code confuses identity and equality (fixed upstream)

[William Cheng]

IMPACT:

Python 3.8 has started to emit warnings for code that confuses equality and identity. For more background see https://adamj.eu/tech/2020/01/21/why-does-python-3-8-syntaxwarning-for-is-literal/

While it is just a warning, it is very visible when running ansible on focal for example, to the point of making the output incredibly hard to follow. Furthermore, the indifference between identity and equality might be creating true bugs as discussed in above blog entry. It seems advisable to fix this incorrect code when found.

TEST CASE:

tbd

REGRESSION POTENTIAL:

The current code checks for identity via "is" and and "is not"...

Original report below:
======================
lsb_release -rd
Description: Ubuntu 20.04.2 LTS
Release: 20.04

apt-cache policy ansible
ansible:
  Installed: 2.9.6+dfsg-1
  Candidate: 2.9.6+dfsg-1
  Version table:
 *** 2.9.6+dfsg-1 500
        500 http://tw.archive.ubuntu.com/ubuntu focal/universe amd64 Packages
        500 http://tw.archive.ubuntu.com/ubuntu focal/universe i386 Packages
        100 /var/lib/dpkg/status

Hi, I install ansible have output some log:

Selecting previously unselected package python3-markupsafe.
(Reading database ... 194136 files and directories currently installed.)
Preparing to unpack .../00-python3-markupsafe_1.1.0-1build2_amd64.deb ...
Unpacking python3-markupsafe (1.1.0-1build2) ...
Selecting previously unselected package python3-jinja2.
Preparing to unpack .../01-python3-jinja2_2.10.1-2_all.deb ...
Unpacking python3-jinja2 (2.10.1-2) ...
Selecting previously unselected package python3-dnspython.
Preparing to unpack .../02-python3-dnspython_1.16.0-1build1_all.deb ...
Unpacking python3-dnspython (1.16.0-1build1) ...
Selecting previously unselected package ieee-data.
Preparing to unpack .../03-ieee-data_20180805.1_all.deb ...
Unpacking ieee-data (20180805.1) ...
Selecting previously unselected package python3-netaddr.
Preparing to unpack .../04-python3-netaddr_0.7.19-3_all.deb ...
Unpacking python3-netaddr (0.7.19-3) ...
Selecting previously unselected package ansible.
Preparing to unpack .../05-ansible_2.9.6+dfsg-1_all.deb ...
Unpacking ansible (2.9.6+dfsg-1) ...
Selecting previously unselected package python3-argcomplete.
Preparing to unpack .../06-python3-argcomplete_1.8.1-1.3ubuntu1_all.deb ...
Unpacking python3-argcomplete (1.8.1-1.3ubuntu1) ...
Selecting previously unselected package python3-jmespath.
Preparing to unpack .../07-python3-jmespath_0.9.4-2_all.deb ...
Unpacking python3-jmespath (0.9.4-2) ...
Selecting previously unselected package python3-kerberos.
Preparing to unpack .../08-python3-kerberos_1.1.14-3.1build1_amd64.deb ...
Unpacking python3-kerberos (1.1.14-3.1build1) ...
Selecting previously unselected package python3-lockfile.
Preparing to unpack .../09-python3-lockfile_1%3a0.12.2-2ubuntu2_all.deb ...
Unpacking python3-lockfile (1:0.12.2-2ubuntu2) ...
Selecting previously unselected package python3-libcloud.
Preparing to unpack .../10-python3-libcloud_2.8.0-1_all.deb ...
Unpacking python3-libcloud (2.8.0-1) ...
Selecting previously unselected package python3-ntlm-auth.
Preparing to unpack .../11-python3-ntlm-auth_1.1.0-1_all.deb ...
Unpacking python3-ntlm-auth (1.1.0-1) ...
Selecting previously unselected package python3-requests-kerberos.
Preparing to unpack .../12-python3-requests-kerberos_0.12.0-2_all.deb ...
Unpacking python3-requests-kerberos (0.12.0-2) ...
Selecting previously unselected package python3-requests-ntlm.
Preparing to unpack .../13-python3-requests-ntlm_1.1.0-1_all.deb ...
Unpacking python3-requests-ntlm (1.1.0-1) ...
Selecting previously unselected package python3-selinux.
Preparing to unpack .../14-python3-selinux_3.0-1build2_amd64.deb ...
Unpacking python3-selinux (3.0-1build2) ...
Selecting previously unselected package python3-xmltodict.
Preparing to unpack .../15-python3-xmltodict_0.12.0-1_all.deb ...
Unpacking python3-xmltodict (0.12.0-1) ...
Selecting previously unselected package python3-winrm.
Preparing to unpack .../16-python3-winrm_0.3.0-2_all.deb ...
Unpacking python3-winrm (0.3.0-2) ...
Setting up python3-lockfile (1:0.12.2-2ubuntu2) ...
Setting up python3-ntlm-auth (1.1.0-1) ...
Setting up python3-kerberos (1.1.14-3.1build1) ...
Setting up python3-libcloud (2.8.0-1) ...
Setting up python3-markupsafe (1.1.0-1build2) ...
Setting up python3-xmltodict (0.12.0-1) ...
Setting up python3-jinja2 (2.10.1-2) ...
Setting up python3-jmespath (0.9.4-2) ...
/usr/lib/python3/dist-packages/jmespath/visitor.py:32: SyntaxWarning: "is" with a literal. Did you mean "=="?
  if x is 0 or x is 1:
/usr/lib/python3/dist-packages/jmespath/visitor.py:32: SyntaxWarning: "is" with a literal. Did you mean "=="?
  if x is 0 or x is 1:
/usr/lib/python3/dist-packages/jmespath/visitor.py:34: SyntaxWarning: "is" with a literal. Did you mean "=="?
  elif y is 0 or y is 1:
/usr/lib/python3/dist-packages/jmespath/visitor.py:34: SyntaxWarning: "is" with a literal. Did you mean "=="?
  elif y is 0 or y is 1:
/usr/lib/python3/dist-packages/jmespath/visitor.py:260: SyntaxWarning: "is" with a literal. Did you mean "=="?
  if original_result is 0:
Setting up python3-requests-kerberos (0.12.0-2) ...
Setting up ieee-data (20180805.1) ...
Setting up python3-dnspython (1.16.0-1build1) ...
Setting up python3-selinux (3.0-1build2) ...
Setting up python3-argcomplete (1.8.1-1.3ubuntu1) ...
Setting up python3-requests-ntlm (1.1.0-1) ...
Setting up python3-netaddr (0.7.19-3) ...
/usr/lib/python3/dist-packages/netaddr/strategy/__init__.py:189: SyntaxWarning: "is not" with a literal. Did you mean "!="?
  if word_sep is not '':
Setting up python3-winrm (0.3.0-2) ...
Setting up ansible (2.9.6+dfsg-1) ...
Processing triggers for man-db (2.9.1-1) ...

[Rolf Leggewie (r0lf)]

This is indeed a bug. Thank you for reporting. More info at https://adamj.eu/tech/2020/01/21/why-does-python-3-8-syntaxwarning-for-is-literal/

[Rolf Leggewie (r0lf)]

affected lines

189: /usr/lib/python3/dist-packages/netaddr/strategy/__init__.py
260: /usr/lib/python3/dist-packages/jmespath/visitor.py
34 : /usr/lib/python3/dist-packages/jmespath/visitor.py

[Rolf Leggewie (r0lf)]

upstream fixed this in https://github.com/netaddr/netaddr/commit/cc2a9bb31fae00f18fcdbd97a29b643581fc2a45#diff-9c22182c07306d34df5b0003c08fab98ab23198b823b9f376b650b31be12f0a2
https://github.com/jmespath/jmespath.py/commit/56263b84cdb0feb7c8d54e426ec472f4dd0de44f#diff-3f700125d837beaff961eb74c6865f849857dbe4313f7f933a03ad64e9ce7911

[Rolf Leggewie (r0lf)]

code inspection shows that both packages have already been fixed in hirsute

[Rolf Leggewie (r0lf)]

bugfixed package available from my SRU PPA
https://launchpad.net/~r0lf/+archive/ubuntu/stable/