Smooth out edges

Author: A5rocks

mypy/checkexpr.py

@@ -1669,12 +1669,6 @@ def check_callable_call(
         if isinstance(callable_node, RefExpr) and callable_node.fullname in ENUM_BASES:
             # An Enum() call that failed SemanticAnalyzerPass2.check_enum_call().
             return callee.ret_type, callee
-        if (
-            isinstance(callable_node, RefExpr)
-            and callable_node.fullname in ("typing.assert_never", "typing_extensions.assert_never")
-            and self.chk.binder.is_unreachable()
-        ):
-            return callee.ret_type, callee
 
         if (
             callee.is_type_obj()
@@ -1804,9 +1798,20 @@ def check_callable_call(
             callable_name,
         )
 
-        self.check_argument_types(
-            arg_types, arg_kinds, args, callee, formal_to_actual, context, object_type=object_type
-        )
+        if not (
+            isinstance(callable_node, RefExpr)
+            and callable_node.fullname in ("typing.assert_never", "typing_extensions.assert_never")
+            and self.chk.binder.is_unreachable()
+        ):
+            self.check_argument_types(
+                arg_types,
+                arg_kinds,
+                args,
+                callee,
+                formal_to_actual,
+                context,
+                object_type=object_type,
+            )
 
         if (
             callee.is_type_obj()

test-data/unit/check-typeis.test

@@ -454,7 +454,10 @@ def g(x: object) -> None: ...
 def test(x: List[Any]) -> None:
     if not(f(x) or isinstance(x, A)):
         return
+
     g(reveal_type(x))  # N: Revealed type is "builtins.list[Any]"
+    # explanation: `if f(x): ...` is assumed always true!
+    # so there's no narrowing here.
 [builtins fixtures/tuple.pyi]
 
 [case testTypeIsMultipleCondition]

test-data/unit/check-unreachable-code.test

@@ -910,7 +910,7 @@ if False:
     # Ignore obvious type errors
     assert_never(expect_str(x))  # E: Argument 1 to "assert_never" has incompatible type "str"; expected "Never" \
                                  # E: Argument 1 to "expect_str" has incompatible type "int"; expected "str"
-    typing_assert_never(expect_str(x))
+    typing_assert_never(expect_str(x))  # E: Argument 1 to "expect_str" has incompatible type "int"; expected "str"
     reveal_type(x)  # E: Statement is unreachable \
                     # N: Revealed type is "builtins.int"
 
@@ -1364,6 +1364,9 @@ def test_untyped_fn(obj):
     obj.update(prop=False)
     obj.reload()
 
+    reveal_type(obj.prop)  # N: Revealed type is "Any" \
+                           # N: 'reveal_type' always outputs 'Any' in unchecked functions
+
     assert obj.prop is False
     reveal_type(obj.prop)  # N: Revealed type is "Any" \
                            # N: 'reveal_type' always outputs 'Any' in unchecked functions