intrusive list with stateful value traits

[Matei David <matei@…>]

In 1.55, in file boost/intrusive/list.hpp, in function list_impl::iterator_to(): when list_impl is instantiated with stateful value traits, the function attempts to call a non-static member without an object.

The problem is that list_impl does not derive from value_traits, instead, only its member data_ derives from value_traits. Then, inside the non-static iterator_to(), the syntax real_value_traits::to_node_ptr() is incorrect. In contrast, e.g., bstbase3 does derive from value_traits, and there the same syntax works just fine.

I'm attaching a file demonstrating the bug. The file contains the sample code at the bottom of http://www.boost.org/doc/libs/1_55_0/doc/html/intrusive/value_traits.html with a single line modification invoking iterator_to(). I'll create a pull request.

[Matei David <matei@…>]

Pull request here: ​https://github.com/boostorg/intrusive/pull/1

[Ion Gaztañaga]

Thanks for the report. The bug is also present in other containers, which shows that stateful value traits are not properly tested.

I also think that all "to_value_ptr" and "to_node_ptr" functions should be const as they are used to implement iterators (and operator-> is a const function and must call "to_value_ptr" with a non-const node) and a node<->conversion should not modify the traits. Do you agree with this?

[Matei David <matei@…>]

Yes, sounds reasonable. Sorry I didn't look at the other containers, I'm only using lists and rbtrees. I'll cancel the pull request because I noticed you have a more thorough fix in 22973145aaa5

[Ion Gaztañaga]

Closed as it was fixed in 22973145aaa5. Thanks.