fix(io): treat a fully transferred read/write as success#319
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read and write reported any error_code surfaced by the final read_some/write_some, even when that completion delivered the last bytes and filled the buffer. A generic observer (when_any/when_all) then saw a completed transfer as a failure. The most common trigger is end-of-stream coincident with a full read (read_some returns [eof, n] that fills the buffer). Report the contingency only when the buffer was not fully transferred: when n == buffer_size(buffers) the transfer succeeded and ec is success. Tighten the documented postcondition accordingly. Codify the same invariant in the ReadStream and WriteStream concept contracts: a read_some/write_some that fills its buffer reports success, so n == buffer_size(buffers) implies no error (a coincident condition such as end-of-stream surfaces on a subsequent call). Add a mock stream that reports a contingency in the same completion that transfers bytes (the test read/write streams report errors with zero bytes) and cover both the filled-is-success and short-transfer-is-reported cases.
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An automated preview of the documentation is available at https://319.capy.prtest3.cppalliance.org/index.html If more commits are pushed to the pull request, the docs will rebuild at the same URL. 2026-06-16 19:25:12 UTC |
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GCOVR code coverage report https://319.capy.prtest3.cppalliance.org/gcovr/index.html Build time: 2026-06-16 19:41:20 UTC |
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## develop #319 +/- ##
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- Coverage 98.09% 98.07% -0.03%
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Files 164 164
Lines 8873 8758 -115
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- Hits 8704 8589 -115
Misses 169 169
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2 participants
Resolves #257.
Resolves #258.
read and write reported any error_code surfaced by the final read_some/write_some, even when that completion delivered the last bytes and filled the buffer. A generic observer (when_any/when_all) then saw a completed transfer as a failure. The most common trigger is end-of-stream coincident with a full read (read_some returns [eof, n] that fills the buffer).
Report the contingency only when the buffer was not fully transferred: when n == buffer_size(buffers) the transfer succeeded and ec is success. Tighten the documented postcondition accordingly.
Codify the same invariant in the ReadStream and WriteStream concept contracts: a read_some/write_some that fills its buffer reports success, so n == buffer_size(buffers) implies no error (a coincident condition such as end-of-stream surfaces on a subsequent call).
Add a mock stream that reports a contingency in the same completion that transfers bytes (the test read/write streams report errors with zero bytes) and cover both the filled-is-success and short-transfer-is-reported cases.