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

Section: 8.2.1.1 [fund.ts.v2::memory.smartptr.shared.const] Status: TS Submitter: Daniel Krügler Opened: 2015-10-24 Last modified: 2017-07-30

Priority: 0

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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 8.2.1.1 [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.