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2856.std::async should be marked as [[nodiscard]]
Section: 32.10.9 [futures.async] Status: Resolved Submitter: Andrey Davydov Opened: 2017-01-20 Last modified: 2020-09-06
Priority: 2
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Discussion:
Because the destructor of the std::future returned from the std::async blocks until the asynchronous operation completes, discarding the std::async return value leads to the synchronous code execution, which is pointless. For example, in the following code
void task1();
void task2();
void foo()
{
std::async(std::launch::async, task1),
std::async(std::launch::async, task2);
}
void bar()
{
std::async(std::launch::async, task1);
std::async(std::launch::async, task2);
}
task1 and task2 will be concurrently executed in the function 'foo', but sequentially in the function 'bar'.
[2017-01-27 Telecon]
Priority 2; Nico to provide wording.
[2017-03-04, Kona]
This should be handled by Nico's paper P0600.
Proposed resolution:
Resolved by adoption of P0600 in Albuquerque
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