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 1/3] 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 8e4cee3a47f41bf9e1584304ef23c8bfccb3d893 Mon Sep 17 00:00:00 2001
From: Alexis Placet <2400067+Alex-PLACET@users.noreply.github.com>
Date: Wed, 6 May 2026 13:31:14 +0200
Subject: [PATCH 2/3] Fix drop function to handle decayed types and add unit
 test for 1D array drop

---
 include/xtensor/views/xslice.hpp |  2 +-
 test/test_xview.cpp              | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/include/xtensor/views/xslice.hpp b/include/xtensor/views/xslice.hpp
index 3b4d3a6fb..775123934 100644
--- a/include/xtensor/views/xslice.hpp
+++ b/include/xtensor/views/xslice.hpp
@@ -484,7 +484,7 @@ namespace xt
     template <class R = std::ptrdiff_t, class T>
     inline auto drop(T&& indices)
     {
-        if constexpr (xtl::is_integral<T>::value)
+        if constexpr (xtl::is_integral<std::decay_t<T>>::value)
         {
             using slice_type = xdrop_slice<R>;
             using container_type = typename slice_type::container_type;
diff --git a/test/test_xview.cpp b/test/test_xview.cpp
index c98993bf9..90647ba85 100644
--- a/test/test_xview.cpp
+++ b/test/test_xview.cpp
@@ -1861,4 +1861,16 @@ namespace xt
 
         XT_ASSERT_THROW(const auto col = xt::col(arr, 0), std::invalid_argument);
     }
+
+    TEST(xview, drop_on_1dim_array)
+    {
+        const auto my_array = xt::xtensor<double, 1>({1, 2, 3});
+
+        xt::view(my_array, xt::drop(1));
+        EXPECT_EQ(my_array, (xt::xtensor<double, 1>{1, 3}));
+
+        const size_t index = 1;
+        xt::view(my_array, xt::drop(index));
+        EXPECT_EQ(my_array, (xt::xtensor<double, 1>{1}));
+    }
 }

From 31d19816f8cb1173508fe37cac425780c6805237 Mon Sep 17 00:00:00 2001
From: Alexis Placet <2400067+Alex-PLACET@users.noreply.github.com>
Date: Wed, 6 May 2026 15:12:43 +0200
Subject: [PATCH 3/3] fix

---
 test/test_xoperation.cpp | 23 +++++++++++++++++++++++
 test/test_xview.cpp      | 17 ++++++++++++-----
 2 files changed, 35 insertions(+), 5 deletions(-)

diff --git a/test/test_xoperation.cpp b/test/test_xoperation.cpp
index fa97a0946..21a9c77bd 100644
--- a/test/test_xoperation.cpp
+++ b/test/test_xoperation.cpp
@@ -858,6 +858,29 @@ namespace xt
             EXPECT_EQ(expected1, res3);
             EXPECT_EQ(expected2, res4);
         }
+
+        TEST_CASE("divide_4d")
+        {
+            using T4 = xt::xtensor<float, 4, xt::layout_type::row_major>;
+            using shape_type = typename T4::shape_type;
+
+            shape_type shape = {2, 3, 2, 2};
+            T4 a(shape, 4.5f);
+            T4 b(shape, 1.3f);
+
+            EXPECT_EQ((a / b)(0, 0, 0, 0), a(0, 0, 0, 0) / b(0, 0, 0, 0));
+
+            float sb = 1.2f;
+            EXPECT_EQ((a / sb)(0, 0, 0, 0), a(0, 0, 0, 0) / sb);
+
+            float sa = 4.6f;
+            EXPECT_EQ((sa / b)(0, 0, 0, 0), sa / b(0, 0, 0, 0));
+
+            // self-divide assignment: a = a / b (no zeros in b)
+            auto a_before = a(1, 2, 1, 1);
+            a = a / b;
+            EXPECT_EQ(a(1, 2, 1, 1), a_before / b(1, 2, 1, 1));
+        }
     }
 
 #undef XOPERATION_TEST_TYPES
diff --git a/test/test_xview.cpp b/test/test_xview.cpp
index 90647ba85..18449b742 100644
--- a/test/test_xview.cpp
+++ b/test/test_xview.cpp
@@ -1864,13 +1864,20 @@ namespace xt
 
     TEST(xview, drop_on_1dim_array)
     {
-        const auto my_array = xt::xtensor<double, 1>({1, 2, 3});
+        auto my_array = xt::xtensor<double, 1>({1, 2, 3});
 
-        xt::view(my_array, xt::drop(1));
-        EXPECT_EQ(my_array, (xt::xtensor<double, 1>{1, 3}));
+        // drop(1) creates a view excluding index 1
+        auto v1 = xt::view(my_array, xt::drop(1));
+        EXPECT_EQ(v1, (xt::xtensor<double, 1>{1, 3}));
 
+        // Assign through the drop view
+        xt::view(my_array, xt::drop(1)) = 0.;
+        EXPECT_EQ(my_array, (xt::xtensor<double, 1>{0, 2, 0}));
+
+        // Reset, then test drop with a variable (the original compilation issue)
+        my_array = xt::xtensor<double, 1>({1, 2, 3});
         const size_t index = 1;
-        xt::view(my_array, xt::drop(index));
-        EXPECT_EQ(my_array, (xt::xtensor<double, 1>{1}));
+        auto v2 = xt::view(my_array, xt::drop(index));
+        EXPECT_EQ(v2, (xt::xtensor<double, 1>{1, 3}));
     }
 }