From df10b674f4266658aa9eaaafb10d9e76f2fc7744 Mon Sep 17 00:00:00 2001
From: amice <amice@mit.edu>
Date: Thu, 13 Jun 2024 15:34:49 -0400
Subject: [PATCH] sparse vector fix

---
 include/pybind11/eigen/matrix.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/pybind11/eigen/matrix.h b/include/pybind11/eigen/matrix.h
index 2f2d2cb2c0..47483def69 100644
--- a/include/pybind11/eigen/matrix.h
+++ b/include/pybind11/eigen/matrix.h
@@ -880,7 +880,11 @@ struct type_caster<Type, enable_if_t<is_eigen_sparse<Type>::value>> {
     }
 
     static handle cast(const Type &src, return_value_policy /* policy */, handle /* parent */) {
-        const_cast<Type &>(src).makeCompressed();
+        if constexpr (!std::is_same_v<Type, Eigen::SparseVector) {
+            const_cast<Type &>(src).makeCompressed();
+        // use type specific operations... 
+        } 
+        
 
         object matrix_type
             = module_::import("scipy.sparse").attr(rowMajor ? "csr_matrix" : "csc_matrix");