Merge branch 'master' into missing-args-callable

Author: lesliehuh

mypy/checkexpr.py

@@ -6333,7 +6333,13 @@ def narrow_type_from_binder(
                     known_type, restriction, prohibit_none_typevar_overlap=True
                 ):
                     return None
-                return narrow_declared_type(known_type, restriction)
+                narrowed = narrow_declared_type(known_type, restriction)
+                if isinstance(get_proper_type(narrowed), UninhabitedType):
+                    # If we hit this case, it means that we can't reliably mark the code as
+                    # unreachable, but the resulting type can't be expressed in type system.
+                    # Falling back to restriction is more intuitive in most cases.
+                    return restriction
+                return narrowed
         return known_type
 
     def has_abstract_type_part(self, caller_type: ProperType, callee_type: ProperType) -> bool:

mypy/semanal.py

@@ -6382,6 +6382,8 @@ class C:
             if node.name not in self.globals:
                 return True
             global_node = self.globals[node.name]
+            if not self.is_textually_before_class(global_node.node):
+                return True
             return not self.is_type_like(global_node.node)
         return False
 
@@ -6409,6 +6411,13 @@ def is_textually_before_statement(self, node: SymbolNode) -> bool:
         else:
             return line_diff > 0
 
+    def is_textually_before_class(self, node: SymbolNode | None) -> bool:
+        """Similar to above, but check if a node is defined before current class."""
+        assert self.type is not None
+        if node is None:
+            return False
+        return node.line < self.type.defn.line
+
     def is_overloaded_item(self, node: SymbolNode, statement: Statement) -> bool:
         """Check whether the function belongs to the overloaded variants"""
         if isinstance(node, OverloadedFuncDef) and isinstance(statement, FuncDef):

test-data/unit/check-isinstance.test

@@ -1812,9 +1812,9 @@ reveal_type(fm)  # N: Revealed type is "__main__.FooMetaclass"
 if issubclass(fm, Foo):
     reveal_type(fm)  # N: Revealed type is "Type[__main__.Foo]"
 if issubclass(fm, Bar):
-    reveal_type(fm)  # N: Revealed type is "Never"
+    reveal_type(fm)  # N: Revealed type is "Type[__main__.Bar]"
 if issubclass(fm, Baz):
-    reveal_type(fm)  # N: Revealed type is "Never"
+    reveal_type(fm)  # N: Revealed type is "Type[__main__.Baz]"
 [builtins fixtures/isinstance.pyi]
 
 [case testIsinstanceAndNarrowTypeVariable]

test-data/unit/check-narrowing.test

@@ -1284,7 +1284,7 @@ def f(t: Type[T], a: A, b: B) -> None:
         reveal_type(a)  # N: Revealed type is "__main__.A"
 
     if type(b) is t:
-        reveal_type(b)  # N: Revealed type is "Never"
+        reveal_type(b)  # N: Revealed type is "T`-1"
     else:
         reveal_type(b)  # N: Revealed type is "__main__.B"
 
@@ -2413,3 +2413,14 @@ def foo(x: T) -> T:
     reveal_type(x)  # N: Revealed type is "T`-1"
     return x
 [builtins fixtures/isinstance.pyi]
+
+[case testDoNotNarrowToNever]
+def any():
+    return 1
+
+def f() -> None:
+    x = "a"
+    x = any()
+    assert isinstance(x, int)
+    reveal_type(x)  # N: Revealed type is "builtins.int"
+[builtins fixtures/isinstance.pyi]

test-data/unit/check-python310.test

@@ -1347,7 +1347,7 @@ m: str
 
 match m:
     case a if a := 1:  # E: Incompatible types in assignment (expression has type "int", variable has type "str")
-        reveal_type(a)  # N: Revealed type is "Never"
+        reveal_type(a)  # N: Revealed type is "Literal[1]?"
 
 [case testMatchAssigningPatternGuard]
 m: str

test-data/unit/check-python312.test

@@ -2004,15 +2004,18 @@ reveal_type(x.related_resources)  # N: Revealed type is "__main__.ResourceRule"
 
 [case testPEP695TypeAliasRecursiveOuterClass]
 class A:
-    type X = X
+    type X = X  # E: Cannot resolve name "X" (possible cyclic definition)
 class X: ...
 
+class AA:
+    XX = XX  # OK, we allow this as a special case.
+class XX: ...
+
 class Y: ...
 class B:
     type Y = Y
 
-x: A.X
-reveal_type(x)  # N: Revealed type is "__main__.X"
+reveal_type(AA.XX)  # N: Revealed type is "def () -> __main__.XX"
 y: B.Y
 reveal_type(y)  # N: Revealed type is "__main__.Y"
 [builtins fixtures/tuple.pyi]
@@ -2042,3 +2045,17 @@ tuple[*tuple[int, ...], *tuple[int, ...]]  # E: More than one Unpack in a type i
 b: tuple[*tuple[int, ...], *tuple[int, ...]]  # E: More than one Unpack in a type is not allowed
 [builtins fixtures/tuple.pyi]
 [typing fixtures/typing-full.pyi]
+
+[case testForwardNestedPrecedesForwardGlobal]
+from typing import NewType
+
+class W[T]: pass
+
+class R:
+    class M(W[Action.V], type):
+        FOO = R.Action.V(0)
+    class Action(metaclass=M):
+        V = NewType('V', int)
+
+class Action:
+    pass