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Section: 31.11.3 [syncstream.osyncstream] Status: C++20 Submitter: Tim Song Opened: 2019-11-06 Last modified: 2021-02-25
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These functions are specified to call emit(), which calls emit() on the basic_syncbuf and sets badbit if it fails. Then, the move assignment is specified to move-assign the basic_syncbuf, while the destructor implicitly needs to destroy the basic_syncbuf data member. This calls emit() on the basic_syncbuf again.Is this intended?
[2020-02-13 Tim adds wording after discussion with Peter]
[2020-02 Status to Immediate Thursday afternoon in Prague.]
This wording is relative to N4849.
[Drafting note: There is no need to explicitly call emit at all in these functions; memberwise move-assignment/destruction is sufficient, so we can strike the specification entirely and rely on the wording in 184.108.40.206 [functions.within.classes]. — end drafting note]
Edit 220.127.116.11 [syncstream.osyncstream.cons] as indicated:
-6- Effects: Calls emit(). If an exception is thrown from emit(), that exception is caught and ignored.
basic_osyncstream& operator=(basic_osyncstream&& rhs) noexcept;
-1- Effects: First, calls emit(). If an exception is thrown from emit(), that exception is caught and ignored. Move assigns sb from rhs.sb. [ Note: This disassociates rhs from its wrapped stream buffer ensuring destruction of rhs produces no output. — end note ] -2- Postconditions: nullptr == rhs.get_wrapped() is true. get_wrapped() returns the value previously returned by rhs.get_wrapped().