bpo-32911: Revert bpo-29463. (GH-7121) (GH-7197)

Remove the docstring attribute of AST types and restore docstring
expression as a first stmt in their body.

Co-authored-by: INADA Naoki <methane@users.noreply.github.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/Lib/ast.py b/Lib/ast.py
index 2ecb03f38b..134d9d2758 100644
--- a/Lib/ast.py
+++ b/Lib/ast.py
@@ -206,7 +206,15 @@ def get_docstring(node, clean=True):
     """
     if not isinstance(node, (AsyncFunctionDef, FunctionDef, ClassDef, Module)):
         raise TypeError("%r can't have docstrings" % node.__class__.__name__)
-    text = node.docstring
+    if not node.body:
+        return None
+    node = node.body[0].value
+    if isinstance(node, Str):
+        text = node.s
+    elif isinstance(node, Constant) and isinstance(node.value, str):
+        text = node.value
+    else:
+        return None
     if clean and text:
         import inspect
         text = inspect.cleandoc(text)