Replace C-style casts to static_cast and reinterpret_cast (#5930)

* Replace C-style casts to static_cast and reinterpret_cast

Signed-off-by: cyy <cyyever@outlook.com>

* style: pre-commit fixes

---------

Signed-off-by: cyy <cyyever@outlook.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

include/pybind11/attr.h

@@ -373,7 +373,7 @@ struct type_record {
                           + (base_has_unique_ptr_holder ? "does not" : "does"));
         }
 
-        bases.append((PyObject *) base_info->type);
+        bases.append(reinterpret_cast<PyObject *>(base_info->type));
 
 #ifdef PYBIND11_BACKWARD_COMPATIBILITY_TP_DICTOFFSET
         dynamic_attr |= base_info->type->tp_dictoffset != 0;
@@ -721,7 +721,9 @@ template <typename... Extra,
           size_t self = constexpr_sum(std::is_same<is_method, Extra>::value...)>
 constexpr bool expected_num_args(size_t nargs, bool has_args, bool has_kwargs) {
     PYBIND11_WORKAROUND_INCORRECT_MSVC_C4100(nargs, has_args, has_kwargs);
-    return named == 0 || (self + named + size_t(has_args) + size_t(has_kwargs)) == nargs;
+    return named == 0
+           || (self + named + static_cast<size_t>(has_args) + static_cast<size_t>(has_kwargs))
+                  == nargs;
 }
 
 PYBIND11_NAMESPACE_END(detail)

include/pybind11/buffer_info.h

@@ -66,10 +66,11 @@ struct buffer_info {
                 bool readonly = false)
         : ptr(ptr), itemsize(itemsize), size(1), format(format), ndim(ndim),
           shape(std::move(shape_in)), strides(std::move(strides_in)), readonly(readonly) {
-        if (ndim != (ssize_t) shape.size() || ndim != (ssize_t) strides.size()) {
+        if (ndim != static_cast<ssize_t>(shape.size())
+            || ndim != static_cast<ssize_t>(strides.size())) {
             pybind11_fail("buffer_info: ndim doesn't match shape and/or strides length");
         }
-        for (size_t i = 0; i < (size_t) ndim; ++i) {
+        for (size_t i = 0; i < static_cast<size_t>(ndim); ++i) {
             size *= shape[i];
         }
     }
@@ -195,7 +196,7 @@ struct compare_buffer_info {
 template <typename T>
 struct compare_buffer_info<T, detail::enable_if_t<std::is_integral<T>::value>> {
     static bool compare(const buffer_info &b) {
-        return (size_t) b.itemsize == sizeof(T)
+        return static_cast<size_t>(b.itemsize) == sizeof(T)
                && (b.format == format_descriptor<T>::value
                    || ((sizeof(T) == sizeof(long))
                        && b.format == (std::is_unsigned<T>::value ? "L" : "l"))

include/pybind11/cast.h

@@ -394,7 +394,8 @@ public:
         }
 
         /* Check if this is a C++ type */
-        const auto &bases = all_type_info((PyTypeObject *) type::handle_of(h).ptr());
+        const auto &bases
+            = all_type_info(reinterpret_cast<PyTypeObject *>(type::handle_of(h).ptr()));
         if (bases.size() == 1) { // Only allowing loading from a single-value type
             value = values_and_holders(reinterpret_cast<instance *>(h.ptr())).begin()->value_ptr();
             return true;
@@ -541,7 +542,7 @@ struct string_caster {
 
         const auto *buffer
             = reinterpret_cast<const CharT *>(PYBIND11_BYTES_AS_STRING(utfNbytes.ptr()));
-        size_t length = (size_t) PYBIND11_BYTES_SIZE(utfNbytes.ptr()) / sizeof(CharT);
+        size_t length = static_cast<size_t>(PYBIND11_BYTES_SIZE(utfNbytes.ptr())) / sizeof(CharT);
         // Skip BOM for UTF-16/32
         if (UTF_N > 8) {
             buffer++;

include/pybind11/detail/argument_vector.h

@@ -231,7 +231,7 @@ public:
             new (&m_repr.hvector) typename repr_type::heap_vector(count, value);
         } else {
             auto &inline_arr = m_repr.iarray;
-            inline_arr.arr.fill(value ? std::size_t(-1) : 0);
+            inline_arr.arr.fill(value ? static_cast<std::size_t>(-1) : 0);
             inline_arr.size = static_cast<decltype(inline_arr.size)>(count);
         }
     }
@@ -273,9 +273,9 @@ public:
                 assert(wbi.word < kWords);
                 assert(wbi.bit < kBitsPerWord);
                 if (b) {
-                    ha.arr[wbi.word] |= (std::size_t(1) << wbi.bit);
+                    ha.arr[wbi.word] |= (static_cast<std::size_t>(1) << wbi.bit);
                 } else {
-                    ha.arr[wbi.word] &= ~(std::size_t(1) << wbi.bit);
+                    ha.arr[wbi.word] &= ~(static_cast<std::size_t>(1) << wbi.bit);
                 }
                 assert(operator[](ha.size - 1) == b);
             }
@@ -300,7 +300,7 @@ private:
         const auto wbi = word_and_bit_index(idx);
         assert(wbi.word < kWords);
         assert(wbi.bit < kBitsPerWord);
-        return m_repr.iarray.arr[wbi.word] & (std::size_t(1) << wbi.bit);
+        return m_repr.iarray.arr[wbi.word] & (static_cast<std::size_t>(1) << wbi.bit);
     }
 
     PYBIND11_NOINLINE void move_to_heap_vector_with_reserved_size(std::size_t reserved_size) {

include/pybind11/detail/class.h

@@ -71,7 +71,7 @@ inline PyTypeObject *make_static_property_type() {
        issue no Python C API calls which could potentially invoke the
        garbage collector (the GC will call type_traverse(), which will in
        turn find the newly constructed type in an invalid state) */
-    auto *heap_type = (PyHeapTypeObject *) PyType_Type.tp_alloc(&PyType_Type, 0);
+    auto *heap_type = reinterpret_cast<PyHeapTypeObject *>(PyType_Type.tp_alloc(&PyType_Type, 0));
     if (!heap_type) {
         pybind11_fail("make_static_property_type(): error allocating type!");
     }
@@ -98,7 +98,7 @@ inline PyTypeObject *make_static_property_type() {
         pybind11_fail("make_static_property_type(): failure in PyType_Ready()!");
     }
 
-    setattr((PyObject *) type, "__module__", str(PYBIND11_DUMMY_MODULE_NAME));
+    setattr(reinterpret_cast<PyObject *>(type), "__module__", str(PYBIND11_DUMMY_MODULE_NAME));
     PYBIND11_SET_OLDPY_QUALNAME(type, name_obj);
 
     return type;
@@ -265,7 +265,7 @@ inline PyTypeObject *make_default_metaclass() {
        issue no Python C API calls which could potentially invoke the
        garbage collector (the GC will call type_traverse(), which will in
        turn find the newly constructed type in an invalid state) */
-    auto *heap_type = (PyHeapTypeObject *) PyType_Type.tp_alloc(&PyType_Type, 0);
+    auto *heap_type = reinterpret_cast<PyHeapTypeObject *>(PyType_Type.tp_alloc(&PyType_Type, 0));
     if (!heap_type) {
         pybind11_fail("make_default_metaclass(): error allocating metaclass!");
     }
@@ -291,7 +291,7 @@ inline PyTypeObject *make_default_metaclass() {
         pybind11_fail("make_default_metaclass(): failure in PyType_Ready()!");
     }
 
-    setattr((PyObject *) type, "__module__", str(PYBIND11_DUMMY_MODULE_NAME));
+    setattr(reinterpret_cast<PyObject *>(type), "__module__", str(PYBIND11_DUMMY_MODULE_NAME));
     PYBIND11_SET_OLDPY_QUALNAME(type, name_obj);
 
     return type;
@@ -306,7 +306,7 @@ inline void traverse_offset_bases(void *valueptr,
                                   instance *self,
                                   bool (*f)(void * /*parentptr*/, instance * /*self*/)) {
     for (handle h : reinterpret_borrow<tuple>(tinfo->type->tp_bases)) {
-        if (auto *parent_tinfo = get_type_info((PyTypeObject *) h.ptr())) {
+        if (auto *parent_tinfo = get_type_info(reinterpret_cast<PyTypeObject *>(h.ptr()))) {
             for (auto &c : parent_tinfo->implicit_casts) {
                 if (c.first == tinfo->cpptype) {
                     auto *parentptr = c.second(valueptr);
@@ -530,7 +530,7 @@ inline PyObject *make_object_base_type(PyTypeObject *metaclass) {
        issue no Python C API calls which could potentially invoke the
        garbage collector (the GC will call type_traverse(), which will in
        turn find the newly constructed type in an invalid state) */
-    auto *heap_type = (PyHeapTypeObject *) metaclass->tp_alloc(metaclass, 0);
+    auto *heap_type = reinterpret_cast<PyHeapTypeObject *>(metaclass->tp_alloc(metaclass, 0));
     if (!heap_type) {
         pybind11_fail("make_object_base_type(): error allocating type!");
     }
@@ -557,11 +557,11 @@ inline PyObject *make_object_base_type(PyTypeObject *metaclass) {
         pybind11_fail("PyType_Ready failed in make_object_base_type(): " + error_string());
     }
 
-    setattr((PyObject *) type, "__module__", str(PYBIND11_DUMMY_MODULE_NAME));
+    setattr(reinterpret_cast<PyObject *>(type), "__module__", str(PYBIND11_DUMMY_MODULE_NAME));
     PYBIND11_SET_OLDPY_QUALNAME(type, name_obj);
 
     assert(!PyType_HasFeature(type, Py_TPFLAGS_HAVE_GC));
-    return (PyObject *) heap_type;
+    return reinterpret_cast<PyObject *>(heap_type);
 }
 
 /// dynamic_attr: Allow the garbage collector to traverse the internal instance `__dict__`.
@@ -746,7 +746,7 @@ inline PyObject *make_new_python_type(const type_record &rec) {
         /* Allocate memory for docstring (Python will free this later on) */
         size_t size = std::strlen(rec.doc) + 1;
 #if PY_VERSION_HEX >= 0x030D0000
-        tp_doc = (char *) PyMem_MALLOC(size);
+        tp_doc = static_cast<char *>(PyMem_MALLOC(size));
 #else
         tp_doc = (char *) PyObject_MALLOC(size);
 #endif
@@ -761,10 +761,10 @@ inline PyObject *make_new_python_type(const type_record &rec) {
        issue no Python C API calls which could potentially invoke the
        garbage collector (the GC will call type_traverse(), which will in
        turn find the newly constructed type in an invalid state) */
-    auto *metaclass
+    auto *metaclass = rec.metaclass.ptr() ? reinterpret_cast<PyTypeObject *>(rec.metaclass.ptr())
-        = rec.metaclass.ptr() ? (PyTypeObject *) rec.metaclass.ptr() : internals.default_metaclass;
+                                          : internals.default_metaclass;
 
-    auto *heap_type = (PyHeapTypeObject *) metaclass->tp_alloc(metaclass, 0);
+    auto *heap_type = reinterpret_cast<PyHeapTypeObject *>(metaclass->tp_alloc(metaclass, 0));
     if (!heap_type) {
         pybind11_fail(std::string(rec.name) + ": Unable to create type object!");
     }
@@ -777,7 +777,7 @@ inline PyObject *make_new_python_type(const type_record &rec) {
     auto *type = &heap_type->ht_type;
     type->tp_name = full_name;
     type->tp_doc = tp_doc;
-    type->tp_base = type_incref((PyTypeObject *) base);
+    type->tp_base = type_incref(reinterpret_cast<PyTypeObject *>(base));
     type->tp_basicsize = static_cast<ssize_t>(sizeof(instance));
     if (!bases.empty()) {
         type->tp_bases = bases.release().ptr();
@@ -818,18 +818,18 @@ inline PyObject *make_new_python_type(const type_record &rec) {
 
     /* Register type with the parent scope */
     if (rec.scope) {
-        setattr(rec.scope, rec.name, (PyObject *) type);
+        setattr(rec.scope, rec.name, reinterpret_cast<PyObject *>(type));
     } else {
         Py_INCREF(type); // Keep it alive forever (reference leak)
     }
 
     if (module_) { // Needed by pydoc
-        setattr((PyObject *) type, "__module__", module_);
+        setattr(reinterpret_cast<PyObject *>(type), "__module__", module_);
     }
 
     PYBIND11_SET_OLDPY_QUALNAME(type, qualname);
 
-    return (PyObject *) type;
+    return reinterpret_cast<PyObject *>(type);
 }
 
 PYBIND11_NAMESPACE_END(detail)

include/pybind11/detail/cpp_conduit.h

@@ -21,13 +21,13 @@ inline bool type_is_managed_by_our_internals(PyTypeObject *type_obj) {
     return bool(internals.registered_types_py.find(type_obj)
                 != internals.registered_types_py.end());
 #else
-    return bool(type_obj->tp_new == pybind11_object_new);
+    return (type_obj->tp_new == pybind11_object_new);
 #endif
 }
 
 inline bool is_instance_method_of_type(PyTypeObject *type_obj, PyObject *attr_name) {
     PyObject *descr = _PyType_Lookup(type_obj, attr_name);
-    return bool((descr != nullptr) && PyInstanceMethod_Check(descr));
+    return ((descr != nullptr) && PyInstanceMethod_Check(descr));
 }
 
 inline object try_get_cpp_conduit_method(PyObject *obj) {

include/pybind11/detail/function_record_pyobject.h

@@ -126,7 +126,7 @@ inline bool is_function_record_PyObject(PyObject *obj) {
 
 inline function_record *function_record_ptr_from_PyObject(PyObject *obj) {
     if (is_function_record_PyObject(obj)) {
-        return ((detail::function_record_PyObject *) obj)->cpp_func_rec;
+        return (reinterpret_cast<detail::function_record_PyObject *>(obj))->cpp_func_rec;
     }
     return nullptr;
 }
@@ -137,7 +137,7 @@ inline object function_record_PyObject_New() {
         throw error_already_set();
     }
     py_func_rec->cpp_func_rec = nullptr; // For clarity/purity. Redundant in practice.
-    return reinterpret_steal<object>((PyObject *) py_func_rec);
+    return reinterpret_steal<object>(reinterpret_cast<PyObject *>(py_func_rec));
 }
 
 PYBIND11_NAMESPACE_BEGIN(function_record_PyTypeObject_methods)

include/pybind11/detail/init.h

@@ -476,9 +476,9 @@ void setstate(value_and_holder &v_h, std::pair<T, O> &&result, bool need_alias)
         return;
     }
     // Our tests never run into an unset dict, but being careful here for now (see #5658)
-    auto dict = getattr((PyObject *) v_h.inst, "__dict__", none());
+    auto dict = getattr(reinterpret_cast<PyObject *>(v_h.inst), "__dict__", none());
     if (dict.is_none()) {
-        setattr((PyObject *) v_h.inst, "__dict__", d);
+        setattr(reinterpret_cast<PyObject *>(v_h.inst), "__dict__", d);
     } else {
         // Keep the original object dict and just update it
         if (PyDict_Update(dict.ptr(), d.ptr()) < 0) {

include/pybind11/detail/internals.h

@@ -606,9 +606,8 @@ public:
             // this could be called without an active interpreter, just use what was cached
             if (!tstate || tstate->interp == last_istate_tls()) {
                 auto tpp = internals_p_tls();
-                if (tpp) {
+
-                    delete tpp;
+                delete tpp;
-                }
             }
             unref();
             return;

include/pybind11/detail/type_caster_base.h

@@ -125,7 +125,7 @@ PYBIND11_NOINLINE void all_type_info_populate(PyTypeObject *t, std::vector<type_
     assert(bases.empty());
     std::vector<PyTypeObject *> check;
     for (handle parent : reinterpret_borrow<tuple>(t->tp_bases)) {
-        check.push_back((PyTypeObject *) parent.ptr());
+        check.push_back(reinterpret_cast<PyTypeObject *>(parent.ptr()));
     }
     auto const &type_dict = get_internals().registered_types_py;
     for (size_t i = 0; i < check.size(); i++) {
@@ -168,7 +168,7 @@ PYBIND11_NOINLINE void all_type_info_populate(PyTypeObject *t, std::vector<type_
                 i--;
             }
             for (handle parent : reinterpret_borrow<tuple>(type->tp_bases)) {
-                check.push_back((PyTypeObject *) parent.ptr());
+                check.push_back(reinterpret_cast<PyTypeObject *>(parent.ptr()));
             }
         }
     }
@@ -286,7 +286,7 @@ PYBIND11_NOINLINE detail::type_info *get_type_info(const std::type_info &tp,
 
 PYBIND11_NOINLINE handle get_type_handle(const std::type_info &tp, bool throw_if_missing) {
     detail::type_info *type_info = get_type_info(tp, throw_if_missing);
-    return handle(type_info ? ((PyObject *) type_info->type) : nullptr);
+    return handle(type_info ? (reinterpret_cast<PyObject *>(type_info->type)) : nullptr);
 }
 
 inline bool try_incref(PyObject *obj) {
@@ -506,7 +506,7 @@ PYBIND11_NOINLINE void instance::allocate_layout() {
         // efficient for small allocations like the one we're doing here;
         // for larger allocations they are just wrappers around malloc.
         // TODO: is this still true for pure Python 3.6?
-        nonsimple.values_and_holders = (void **) PyMem_Calloc(space, sizeof(void *));
+        nonsimple.values_and_holders = static_cast<void **>(PyMem_Calloc(space, sizeof(void *)));
         if (!nonsimple.values_and_holders) {
             throw std::bad_alloc();
         }
@@ -537,7 +537,7 @@ PYBIND11_NOINLINE handle get_object_handle(const void *ptr, const detail::type_i
         for (auto it = range.first; it != range.second; ++it) {
             for (const auto &vh : values_and_holders(it->second)) {
                 if (vh.type == type) {
-                    return handle((PyObject *) it->second);
+                    return handle(reinterpret_cast<PyObject *>(it->second));
                 }
             }
         }
@@ -1700,7 +1700,7 @@ inline std::string quote_cpp_type_name(const std::string &cpp_type_name) {
 
 PYBIND11_NOINLINE std::string type_info_description(const std::type_info &ti) {
     if (auto *type_data = get_type_info(ti)) {
-        handle th((PyObject *) type_data->type);
+        handle th(reinterpret_cast<PyObject *>(type_data->type));
         return th.attr("__module__").cast<std::string>() + '.'
                + th.attr("__qualname__").cast<std::string>();
     }

include/pybind11/detail/value_and_holder.h

@@ -54,7 +54,8 @@ struct value_and_holder {
         } else if (v) {
             inst->nonsimple.status[index] |= instance::status_holder_constructed;
         } else {
-            inst->nonsimple.status[index] &= (std::uint8_t) ~instance::status_holder_constructed;
+            inst->nonsimple.status[index]
+                &= static_cast<std::uint8_t>(~instance::status_holder_constructed);
         }
     }
     bool instance_registered() const {
@@ -69,7 +70,8 @@ struct value_and_holder {
         } else if (v) {
             inst->nonsimple.status[index] |= instance::status_instance_registered;
         } else {
-            inst->nonsimple.status[index] &= (std::uint8_t) ~instance::status_instance_registered;
+            inst->nonsimple.status[index]
+                &= static_cast<std::uint8_t>(~instance::status_instance_registered);
         }
     }
 };

include/pybind11/pybind11.h

@@ -159,7 +159,7 @@ inline std::string generate_function_signature(const char *type_caster_name_fiel
                 pybind11_fail("Internal error while parsing type signature (1)");
             }
             if (auto *tinfo = detail::get_type_info(*t)) {
-                handle th((PyObject *) tinfo->type);
+                handle th(reinterpret_cast<PyObject *>(tinfo->type));
                 signature += th.attr("__module__").cast<std::string>() + "."
                              + th.attr("__qualname__").cast<std::string>();
             } else if (auto th = detail::global_internals_native_enum_type_map_get_item(*t)) {
@@ -642,7 +642,7 @@ protected:
 
         rec->signature = guarded_strdup(signature.c_str());
         rec->args.shrink_to_fit();
-        rec->nargs = (std::uint16_t) args;
+        rec->nargs = static_cast<std::uint16_t>(args);
 
         if (rec->sibling && PYBIND11_INSTANCE_METHOD_CHECK(rec->sibling.ptr())) {
             rec->sibling = PYBIND11_INSTANCE_METHOD_GET_FUNCTION(rec->sibling.ptr());
@@ -681,7 +681,7 @@ protected:
             rec->def->ml_flags = METH_VARARGS | METH_KEYWORDS;
 
             object py_func_rec = detail::function_record_PyObject_New();
-            ((detail::function_record_PyObject *) py_func_rec.ptr())->cpp_func_rec
+            (reinterpret_cast<detail::function_record_PyObject *>(py_func_rec.ptr()))->cpp_func_rec
                 = unique_rec.release();
             guarded_strdup.release();
 
@@ -715,8 +715,8 @@ protected:
                 // chain.
                 chain_start = rec;
                 rec->next = chain;
-                auto *py_func_rec
+                auto *py_func_rec = reinterpret_cast<detail::function_record_PyObject *>(
-                    = (detail::function_record_PyObject *) PyCFunction_GET_SELF(m_ptr);
+                    PyCFunction_GET_SELF(m_ptr));
                 py_func_rec->cpp_func_rec = unique_rec.release();
                 guarded_strdup.release();
             } else {
@@ -776,7 +776,7 @@ protected:
             }
         }
 
-        auto *func = (PyCFunctionObject *) m_ptr;
+        auto *func = reinterpret_cast<PyCFunctionObject *>(m_ptr);
         // Install docstring if it's non-empty (when at least one option is enabled)
         auto *doc = signatures.empty() ? nullptr : PYBIND11_COMPAT_STRDUP(signatures.c_str());
         std::free(const_cast<char *>(PYBIND11_PYCFUNCTION_GET_DOC(func)));
@@ -851,7 +851,7 @@ protected:
 
         /* Need to know how many arguments + keyword arguments there are to pick the right
            overload */
-        const auto n_args_in = (size_t) PyTuple_GET_SIZE(args_in);
+        const auto n_args_in = static_cast<size_t>(PyTuple_GET_SIZE(args_in));
 
         handle parent = n_args_in > 0 ? PyTuple_GET_ITEM(args_in, 0) : nullptr,
                result = PYBIND11_TRY_NEXT_OVERLOAD;
@@ -865,7 +865,8 @@ protected:
                 return nullptr;
             }
 
-            auto *const tinfo = get_type_info((PyTypeObject *) overloads->scope.ptr());
+            auto *const tinfo
+                = get_type_info(reinterpret_cast<PyTypeObject *>(overloads->scope.ptr()));
             auto *const pi = reinterpret_cast<instance *>(parent.ptr());
             self_value_and_holder = pi->get_value_and_holder(tinfo, true);
 
@@ -1296,7 +1297,7 @@ PYBIND11_NAMESPACE_BEGIN(function_record_PyTypeObject_methods)
 
 // This implementation needs the definition of `class cpp_function`.
 inline void tp_dealloc_impl(PyObject *self) {
-    auto *py_func_rec = (function_record_PyObject *) self;
+    auto *py_func_rec = reinterpret_cast<function_record_PyObject *>(self);
     cpp_function::destruct(py_func_rec->cpp_func_rec);
     py_func_rec->cpp_func_rec = nullptr;
 }
@@ -1669,7 +1670,7 @@ protected:
 
         /* Register supplemental type information in C++ dict */
         auto *tinfo = new detail::type_info();
-        tinfo->type = (PyTypeObject *) m_ptr;
+        tinfo->type = reinterpret_cast<PyTypeObject *>(m_ptr);
         tinfo->cpptype = rec.type;
         tinfo->type_size = rec.type_size;
         tinfo->type_align = rec.type_align;
@@ -1704,7 +1705,7 @@ protected:
             PYBIND11_WARNING_DISABLE_GCC("-Warray-bounds")
             PYBIND11_WARNING_DISABLE_GCC("-Wstringop-overread")
 #endif
-            internals.registered_types_py[(PyTypeObject *) m_ptr] = {tinfo};
+            internals.registered_types_py[reinterpret_cast<PyTypeObject *>(m_ptr)] = {tinfo};
             PYBIND11_WARNING_POP
         });
 
@@ -1712,7 +1713,8 @@ protected:
             mark_parents_nonsimple(tinfo->type);
             tinfo->simple_ancestors = false;
         } else if (rec.bases.size() == 1) {
-            auto *parent_tinfo = get_type_info((PyTypeObject *) rec.bases[0].ptr());
+            auto *parent_tinfo
+                = get_type_info(reinterpret_cast<PyTypeObject *>(rec.bases[0].ptr()));
             assert(parent_tinfo != nullptr);
             bool parent_simple_ancestors = parent_tinfo->simple_ancestors;
             tinfo->simple_ancestors = parent_simple_ancestors;
@@ -1731,17 +1733,17 @@ protected:
     void mark_parents_nonsimple(PyTypeObject *value) {
         auto t = reinterpret_borrow<tuple>(value->tp_bases);
         for (handle h : t) {
-            auto *tinfo2 = get_type_info((PyTypeObject *) h.ptr());
+            auto *tinfo2 = get_type_info(reinterpret_cast<PyTypeObject *>(h.ptr()));
             if (tinfo2) {
                 tinfo2->simple_type = false;
             }
-            mark_parents_nonsimple((PyTypeObject *) h.ptr());
+            mark_parents_nonsimple(reinterpret_cast<PyTypeObject *>(h.ptr()));
         }
     }
 
     void install_buffer_funcs(buffer_info *(*get_buffer)(PyObject *, void *),
                               void *get_buffer_data) {
-        auto *type = (PyHeapTypeObject *) m_ptr;
+        auto *type = reinterpret_cast<PyHeapTypeObject *>(m_ptr);
         auto *tinfo = detail::get_type_info(&type->ht_type);
 
         if (!type->ht_type.tp_as_buffer) {
@@ -1763,8 +1765,8 @@ protected:
         const auto is_static = (rec_func != nullptr) && !(rec_func->is_method && rec_func->scope);
         const auto has_doc = (rec_func != nullptr) && (rec_func->doc != nullptr)
                              && pybind11::options::show_user_defined_docstrings();
-        auto property = handle(
+        auto property = handle(reinterpret_cast<PyObject *>(
-            (PyObject *) (is_static ? get_internals().static_property_type : &PyProperty_Type));
+            is_static ? get_internals().static_property_type : &PyProperty_Type));
         attr(name) = property(fget.ptr() ? fget : none(),
                               fset.ptr() ? fset : none(),
                               /*deleter*/ none(),
@@ -2698,8 +2700,9 @@ struct enum_base {
 
     PYBIND11_NOINLINE void init(bool is_arithmetic, bool is_convertible) {
         m_base.attr("__entries") = dict();
-        auto property = handle((PyObject *) &PyProperty_Type);
+        auto property = handle(reinterpret_cast<PyObject *>(&PyProperty_Type));
-        auto static_property = handle((PyObject *) get_internals().static_property_type);
+        auto static_property
+            = handle(reinterpret_cast<PyObject *>(get_internals().static_property_type));
 
         m_base.attr("__repr__") = cpp_function(
             [](const object &arg) -> str {
@@ -2730,7 +2733,7 @@ struct enum_base {
                     [](handle arg) -> std::string {
                         std::string docstring;
                         dict entries = arg.attr("__entries");
-                        if (((PyTypeObject *) arg.ptr())->tp_doc) {
+                        if ((reinterpret_cast<PyTypeObject *>(arg.ptr()))->tp_doc) {
                             docstring += std::string(
                                 reinterpret_cast<PyTypeObject *>(arg.ptr())->tp_doc);
                             docstring += "\n\n";
@@ -2856,7 +2859,7 @@ struct enum_base {
         dict entries = m_base.attr("__entries");
         str name(name_);
         if (entries.contains(name)) {
-            std::string type_name = (std::string) str(m_base.attr("__name__"));
+            std::string type_name = std::string(str(m_base.attr("__name__")));
             throw value_error(std::move(type_name) + ": element \"" + std::string(name_)
                               + "\" already exists!");
         }
@@ -3051,7 +3054,7 @@ all_type_info_get_cache(PyTypeObject *type) {
     if (res.second) {
         // New cache entry created; set up a weak reference to automatically remove it if the type
         // gets destroyed:
-        weakref((PyObject *) type, cpp_function([type](handle wr) {
+        weakref(reinterpret_cast<PyObject *>(type), cpp_function([type](handle wr) {
                     with_internals([type](internals &internals) {
                         internals.registered_types_py.erase(type);
 
@@ -3292,7 +3295,7 @@ void implicitly_convertible() {
         }
         tuple args(1);
         args[0] = obj;
-        PyObject *result = PyObject_Call((PyObject *) type, args.ptr(), nullptr);
+        PyObject *result = PyObject_Call(reinterpret_cast<PyObject *>(type), args.ptr(), nullptr);
         if (result == nullptr) {
             PyErr_Clear();
         }
@@ -3508,7 +3511,7 @@ get_type_override(const void *this_ptr, const type_info *this_type, const char *
     if (frame != nullptr) {
         PyCodeObject *f_code = PyFrame_GetCode(frame);
         // f_code is guaranteed to not be NULL
-        if ((std::string) str(f_code->co_name) == name && f_code->co_argcount > 0) {
+        if (std::string(str(f_code->co_name)) == name && f_code->co_argcount > 0) {
 #        if PY_VERSION_HEX >= 0x030d0000
             PyObject *locals = PyEval_GetFrameLocals();
 #        else

include/pybind11/pytypes.h

@@ -547,7 +547,7 @@ struct error_fetch_and_normalize {
         // The presence of __notes__ is likely due to exception normalization
         // errors, although that is not necessarily true, therefore insert a
         // hint only:
-        if (PyObject_HasAttrString(m_value.ptr(), "__notes__")) {
+        if (PyObject_HasAttrString(m_value.ptr(), "__notes__") != 0) {
             m_lazy_error_string += "[WITH __notes__]";
         }
 #else
@@ -1563,7 +1563,9 @@ public:
     PYBIND11_OBJECT(type, object, PyType_Check)
 
     /// Return a type handle from a handle or an object
-    static handle handle_of(handle h) { return handle((PyObject *) Py_TYPE(h.ptr())); }
+    static handle handle_of(handle h) {
+        return handle(reinterpret_cast<PyObject *>(Py_TYPE(h.ptr())));
+    }
 
     /// Return a type object from a handle or an object
     static type of(handle h) { return type(type::handle_of(h), borrowed_t{}); }
@@ -1661,7 +1663,7 @@ public:
         if (PyBytes_AsStringAndSize(temp.ptr(), &buffer, &length) != 0) {
             throw error_already_set();
         }
-        return std::string(buffer, (size_t) length);
+        return std::string(buffer, static_cast<size_t>(length));
     }
 
     template <typename... Args>
@@ -1861,10 +1863,12 @@ template <typename Unsigned>
 Unsigned as_unsigned(PyObject *o) {
     if (sizeof(Unsigned) <= sizeof(unsigned long)) {
         unsigned long v = PyLong_AsUnsignedLong(o);
-        return v == (unsigned long) -1 && PyErr_Occurred() ? (Unsigned) -1 : (Unsigned) v;
+        return v == static_cast<unsigned long>(-1) && PyErr_Occurred() ? (Unsigned) -1
+                                                                       : (Unsigned) v;
     }
     unsigned long long v = PyLong_AsUnsignedLongLong(o);
-    return v == (unsigned long long) -1 && PyErr_Occurred() ? (Unsigned) -1 : (Unsigned) v;
+    return v == static_cast<unsigned long long>(-1) && PyErr_Occurred() ? (Unsigned) -1
+                                                                        : (Unsigned) v;
 }
 PYBIND11_NAMESPACE_END(detail)
 
@@ -1908,7 +1912,7 @@ public:
     PYBIND11_OBJECT_CVT(float_, object, PyFloat_Check, PyNumber_Float)
     // Allow implicit conversion from float/double:
     // NOLINTNEXTLINE(google-explicit-constructor)
-    float_(float value) : object(PyFloat_FromDouble((double) value), stolen_t{}) {
+    float_(float value) : object(PyFloat_FromDouble(static_cast<double>(value)), stolen_t{}) {
         if (!m_ptr) {
             pybind11_fail("Could not allocate float object!");
         }
@@ -1920,7 +1924,7 @@ public:
         }
     }
     // NOLINTNEXTLINE(google-explicit-constructor)
-    operator float() const { return (float) PyFloat_AsDouble(m_ptr); }
+    operator float() const { return static_cast<float>(PyFloat_AsDouble(m_ptr)); }
     // NOLINTNEXTLINE(google-explicit-constructor)
     operator double() const { return PyFloat_AsDouble(m_ptr); }
 };
@@ -2122,7 +2126,7 @@ public:
             pybind11_fail("Could not allocate tuple object!");
         }
     }
-    size_t size() const { return (size_t) PyTuple_Size(m_ptr); }
+    size_t size() const { return static_cast<size_t>(PyTuple_Size(m_ptr)); }
     bool empty() const { return size() == 0; }
     detail::tuple_accessor operator[](size_t index) const { return {*this, index}; }
     template <typename T, detail::enable_if_t<detail::is_pyobject<T>::value, int> = 0>
@@ -2156,7 +2160,7 @@ public:
               typename collector = detail::deferred_t<detail::unpacking_collector<>, Args...>>
     explicit dict(Args &&...args) : dict(collector(std::forward<Args>(args)...).kwargs()) {}
 
-    size_t size() const { return (size_t) PyDict_Size(m_ptr); }
+    size_t size() const { return static_cast<size_t>(PyDict_Size(m_ptr)); }
     bool empty() const { return size() == 0; }
     detail::dict_iterator begin() const { return {*this, 0}; }
     detail::dict_iterator end() const { return {}; }
@@ -2176,7 +2180,8 @@ private:
         if (PyDict_Check(op)) {
             return handle(op).inc_ref().ptr();
         }
-        return PyObject_CallFunctionObjArgs((PyObject *) &PyDict_Type, op, nullptr);
+        return PyObject_CallFunctionObjArgs(
+            reinterpret_cast<PyObject *>(&PyDict_Type), op, nullptr);
     }
 };
 
@@ -2188,7 +2193,7 @@ public:
         if (result == -1) {
             throw error_already_set();
         }
-        return (size_t) result;
+        return static_cast<size_t>(result);
     }
     bool empty() const { return size() == 0; }
     detail::sequence_accessor operator[](size_t index) const { return {*this, index}; }
@@ -2211,7 +2216,7 @@ public:
             pybind11_fail("Could not allocate list object!");
         }
     }
-    size_t size() const { return (size_t) PyList_Size(m_ptr); }
+    size_t size() const { return static_cast<size_t>(PyList_Size(m_ptr)); }
     bool empty() const { return size() == 0; }
     detail::list_accessor operator[](size_t index) const { return {*this, index}; }
     template <typename T, detail::enable_if_t<detail::is_pyobject<T>::value, int> = 0>
@@ -2497,7 +2502,7 @@ inline size_t len(handle h) {
     if (result < 0) {
         throw error_already_set();
     }
-    return (size_t) result;
+    return static_cast<size_t>(result);
 }
 
 /// Get the length hint of a Python object.
@@ -2510,7 +2515,7 @@ inline size_t len_hint(handle h) {
         PyErr_Clear();
         return 0;
     }
-    return (size_t) result;
+    return static_cast<size_t>(result);
 }
 
 inline str repr(handle h) {