Diffusion KIO 80ccfabb06ff

Allow move semantics to be generated for KFileItem. The existing copy…

Authored by markg on Feb 6 2018, 2:17 PM.


Allow move semantics to be generated for KFileItem. The existing copy constructor, destructor and copy assignment operator are now also generated by the compiler.

This allows the compiler to generate:

  • Move constructor
  • Move assingment
  • Copy constructor
  • Copy assignment
  • Destructor

This in turn allows further KFileItem optimization throughout KIO and Dolphin.
Also added a quite minimal test to see if move semantics work.

As implemented now it roughly follows the "rule-of-five-default": http://scottmeyers.blogspot.nl/2014/03/a-concern-about-rule-of-zero.html
I was tempted to go for the "rule-of-zero" which means not implementing any of those functions (thus the compiler generates them), but that - in my opinion - is not really clear as it's easy to add the destructor and then be surprised by not having move
semantics anymore.

Test Plan:
New test for move semantics (it passes, would probably pass without as well but just be a copy).
Existing relevant tests (kfileitemtest and kdirmodeltest) all pass just fine.
Running the new "testMove" through callgrind shows that the move constructor and assignment operator are really being used by that test.

Reviewers: dfaure, mwolff

Reviewed By: dfaure

Subscribers: ngraham, Frameworks

Tags: Frameworks

Differential Revision: https://phabricator.kde.org/D10341