AW: [eigen] Eigen 3.3.0 compile error with aligned

No problem, not urgent for me, i can live with eigen 3.2.8 currently. I only wanted to report it since it seems for me to be a problem in eigen, (but truly I am not sure):

My exact workflow was building trunk (1 week old or so) of the PCL (point cloud library) with latest boost 1.62.0 and latest Eigen 3.3.0 (and also tested all versions above 3.2.8) with visual studio professional 2013 x64 (with some other 3rd parties but should not be related to that). Then I got the below compiler error in the pcl/surface package in the grid_projection.h on instantiation of typedef boost::unordered_map<int, Leaf, boost::hash<int>, std::equal_to<int>, Eigen::aligned_allocator<int> > HashMap;.

If you give me some time (currently I am external and not in office, maybe next 3 days) I could recompile your minimal example with eigen 3.3 and test it on your minimal example…. But I also downloaded the official PCL binary installer package and inside that I found all latest 3rd party librearies expect those from Eigen which is an older one (so there seems to be also a problem for the builder of that official PCL package with the newest version, or it is an extreme random chance/huge coincidence that they forgot to update it)

Best regards,

Gerald

Von: Gael Guennebaud [mailto:gael.guennebaud@xxxxxxxxx]
Gesendet: Mittwoch, 23. November 2016 13:51
An: eigen
Betreff: Re: [eigen] Eigen 3.3.0 compile error with aligned_allocator

Hi,

sorry for late reply, but I cannot reproduce. I tried clang, gcc, and MSVC 19.00 (boost 1.59 and 1.60).

See this self-contained example:

http://rextester.com/XHGN60496

BTW, I don't see how the reported error is related to operator==. Moreover, I think that the error message is incomplete, please paste the complete error message so that we can see what the template instantiations that led to this error.

gael

On Wed, Nov 16, 2016 at 8:38 AM, Lodron, Gerald <Gerald.Lodron@xxxxxxxxxxx> wrote:

Hi

I am compiling PCL trunk with Eigen3.3.0 (and VS2013x64, boost 1.62.0) and get a compilation error on the intantiation of
…
typedef boost::unordered_map<int, Leaf, boost::hash<int>, std::equal_to<int>, Eigen::aligned_allocator<int> > HashMap;
…
HashMap cell_hash_map_;

E:\Develop\Libraries120_x64\boost\1.62.0-NoPython\include\boost-1_62\boost/unordered/detail/allocate.hpp(497) : error C2664: 'Eigen::aligned_allocator<U>::aligned_allocator(const Eigen::aligned_allocator<U> &)' : cannot convert argument 1 from 'std::allocator<T>' to 'const Eigen::aligned_allocator<U> &'
with
[
U=boost::unordered::detail::ptr_node<std::pair<const int,pcl::GridProjection<pcl::PointNormal>::Leaf>>
]
and
[
T=boost::unordered::detail::ptr_node<std::pair<const int,pcl::GridProjection<pcl::PointNormal>::Leaf>>
]
and
[
U=boost::unordered::detail::ptr_node<std::pair<const int,pcl::GridProjection<pcl::PointNormal>::Leaf>>
]
Reason: cannot convert from 'std::allocator<T>' to 'const Eigen::aligned_allocator<U>'

I googled a little bit and found
http://stackoverflow.com/questions/16126133/compiling-issue-with-custom-allocators-when-std-c0x-is-enabled

“The error message actually contains the hint. I’ve reformulated it slightly here:
error: invalid operands [of type aligned_allocator<int>] to binary _expression_ […] __x._M_get_Tp_allocator() == this->_M_get_Tp_allocator()
In other words, your allocator type needs to provide an operator ==.
This is part of the allocator requirements (§17.6.3.5, table 28). This has always been the case. But until C++11 allocators were stateless and operator == consequently always returned true, so the standard library containers probably never called the operator. This would explain why the code compiles without -std=++0x.
“

Could it be that you need some operator definitions in the aligned_allocator of eigen? The compilation error is only since eigen 3.2.9, on eigen 3.2.8 it works. The difference which causes the error is the inheritance from std::allocator of Eigen::aligned_allocator....