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Section: 31.11.2.1 [syncstream.syncbuf.overview], 31.11.2.3 [syncstream.syncbuf.assign] Status: WP Submitter: Jonathan Wakely Opened: 2020-11-10 Last modified: 2021-10-14
Priority: 3
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Discussion:
The synopsis in 31.11.2.1 [syncstream.syncbuf.overview] shows the move assignment operator and swap member as potentially throwing. The detailed descriptions in 31.11.2.3 [syncstream.syncbuf.assign] are noexcept.
Daniel: This mismatch is already present in the originally accepted paper P0053R7, so this is nothing that could be resolved editorially.[2020-11-21; Reflector prioritization]
Set priority to 3 during reflector discussions.
[2021-05-22 Tim adds PR]
The move assignment is specified to call emit() which can throw, and there's nothing in the wording providing for catching/ignoring the exception, so it can't be noexcept. The swap needs to call basic_streambuf::swap, which isn't noexcept, so it shouldn't be noexcept either.
[2021-06-23; Reflector poll]
Set status to Tentatively Ready after eight votes in favour during reflector poll.
[2021-10-14 Approved at October 2021 virtual plenary. Status changed: Voting → WP.]
Proposed resolution:
This wording is relative to N4885.
Modify 31.11.2.3 [syncstream.syncbuf.assign] as indicated:
basic_syncbuf& operator=(basic_syncbuf&& rhs)noexcept;-1- Effects: […]
-2- Postconditions: […] -3- Returns: […] -4- Remarks: […]void swap(basic_syncbuf& other)noexcept;-5- Preconditions: […]
-6- Effects: […]