Some fixes for Python 3

[cclauss]

Python 3 compatibility fixes as discussed in #23659 (comment)

These changes get the test scores equivalent on the following two tests.

• python2 -m flake8 . --exclude=./deps/v8,./deps/npm/node_modules/node-gyp --count --show-source --statistics --select=E901,E999,F821,F822,F823
• python3 -m flake8 . --exclude=./deps/v8,./deps/npm/node_modules/node-gyp --count --show-source --statistics --select=E901,E999,F821,F822,F823

E901,E999,F821,F822,F823 are the "showstopper" flake8 issues that can halt the runtime with a SyntaxError, NameError, etc. Most other flake8 issues are merely "style violations" -- useful for readability but they do not effect runtime safety.

• F821: undefined name name
• F822: undefined name name in __all__
• F823: local variable name referenced before assignment
• E901: SyntaxError or IndentationError
• E999: SyntaxError -- failed to compile a file into an Abstract Syntax Tree

@refack @eirnym

[Trott]

The change to the one file in deps will need to be upstreamed to OpenSSL rather than changed in our source code directly.

[cclauss]

Done in openssl/openssl#7409

[silverwind]

Generally LGTM, but isn't pylint the go-to python linter nowadays? If so I'd suggest not introducing pyflakes specific comments.

[refack]

Generally LGTM, but isn't pylint the go-to python linter nowadays? If so I'd suggest not introducing pyflakes specific comments.

The popular linter these days is flake8 🤷‍♂️
For the time being I'm coordinating the GYP changes in nodejs/node-gyp, then I'm planning on running GYP's original test suite to get some coverage. So actually it might be better to remove the GYP changes from this PR.

[cclauss]

@silverwind PyLint in its default configuration does not do very will on the following...

import sys
abc = collections.namedtuple("abc", "a b c")  # Missing import
hi = ur"hello"                     # Illegal in Python 3
for i in xrange(2):                # Illegal in Python 3
    long_i = long(i)               # Illegal in Python 3
    print i                        # Illegal in Python 3
    if isinstance(i, basestring):  # Illegal in Python 3
        print(unicode(i))          # Illegal in Python 3
reload(sys)                        # Illegal in Python 3
sys.setdefaultencoding("utf-8")    # Illegal in Python 3

async def async_print(s):          # Illegal in Python 2
    print(s, end=" ")              # Illegal in Python 2

[cclauss]

Merged in upstream in openssl/openssl#7409 but retained here because openssl in not pip installed but is vendored in.

[silverwind]

PyLint in its default configuration does not do very will on the following

Yes, IIRC, pylint needs quite a bit of configuration to be useful. Anyways, I'd appreciate if you'd remove linter-specific comments, we can decide on a python linter later on, this PR should be about fixing compatibilty only, the lint result doesn't need to be 100% clean.

[silverwind]

suggesting to drop these based on my earlier comment.

[refack]

+1

It's also excluded from new lint-py target:
https://github.com/nodejs/node/blob/4458162cfaf8c1eed987323fbb21c86783a8e914/Makefile#L1221-L1223

[refack]

@cclauss do you mind if I close this issue as superseded?