It is not clear to me that this is the right thing to do:
- it is done for some classes
- but in some test, a comment mention that it should be uninitialized
(the test works if init to -1 but not to 0).
- Base_time_stamper is doing an init to -2
## Summary of Changes
Update our CMake supported versions to ...3.31. That will suppress the
warnings about `CMP0167` (from CMake 3.30):
```
CMake Warning (dev) at cmake/modules/display-third-party-libs-versions.cmake:37 (find_package):
Policy CMP0167 is not set: The FindBoost module is removed. Run "cmake
--help-policy CMP0167" for policy details. Use the cmake_policy command to
set the policy and suppress this warning.
```
## Release Management
* Affected package(s): all cmake scripts
* License and copyright ownership: maintenance by GF
That will suppress the warnings about `CMP0167` (from CMake 3.30):
```
CMake Warning (dev) at cmake/modules/display-third-party-libs-versions.cmake:37 (find_package):
Policy CMP0167 is not set: The FindBoost module is removed. Run "cmake
--help-policy CMP0167" for policy details. Use the cmake_policy command to
set the policy and suppress this warning.
```
One cannot call `std::allocator_traits<Alloc>::construct`, because some of linear cell complex classes have protected constructors with a lot of friend classes. They cannot be friend of all possible allocator classes, so...
The regular expression I used was:
```
((?!(?:^.*(\/\/|\/\*).*|^ *\* .*|^[^"]*"(?:"[^"]*"|[^"])*))^(?:.*[ ,\(]|))(\b(?:(?:[A-Za-z]+::)*)(?:max|min))\b *\(
```
...and `refactor Polyline_constraint_hierarchy_2` to use it.
`CGAL::unordered_flat_map` will be Boost `unordered_flat_map` if availlable, or the standard `std::unordered_map` otherwise.
## Summary of Changes
- Changed `PUBLIC` to `PRIVATE` in the `target_link_libraries()`
- ~~Link against `Boost::<COMPONENT>`~~ as we do more than just linking
and must use the `CGAL::_.._support`
- Use `target_compile_definitions()` and `add_compile_definitions()`
More to be done.
## Release Management
* Affected package(s): all
* Issue(s) solved (if any): fix one item of #4815
* License and copyright ownership: unchanged