bpo-38641: Add support of starred expressions in return/yield to lib2to3

[vemel]

Goal

bpo-32117 is fixed, but unfortunately lib2to3 still does not support unpacking in return and yield without parentheses.

def test():
    my_list = ["value2", "value3"]
    yield "value1", *my_list
    return "value1", *my_list

Changes

• Use testlist_star_expr in return_stmt
• Use testlist_star_expr in yield_arg

Summary

This is a backwards compatible change, because testlist_star_expr supports test as well like testlist does.

https://bugs.python.org/issue38641

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[pablogsal]

Hi @vemel and thanks for the change!

Could you sign the CLA and add a NEWS entry? Thanks!

[vemel]

Hi @vemel and thanks for the change!

Could you sign the CLA and add a NEWS entry? Thanks!

I have already signed CLA. Going to add news section now.
I also adapted grammar unit tests

[vemel]

Just added news section.

[isidentical]

Can you specify this is a bug related to lib2to3 here, also you can add a Patch by <name>. attribution at the end of news.

[vemel]

Updated, thank you!

[codecov]

Codecov Report

Merging #16994 into master will increase coverage by 0.00%.
The diff coverage is n/a.

@@            Coverage Diff            @@
##           master   #16994     +/-   ##
=========================================
  Coverage   82.11%   82.12%             
=========================================
  Files        1956     1955      -1     
  Lines      589364   584024   -5340     
  Branches    44457    44457             
=========================================
- Hits       483966   479605   -4361     
+ Misses      95746    94772    -974     
+ Partials     9652     9647      -5     

Impacted Files	Coverage Δ
Lib/distutils/tests/test_bdist_rpm.py	30.00% <0.00%> (-65.00%)	⬇️
Lib/distutils/command/bdist_rpm.py	7.63% <0.00%> (-56.88%)	⬇️
Lib/test/test_urllib2net.py	76.92% <0.00%> (-13.85%)	⬇️
Lib/test/test_smtpnet.py	78.57% <0.00%> (-7.15%)	⬇️
Lib/ftplib.py	63.85% <0.00%> (-6.06%)	⬇️
Lib/test/test_ftplib.py	87.11% <0.00%> (-4.72%)	⬇️
Tools/scripts/db2pickle.py	17.82% <0.00%> (-3.97%)	⬇️
Tools/scripts/pickle2db.py	16.98% <0.00%> (-3.78%)	⬇️
Lib/test/test_socket.py	71.94% <0.00%> (-3.77%)	⬇️
Lib/test/test_asyncio/test_base_events.py	91.84% <0.00%> (-3.30%)	⬇️
... and 325 more

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[vemel]

Looks like unit test for MacOS are broken, but it is not related to current PR. Probably it makes sense to fix them in another PR.

[isidentical]

LGTM except for the ACKS file, I think you did something wrong while you were rebasing/merging. Can you check it again @vemel

[vemel]

LGTM except for the ACKS file, I think you did something wrong while you were rebasing/merging. Can you check it again @vemel

Indeed. Fixed.

[pablogsal]

LGTM

Thanks, @vemel for the PR and @isidentical for the review :)

[isidentical]

Thanks @vemel for the PR!