clean python 3 specific stuff from stdlib/@python2 stubs

[Akuli]

#5442 copied files

Done with quick and dirty script:

import pathlib
import re
import sys   # Needed for evil eval haxor


version_check_regex = r'''
^( *)if sys\.version_info (>=|>|<=|<|==) .+: *(#.*)?\n(\1    .*\n|\n)+
(\1elif sys\.version_info (>=|>|<=|<|==) .+: *(#.*)?\n(\1    .*\n|\n)+)*
(\1else: *(#.*)?\n((\1    .*\n|\n)+))?
'''.replace('\n', '')


def sub_callback(match):
    indent = match.group(1)
    cases = re.split('^' + indent + 'el', match.group(0), flags=re.MULTILINE)

    if cases[-1].startswith('se:'):
        ifs = cases[:-1]    # skip else
        the_else = '\n'.join(cases[-1].split('\n')[1:])
    else:
        ifs = cases
        the_else = ''

    for if_part in ifs:
        code = if_part.split('\n')[0].replace('if', '').replace(':', '')
        if eval(code.replace('sys.version_info', '(2, 7)').strip()):
            replacement = '\n'.join(if_part.split('\n')[1:])
            break
    else:
        replacement = the_else

    if replacement:
        assert replacement.endswith('\n')

    return re.sub('^    ', '', replacement, flags=re.MULTILINE)


for path in pathlib.Path('stdlib/@python2').rglob('*.pyi'):
    print(path)
    text = path.read_text()
    text = re.sub(version_check_regex, sub_callback, text, flags=re.MULTILINE)
    path.write_text(text)

[Akuli]

Script breaks elif, will fix

edit: done

[JelleZijlstra]

Only read as far as array

[JelleZijlstra]

Suggested change

# Used by type checkers for checks involving None (does not exist at runtime)

It does exist in Python 2

$ python2
Python 2.7.12 (default, Nov 12 2018, 14:36:49) 
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import types
>>> types.NoneType
<type 'NoneType'>
>>> 

[Akuli]

Yes, types.NoneType exists, but the comment is about _typeshed.NoneType.

[JelleZijlstra]

My reading comprehension needs some work sometimes :)

In that case the comment still doesn't make much sense, since none of this file exists at runtime.

[JelleZijlstra]

I guess you'll have to remove the import too.

[Akuli]

The Python 2 stubs don't get checked for missing imports. We have this in .flake8:

exclude = .venv*,@*,.git,*_pb2.pyi

Is this intentional?

[JelleZijlstra]

Not sure what that's there for. It predates the @python2 directory, since it was there before 9af49c0. I think we can just remove it.

[Akuli]

Looking at git history, this is not intentional; ignoring @* was added before the big directory restructuring.

[srittau]

We should probably remove it after this PR, since I expect many new errors.

[Akuli]

I started cleaning unused imports from Python 2 stubs, but I'd rather have that in a separate PR because it's a lot of manual work.

[JelleZijlstra]

Sounds good. I think we should just merge this PR and follow up on other issues later.