Created attachment 955 [details]
Package of code, build script (under Visual Studio Developer Command Prompt), and built x64 binaries

The following code fails on VS 2017/2019, Eigen 3.3.7/TIP (323c052e1731/70e55a287bfe), x86/x64
Expected behavior: exit without showing anything.
Actual behavior: Assertion failed: it.row() < xm, file test_case.cc, line 17
Note: cannot reproduce on Linux. GCC works fine.

#include "assert.h"
#include <vector>

#include <Eigen/Core>
#include <Eigen/SparseCore>

constexpr int K = 4;
typedef Eigen::Triplet<double> Tri;

void iter(const Eigen::SparseMatrix<double>& X)
{
	int xm = X.rows();
	int xn = X.cols();
	for (int k = 0; k < X.outerSize(); ++k) {
		for (typename Eigen::SparseMatrix<double>::InnerIterator it(X, k); it; ++it) {
			assert(it.row() >= 0);
			assert(it.row() < xm);
			assert(it.col() >= 0);
			assert(it.col() < xn);
		}
	}
}

int main()
{
	Eigen::SparseMatrix<double> M(K, K);
	std::vector<Tri> tris;
	tris.reserve(K);
	for (int i = 0; i < K; i++)
		tris.emplace_back(i, i, 1.0);
	M.setFromTriplets(tris.begin(), tris.end());
	const Eigen::SparseMatrix<double> Aeq = M.diagonal().transpose().sparseView();
	iter(Aeq);

	return 0;
}