ISSUE-1902 Fix Template::is_up_to_date contract

CHANGES.rst

@@ -5,6 +5,7 @@ Version 3.2.0
 
 Unreleased
 
+-   Fix Template's type hint contract :pr: `1903`
 -   Use modern packaging metadata with ``pyproject.toml`` instead of ``setup.cfg``.
     :pr:`1793`
 -   Use ``flit_core`` instead of ``setuptools`` as build backend.

src/jinja2/environment.py

@@ -1493,7 +1493,7 @@ def is_up_to_date(self) -> bool:
         """If this variable is `False` there is a newer version available."""
         if self._uptodate is None:
             return True
-        return self._uptodate()
+        return self._uptodate() if callable(self._uptodate) else self._uptodate
 
     @property
     def debug_info(self) -> t.List[t.Tuple[int, int]]:

tests/test_regression.py

@@ -11,6 +11,28 @@
 
 
 class TestCorner:
+    def test_uptodate_loader(self, env):
+        class UpToDateDictLoader(DictLoader):
+            def get_source(self, environment: "Environment", template: str):
+                contents, path, uptodate = super().get_source(environment, template)
+                return contents, path, True
+
+        env = Environment(
+            loader=UpToDateDictLoader(
+                {
+                    "a.html": """
+                        {%- set foo = 'bar' -%}
+                        {% include 'x.html' -%}{% include 'x.html' -%}
+                    """,
+                    "x.html": """{{ foo }}|{{ test }}""",
+                }
+            )
+        )
+
+        a = env.get_template("a.html")
+
+        assert a.render(test="x").strip() == "bar|xbar|x"
+
     def test_assigned_scoping(self, env):
         t = env.from_string(
             """