From a636243ec03f60effbf79efdae5e0aa9ed197592 Mon Sep 17 00:00:00 2001
From: Gabriel <bielpaess912@gmail.com>
Date: Wed, 24 Jun 2026 00:36:41 -0300
Subject: [PATCH] fix: materialize Eigen cast expression before passing to
 distance_to_squared

Eigen's .cast<T>() returns a lazy CwiseUnaryOp expression, not a materialized
Matrix. The distance_to_squared overload taking a nearest_point output parameter
expects a concrete Eigen::Matrix, so template deduction fails on clang-cl.

Materialize the cast into a local Vec variable before passing it.
MSVC accepted the expression directly; clang-cl correctly rejects it.
---
 src/libslic3r/AABBTreeLines.hpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/libslic3r/AABBTreeLines.hpp b/src/libslic3r/AABBTreeLines.hpp
index 97ad1bdf44..b13fe03401 100644
--- a/src/libslic3r/AABBTreeLines.hpp
+++ b/src/libslic3r/AABBTreeLines.hpp
@@ -32,7 +32,8 @@ namespace AABBTreeLines {
             {
                 Vec<LineType::Dim, typename LineType::Scalar> nearest_point;
                 const LineType& line = lines[primitive_index];
-                squared_distance = line_alg::distance_to_squared(line, origin.template cast<typename LineType::Scalar>(), &nearest_point);
+                const Vec<LineType::Dim, typename LineType::Scalar> origin_cast = origin.template cast<typename LineType::Scalar>();
+                squared_distance = line_alg::distance_to_squared(line, origin_cast, &nearest_point);
                 return nearest_point.template cast<ScalarType>();
             }
         };