Bug #2966
closed
Move constructors and assignment operators should be declared noexcept
Added by Davide Pesavento over 9 years ago.
Updated over 9 years ago.
Description
While looking at some code I noticed that we have move constructors that are not declared noexcept, which in general is a bad thing.
From a quick search in ndn-cxx I've found:
src/util/signal-scoped-connection.hpp: ScopedConnection(ScopedConnection&& other);
src/util/scheduler-scoped-event-id.hpp: ScopedEventId(ScopedEventId&& other);
There might be more.
From 12.5.4 Declare noexcept the move constructor and move assignment operator:
If the move constructor for an element type in a container is not noexcept then the container will use the copy constructor rather than the move constructor.
This loses most benefits of defining move constructor and move assignment operator.
- Description updated (diff)
- Estimated time set to 1.50 h
Agreed.
We need to make this a code-style rule, so that there won't be violations in the future.
From 12.5.4 Declare noexcept the move constructor and move assignment operator:
If the move constructor for an element type in a container is not noexcept then the container will use the copy constructor rather than the move constructor.
This loses most benefits of defining move constructor and move assignment operator.
Junxiao Shi wrote:
This loses most benefits of defining move constructor and move assignment operator.
Yep, this is the main reason why I said lack of noexcept is bad, in turn caused by the widespread usage of move_if_noexcept in the standard library.
- Category set to Utils
- Assignee set to Junxiao Shi
- Estimated time changed from 1.50 h to 1.00 h
- Status changed from New to In Progress
- Status changed from In Progress to Code review
- % Done changed from 0 to 100
http://gerrit.named-data.net/2179
I have upgraded std::is_move_constructible and std::is_move_assignable to std::is_nothrow_move_constructible and std::is_nothrow_move_assignable.
For signal::ScopedConnection and scheduler::ScopedEventId, noexcept is added to move constructor, but they are designed to be not MoveAssignable.
- Status changed from Code review to Closed
Have you checked that there aren't other instances of missing noexcept in the codebase?
Have you checked that there aren't other instances of missing noexcept in the codebase?
I do not have the necessary tool to perform an exhaustive search.
Please reopen this issue if you find any.
- Description updated (diff)
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