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Incorrect syntax error message for incorrect argument unpacking #110696

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Incorrect syntax error message for incorrect argument unpacking#110696
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interpreter-core(Objects, Python, Grammar, and Parser dirs)type-bugAn unexpected behavior, bug, or error

Description

@thatbirdguythatuknownot
thatbirdguythatuknownot
opened on Oct 11, 2023

Bug report

Bug description:

I don't think SyntaxError: iterable argument unpacking follows keyword argument unpacking should be present in a case like this (minimal reproducible example):

>>> func(t, *:)
  File "<stdin>", line 1
    func(t, *:)
         ^
SyntaxError: iterable argument unpacking follows keyword argument unpacking

So it seems like if * is followed by code that triggers a generic SyntaxError: invalid syntax error, the former error triggers and overshadows the generic error. This has somewhat made checking the error in the expression following that * a bit harder.
I have another question. func(a=5, *b) is apparently allowed but from the error func(**{'a': 7}, *b) isn't? I don't know what the PEP is for this so I'll try to search it up later.

CPython versions tested on:

3.12

Operating systems tested on:

Windows

Linked PRs

Activity

  1. thatbirdguythatuknownot
    added
    type-bugAn unexpected behavior, bug, or error
    on Oct 11, 2023

  2. Eclips4 commented on Oct 11, 2023

    @Eclips4
    Eclips4
    on Oct 11, 2023
    Member

    cc @pablogsal

  3. pablogsal
    added a commit that references this issue on Oct 11, 2023

    pythongh-110696: Fix incorrect syntax error message for incorrect arg…

    8703330
  4. pablogsal
    changed the title [-]Wrong error message?[/-] [+]Incorrect syntax error message for incorrect argument unpacking[/+] on Oct 11, 2023
  5. pablogsal
    added a commit that references this issue on Oct 11, 2023

    fixup! pythongh-110696: Fix incorrect syntax error message for incorr…

    7b325ba
  6. terryjreedy
    added
    interpreter-core(Objects, Python, Grammar, and Parser dirs)
    on Oct 11, 2023
  7. pablogsal
    added a commit that references this issue on Oct 12, 2023

    gh-110696: Fix incorrect syntax error message for incorrect argument …

    3d18034

  8. thatbirdguythatuknownot commented on Oct 12, 2023

    @thatbirdguythatuknownot
    thatbirdguythatuknownot
    on Oct 12, 2023
    ContributorAuthor

    As for my question, it seems that func(a=5, *b) shouldn't be valid? All the other alternative ways to write it are invalid syntax.

    # not allowed
func(a=5, 1, 2)
func(**{'a': 5}, 1, 2)
func(**{'a': 5}, *(1, 2))
# allowed
func(a=7, *(1, 2))

    I might have to follow this up with a different issue.

  9. pablogsal
    added 2 commits that reference this issue on Oct 12, 2023

    [3.12] pythongh-110696: Fix incorrect syntax error message for incorr…

    e1b8f4e

    [3.11] pythongh-110696: Fix incorrect syntax error message for incorr…

    2a1d64e

  10. pablogsal commented on Oct 12, 2023

    @pablogsal
    pablogsal
    on Oct 12, 2023
    Member

    As for my question, it seems that func(a=5, *b) shouldn't be valid? All the other alternative ways to write it are invalid syntax.

    It was valid before (3.9 and older) so we cannot just make invalid now for backwards compatibility reasons.

  11. pablogsal
    closed this as completedon Oct 12, 2023
  12. pablogsal
    added 3 commits that reference this issue on Oct 12, 2023

    [3.12] gh-110696: Fix incorrect syntax error message for incorrect ar…

    4d0e6c8

    fixup! [3.11] pythongh-110696: Fix incorrect syntax error message for…

    f028085

    [3.11] gh-110696: Fix incorrect syntax error message for incorrect ar…

    4e4a3e1
  13. Glyphack
    added a commit that references this issue on Sep 2, 2024

    pythongh-110696: Fix incorrect syntax error message for incorrect arg…

    00234ad
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