Issue 2401: std::function needs more noexcept

Title: std::function needs more noexcept
Status: c++17
Section: [func.wrap.func]
Submitter: Stephan T. Lavavej

Created on 2014-06-14.00:00:00 last changed 101 months ago

Messages

Date: 2014-06-16.23:43:35

Proposed resolution:

This wording is relative to N3936.

Change [function.objects] p2, header <functional> synopsis, as indicated:

namespace std {
  […]
  // 20.9.11 polymorphic function wrappers:
  […]
  template<class R, class... ArgTypes>
  bool operator==(const function<R(ArgTypes...)>&, nullptr_t) noexcept;
  template<class R, class... ArgTypes>
  bool operator==(nullptr_t, const function<R(ArgTypes...)>&) noexcept;
  template<class R, class... ArgTypes>
  bool operator!=(const function<R(ArgTypes...)>&, nullptr_t) noexcept;
  template<class R, class... ArgTypes>
  bool operator!=(nullptr_t, const function<R(ArgTypes...)>&) noexcept;
  […]
}

Change [func.wrap.func], class template function synopsis, as indicated:

[…]
// 20.9.11.2.1, construct/copy/destroy:
[…]
function& operator=(nullptr_t) noexcept;
[…]

Change [func.wrap.func.con] before p16 as indicated:
```
function& operator=(nullptr_t) noexcept;
```

msg7033 (view)

Date: 2014-06-16.00:00:00

[ 2014-06-16 Rapperswil ]

Move to Ready

msg7032 (view)

Date: 2014-06-14.00:00:00

There are two issues here:

std::function's constructor from nullptr_t is marked as noexcept, but its assignment operator from nullptr_t isn't. This assignment can and should be marked as noexcept.
std::function's comparisons with nullptr_t are marked as noexcept in two out of three places.

History
Date	User	Action	Args
2017-07-30 20:15:43	admin	set	status: wp -> c++17
2014-11-08 19:44:42	admin	set	status: voting -> wp
2014-11-04 10:26:50	admin	set	status: ready -> voting
2014-06-16 23:43:35	admin	set	messages: + msg7054
2014-06-16 23:43:35	admin	set	status: new -> ready
2014-06-14 17:51:24	admin	set	messages: + msg7033
2014-06-14 00:00:00	admin	create