disallow mode="function" in compile_restricted

CHANGES.rst

@@ -6,6 +6,8 @@ Changes
 
 - Allow ``ast.Module``, ``ast.Expression`` and ``ast.Interactive`` as body in compile_restricted_function
 
+- Disallow ``mode="function"`` in ``compile_restricted`` (it never worked).
+
 8.3 (2026-06-16)
 ----------------
 

docs/usage/api.rst

@@ -11,7 +11,7 @@ API overview
 
     :param source: (required). the source code that should be compiled
     :param filename: (optional). defaults to ``'<unknown>'``
-    :param mode: (optional). Use ``'exec'``, ``'eval'``, ``'single'`` or ``'function'``. defaults to ``'exec'``
+    :param mode: (optional). Use ``'exec'``, ``'eval'`` or ``'single'``. defaults to ``'exec'``
     :param flags: (optional). defaults to ``0``
     :param dont_inherit: (optional). defaults to ``False``
     :param policy: (optional). defaults to ``RestrictingNodeTransformer``

src/RestrictedPython/compile.py

@@ -206,7 +206,7 @@ def compile_restricted(
     policy ... `ast.NodeTransformer` class defining the restrictions.
 
     """
-    if mode in ['exec', 'eval', 'single', 'function']:
+    if mode in ['exec', 'eval', 'single']:
         result = _compile_restricted_mode(
             source,
             filename=filename,