Meta LWG issue: 2024-06 meeting

[StephanTLavavej]

(Previous meta-issue: #4491)

At the June 2024 meeting, the following LWG issues were resolved in the C++ Working Paper.

❔ Not yet analyzed

• Remaining issues:
  • All done!

❌ Not applicable

If an issue requires no action from implementers, we mark it as N/A. Categories:

• Pure wording clarifications with nothing to implement (these can be changes to non-normative text like examples and informative notes, or wording cleanups to normative text that don't impact observable behavior)
  • LWG-4076 concat_view should be freestanding
• Something that increases the restrictions placed on users, but implementers aren't expected to enforce those restrictions
• Fixes for obviously broken wording, where implementers would have done the right thing anyways

😸 Already implemented

Sometimes we cite LWG issues in product code comments as we're implementing their proposed resolutions. When the resolutions are officially accepted, we should remove the citations (as the default assumption is that we're implementing what the Standard says). If something is especially subtle, we can convert the citation to mention the relevant Standard section. Sometimes we should add test coverage - e.g. when the Standard begins requiring something that we were already doing, but weren't explicitly testing for.

• Already implemented, comments need to be removed and messages need to cite the Standard
• Implemented without comments

🩹 Patches an unimplemented feature

We should record this LWG issue in the GitHub issue tracking the feature. That way, we'll remember to verify it, but it doesn't represent net new work.

• LWG-4060 submdspan preconditions do not forbid creating invalid pointer
  • Recorded in P2642R6 Padded mdspan Layouts #4516.
• LWG-4071 reference_wrapper comparisons are not SFINAE-friendly
  • Recorded in P2944R3 Comparisons For reference_wrapper #4522.
• LWG-4079 Missing Preconditions in concat_view::iterator's conversion constructor
  • Recorded in P2542R8 views::concat #4514.
• LWG-4082 views::concat(r) is well-formed when r is an output_range
  • Recorded in P2542R8 views::concat #4514.

🐞 Not yet implemented

• Filed a GitHub issue labeled LWG
  • LWG-3944 Formatters converting sequences of char to sequences of wchar_t
    • LWG-3944 Formatters converting sequences of char to sequences of wchar_t #4760
  • LWG-4074 compatible-joinable-ranges is underconstrained
    • LWG-4074 compatible-joinable-ranges is underconstrained #4761
  • LWG-4083 views::as_rvalue should reject non-input ranges
    • LWG-4083 views::as_rvalue should reject non-input ranges #4762
  • LWG-4096 views::iota(views::iota(0)) should be rejected
    • LWG-4096 views::iota(views::iota(0)) should be rejected #4763
  • LWG-4098 views::adjacent<0> should reject non-forward ranges
    • LWG-4098 views::adjacent<0> should reject non-forward ranges #4764
  • LWG-4105 ranges::ends_with's Returns misses difference casting
    • LWG-4105 ranges::ends_with's Returns misses difference casting #4765
• PR out for review
  • LWG-4061 Should std::basic_format_context be default-constructible/copyable/movable?
    • Implement LWG-4061 Should std::basic_format_context be default-constructible/copyable/movable? #4758
  • LWG-4106 basic_format_args should not be default-constructible
    • Implement LWG-4106 basic_format_args should not be default-constructible #4757