feat: add returning overload to tcp_acceptor::accept()

[mvandeberg]

Add accept() with no arguments returning io_result<tcp_socket>, so the acceptor constructs the peer socket itself instead of requiring the caller to pass one in:

auto [ec, peer] = co_await acc.accept();

Closes #227

[cppalliance-bot]

An automated preview of the documentation is available at https://274.corosio.prtest3.cppalliance.org/index.html

If more commits are pushed to the pull request, the docs will rebuild at the same URL.

2026-06-11 17:02:30 UTC

[cppalliance-bot]

GCOVR code coverage report https://274.corosio.prtest3.cppalliance.org/gcovr/index.html
LCOV code coverage report https://274.corosio.prtest3.cppalliance.org/genhtml/index.html
Coverage Diff Report https://274.corosio.prtest3.cppalliance.org/diff-report/index.html

Build time: 2026-06-11 17:16:59 UTC

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.73%. Comparing base (a0d0d1c) to head (9cb4ca0).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #274   +/-   ##
========================================
  Coverage    77.73%   77.73%           
========================================
  Files           96       96           
  Lines         7234     7234           
  Branches      1764     1764           
========================================
  Hits          5623     5623           
  Misses        1102     1102           
  Partials       509      509           

Files with missing lines	Coverage Δ
...clude/boost/corosio/native/native_tcp_acceptor.hpp	90.90% <ø> (ø)
include/boost/corosio/tcp_acceptor.hpp	91.83% <ø> (ø)

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