fix actual_ret_type for TypeGuard

Author: sloboegen

mypy/constraints.py

@@ -17,6 +17,9 @@
     CONTRAVARIANT,
     COVARIANT,
     ArgKind,
+    Block,
+    ClassDef,
+    SymbolTable,
     TypeInfo,
 )
 from mypy.types import (
@@ -1026,25 +1029,18 @@ def visit_callable_type(self, template: CallableType) -> list[Constraint]:
             param_spec = template.param_spec()
 
             template_ret_type, cactual_ret_type = template.ret_type, cactual.ret_type
-            bool_type = UnionType(
-                [LiteralType(True, cactual_ret_type), LiteralType(False, cactual_ret_type)]  # type: ignore[arg-type]
-            )
 
             if template.type_guard is not None and cactual.type_guard is not None:
                 template_ret_type = template.type_guard
                 cactual_ret_type = cactual.type_guard
             elif template.type_guard is not None:
                 template_ret_type = AnyType(TypeOfAny.special_form)
-            elif cactual.type_guard is not None:
-                cactual_ret_type = bool_type
 
             if template.type_is is not None and cactual.type_is is not None:
                 template_ret_type = template.type_is
                 cactual_ret_type = cactual.type_is
             elif template.type_is is not None:
                 template_ret_type = AnyType(TypeOfAny.special_form)
-            elif cactual.type_is is not None:
-                cactual_ret_type = bool_type
 
             res.extend(infer_constraints(template_ret_type, cactual_ret_type, self.direction))
 
@@ -1352,6 +1348,40 @@ def visit_type_type(self, template: TypeType) -> list[Constraint]:
         else:
             return []
 
+    def _make_type_info(
+        self,
+        name: str,
+        module_name: str | None = None,
+        mro: list[TypeInfo] | None = None,
+        bases: list[Instance] | None = None,
+    ) -> TypeInfo:
+        """Make a TypeInfo suitable for use in unit tests."""
+
+        class_def = ClassDef(name, Block([]), None, [])
+        class_def.fullname = name
+
+        if module_name is None:
+            if "." in name:
+                module_name = name.rsplit(".", 1)[0]
+            else:
+                module_name = "__main__"
+
+        info = TypeInfo(SymbolTable(), class_def, module_name)
+        if mro is None:
+            mro = []
+            if name != "builtins.object":
+                mro.append(self.oi)
+        info.mro = [info] + mro
+        if bases is None:
+            if mro:
+                # By default, assume that there is a single non-generic base.
+                bases = [Instance(mro[0], [])]
+            else:
+                bases = []
+        info.bases = bases
+
+        return info
+
 
 def neg_op(op: int) -> int:
     """Map SubtypeOf to SupertypeOf and vice versa."""