diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index fc45c0cdb..daf5c2c5b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -70,7 +70,7 @@ jobs:
     runs-on: ${{ matrix.runs-on }}
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup Python ${{ matrix.python }}
       uses: actions/setup-python@v4
@@ -206,7 +206,7 @@ jobs:
     runs-on: ubuntu-20.04
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup Python ${{ matrix.python-version }} (deadsnakes)
       uses: deadsnakes/action@v3.0.1
@@ -311,7 +311,7 @@ jobs:
     container: "silkeh/clang:${{ matrix.clang }}${{ matrix.container_suffix }}"
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Add wget and python3
       run: apt-get update && apt-get install -y python3-dev python3-numpy python3-pytest libeigen3-dev
@@ -345,7 +345,7 @@ jobs:
     container: nvidia/cuda:12.2.0-devel-ubuntu22.04
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     # tzdata will try to ask for the timezone, so set the DEBIAN_FRONTEND
     - name: Install 🐍 3
@@ -369,7 +369,7 @@ jobs:
 #    container: centos:8
 #
 #    steps:
-#    - uses: actions/checkout@v3
+#    - uses: actions/checkout@v4
 #
 #    - name: Add Python 3 and a few requirements
 #      run: yum update -y && yum install -y git python3-devel python3-numpy python3-pytest make environment-modules
@@ -414,7 +414,7 @@ jobs:
       # tzdata will try to ask for the timezone, so set the DEBIAN_FRONTEND
       DEBIAN_FRONTEND: 'noninteractive'
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Add NVHPC Repo
       run: |
@@ -476,7 +476,7 @@ jobs:
     container: "gcc:${{ matrix.gcc }}"
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Add Python 3
       run: apt-get update; apt-get install -y python3-dev python3-numpy python3-pytest python3-pip libeigen3-dev
@@ -536,7 +536,7 @@ jobs:
     name: "🐍 3 • ICC latest • x64"
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Add apt repo
       run: |
@@ -640,7 +640,13 @@ jobs:
     container: "${{ matrix.container }}"
 
     steps:
-    - uses: actions/checkout@v3
+    - name: Latest actions/checkout
+      uses: actions/checkout@v4
+      if: matrix.container != 'centos:7'
+
+    - name: Pin actions/checkout as required for centos:7
+      uses: actions/checkout@v3
+      if: matrix.container == 'centos:7'
 
     - name: Add Python 3 (RHEL 7)
       if: matrix.container == 'centos:7'
@@ -688,7 +694,7 @@ jobs:
     container: i386/debian:buster
 
     steps:
-    - uses: actions/checkout@v1  # Required to run inside docker
+    - uses: actions/checkout@v1  # v1 is required to run inside docker
 
     - name: Install requirements
       run: |
@@ -731,7 +737,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - uses: actions/setup-python@v4
       with:
@@ -783,7 +789,7 @@ jobs:
     runs-on: windows-2019
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup Python ${{ matrix.python }}
       uses: actions/setup-python@v4
@@ -836,7 +842,7 @@ jobs:
     runs-on: windows-2019
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup Python ${{ matrix.python }}
       uses: actions/setup-python@v4
@@ -884,7 +890,7 @@ jobs:
     runs-on: windows-2022
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup Python ${{ matrix.python }}
       uses: actions/setup-python@v4
@@ -962,7 +968,7 @@ jobs:
           mingw-w64-${{matrix.env}}-boost
           mingw-w64-${{matrix.env}}-catch
 
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Configure C++11
       # LTO leads to many undefined reference like
@@ -1033,7 +1039,7 @@ jobs:
         run: env
 
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Set up Clang
         uses: egor-tensin/setup-clang@v1
@@ -1102,7 +1108,7 @@ jobs:
         run: env
 
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: Show Clang++ version before brew install llvm
         run: clang++ --version
diff --git a/.github/workflows/configure.yml b/.github/workflows/configure.yml
index 360d999fb..1c215b1c2 100644
--- a/.github/workflows/configure.yml
+++ b/.github/workflows/configure.yml
@@ -50,7 +50,7 @@ jobs:
     runs-on: ${{ matrix.runs-on }}
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup Python 3.7
       uses: actions/setup-python@v4
diff --git a/.github/workflows/format.yml b/.github/workflows/format.yml
index ce666cdab..0d31f1f0c 100644
--- a/.github/workflows/format.yml
+++ b/.github/workflows/format.yml
@@ -26,7 +26,7 @@ jobs:
     name: Format
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - uses: actions/setup-python@v4
       with:
         python-version: "3.x"
@@ -44,7 +44,7 @@ jobs:
     runs-on: ubuntu-latest
     container: silkeh/clang:15-bullseye
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Install requirements
       run: apt-get update && apt-get install -y git python3-dev python3-pytest
diff --git a/.github/workflows/pip.yml b/.github/workflows/pip.yml
index 54a0665f9..6d4dae225 100644
--- a/.github/workflows/pip.yml
+++ b/.github/workflows/pip.yml
@@ -29,7 +29,7 @@ jobs:
     runs-on: windows-latest
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup 🐍 3.6
       uses: actions/setup-python@v4
@@ -51,7 +51,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup 🐍 3.8
       uses: actions/setup-python@v4
diff --git a/.github/workflows/upstream.yml b/.github/workflows/upstream.yml
index dd8a1c960..5d893cd85 100644
--- a/.github/workflows/upstream.yml
+++ b/.github/workflows/upstream.yml
@@ -25,7 +25,7 @@ jobs:
     if: "contains(github.event.pull_request.labels.*.name, 'python dev')"
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
 
     - name: Setup Python 3.12
       uses: actions/setup-python@v4
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index bc5b30ef5..f4f392c8c 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -31,21 +31,21 @@ repos:
     types_or: [c++, c, cuda]
 
 # Black, the code formatter, natively supports pre-commit
-- repo: https://github.com/psf/black
+- repo: https://github.com/psf/black-pre-commit-mirror
   rev: "23.7.0" # Keep in sync with blacken-docs
   hooks:
   - id: black
 
 # Ruff, the Python auto-correcting linter written in Rust
 - repo: https://github.com/astral-sh/ruff-pre-commit
-  rev: v0.0.281
+  rev: v0.0.287
   hooks:
   - id: ruff
     args: ["--fix", "--show-fixes"]
 
 # Check static types with mypy
 - repo: https://github.com/pre-commit/mirrors-mypy
-  rev: "v1.4.1"
+  rev: "v1.5.1"
   hooks:
   - id: mypy
     args: []
@@ -85,7 +85,7 @@ repos:
 
 # Also code format the docs
 - repo: https://github.com/asottile/blacken-docs
-  rev: "1.15.0"
+  rev: "1.16.0"
   hooks:
   - id: blacken-docs
     additional_dependencies:
@@ -93,7 +93,7 @@ repos:
 
 # Changes tabs to spaces
 - repo: https://github.com/Lucas-C/pre-commit-hooks
-  rev: "v1.5.1"
+  rev: "v1.5.4"
   hooks:
   - id: remove-tabs
     exclude: (^docs/.*|\.patch)?$
@@ -149,7 +149,7 @@ repos:
 
 # PyLint has native support - not always usable, but works for us
 - repo: https://github.com/PyCQA/pylint
-  rev: "v3.0.0a6"
+  rev: "v3.0.0a7"
   hooks:
   - id: pylint
     files: ^pybind11
diff --git a/.readthedocs.yml b/.readthedocs.yml
index c9c61617c..a2b802f73 100644
--- a/.readthedocs.yml
+++ b/.readthedocs.yml
@@ -1,3 +1,20 @@
+# https://blog.readthedocs.com/migrate-configuration-v2/
+
+version: 2
+
+build:
+  os: ubuntu-22.04
+  apt_packages:
+    - librsvg2-bin
+  tools:
+    python: "3.11"
+
+sphinx:
+  configuration: docs/conf.py
+
 python:
-  version: 3
-requirements_file: docs/requirements.txt
+  install:
+  - requirements: docs/requirements.txt
+
+formats:
+  - pdf
diff --git a/docs/advanced/functions.rst b/docs/advanced/functions.rst
index 69e3d8a1d..372934b09 100644
--- a/docs/advanced/functions.rst
+++ b/docs/advanced/functions.rst
@@ -16,7 +16,7 @@ lifetime of objects managed by them. This can lead to issues when creating
 bindings for functions that return a non-trivial type. Just by looking at the
 type information, it is not clear whether Python should take charge of the
 returned value and eventually free its resources, or if this is handled on the
-C++ side. For this reason, pybind11 provides a several *return value policy*
+C++ side. For this reason, pybind11 provides several *return value policy*
 annotations that can be passed to the :func:`module_::def` and
 :func:`class_::def` functions. The default policy is
 :enum:`return_value_policy::automatic`.
diff --git a/docs/benchmark.py b/docs/benchmark.py
index 2150b6ca7..fb49fd048 100644
--- a/docs/benchmark.py
+++ b/docs/benchmark.py
@@ -70,7 +70,7 @@ def generate_dummy_code_boost(nclasses=10):
 
 for codegen in [generate_dummy_code_pybind11, generate_dummy_code_boost]:
     print("{")
-    for i in range(0, 10):
+    for i in range(10):
         nclasses = 2**i
         with open("test.cpp", "w") as f:
             f.write(codegen(nclasses))
diff --git a/include/pybind11/cast.h b/include/pybind11/cast.h
index 0d60da0c5..fc8f22d52 100644
--- a/include/pybind11/cast.h
+++ b/include/pybind11/cast.h
@@ -936,6 +936,10 @@ struct handle_type_name<float_> {
     static constexpr auto name = const_name("float");
 };
 template <>
+struct handle_type_name<function> {
+    static constexpr auto name = const_name("Callable");
+};
+template <>
 struct handle_type_name<none> {
     static constexpr auto name = const_name("None");
 };
diff --git a/include/pybind11/detail/internals.h b/include/pybind11/detail/internals.h
index 597a9b959..b9b0c9506 100644
--- a/include/pybind11/detail/internals.h
+++ b/include/pybind11/detail/internals.h
@@ -35,8 +35,9 @@
 /// further ABI-incompatible changes may be made before the ABI is officially
 /// changed to the new version.
 #ifndef PYBIND11_INTERNALS_VERSION
-#    if PY_VERSION_HEX >= 0x030C0000
+#    if PY_VERSION_HEX >= 0x030C0000 || defined(_MSC_VER)
 // Version bump for Python 3.12+, before first 3.12 beta release.
+// Version bump for MSVC piggy-backed on PR #4779. See comments there.
 #        define PYBIND11_INTERNALS_VERSION 5
 #    else
 #        define PYBIND11_INTERNALS_VERSION 4
@@ -292,9 +293,12 @@ struct type_info {
 #endif
 
 /// On Linux/OSX, changes in __GXX_ABI_VERSION__ indicate ABI incompatibility.
+/// On MSVC, changes in _MSC_VER may indicate ABI incompatibility (#2898).
 #ifndef PYBIND11_BUILD_ABI
 #    if defined(__GXX_ABI_VERSION)
 #        define PYBIND11_BUILD_ABI "_cxxabi" PYBIND11_TOSTRING(__GXX_ABI_VERSION)
+#    elif defined(_MSC_VER)
+#        define PYBIND11_BUILD_ABI "_mscver" PYBIND11_TOSTRING(_MSC_VER)
 #    else
 #        define PYBIND11_BUILD_ABI ""
 #    endif
diff --git a/include/pybind11/pybind11.h b/include/pybind11/pybind11.h
index d5cabefde..661e9c844 100644
--- a/include/pybind11/pybind11.h
+++ b/include/pybind11/pybind11.h
@@ -53,6 +53,45 @@ PYBIND11_WARNING_DISABLE_MSVC(4127)
 
 PYBIND11_NAMESPACE_BEGIN(detail)
 
+inline std::string replace_newlines_and_squash(const char *text) {
+    const char *whitespaces = " \t\n\r\f\v";
+    std::string result(text);
+    bool previous_is_whitespace = false;
+
+    // Do not modify string representations
+    char first_char = result[0];
+    char last_char = result[result.size() - 1];
+    if (first_char == last_char && first_char == '\'') {
+        return result;
+    }
+    result.clear();
+
+    // Replace characters in whitespaces array with spaces and squash consecutive spaces
+    while (*text != '\0') {
+        if (std::strchr(whitespaces, *text)) {
+            if (!previous_is_whitespace) {
+                result += ' ';
+                previous_is_whitespace = true;
+            }
+        } else {
+            result += *text;
+            previous_is_whitespace = false;
+        }
+        ++text;
+    }
+
+    // Strip leading and trailing whitespaces
+    const size_t str_begin = result.find_first_not_of(whitespaces);
+    if (str_begin == std::string::npos) {
+        return "";
+    }
+
+    const size_t str_end = result.find_last_not_of(whitespaces);
+    const size_t str_range = str_end - str_begin + 1;
+
+    return result.substr(str_begin, str_range);
+}
+
 // Apply all the extensions translators from a list
 // Return true if one of the translators completed without raising an exception
 // itself. Return of false indicates that if there are other translators
@@ -425,7 +464,7 @@ protected:
                 // Write default value if available.
                 if (!is_starred && arg_index < rec->args.size() && rec->args[arg_index].descr) {
                     signature += " = ";
-                    signature += rec->args[arg_index].descr;
+                    signature += detail::replace_newlines_and_squash(rec->args[arg_index].descr);
                 }
                 // Separator for positional-only arguments (placed after the
                 // argument, rather than before like *
@@ -681,7 +720,7 @@ protected:
         /* Iterator over the list of potentially admissible overloads */
         const function_record *overloads = reinterpret_cast<function_record *>(
                                   PyCapsule_GetPointer(self, get_function_record_capsule_name())),
-                              *it = overloads;
+                              *current_overload = overloads;
         assert(overloads != nullptr);
 
         /* Need to know how many arguments + keyword arguments there are to pick the right
@@ -719,9 +758,10 @@ protected:
             std::vector<function_call> second_pass;
 
             // However, if there are no overloads, we can just skip the no-convert pass entirely
-            const bool overloaded = it != nullptr && it->next != nullptr;
+            const bool overloaded
+                = current_overload != nullptr && current_overload->next != nullptr;
 
-            for (; it != nullptr; it = it->next) {
+            for (; current_overload != nullptr; current_overload = current_overload->next) {
 
                 /* For each overload:
                    1. Copy all positional arguments we were given, also checking to make sure that
@@ -742,7 +782,7 @@ protected:
                    a result other than PYBIND11_TRY_NEXT_OVERLOAD.
                  */
 
-                const function_record &func = *it;
+                const function_record &func = *current_overload;
                 size_t num_args = func.nargs; // Number of positional arguments that we need
                 if (func.has_args) {
                     --num_args; // (but don't count py::args
@@ -980,10 +1020,10 @@ protected:
                     }
 
                     if (result.ptr() != PYBIND11_TRY_NEXT_OVERLOAD) {
-                        // The error reporting logic below expects 'it' to be valid, as it would be
-                        // if we'd encountered this failure in the first-pass loop.
+                        // The error reporting logic below expects 'current_overload' to be valid,
+                        // as it would be if we'd encountered this failure in the first-pass loop.
                         if (!result) {
-                            it = &call.func;
+                            current_overload = &call.func;
                         }
                         break;
                     }
@@ -1130,7 +1170,8 @@ protected:
         if (!result) {
             std::string msg = "Unable to convert function return value to a "
                               "Python type! The signature was\n\t";
-            msg += it->signature;
+            assert(current_overload != nullptr);
+            msg += current_overload->signature;
             append_note_if_missing_header_is_suspected(msg);
             // Attach additional error info to the exception if supported
             if (PyErr_Occurred()) {
@@ -2235,7 +2276,7 @@ struct enum_base {
                 object type_name = type::handle_of(arg).attr("__name__");
                 return pybind11::str("{}.{}").format(std::move(type_name), enum_name(arg));
             },
-            name("name"),
+            name("__str__"),
             is_method(m_base));
 
         if (options::show_enum_members_docstring()) {
@@ -2653,7 +2694,7 @@ iterator make_iterator_impl(Iterator first, Sentinel last, Extra &&...extra) {
                 Policy);
     }
 
-    return cast(state{first, last, true});
+    return cast(state{std::forward<Iterator>(first), std::forward<Sentinel>(last), true});
 }
 
 PYBIND11_NAMESPACE_END(detail)
@@ -2670,7 +2711,9 @@ iterator make_iterator(Iterator first, Sentinel last, Extra &&...extra) {
                                       Iterator,
                                       Sentinel,
                                       ValueType,
-                                      Extra...>(first, last, std::forward<Extra>(extra)...);
+                                      Extra...>(std::forward<Iterator>(first),
+                                                std::forward<Sentinel>(last),
+                                                std::forward<Extra>(extra)...);
 }
 
 /// Makes a python iterator over the keys (`.first`) of a iterator over pairs from a
@@ -2686,7 +2729,9 @@ iterator make_key_iterator(Iterator first, Sentinel last, Extra &&...extra) {
                                       Iterator,
                                       Sentinel,
                                       KeyType,
-                                      Extra...>(first, last, std::forward<Extra>(extra)...);
+                                      Extra...>(std::forward<Iterator>(first),
+                                                std::forward<Sentinel>(last),
+                                                std::forward<Extra>(extra)...);
 }
 
 /// Makes a python iterator over the values (`.second`) of a iterator over pairs from a
@@ -2702,7 +2747,9 @@ iterator make_value_iterator(Iterator first, Sentinel last, Extra &&...extra) {
                                       Iterator,
                                       Sentinel,
                                       ValueType,
-                                      Extra...>(first, last, std::forward<Extra>(extra)...);
+                                      Extra...>(std::forward<Iterator>(first),
+                                                std::forward<Sentinel>(last),
+                                                std::forward<Extra>(extra)...);
 }
 
 /// Makes an iterator over values of an stl container or other container supporting
diff --git a/pyproject.toml b/pyproject.toml
index 59c15ea63..ef2a8736b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -94,5 +94,5 @@ line-length = 120
 isort.known-first-party = ["env", "pybind11_cross_module_tests", "pybind11_tests"]
 
 [tool.ruff.per-file-ignores]
-"tests/**" = ["EM", "N"]
+"tests/**" = ["EM", "N", "E721"]
 "tests/test_call_policies.py" = ["PLC1901"]
diff --git a/tests/test_callbacks.py b/tests/test_callbacks.py
index 4a652f53e..86c767455 100644
--- a/tests/test_callbacks.py
+++ b/tests/test_callbacks.py
@@ -216,3 +216,10 @@ def test_custom_func():
 def test_custom_func2():
     assert m.custom_function2(3) == 27
     assert m.roundtrip(m.custom_function2)(3) == 27
+
+
+def test_callback_docstring():
+    assert (
+        m.test_tuple_unpacking.__doc__.strip()
+        == "test_tuple_unpacking(arg0: Callable) -> object"
+    )
diff --git a/tests/test_eigen_matrix.cpp b/tests/test_eigen_matrix.cpp
index 554cc4d7f..0c003d05e 100644
--- a/tests/test_eigen_matrix.cpp
+++ b/tests/test_eigen_matrix.cpp
@@ -330,6 +330,23 @@ TEST_SUBMODULE(eigen_matrix, m) {
     m.def("dense_c", [mat]() -> DenseMatrixC { return DenseMatrixC(mat); });
     m.def("dense_copy_r", [](const DenseMatrixR &m) -> DenseMatrixR { return m; });
     m.def("dense_copy_c", [](const DenseMatrixC &m) -> DenseMatrixC { return m; });
+    // test_defaults
+    bool have_numpy = true;
+    try {
+        py::module_::import("numpy");
+    } catch (const py::error_already_set &) {
+        have_numpy = false;
+    }
+    if (have_numpy) {
+        py::module_::import("numpy");
+        Eigen::Matrix<double, 3, 3> defaultMatrix = Eigen::Matrix3d::Identity();
+        m.def(
+            "defaults_mat", [](const Eigen::Matrix3d &) {}, py::arg("mat") = defaultMatrix);
+
+        Eigen::VectorXd defaultVector = Eigen::VectorXd::Ones(32);
+        m.def(
+            "defaults_vec", [](const Eigen::VectorXd &) {}, py::arg("vec") = defaultMatrix);
+    }
     // test_sparse, test_sparse_signature
     m.def("sparse_r", [mat]() -> SparseMatrixR {
         // NOLINTNEXTLINE(clang-analyzer-core.uninitialized.UndefReturn)
diff --git a/tests/test_eigen_matrix.py b/tests/test_eigen_matrix.py
index b2e76740b..a486c2f93 100644
--- a/tests/test_eigen_matrix.py
+++ b/tests/test_eigen_matrix.py
@@ -716,6 +716,11 @@ def test_dense_signature(doc):
     )
 
 
+def test_defaults(doc):
+    assert "\n" not in str(doc(m.defaults_mat))
+    assert "\n" not in str(doc(m.defaults_vec))
+
+
 def test_named_arguments():
     a = np.array([[1.0, 2], [3, 4], [5, 6]])
     b = np.ones((2, 1))
diff --git a/tests/test_enum.py b/tests/test_enum.py
index 4e85d29c3..b97b0fa56 100644
--- a/tests/test_enum.py
+++ b/tests/test_enum.py
@@ -264,3 +264,8 @@ def test_docstring_signatures():
         for attr in enum_type.__dict__.values():
             # Issue #2623/PR #2637: Add argument names to enum_ methods
             assert "arg0" not in (attr.__doc__ or "")
+
+
+def test_str_signature():
+    for enum_type in [m.ScopedEnum, m.UnscopedEnum]:
+        assert enum_type.__str__.__doc__.startswith("__str__")
diff --git a/tests/test_kwargs_and_defaults.cpp b/tests/test_kwargs_and_defaults.cpp
index 77e72c0c7..614c826da 100644
--- a/tests/test_kwargs_and_defaults.cpp
+++ b/tests/test_kwargs_and_defaults.cpp
@@ -42,6 +42,50 @@ TEST_SUBMODULE(kwargs_and_defaults, m) {
     m.def("kw_func_udl", kw_func, "x"_a, "y"_a = 300);
     m.def("kw_func_udl_z", kw_func, "x"_a, "y"_a = 0);
 
+    // test line breaks in default argument representation
+    struct CustomRepr {
+        std::string repr_string;
+
+        explicit CustomRepr(const std::string &repr) : repr_string(repr) {}
+
+        std::string __repr__() const { return repr_string; }
+    };
+
+    py::class_<CustomRepr>(m, "CustomRepr")
+        .def(py::init<const std::string &>())
+        .def("__repr__", &CustomRepr::__repr__);
+
+    m.def(
+        "kw_lb_func0",
+        [](const CustomRepr &) {},
+        py::arg("custom") = CustomRepr("  array([[A, B], [C, D]])  "));
+    m.def(
+        "kw_lb_func1",
+        [](const CustomRepr &) {},
+        py::arg("custom") = CustomRepr("  array([[A, B],\n[C, D]])  "));
+    m.def(
+        "kw_lb_func2",
+        [](const CustomRepr &) {},
+        py::arg("custom") = CustomRepr("\v\n   array([[A, B], [C, D]])"));
+    m.def(
+        "kw_lb_func3",
+        [](const CustomRepr &) {},
+        py::arg("custom") = CustomRepr("array([[A, B], [C, D]])   \f\n"));
+    m.def(
+        "kw_lb_func4",
+        [](const CustomRepr &) {},
+        py::arg("custom") = CustomRepr("array([[A, B],\n\f\n[C, D]])"));
+    m.def(
+        "kw_lb_func5",
+        [](const CustomRepr &) {},
+        py::arg("custom") = CustomRepr("array([[A, B],\r  [C, D]])"));
+    m.def(
+        "kw_lb_func6", [](const CustomRepr &) {}, py::arg("custom") = CustomRepr(" \v\t "));
+    m.def(
+        "kw_lb_func7",
+        [](const std::string &) {},
+        py::arg("str_arg") = "First line.\n  Second line.");
+
     // test_args_and_kwargs
     m.def("args_function", [](py::args args) -> py::tuple {
         PYBIND11_WARNING_PUSH
diff --git a/tests/test_kwargs_and_defaults.py b/tests/test_kwargs_and_defaults.py
index 7174726fc..b57700197 100644
--- a/tests/test_kwargs_and_defaults.py
+++ b/tests/test_kwargs_and_defaults.py
@@ -23,6 +23,38 @@ def test_function_signatures(doc):
         doc(m.KWClass.foo1)
         == "foo1(self: m.kwargs_and_defaults.KWClass, x: int, y: float) -> None"
     )
+    assert (
+        doc(m.kw_lb_func0)
+        == "kw_lb_func0(custom: m.kwargs_and_defaults.CustomRepr = array([[A, B], [C, D]])) -> None"
+    )
+    assert (
+        doc(m.kw_lb_func1)
+        == "kw_lb_func1(custom: m.kwargs_and_defaults.CustomRepr = array([[A, B], [C, D]])) -> None"
+    )
+    assert (
+        doc(m.kw_lb_func2)
+        == "kw_lb_func2(custom: m.kwargs_and_defaults.CustomRepr = array([[A, B], [C, D]])) -> None"
+    )
+    assert (
+        doc(m.kw_lb_func3)
+        == "kw_lb_func3(custom: m.kwargs_and_defaults.CustomRepr = array([[A, B], [C, D]])) -> None"
+    )
+    assert (
+        doc(m.kw_lb_func4)
+        == "kw_lb_func4(custom: m.kwargs_and_defaults.CustomRepr = array([[A, B], [C, D]])) -> None"
+    )
+    assert (
+        doc(m.kw_lb_func5)
+        == "kw_lb_func5(custom: m.kwargs_and_defaults.CustomRepr = array([[A, B], [C, D]])) -> None"
+    )
+    assert (
+        doc(m.kw_lb_func6)
+        == "kw_lb_func6(custom: m.kwargs_and_defaults.CustomRepr = ) -> None"
+    )
+    assert (
+        doc(m.kw_lb_func7)
+        == "kw_lb_func7(str_arg: str = 'First line.\\n  Second line.') -> None"
+    )
 
 
 def test_named_arguments():
diff --git a/tests/test_sequences_and_iterators.cpp b/tests/test_sequences_and_iterators.cpp
index 1de65edbf..4a1d37f4d 100644
--- a/tests/test_sequences_and_iterators.cpp
+++ b/tests/test_sequences_and_iterators.cpp
@@ -28,6 +28,13 @@ class NonZeroIterator {
 
 public:
     explicit NonZeroIterator(const T *ptr) : ptr_(ptr) {}
+
+    // Make the iterator non-copyable and movable
+    NonZeroIterator(const NonZeroIterator &) = delete;
+    NonZeroIterator(NonZeroIterator &&) noexcept = default;
+    NonZeroIterator &operator=(const NonZeroIterator &) = delete;
+    NonZeroIterator &operator=(NonZeroIterator &&) noexcept = default;
+
     const T &operator*() const { return *ptr_; }
     NonZeroIterator &operator++() {
         ++ptr_;
@@ -78,6 +85,7 @@ private:
     int value_;
 };
 using NonCopyableIntPair = std::pair<NonCopyableInt, NonCopyableInt>;
+
 PYBIND11_MAKE_OPAQUE(std::vector<NonCopyableInt>);
 PYBIND11_MAKE_OPAQUE(std::vector<NonCopyableIntPair>);
 
@@ -375,6 +383,17 @@ TEST_SUBMODULE(sequences_and_iterators, m) {
     private:
         std::vector<std::pair<int, int>> data_;
     };
+
+    {
+        // #4383 : Make sure `py::make_*iterator` functions work with move-only iterators
+        using iterator_t = NonZeroIterator<std::pair<int, int>>;
+
+        static_assert(std::is_move_assignable<iterator_t>::value, "");
+        static_assert(std::is_move_constructible<iterator_t>::value, "");
+        static_assert(!std::is_copy_assignable<iterator_t>::value, "");
+        static_assert(!std::is_copy_constructible<iterator_t>::value, "");
+    }
+
     py::class_<IntPairs>(m, "IntPairs")
         .def(py::init<std::vector<std::pair<int, int>>>())
         .def(
diff --git a/tests/test_stl_binders.py b/tests/test_stl_binders.py
index e002f5b67..79923f482 100644
--- a/tests/test_stl_binders.py
+++ b/tests/test_stl_binders.py
@@ -209,7 +209,7 @@ def test_map_string_double_const():
 def test_noncopyable_containers():
     # std::vector
     vnc = m.get_vnc(5)
-    for i in range(0, 5):
+    for i in range(5):
         assert vnc[i].value == i + 1
 
     for i, j in enumerate(vnc, start=1):
@@ -217,7 +217,7 @@ def test_noncopyable_containers():
 
     # std::deque
     dnc = m.get_dnc(5)
-    for i in range(0, 5):
+    for i in range(5):
         assert dnc[i].value == i + 1
 
     i = 1
@@ -252,7 +252,7 @@ def test_noncopyable_containers():
     # nested std::map<std::vector>
     nvnc = m.get_nvnc(5)
     for i in range(1, 6):
-        for j in range(0, 5):
+        for j in range(5):
             assert nvnc[i][j].value == j + 1
 
     # Note: maps do not have .values()