From 68a21c5a5952913d6192be747efd245887bc36cc Mon Sep 17 00:00:00 2001
From: Alexis Placet <2400067+Alex-PLACET@users.noreply.github.com>
Date: Thu, 30 Apr 2026 13:24:54 +0200
Subject: [PATCH 1/2] Fix substring calculation in CSV cell parsing and add
 lexical_cast for signed and unsigned char

---
 include/xtensor/io/xcsv.hpp | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/include/xtensor/io/xcsv.hpp b/include/xtensor/io/xcsv.hpp
index 080ccaf54..2fd347745 100644
--- a/include/xtensor/io/xcsv.hpp
+++ b/include/xtensor/io/xcsv.hpp
@@ -66,7 +66,7 @@ namespace xt
             }
 
             size_t last = cell.find_last_not_of(' ');
-            return cell.substr(first, last == std::string::npos ? cell.size() : last + 1);
+            return cell.substr(first, last == std::string::npos ? cell.size() : last - first + 1);
         }
 
         template <>
@@ -93,6 +93,18 @@ namespace xt
             return std::stoi(cell);
         }
 
+        template <>
+        inline signed char lexical_cast<signed char>(const std::string& cell)
+        {
+            return static_cast<signed char>(std::stoi(cell));
+        }
+
+        template <>
+        inline unsigned char lexical_cast<unsigned char>(const std::string& cell)
+        {
+            return static_cast<unsigned char>(std::stoul(cell));
+        }
+
         template <>
         inline long lexical_cast<long>(const std::string& cell)
         {

From d8553adfecf0dae33517f73ea92e94e07fbf25c4 Mon Sep 17 00:00:00 2001
From: Alexis Placet <alexis.placet.dev@pm.me>
Date: Mon, 24 Aug 2026 15:10:21 +0200
Subject: [PATCH 2/2] Fix SIMD assign through reshape_view of lazy expressions
 (#2929)

load_simd/store_simd take the address of the view's flat storage, which
requires lvalue references. Gate provides_simd_interface on the storage
exposing lvalue references so strided views over lazy expressions fall
back to the scalar assign path instead of hard-erroring.
---
 include/xtensor/views/xstrided_view.hpp |  7 ++++++-
 test/test_xstrided_view.cpp             | 23 +++++++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/include/xtensor/views/xstrided_view.hpp b/include/xtensor/views/xstrided_view.hpp
index 3faff70c8..b0fe2c6e0 100644
--- a/include/xtensor/views/xstrided_view.hpp
+++ b/include/xtensor/views/xstrided_view.hpp
@@ -179,8 +179,13 @@ namespace xt
         using simd_value_type = xt_simd::simd_type<value_type>;
         using bool_load_type = typename base_type::bool_load_type;
 
+        // load_simd/store_simd take the address of the flat storage, which requires the
+        // storage to expose lvalue references (not the case for lazy expressions wrapped
+        // in a flat_expression_adaptor).
         static constexpr bool provides_simd_interface = has_simd_interface<xexpression_type>::value
-                                                        && L != layout_type::dynamic;
+                                                        && L != layout_type::dynamic
+                                                        && std::is_lvalue_reference_v<
+                                                            decltype(std::declval<const storage_type&>()[0])>;
 
         template <class CTA, class SA>
         xstrided_view(CTA&& e, SA&& shape, strides_type&& strides, std::size_t offset, layout_type layout) noexcept;
diff --git a/test/test_xstrided_view.cpp b/test/test_xstrided_view.cpp
index 5b8f8c01d..b916d2473 100644
--- a/test/test_xstrided_view.cpp
+++ b/test/test_xstrided_view.cpp
@@ -723,6 +723,29 @@ namespace xt
         EXPECT_TRUE(std::equal(nv.shape().begin(), nv.shape().end(), expected_shape.begin()));
     }
 
+    TEST(xstrided_view, reshape_view_lazy_expression)
+    {
+        const std::size_t G = 8, N = 4;
+        xtensor<double, 1> w = xt::arange<double>(G) + 1.0;
+        xtensor<double, 2> Phi = 3.0 * xt::ones<double>({G, N});
+
+        // reshape_view over a lazy expression must not enable the SIMD assign path,
+        // which takes the address of the (computed) flat storage.
+        auto col = xt::reshape_view(w * w, {G, std::size_t(1)});
+        xtensor<double, 2> out = Phi * col;
+
+#if XTENSOR_USE_XSIMD
+        using lazy_traits = xassign_traits<xtensor<double, 2>, decltype(Phi * col)>;
+        EXPECT_FALSE(lazy_traits::simd_linear_assign());
+
+        auto colc = xt::reshape_view(w, {G, std::size_t(1)});
+        using cont_traits = xassign_traits<xtensor<double, 2>, decltype(Phi * colc)>;
+        EXPECT_TRUE(cont_traits::simd_linear_assign());
+#endif
+
+        EXPECT_EQ(108.0, out(5, 2));
+    }
+
     TEST(xstrided_view, reshape_view_assign)
     {
         xarray<int, layout_type::column_major> xa = {{1, 2, 3}, {4, 5, 6}};