Hi Everyone,

I have compilation error with this code on 3.3.1:

Code: Select all

#include <Eigen/Core>
class MyVector{
public:
  MyVector(){x=1;y=2;z=3;}
   double x,y,z;
   operator Eigen::Matrix<double,3,1>() const {return Eigen::Matrix<double,3,1>(x,y,z);}
};
int main(){
   MyVector a;
   Eigen::Matrix<double,3 ,1> b(a);
}


Error messages are as follows:

Code: Select all

In file included from Eigen/Core:432:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/Matrix.h: In instantiation of ‘Eigen::Matrix<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols>::Matrix(const T&) [with T = MyVector; _Scalar = double; int _Rows = 3; int _Cols = 1; int _Options = 0; int _MaxRows = 3; int _MaxCols = 1]’:
eigentest2.cpp:14:32:   required from here
Eigen/src/Core/Matrix.h:296:31: error: no matching function for call to ‘Eigen::Matrix<double, 3, 1>::_init1(const MyVector&)’
       Base::template _init1<T>(x);
                               ^
In file included from Eigen/Core:431:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/PlainObjectBase.h:761:30: note: candidate: template<class T> void Eigen::PlainObjectBase<Derived>::_init1(Eigen::Index, typename Eigen::internal::enable_if<(((typename Eigen::internal::dense_xpr_base<Derived>::type:: SizeAtCompileTime != 1) || (! Eigen::internal::is_convertible<T, typename Eigen::internal::traits<T>::Scalar>::value)) && ((! Eigen::internal::is_same<typename Eigen::internal::traits<T>::XprKind, Eigen::ArrayXpr>::value) || (typename Eigen::internal::dense_xpr_base<Derived>::type:: SizeAtCompileTime == Eigen::Dynamic))), T>::type*) [with T = T; Derived = Eigen::Matrix<double, 3, 1>]
     EIGEN_STRONG_INLINE void _init1(Index size, typename internal::enable_if<    (Base::SizeAtCompileTime!=1 || !internal::is_convertible<T, Scalar>::value)
                              ^
Eigen/src/Core/PlainObjectBase.h:761:30: note:   template argument deduction/substitution failed:
In file included from Eigen/Core:432:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/Matrix.h:296:31: note:   cannot convert ‘x’ (type ‘const MyVector’) to type ‘Eigen::Index {aka long int}’
       Base::template _init1<T>(x);
                               ^
In file included from Eigen/Core:431:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/PlainObjectBase.h:775:30: note: candidate: template<class T> void Eigen::PlainObjectBase<Derived>::_init1(const Scalar&, typename Eigen::internal::enable_if<((typename Eigen::internal::dense_xpr_base<Derived>::type:: SizeAtCompileTime == 1) && Eigen::internal::is_convertible<T, typename Eigen::internal::traits<T>::Scalar>::value), T>::type*) [with T = T; Derived = Eigen::Matrix<double, 3, 1>]
     EIGEN_STRONG_INLINE void _init1(const Scalar& val0, typename internal::enable_if<Base::SizeAtCompileTime==1 && internal::is_convertible<T, Scalar>::value,T>::type* = 0)
                              ^
Eigen/src/Core/PlainObjectBase.h:775:30: note:   template argument deduction/substitution failed:
Eigen/src/Core/PlainObjectBase.h: In substitution of ‘template<class T> void Eigen::PlainObjectBase<Derived>::_init1(const Scalar&, typename Eigen::internal::enable_if<((typename Eigen::internal::dense_xpr_base<Derived>::type:: SizeAtCompileTime == 1) && Eigen::internal::is_convertible<T, typename Eigen::internal::traits<T>::Scalar>::value), T>::type*) [with T = MyVector]’:
Eigen/src/Core/Matrix.h:296:31:   required from ‘Eigen::Matrix<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols>::Matrix(const T&) [with T = MyVector; _Scalar = double; int _Rows = 3; int _Cols = 1; int _Options = 0; int _MaxRows = 3; int _MaxCols = 1]’
eigentest2.cpp:14:32:   required from here
Eigen/src/Core/PlainObjectBase.h:775:30: error: invalid use of incomplete type ‘struct Eigen::internal::enable_if<false, MyVector>’
In file included from Eigen/Core:341:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/util/Meta.h:162:50: note: declaration of ‘struct Eigen::internal::enable_if<false, MyVector>’
 template<bool Condition, typename T=void> struct enable_if;
                                                  ^
In file included from Eigen/Core:431:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/Matrix.h: In instantiation of ‘Eigen::Matrix<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols>::Matrix(const T&) [with T = MyVector; _Scalar = double; int _Rows = 3; int _Cols = 1; int _Options = 0; int _MaxRows = 3; int _MaxCols = 1]’:
eigentest2.cpp:14:32:   required from here
Eigen/src/Core/PlainObjectBase.h:784:30: note: candidate: template<class T> void Eigen::PlainObjectBase<Derived>::_init1(const Index&, typename Eigen::internal::enable_if<((((! Eigen::internal::is_same<long int, typename Eigen::internal::traits<T>::Scalar>::value) && Eigen::internal::is_same<long int, T>::value) && (typename Eigen::internal::dense_xpr_base<Derived>::type:: SizeAtCompileTime == 1)) && Eigen::internal::is_convertible<T, typename Eigen::internal::traits<T>::Scalar>::value), T*>::type*) [with T = T; Derived = Eigen::Matrix<double, 3, 1>]
     EIGEN_STRONG_INLINE void _init1(const Index& val0,
                              ^
Eigen/src/Core/PlainObjectBase.h:784:30: note:   template argument deduction/substitution failed:
Eigen/src/Core/PlainObjectBase.h: In substitution of ‘template<class T> void Eigen::PlainObjectBase<Derived>::_init1(const Index&, typename Eigen::internal::enable_if<((((! Eigen::internal::is_same<long int, typename Eigen::internal::traits<T>::Scalar>::value) && Eigen::internal::is_same<long int, T>::value) && (typename Eigen::internal::dense_xpr_base<Derived>::type:: SizeAtCompileTime == 1)) && Eigen::internal::is_convertible<T, typename Eigen::internal::traits<T>::Scalar>::value), T*>::type*) [with T = MyVector]’:
Eigen/src/Core/Matrix.h:296:31:   required from ‘Eigen::Matrix<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols>::Matrix(const T&) [with T = MyVector; _Scalar = double; int _Rows = 3; int _Cols = 1; int _Options = 0; int _MaxRows = 3; int _MaxCols = 1]’
eigentest2.cpp:14:32:   required from here
Eigen/src/Core/PlainObjectBase.h:784:30: error: invalid use of incomplete type ‘struct Eigen::internal::enable_if<false, MyVector*>’
In file included from Eigen/Core:341:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/util/Meta.h:162:50: note: declaration of ‘struct Eigen::internal::enable_if<false, MyVector*>’
 template<bool Condition, typename T=void> struct enable_if;
                                                  ^
In file included from Eigen/Core:431:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/Matrix.h: In instantiation of ‘Eigen::Matrix<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols>::Matrix(const T&) [with T = MyVector; _Scalar = double; int _Rows = 3; int _Cols = 1; int _Options = 0; int _MaxRows = 3; int _MaxCols = 1]’:
eigentest2.cpp:14:32:   required from here
Eigen/src/Core/PlainObjectBase.h:797:30: note: candidate: template<class T> void Eigen::PlainObjectBase<Derived>::_init1(const Scalar*) [with T = T; Derived = Eigen::Matrix<double, 3, 1>]
     EIGEN_STRONG_INLINE void _init1(const Scalar* data){
                              ^
Eigen/src/Core/PlainObjectBase.h:797:30: note:   template argument deduction/substitution failed:
In file included from Eigen/Core:432:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/Matrix.h:296:31: note:   cannot convert ‘x’ (type ‘const MyVector’) to type ‘const Scalar* {aka const double*}’
       Base::template _init1<T>(x);
                               ^
In file included from Eigen/Core:431:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/PlainObjectBase.h:804:30: note: candidate: template<class T, class OtherDerived> void Eigen::PlainObjectBase<Derived>::_init1(const Eigen::DenseBase<ElseDerived>&) [with T = T; OtherDerived = OtherDerived; Derived = Eigen::Matrix<double, 3, 1>]
     EIGEN_STRONG_INLINE void _init1(const DenseBase<OtherDerived>& other){
                              ^
Eigen/src/Core/PlainObjectBase.h:804:30: note:   template argument deduction/substitution failed:
In file included from Eigen/Core:432:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/Matrix.h:296:31: note:   ‘const MyVector’ is not derived from ‘const Eigen::DenseBase<Derived>’
       Base::template _init1<T>(x);
                               ^
In file included from Eigen/Core:431:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/PlainObjectBase.h:811:30: note: candidate: template<class T, class OtherDerived> void Eigen::PlainObjectBase<Derived>::_init1(const Eigen::EigenBase<OtherDerived>&) [with T = T; OtherDerived = OtherDerived; Derived = Eigen::Matrix<double, 3, 1>]
     EIGEN_STRONG_INLINE void _init1(const EigenBase<OtherDerived>& other){
                              ^
Eigen/src/Core/PlainObjectBase.h:811:30: note:   template argument deduction/substitution failed:
In file included from Eigen/Core:432:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/Matrix.h:296:31: note:   ‘const MyVector’ is not derived from ‘const Eigen::EigenBase<OtherDerived>’
       Base::template _init1<T>(x);
                               ^
In file included from Eigen/Core:431:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/PlainObjectBase.h:817:30: note: candidate: template<class T, class OtherDerived> void Eigen::PlainObjectBase<Derived>::_init1(const Eigen::ReturnByValue<OtherDerived>&) [with T = T; OtherDerived = OtherDerived; Derived = Eigen::Matrix<double, 3, 1>]
     EIGEN_STRONG_INLINE void _init1(const ReturnByValue<OtherDerived>& other)
                              ^
Eigen/src/Core/PlainObjectBase.h:817:30: note:   template argument deduction/substitution failed:
In file included from Eigen/Core:432:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/Matrix.h:296:31: note:   ‘const MyVector’ is not derived from ‘const Eigen::ReturnByValue<OtherDerived>’
       Base::template _init1<T>(x);
                               ^
In file included from Eigen/Core:431:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/PlainObjectBase.h:825:30: note: candidate: template<class T, class OtherDerived, int ColsAtCompileTime> void Eigen::PlainObjectBase<Derived>::_init1(const Eigen::RotationBase<OtherDerived, ColsAtCompileTime>&) [with T = T; OtherDerived = OtherDerived; int ColsAtCompileTime = ColsAtCompileTime; Derived = Eigen::Matrix<double, 3, 1>]
     EIGEN_STRONG_INLINE void _init1(const RotationBase<OtherDerived,ColsAtCompileTime>& r)
                              ^
Eigen/src/Core/PlainObjectBase.h:825:30: note:   template argument deduction/substitution failed:
In file included from Eigen/Core:432:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/Matrix.h:296:31: note:   ‘const MyVector’ is not derived from ‘const Eigen::RotationBase<OtherDerived, ColsAtCompileTime>’
       Base::template _init1<T>(x);
                               ^
In file included from Eigen/Core:431:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/PlainObjectBase.h:833:30: note: candidate: template<class T> void Eigen::PlainObjectBase<Derived>::_init1(const Scalar&, typename Eigen::internal::enable_if<((((typename Eigen::internal::dense_xpr_base<Derived>::type:: SizeAtCompileTime != Eigen::Dynamic) && (typename Eigen::internal::dense_xpr_base<Derived>::type:: SizeAtCompileTime != 1)) && Eigen::internal::is_convertible<T, typename Eigen::internal::traits<T>::Scalar>::value) && Eigen::internal::is_same<typename Eigen::internal::traits<T>::XprKind, Eigen::ArrayXpr>::value), T>::type*) [with T = T; Derived = Eigen::Matrix<double, 3, 1>]
     EIGEN_STRONG_INLINE void _init1(const Scalar& val0,
                              ^
Eigen/src/Core/PlainObjectBase.h:833:30: note:   template argument deduction/substitution failed:
Eigen/src/Core/PlainObjectBase.h: In substitution of ‘template<class T> void Eigen::PlainObjectBase<Derived>::_init1(const Scalar&, typename Eigen::internal::enable_if<((((typename Eigen::internal::dense_xpr_base<Derived>::type:: SizeAtCompileTime != Eigen::Dynamic) && (typename Eigen::internal::dense_xpr_base<Derived>::type:: SizeAtCompileTime != 1)) && Eigen::internal::is_convertible<T, typename Eigen::internal::traits<T>::Scalar>::value) && Eigen::internal::is_same<typename Eigen::internal::traits<T>::XprKind, Eigen::ArrayXpr>::value), T>::type*) [with T = MyVector]’:
Eigen/src/Core/Matrix.h:296:31:   required from ‘Eigen::Matrix<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols>::Matrix(const T&) [with T = MyVector; _Scalar = double; int _Rows = 3; int _Cols = 1; int _Options = 0; int _MaxRows = 3; int _MaxCols = 1]’
eigentest2.cpp:14:32:   required from here
Eigen/src/Core/PlainObjectBase.h:833:30: error: invalid use of incomplete type ‘struct Eigen::internal::enable_if<false, MyVector>’
In file included from Eigen/Core:341:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/util/Meta.h:162:50: note: declaration of ‘struct Eigen::internal::enable_if<false, MyVector>’
 template<bool Condition, typename T=void> struct enable_if;
                                                  ^
In file included from Eigen/Core:431:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/Matrix.h: In instantiation of ‘Eigen::Matrix<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols>::Matrix(const T&) [with T = MyVector; _Scalar = double; int _Rows = 3; int _Cols = 1; int _Options = 0; int _MaxRows = 3; int _MaxCols = 1]’:
eigentest2.cpp:14:32:   required from here
Eigen/src/Core/PlainObjectBase.h:844:30: note: candidate: template<class T> void Eigen::PlainObjectBase<Derived>::_init1(const Index&, typename Eigen::internal::enable_if<((((((! Eigen::internal::is_same<long int, typename Eigen::internal::traits<T>::Scalar>::value) && Eigen::internal::is_same<long int, T>::value) && (typename Eigen::internal::dense_xpr_base<Derived>::type:: SizeAtCompileTime != Eigen::Dynamic)) && (typename Eigen::internal::dense_xpr_base<Derived>::type:: SizeAtCompileTime != 1)) && Eigen::internal::is_convertible<T, typename Eigen::internal::traits<T>::Scalar>::value) && Eigen::internal::is_same<typename Eigen::internal::traits<T>::XprKind, Eigen::ArrayXpr>::value), T*>::type*) [with T = T; Derived = Eigen::Matrix<double, 3, 1>]
     EIGEN_STRONG_INLINE void _init1(const Index& val0,
                              ^
Eigen/src/Core/PlainObjectBase.h:844:30: note:   template argument deduction/substitution failed:
Eigen/src/Core/PlainObjectBase.h: In substitution of ‘template<class T> void Eigen::PlainObjectBase<Derived>::_init1(const Index&, typename Eigen::internal::enable_if<((((((! Eigen::internal::is_same<long int, typename Eigen::internal::traits<T>::Scalar>::value) && Eigen::internal::is_same<long int, T>::value) && (typename Eigen::internal::dense_xpr_base<Derived>::type:: SizeAtCompileTime != Eigen::Dynamic)) && (typename Eigen::internal::dense_xpr_base<Derived>::type:: SizeAtCompileTime != 1)) && Eigen::internal::is_convertible<T, typename Eigen::internal::traits<T>::Scalar>::value) && Eigen::internal::is_same<typename Eigen::internal::traits<T>::XprKind, Eigen::ArrayXpr>::value), T*>::type*) [with T = MyVector]’:
Eigen/src/Core/Matrix.h:296:31:   required from ‘Eigen::Matrix<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols>::Matrix(const T&) [with T = MyVector; _Scalar = double; int _Rows = 3; int _Cols = 1; int _Options = 0; int _MaxRows = 3; int _MaxCols = 1]’
eigentest2.cpp:14:32:   required from here
Eigen/src/Core/PlainObjectBase.h:844:30: error: invalid use of incomplete type ‘struct Eigen::internal::enable_if<false, MyVector*>’
In file included from Eigen/Core:341:0,
                 from eigentest2.cpp:1:
Eigen/src/Core/util/Meta.h:162:50: note: declaration of ‘struct Eigen::internal::enable_if<false, MyVector*>’
 template<bool Condition, typename T=void> struct enable_if;


It was working on 3.2.9. I'm using gcc version 5.4.0 on Ubuntu(x86_64-linux-gnu).
Could you give me some advice on this?
Thank you very much in advance!
Hiroshi

This is because in 3.3 we had to introduce a generic ctor:

Code: Select all

template<typename T> explicit Matrix(const T& x) {...}


that prevents your conversion operator to be called. On the other hand, since this generic ctor is explicit, you can easily workaround with:

Code: Select all

Eigen::Matrix<double,3 ,1> b = a;


I could successfully compile my code. Thank you very much for the help!