Type alias stubgen fix

mypy/stubgen.py

@@ -920,13 +920,14 @@ def visit_assignment_stmt(self, o: AssignmentStmt) -> None:
                     continue
             if (
                 isinstance(lvalue, NameExpr)
-                and not self.is_private_name(lvalue.name)
-                # it is never an alias with explicit annotation
-                and not o.unanalyzed_type
                 and self.is_alias_expression(o.rvalue)
+                and not self.is_private_name(lvalue.name)
             ):
-                self.process_typealias(lvalue, o.rvalue)
-                continue
+                is_type_alias = o.unanalyzed_type and getattr(o.type, "name", None) == "TypeAlias"
+                if not o.unanalyzed_type or is_type_alias:
+                    self.process_typealias(lvalue, o.rvalue)
+                    continue
+
             if isinstance(lvalue, (TupleExpr, ListExpr)):
                 items = lvalue.items
                 if isinstance(o.unanalyzed_type, TupleType):  # type: ignore[misc]
@@ -1141,7 +1142,7 @@ def is_alias_expression(self, expr: Expression, top_level: bool = True) -> bool:
 
     def process_typealias(self, lvalue: NameExpr, rvalue: Expression) -> None:
         p = AliasPrinter(self)
-        self.add(f"{self._indent}{lvalue.name} = {rvalue.accept(p)}\n")
+        self.add(f"{self._indent}{lvalue.name}: TypeAlias = {rvalue.accept(p)}\n")
         self.record_name(lvalue.name)
         self._vars[-1].append(lvalue.name)
 
@@ -1194,6 +1195,7 @@ def visit_import_from(self, o: ImportFrom) -> None:
                 self.import_tracker.reexport(name)
                 as_name = name
             import_names.append((name, as_name))
+        # here's required = False
         self.import_tracker.add_import_from("." * relative + module, import_names)
         self._vars[-1].extend(alias or name for name, alias in import_names)
         for name, alias in import_names:

test-data/unit/stubgen.test

@@ -1544,6 +1544,15 @@ from typing import TypeVar
 T = TypeVar('T')
 alias = Union[T, List[T]]
 
+[case testTypeAlias]
+from typing import TypeAlias
+
+alias: TypeAlias = tuple[int, str]
+
+[out]
+alias: TypeAlias = tuple[int, str]
+
+
 [case testEllipsisAliasPreserved]
 
 alias = Tuple[int, ...]