, UninhabitedType):
+        return UninhabitedType()
     return report_missing_attribute(mx.original_type, typ, name, mx)
 
 

test-data/unit/check-expressions.test

@@ -1506,7 +1506,7 @@ z = x.append(y) if bool() else x.append(y) # E: "append" of "list" does not retu
 from typing import TypeVar
 T = TypeVar("T", int, str)
 def foo(x: T) -> T:
-    return x + 1 if isinstance(x, int) else x + "a"  # E: Unsupported left operand type for + ("Never")
+    return x + 1 if isinstance(x, int) else x + "a"  # E: "Never" not callable
 [builtins fixtures/isinstancelist.pyi]
 
 -- Special cases

test-data/unit/check-isinstance.test

@@ -736,7 +736,7 @@ while bool():
     # TODO: only report unreachability once
     elif isinstance(x, str):  # E: Statement is unreachable
         _ = "unreachable"  # E: Statement is unreachable
-        x + 'a'  # E: Unsupported left operand type for + ("Never")
+        x + 'a'  # E: "Never" not callable
         break
     _ = "unreachable"  # E: Statement is unreachable
 x + [1]               # E: Unsupported operand types for + ("int" and "List[int]") \
@@ -1274,7 +1274,7 @@ if isinstance(y, int) and isinstance(x, B):  # E: Subclass of "A" and "int" cann
     _ = "unreachable"  # E: Statement is unreachable
 if isinstance(y, int) and y > 42:  # E: Subclass of "A" and "int" cannot exist: would have incompatible method signatures \
                                    # E: Right operand of "and" is never evaluated \
-                                   # E: Unsupported left operand type for > ("Never")
+                                   # E: "Never" not callable
     _ = "unreachable"  # E: Statement is unreachable
 [builtins fixtures/isinstancelist.pyi]
 
@@ -2428,7 +2428,7 @@ class B:
     def t0(self) -> None:
         if isinstance(self, A0):        # E: Subclass of "B" and "A0" cannot exist: would have incompatible method signatures
             x0: Literal[0] = self.f()   # E: Statement is unreachable \
-                                        # E: "Never" has no attribute "f"
+                                        # E: "Never" not callable
 
     def t1(self) -> None:
         if isinstance(self, A1):

test-data/unit/check-optional.test

@@ -585,7 +585,7 @@ x is not None and x + '42'  # E: Unsupported operand types for + ("int" and "str
 from typing import Optional
 
 x: None = None
-x is not None and x + 42  # E: Unsupported left operand type for + ("Never")
+x is not None and x + 42  # E: "Never" not callable
 [builtins fixtures/isinstance.pyi]
 
 [case testOptionalLambdaInference]