Warn that compile() can crash when compiling to an AST object (GH-6043) (GH-6045)

(cherry picked from commit f7a6ff6fcab32a53f262ba3f8a072c27afc330d7)

Co-authored-by: Brett Cannon <brettcannon@users.noreply.github.com>
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index bfb813c..3ddd280 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -274,6 +274,12 @@
       character.  This is to facilitate detection of incomplete and complete
       statements in the :mod:`code` module.
 
+   .. warning::
+
+      It is possible to crash the Python interpreter with a
+      sufficiently large/complex string when compiling to an AST
+      object due to stack depth limitations in Python's AST compiler.
+
    .. versionchanged:: 3.2
       Allowed use of Windows and Mac newlines.  Also input in ``'exec'`` mode
       does not have to end in a newline anymore.  Added the *optimize* parameter.