const_iterator vs iterator compilation error
Submitted by w.h..@..il.com
Assigned to Nobody
Link to original bugzilla bug (#1619)
Version: 3.4 (development)
Description
I was experimenting with the new STL-compatible iterator capability using VS 2017. The following code snippet compiles correctly:
const int n = 6;
typedef Eigen::VectorXd V;
V v(n);
v << 1, 4, 6, 17, 33, 8;
cout << v.transpose() << endl;
for (V::iterator it = v.begin(); it != v.end(); ++it)
cout << *it << ", "; However, if I replace V::iterator with V::const_iterator, VS produces these
compilation errors:
1>------ Build started: Project: eigenXTests, Configuration: Debug x64 ------
1>eigenXTests.cpp
1>c:\wgreene\tests\c++\vs2017tests\eigenxtests\eigenxtests.cpp(18): error C2440: 'initializing': cannot convert from 'Eigen::internal::pointer_based_stl_iterator<Derived>' to 'Eigen::internal::pointer_based_stl_iterator<const Derived>'
1> with
1> [
1> Derived=Eigen::Matrix<double,-1,1,0,-1,1>
1> ]
1>c:\wgreene\tests\c++\vs2017tests\eigenxtests\eigenxtests.cpp(18): note: No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
1>c:\wgreene\tests\c++\vs2017tests\eigenxtests\eigenxtests.cpp(18): error C2679: binary '!=': no operator found which takes a right-hand operand of type 'Eigen::internal::pointer_based_stl_iterator<Derived>' (or there is no acceptable conversion)
1> with
1> [
1> Derived=Eigen::Matrix<double,-1,1,0,-1,1>
1> ]
1>c:\wgreene\src\eigen\eigen-3.3.x\eigen\src\core\stliterators.h(96): note: could be 'bool Eigen::internal::pointer_based_stl_iterator<const Derived>::operator !=(const Eigen::internal::pointer_based_stl_iterator<const Derived> &)'
1> with
1> [
1> Derived=Eigen::Matrix<double,-1,1,0,-1,1>
1> ]
1>c:\wgreene\tests\c++\vs2017tests\eigenxtests\eigenxtests.cpp(18): note: while trying to match the argument list '(Eigen::internal::pointer_based_stl_iterator<const Derived>, Eigen::internal::pointer_based_stl_iterator<Derived>)'
1> with
1> [
1> Derived=Eigen::Matrix<double,-1,1,0,-1,1>
1> ]
1>Done building project "eigenXTests.vcxproj" -- FAILED.
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========