>> We have already Constant and NameConstant.  So it seems there are no need for
>> None, Bool, TupleConst, SetConst nodes.
> Yes, Constant is Victor's version of Lit.

Then, may I remove ast.Lit, and use Constant and NameConstant?


>> I think converting Num, Str, Bytes, Ellipsis into Constant in folding stage
>> is easier than fixing all tests.
> Fixing tests was fairly easy the last time. I think the question is what changes to the public API of AST are acceptable.

I think backward compatibility is not guaranteed.
But there are some usage of ast. (https://github.com/search?l=Python&p=2&q=ast.Num&type=Code&utf8=%E2%9C%93 )

So I think we should make change small as possible.


>> Take docstring before constant folding isn't enough?
>> (I'm sorry if I'm wrong.  I haven't tried it yet.)
> It may be doable, but seems very messy. Instead of a clean pipeline text -> AST -> Optimized AST -> bytecode, you have to collect all docstrings, and pass them around in a side structure.
>
> With the current code there can be a simple fix. If original string literals are Str, but constant-folded string  constants are Constant, only treat Strs as docstrings. Then the optimizer needs a change to always preserve Str as a first statement in a function/module, and that's it.
> I still think that having a dedicated docstring attribute in AST is cleaner, though.

OK.


>> They are all NameConstant already.
> Keep in mind this patch is 6 years old :)

I know. I want to move this patch forward, but I'm not frontend (parser, AST, and compiler) expert.
I can't make design decision without expert's advice.  Thanks for your reply.

Then, may I update the patch in following  direction?

* Remove ast.Lit.
* Keep docstring change.