Since commit cb41b2766de646435743b6af7dd152751b54e73f (Python 3.7a0), string literals are not parsed the same way.

ast.parse("'test'").body used to be a list with one item containing 'test'; but now it is an empty list:


Python 3.5.2+ (default, Dec 13 2016, 14:16:35) 
[GCC 6.2.1 20161124] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import ast
>>> print(ast.parse("'test'"))
<_ast.Module object at 0x7fa37ae4c630>
>>> print(ast.parse("'test'").body)
[<_ast.Expr object at 0x7fa37ae4c630>]
>>> print(ast.parse("'test'").docstring)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'Module' object has no attribute 'docstring'





Python 3.7.0a0 (default, Feb 24 2017, 21:38:30) 
[GCC 6.3.0 20170205] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import ast
>>> print(ast.parse("'test'"))
<_ast.Module object at 0x7fe2aa415eb8>
>>> print(ast.parse("'test'").body)
[]
>>> print(ast.parse("'test'").docstring)
test

(Oops, submitted too soon.)

I understand the rational of this change, so I am not sure if this is actually a bug.

However, if someone wants to parse a simple expression that may be a string, they need to add a special handling in case it's a string interpreted as a module docstring.

If someone wants to parse a simple expression that may be a string he should use the "eval" mode.

>>> ast.dump(ast.parse("'test'"))
"Module(body=[], docstring='test')"
>>> ast.dump(ast.parse("'test'", mode='eval'))
"Expression(body=Str(s='test'))"

Indeed, thanks.

I should have done that when I migrated from compiler.parse.