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Section: 32.5.8[atomics.types.generic]Status:ResolvedSubmitter: Anthony WilliamsOpened: 2008-09-26Last modified: 2017-11-29
Priority:Not Prioritized
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Discussion:
Addresses US 90
The deleted copy-assignment operators for the atomic types are notmarked as volatile in N2723, whereas the assignment operators from theassociated non-atomic types are. e.g.
atomic_bool& operator=(atomic_bool const&) = delete;atomic_bool& operator=(bool) volatile;
This leads to ambiguity when assigning a non-atomic value to anon-volatile instance of an atomic type:
atomic_bool b;b=false;
Both assignment operators require a standard conversions: thecopy-assignment operator can use the implicitatomic_bool(bool)conversion constructor to convertfalse to an instance ofatomic_bool, orb can undergo a qualification conversion in order touse the assignment from a plainbool.
This is only a problem once issue845(i) is applied.
[Summit:]
Move to open. Assign to Lawrence. Related to US 90 comment.
[2009-08-17 Handled byN2925.]
[2009-10 Santa Cruz:]
NAD EditorialResolved. Addressed byN2992.
Proposed resolution:
Add volatile qualification to the deleted copy-assignment operator ofall the atomic types:
atomic_bool& operator=(atomic_bool const&)volatile = delete;atomic_itype& operator=(atomic_itype const&)volatile = delete;
etc.
This will mean that the deleted copy-assignment operator will requiretwo conversions in the above example, and thus be a worse match thanthe assignment from plainbool.