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3020. [networking.ts] Remove spurious nested value_type buffer sequence requirement

Section: 16.2 [networking.ts::buffer.reqmts] Status: C++23 Submitter: Vinnie Falco Opened: 2017-09-20 Last modified: 2023-11-22

Priority: 0

View all other issues in [networking.ts::buffer.reqmts].

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Discussion:

Addresses: networking.ts

The post-condition requirements for ConstBufferSequence and MutableBufferSequence refer to X::value_type, but no such nested type is required. The lambda expression passed to equal can use auto const& parameter types instead.

Previous resolution: [SUPERSEDED]

This wording is relative to N4588.

  1. Modify 16.2.1 [networking.ts::buffer.reqmts.mutablebuffersequence] Table 12 "MutableBufferSequence requirements" as indicated:

    Table 12 — MutableBufferSequence requirements
    expression return type assertion/note pre/post-condition
    […]
    X u(x); post:
    equal(
  net::buffer_sequence_begin(x),
  net::buffer_sequence_end(x),
  net::buffer_sequence_begin(u),
  net::buffer_sequence_end(u),
  [](const typename X::value_typeauto& v1,
     const typename X::value_typeauto& v2)
    {
      mutable_buffer b1(v1);
      mutable_buffer b2(v2);
      return b1.data() == b2.data()
          && b1.size() == b2.size();
    })

  2. Modify 16.2.2 [networking.ts::buffer.reqmts.constbuffersequence] Table 13 "ConstBufferSequence requirements" as indicated:

    Table 13 — ConstBufferSequence requirements
    expression return type assertion/note pre/post-condition
    […]
    X u(x); post:
    equal(
  net::buffer_sequence_begin(x),
  net::buffer_sequence_end(x),
  net::buffer_sequence_begin(u),
  net::buffer_sequence_end(u),
  [](const typename X::value_typeauto& v1,
     const typename X::value_typeauto& v2)
    {
      const_buffer b1(v1);
      const_buffer b2(v2);
      return b1.data() == b2.data()
          && b1.size() == b2.size();
    })

[2017-10-19, Peter Dimov provides improved wording]

The alternative wording prevents the need for auto parameters because it takes advantage of the "convertible to" requirement.

[ 2017-10-20 Moved to Tentatively Ready after 5 positive votes on c++std-lib. ]

[2018-3-17 Adopted in Jacksonville]

Proposed resolution:

This wording is relative to N4588.

  1. Modify 16.2.1 [networking.ts::buffer.reqmts.mutablebuffersequence] Table 12 "MutableBufferSequence requirements" as indicated:

    Table 12 — MutableBufferSequence requirements
    expression return type assertion/note pre/post-condition
    […]
    X u(x); post:
    equal(
  net::buffer_sequence_begin(x),
  net::buffer_sequence_end(x),
  net::buffer_sequence_begin(u),
  net::buffer_sequence_end(u),
  [](const typename X::value_type& v1mutable_buffer& b1,
     const typename X::value_type& v2mutable_buffer& b2)
    {
      mutable_buffer b1(v1);
      mutable_buffer b2(v2);
      return b1.data() == b2.data()
          && b1.size() == b2.size();
    })

  2. Modify 16.2.2 [networking.ts::buffer.reqmts.constbuffersequence] Table 13 "ConstBufferSequence requirements" as indicated:

    Table 13 — ConstBufferSequence requirements
    expression return type assertion/note pre/post-condition
    […]
    X u(x); post:
    equal(
  net::buffer_sequence_begin(x),
  net::buffer_sequence_end(x),
  net::buffer_sequence_begin(u),
  net::buffer_sequence_end(u),
  [](const typename X::value_type& v1const_buffer& b1,
     const typename X::value_type& v2const_buffer& v2)
    {
      const_buffer b1(v1);
      const_buffer b2(v2);
      return b1.data() == b2.data()
          && b1.size() == b2.size();
    })