2551. [fund.ts.v2] "Exception safety" cleanup in library fundamentals required

Section: 99 [fund.ts.v2::memory.smartptr.shared.const] Status: TS Submitter: Daniel Krügler Opened: 2015-10-24 Last modified: 2017-07-30

Priority: 0

View all issues with TS status.

Discussion:

Addresses: fund.ts.v2

Similar to LWG 2495, the current library fundamentals working paper refers to several "Exception safety" elements without providing a definition for this element type.

Proposed resolution:

This wording is relative to N4529.

  1. Change 99 [fund.ts.v2::memory.smartptr.shared.const] as indicated:

    template<class Y> explicit shared_ptr(Y* p);
    

    […]

    -3- Effects: When T is not an array type, constructs a shared_ptr object that owns the pointer p. Otherwise, constructs a shared_ptr that owns p and a deleter of an unspecified type that calls delete[] p. If an exception is thrown, delete p is called when T is not an array type, delete[] p otherwise.

    […]

    -6- Exception safety: If an exception is thrown, delete p is called when T is not an array type, delete[] p otherwise.

    template<class Y, class D> shared_ptr(Y* p, D d);
    template<class Y, class D, class A> shared_ptr(Y* p, D d, A a);
    template <class D> shared_ptr(nullptr_t p, D d);
    template <class D, class A> shared_ptr(nullptr_t p, D d, A a);
    

    […]

    -9- Effects: Constructs a shared_ptr object that owns the object p and the deleter d. The second and fourth constructors shall use a copy of a to allocate memory for internal use. If an exception is thrown, d(p) is called.

    […]

    -12- Exception safety: If an exception is thrown, d(p) is called.

    […]

    template<class Y> explicit shared_ptr(const weak_ptr<Y>& r);
    

    […]

    -28- Effects: Constructs a shared_ptr object that shares ownership with r and stores a copy of the pointer stored in r. If an exception is thrown, the constructor has no effect.

    […]

    -31- Exception safety: If an exception is thrown, the constructor has no effect.

    template <class Y, class D> shared_ptr(unique_ptr<Y, D>&& r);
    

    […]

    -34- Effects: Equivalent to shared_ptr(r.release(), r.get_deleter()) when D is not a reference type, otherwise shared_ptr(r.release(), ref(r.get_deleter())). If an exception is thrown, the constructor has no effect.

    -35- Exception safety: If an exception is thrown, the constructor has no effect.