问题
I created a fresh C++ (empty) project in VS2015, and then placed the Eigen 3.3.1 source code in an 'inc' folder in solution dir, such that the path to Matrix.h, for example, is inc/Eigen/Core/. I have set this inc/ path as an additional include directory, and have also tried with inc/Eigen/ as another include directory in case the files had issues including each other, but this changed nothing.
In main.cpp, I have the following:
#include "Eigen/Core/Matrix.h"
int main()
{
return 0;
}
This gives me, when compiling for x64:
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(18): error C2988: unrecognizable template declaration/definition
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(18): error C2143: syntax error: missing ';' before '<'
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(18): error C2059: syntax error: '<'
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(19): error C2143: syntax error: missing ';' before '{'
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(19): error C2447: '{': missing function header (old-style formal list?)
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(179): error C2143: syntax error: missing ',' before '<'
1> c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(404): note: see reference to class template instantiation 'Eigen::Matrix<_Scalar,_Rows,_Cols,_Options,_MaxRows,_MaxCols>' being compiled
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(186): error C2143: syntax error: missing ';' before '<'
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(186): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(186): error C2238: unexpected token(s) preceding ';'
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(192): error C2653: 'Base': is not a class or namespace name
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(192): error C2144: syntax error: 'int' should be preceded by ';'
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(192): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(192): warning C4183: 'EIGEN_DENSE_PUBLIC_INTERFACE': missing return type; assumed to be a member function returning 'int'
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(192): error C3646: 'PlainObject': unknown override specifier
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(194): error C2653: 'Base': is not a class or namespace name
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(195): error C2653: 'Base': is not a class or namespace name
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(206): error C3646: 'EIGEN_STRONG_INLINE': unknown override specifier
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(206): error C3646: 'Matrix': unknown override specifier
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(206): error C2143: syntax error: missing ';' before '&'
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(206): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(207): error C2334: unexpected token(s) preceding '{'; skipping apparent function body
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(223): error C2061: syntax error: identifier 'EIGEN_STRONG_INLINE'
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(237): error C2334: unexpected token(s) preceding '{'; skipping apparent function body
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(243): error C2061: syntax error: identifier 'EIGEN_STRONG_INLINE'
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(259): error C2334: unexpected token(s) preceding ':'; skipping apparent function body
1>c:\users\brody\documents\visual studio 2015\projects\eigentest\inc\eigen\core\matrix.h(14): fatal error C1075: the left brace '{' was unmatched at the end of the file
Which complains about line 18 of Matrix.h:
#ifndef EIGEN_MATRIX_H
#define EIGEN_MATRIX_H
namespace Eigen {
namespace internal {
template<typename _Scalar, int _Rows, int _Cols, int _Options, int _MaxRows, int _MaxCols>
struct traits<Matrix<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols> > // line 18
{
private:
// etc...
Similar issues occur with any other Eigen #include. Have I missed some required #include ordering or some compile flag or setting? Thanks!
回答1:
You must copy the entire Eigen directory not just the src subfolder. And you must not include files from the src subfolder directly, but include the files in the Eigen directory. E.g., #include <Eigen/Core> will include all core functionality, #include <Eigen/Dense> will include all dense functionality (this includes Core, Geometry and the decompositions).
来源：https://stackoverflow.com/questions/41404917/include-of-any-eigen-3-3-1-files-in-fresh-visual-studio-project-wont-compile