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noexcept in shared_ptr::shared_ptr(nullptr_t)Section: 20.3.2.2 [util.smartptr.shared] Status: C++17 Submitter: Cassio Neri Opened: 2014-02-13 Last modified: 2017-07-30
Priority: Not Prioritized
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Discussion:
The declaration and definition of shared_ptr::shared_ptr(nullptr_t), given in 20.3.2.2 [util.smartptr.shared], is
constexpr shared_ptr(nullptr_t) : shared_ptr() { }
The intention seems clear: this constructor should have the same semantics of the default constructor. However, contrarily to the
default constructor, this one is not noexcept. In contrast, unique_ptr::unique_ptr(nullptr_t) is noexcept,
as per 20.3.1.3 [unique.ptr.single]:
constexpr unique_ptr(nullptr_t) noexcept : unique_ptr() { }
Both libstdc++ and libc++ have added noexcept to shared_ptr::shared_ptr(nullptr_t). Microsoft's STL has not.
[2014-03-26 Library reflector vote]
The issue has been identified as Tentatively Ready based on six votes in favour.
Proposed resolution:
This wording is relative to N3936.
Change class template shared_ptr synopsis, 20.3.2.2 [util.smartptr.shared], as indicated:
constexpr shared_ptr(nullptr_t) noexcept : shared_ptr() { }