Re: [eigen] XLC Port: Part II - External definition of a template member function of a template class causing the problems?

[Aron Ahmadia <aja2111@xxxxxxxxxxxx>]

Hi Benoit,

I got that code workarounding by inlining the template function member
definitions into the class definition.  I decided to skip forward and
see if there were any other big issues that were causing the XLC
compiler to crash, and ei_traits appears to be another one.  The XLC
compiler is complaining when it tries to instansiate the ei_traits
template class using a single template argument (MatrixType) with the
error that the undefined class is not valid:

"eigen/Eigen/src/Core/util/ForwardDeclarations.h", line 46.30:
1540-1109 (S) The use of undefined class
"Eigen::ei_traits<Eigen::Matrix<float,3,3,0,3,3> >" is not valid.

My suspicion is that ei_traits is not defined in a manner that XLC
approves of, or that it is bugging out for another reason.  I will
spend some time investigating this week and try to narrow down exactly
how and where XLC is breaking.  One possibility is that it can't
handle a template class instantiation to resolve another template
argument.  Another possibility is that it can't find a definition of
ei_traits that it likes.  I think I can eliminate the second
possibility by trying to explicitly instantiate an ei_traits object
with the given argument.s

Nevermind, I just tried it.  XLC is okay with this:
Eigen::ei_traits<Eigen::Matrix<float,3,3,0,3,3> > a;

and compiles, links, and runs it through a main.cpp routine.
It gives the same errors about ei_traits with these lines of code:
Eigen::Matrix<float,3,3,0,3,3> m;
Matrix3f m3;

"eigen/Eigen/src/Core/util/ForwardDeclarations.h", line 44.30:
1540-1109 (S) The use of undefined class
"Eigen::ei_traits<Eigen::Matrix<float,3,3,0,3,3> >" is not valid.

I think this points to your use of ei_traits here:
template<typename MatrixType, int BlockRows=Dynamic, int BlockCols=Dynamic,
  int _DirectAccessStatus =
(ei_traits<MatrixType>::Flags&DirectAccessBit) ? HasDirectAccess :
NoDirectAccess> class Block;

Some other compiler errors in the code seem to indicate that XLC is
unable to handle the instantiation of a template class to resolve a
non-class template argument.

Cheers,
Aron

On Sat, Jan 30, 2010 at 4:56 PM, Benoit Jacob <jacob.benoit.1@xxxxxxxxx> wrote:
> 2010/1/27 Aron Ahmadia <aja2111@xxxxxxxxxxxx>:
>> Hi all,
>>
>> I'm still looking at the port, and I've managed to narrow down the
>> problem.  For those of you who've been following along at home, XLC
>> has been throwing this error when trying to compile the Eigen files:
>>                                              [0]
>> "eigen/Eigen/src/Core/SelfAdjointView.h", line 147.81: 1540-0716 (S)
>> The template argument "Eigen::SelfAdjointView" does not match the
>> template parameter "class T".
>> "eigen/Eigen/src/Core/SelfAdjointView.h", line 134.112: 1540-0716 (S)
>> The template argument "Eigen::SelfAdjointView" does not match the
>> template parameter "class T".
>>
>> Suspiciously, there's no trace of SelfAdjointView being used as a
>> template parameter argument anywhere in there, or any trace of a
>> parameter named 'class T'.
>>
>> So I decided to create a new test file, slowly adding in the Eigen
>> header files from Core until I got compiler errors.  Here's the
>> current file: http://pastebin.com/m267235e7
>>
>> If you'll notice, SelfAdjointView.h is being successfully included
>> here.  What causes the breakage is SelfadjointProduct.h.  This
>> actually isn't that surprising, since a function that declared in
>> SelfAdjointView.h is later defined in SelfadjointProduct.h (By the
>> way, should this be renamed to SelfAdjointProduct.h to fit the rest of
>> the naming scheme better?)
>>
>> Here is the declaration and the definition:
>>
>> template<typename DerivedU>
>> SelfAdjointView& rankUpdate(const MatrixBase<DerivedU>& u, Scalar alpha)
>>
>>
>> template<typename MatrixType, unsigned int UpLo>
>> template<typename DerivedU>
>> SelfAdjointView<MatrixType,UpLo>& SelfAdjointView<MatrixType,UpLo>
>> ::rankUpdate(const MatrixBase<DerivedU>& u, Scalar alpha)
>> {
>>  typedef ei_blas_traits<DerivedU> UBlasTraits;
>>  typedef typename UBlasTraits::DirectLinearAccessType ActualUType;
>>  typedef typename ei_cleantype<ActualUType>::type _ActualUType;
>>  const ActualUType actualU = UBlasTraits::extract(u.derived());
>>
>>  Scalar actualAlpha = alpha * UBlasTraits::extractScalarFactor(u.derived());
>>
>>  enum { IsRowMajor = (ei_traits<MatrixType>::Flags&RowMajorBit) ? 1 : 0 };
>>
>>  ei_selfadjoint_product<Scalar,
>>    _ActualUType::Flags&RowMajorBit ? RowMajor : ColMajor,
>>    ei_traits<MatrixType>::Flags&RowMajorBit ? RowMajor : ColMajor,
>>    !UBlasTraits::NeedToConjugate, UpLo>
>>    ::run(_expression().cols(), actualU.cols(), &actualU.coeff(0,0),
>> actualU.stride(),
>>          const_cast<Scalar*>(_expression().data()),
>> _expression().stride(), actualAlpha);
>>
>>  return *this;
>> }
>>
>> So according to this page here:
>> http://www.comeaucomputing.com/techtalk/templates
>>
>> You're not allowed to do the above because SelfAdjointView is the
>> 'primary template argument'.  Unfortunately, the code refuses to
>> compile if the template arguments are removed.
>
> I'm sorry, I still don't understand what is not allowed with the code
> that you pasted here?
>
> Benoit
>
>
>