diff --git a/.clang-tidy b/.clang-tidy
index d853a703..97bbd539 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -31,6 +31,7 @@ modernize-use-override,
 modernize-use-using,
 *performance*,
 readability-avoid-const-params-in-decls,
+readability-braces-around-statements,
 readability-const-return-type,
 readability-container-size-empty,
 readability-delete-null-pointer,
diff --git a/include/pybind11/attr.h b/include/pybind11/attr.h
index f1b66fb8..f23582b1 100644
--- a/include/pybind11/attr.h
+++ b/include/pybind11/attr.h
@@ -330,11 +330,13 @@ struct type_record {
 
         bases.append((PyObject *) base_info->type);
 
-        if (base_info->type->tp_dictoffset != 0)
+        if (base_info->type->tp_dictoffset != 0) {
             dynamic_attr = true;
+        }
 
-        if (caster)
+        if (caster) {
             base_info->implicit_casts.emplace_back(type, caster);
+        }
     }
 };
 
@@ -410,13 +412,16 @@ template <> struct process_attribute<is_new_style_constructor> : process_attribu
 };
 
 inline void check_kw_only_arg(const arg &a, function_record *r) {
-    if (r->args.size() > r->nargs_pos && (!a.name || a.name[0] == '\0'))
-        pybind11_fail("arg(): cannot specify an unnamed argument after a kw_only() annotation or args() argument");
+    if (r->args.size() > r->nargs_pos && (!a.name || a.name[0] == '\0')) {
+        pybind11_fail("arg(): cannot specify an unnamed argument after a kw_only() annotation or "
+                      "args() argument");
+    }
 }
 
 inline void append_self_arg_if_needed(function_record *r) {
-    if (r->is_method && r->args.empty())
-        r->args.emplace_back("self", nullptr, handle(), /*convert=*/ true, /*none=*/ false);
+    if (r->is_method && r->args.empty()) {
+        r->args.emplace_back("self", nullptr, handle(), /*convert=*/true, /*none=*/false);
+    }
 }
 
 /// Process a keyword argument attribute (*without* a default value)
@@ -432,8 +437,10 @@ template <> struct process_attribute<arg> : process_attribute_default<arg> {
 /// Process a keyword argument attribute (*with* a default value)
 template <> struct process_attribute<arg_v> : process_attribute_default<arg_v> {
     static void init(const arg_v &a, function_record *r) {
-        if (r->is_method && r->args.empty())
-            r->args.emplace_back("self", /*descr=*/ nullptr, /*parent=*/ handle(), /*convert=*/ true, /*none=*/ false);
+        if (r->is_method && r->args.empty()) {
+            r->args.emplace_back(
+                "self", /*descr=*/nullptr, /*parent=*/handle(), /*convert=*/true, /*none=*/false);
+        }
 
         if (!a.value) {
 #if !defined(NDEBUG)
@@ -466,8 +473,10 @@ template <> struct process_attribute<arg_v> : process_attribute_default<arg_v> {
 template <> struct process_attribute<kw_only> : process_attribute_default<kw_only> {
     static void init(const kw_only &, function_record *r) {
         append_self_arg_if_needed(r);
-        if (r->has_args && r->nargs_pos != static_cast<std::uint16_t>(r->args.size()))
-            pybind11_fail("Mismatched args() and kw_only(): they must occur at the same relative argument location (or omit kw_only() entirely)");
+        if (r->has_args && r->nargs_pos != static_cast<std::uint16_t>(r->args.size())) {
+            pybind11_fail("Mismatched args() and kw_only(): they must occur at the same relative "
+                          "argument location (or omit kw_only() entirely)");
+        }
         r->nargs_pos = static_cast<std::uint16_t>(r->args.size());
     }
 };
@@ -477,8 +486,9 @@ template <> struct process_attribute<pos_only> : process_attribute_default<pos_o
     static void init(const pos_only &, function_record *r) {
         append_self_arg_if_needed(r);
         r->nargs_pos_only = static_cast<std::uint16_t>(r->args.size());
-        if (r->nargs_pos_only > r->nargs_pos)
+        if (r->nargs_pos_only > r->nargs_pos) {
             pybind11_fail("pos_only(): cannot follow a py::args() argument");
+        }
             // It also can't follow a kw_only, but a static_assert in pybind11.h checks that
     }
 };
diff --git a/include/pybind11/buffer_info.h b/include/pybind11/buffer_info.h
index eba68d1a..1dd69555 100644
--- a/include/pybind11/buffer_info.h
+++ b/include/pybind11/buffer_info.h
@@ -19,9 +19,11 @@ PYBIND11_NAMESPACE_BEGIN(detail)
 inline std::vector<ssize_t> c_strides(const std::vector<ssize_t> &shape, ssize_t itemsize) {
     auto ndim = shape.size();
     std::vector<ssize_t> strides(ndim, itemsize);
-    if (ndim > 0)
-        for (size_t i = ndim - 1; i > 0; --i)
+    if (ndim > 0) {
+        for (size_t i = ndim - 1; i > 0; --i) {
             strides[i - 1] = strides[i] * shape[i];
+        }
+    }
     return strides;
 }
 
@@ -29,8 +31,9 @@ inline std::vector<ssize_t> c_strides(const std::vector<ssize_t> &shape, ssize_t
 inline std::vector<ssize_t> f_strides(const std::vector<ssize_t> &shape, ssize_t itemsize) {
     auto ndim = shape.size();
     std::vector<ssize_t> strides(ndim, itemsize);
-    for (size_t i = 1; i < ndim; ++i)
+    for (size_t i = 1; i < ndim; ++i) {
         strides[i] = strides[i - 1] * shape[i - 1];
+    }
     return strides;
 }
 
@@ -53,10 +56,12 @@ struct buffer_info {
                 detail::any_container<ssize_t> shape_in, detail::any_container<ssize_t> strides_in, 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 != (ssize_t) shape.size() || ndim != (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 < (size_t) ndim; ++i) {
             size *= shape[i];
+        }
     }
 
     template <typename T>
diff --git a/include/pybind11/cast.h b/include/pybind11/cast.h
index a3924008..71b8c2f0 100644
--- a/include/pybind11/cast.h
+++ b/include/pybind11/cast.h
@@ -60,8 +60,10 @@ public:
     static constexpr auto name = caster_t::name;
     static handle cast(const std::reference_wrapper<type> &src, return_value_policy policy, handle parent) {
         // It is definitely wrong to take ownership of this pointer, so mask that rvp
-        if (policy == return_value_policy::take_ownership || policy == return_value_policy::automatic)
+        if (policy == return_value_policy::take_ownership
+            || policy == return_value_policy::automatic) {
             policy = return_value_policy::automatic_reference;
+        }
         return caster_t::cast(&src.get(), policy, parent);
     }
     template <typename T> using cast_op_type = std::reference_wrapper<type>;
@@ -112,8 +114,9 @@ public:
     bool load(handle src, bool convert) {
         py_type py_value;
 
-        if (!src)
+        if (!src) {
             return false;
+        }
 
 #if !defined(PYPY_VERSION)
         auto index_check = [](PyObject *o) { return PyIndex_Check(o); };
@@ -124,10 +127,11 @@ public:
 #endif
 
         if (std::is_floating_point<T>::value) {
-            if (convert || PyFloat_Check(src.ptr()))
+            if (convert || PyFloat_Check(src.ptr())) {
                 py_value = (py_type) PyFloat_AsDouble(src.ptr());
-            else
+            } else {
                 return false;
+            }
         } else if (PyFloat_Check(src.ptr())
                    || (!convert && !PYBIND11_LONG_CHECK(src.ptr()) && !index_check(src.ptr()))) {
             return false;
@@ -214,8 +218,9 @@ public:
 template<typename T> struct void_caster {
 public:
     bool load(handle src, bool) {
-        if (src && src.is_none())
+        if (src && src.is_none()) {
             return true;
+        }
         return false;
     }
     static handle cast(T, return_value_policy /* policy */, handle /* parent */) {
@@ -257,8 +262,9 @@ public:
     }
 
     static handle cast(const void *ptr, return_value_policy /* policy */, handle /* parent */) {
-        if (ptr)
+        if (ptr) {
             return capsule(ptr).release();
+        }
         return none().inc_ref();
     }
 
@@ -274,7 +280,9 @@ template <> class type_caster<std::nullptr_t> : public void_caster<std::nullptr_
 template <> class type_caster<bool> {
 public:
     bool load(handle src, bool convert) {
-        if (!src) return false;
+        if (!src) {
+            return false;
+        }
         if (src.ptr() == Py_True) {
             value = true;
             return true;
@@ -391,8 +399,9 @@ template <typename StringType, bool IsView = false> struct string_caster {
         value = StringType(buffer, length);
 
         // If we're loading a string_view we need to keep the encoded Python object alive:
-        if (IsView)
+        if (IsView) {
             loader_life_support::add_patient(utfNbytes);
+        }
 
         return true;
     }
@@ -401,7 +410,9 @@ template <typename StringType, bool IsView = false> struct string_caster {
         const char *buffer = reinterpret_cast<const char *>(src.data());
         auto nbytes = ssize_t(src.size() * sizeof(CharT));
         handle s = decode_utfN(buffer, nbytes);
-        if (!s) throw error_already_set();
+        if (!s) {
+            throw error_already_set();
+        }
         return s;
     }
 
@@ -463,10 +474,14 @@ template <typename CharT> struct type_caster<CharT, enable_if_t<is_std_char_type
     CharT one_char = 0;
 public:
     bool load(handle src, bool convert) {
-        if (!src) return false;
+        if (!src) {
+            return false;
+        }
         if (src.is_none()) {
             // Defer accepting None to other overloads (if we aren't in convert mode):
-            if (!convert) return false;
+            if (!convert) {
+                return false;
+            }
             none = true;
             return true;
         }
@@ -474,14 +489,18 @@ public:
     }
 
     static handle cast(const CharT *src, return_value_policy policy, handle parent) {
-        if (src == nullptr) return pybind11::none().inc_ref();
+        if (src == nullptr) {
+            return pybind11::none().inc_ref();
+        }
         return StringCaster::cast(StringType(src), policy, parent);
     }
 
     static handle cast(CharT src, return_value_policy policy, handle parent) {
         if (std::is_same<char, CharT>::value) {
             handle s = PyUnicode_DecodeLatin1((const char *) &src, 1, nullptr);
-            if (!s) throw error_already_set();
+            if (!s) {
+                throw error_already_set();
+            }
             return s;
         }
         return StringCaster::cast(StringType(1, src), policy, parent);
@@ -491,13 +510,15 @@ public:
         return none ? nullptr : const_cast<CharT *>(static_cast<StringType &>(str_caster).c_str());
     }
     explicit operator CharT &() {
-        if (none)
+        if (none) {
             throw value_error("Cannot convert None to a character");
+        }
 
         auto &value = static_cast<StringType &>(str_caster);
         size_t str_len = value.size();
-        if (str_len == 0)
+        if (str_len == 0) {
             throw value_error("Cannot convert empty string to a character");
+        }
 
         // If we're in UTF-8 mode, we have two possible failures: one for a unicode character that
         // is too high, and one for multiple unicode characters (caught later), so we need to figure
@@ -531,12 +552,14 @@ public:
         // string was too long" error).
         else if (PYBIND11_SILENCE_MSVC_C4127(StringCaster::UTF_N == 16) && str_len == 2) {
             one_char = static_cast<CharT>(value[0]);
-            if (one_char >= 0xD800 && one_char < 0xE000)
+            if (one_char >= 0xD800 && one_char < 0xE000) {
                 throw value_error("Character code point not in range(0x10000)");
+            }
         }
 
-        if (str_len != 1)
+        if (str_len != 1) {
             throw value_error("Expected a character, but multi-character string found");
+        }
 
         one_char = value[0];
         return one_char;
@@ -554,11 +577,13 @@ template <template<typename...> class Tuple, typename... Ts> class tuple_caster
 public:
 
     bool load(handle src, bool convert) {
-        if (!isinstance<sequence>(src))
+        if (!isinstance<sequence>(src)) {
             return false;
+        }
         const auto seq = reinterpret_borrow<sequence>(src);
-        if (seq.size() != size)
+        if (seq.size() != size) {
             return false;
+        }
         return load_impl(seq, convert, indices{});
     }
 
@@ -570,7 +595,9 @@ public:
     // copied from the PYBIND11_TYPE_CASTER macro
     template <typename T>
     static handle cast(T *src, return_value_policy policy, handle parent) {
-        if (!src) return none().release();
+        if (!src) {
+            return none().release();
+        }
         if (policy == return_value_policy::take_ownership) {
             auto h = cast(std::move(*src), policy, parent);
             delete src;
@@ -597,8 +624,9 @@ protected:
     template <size_t... Is>
     bool load_impl(const sequence &seq, bool convert, index_sequence<Is...>) {
 #ifdef __cpp_fold_expressions
-        if ((... || !std::get<Is>(subcasters).load(seq[Is], convert)))
+        if ((... || !std::get<Is>(subcasters).load(seq[Is], convert))) {
             return false;
+        }
 #else
         for (bool r : {std::get<Is>(subcasters).load(seq[Is], convert)...})
             if (!r)
@@ -615,13 +643,16 @@ protected:
         std::array<object, size> entries{{
             reinterpret_steal<object>(make_caster<Ts>::cast(std::get<Is>(std::forward<T>(src)), policy, parent))...
         }};
-        for (const auto &entry: entries)
-            if (!entry)
+        for (const auto &entry : entries) {
+            if (!entry) {
                 return handle();
+            }
+        }
         tuple result(size);
         int counter = 0;
-        for (auto & entry: entries)
+        for (auto &entry : entries) {
             PyTuple_SET_ITEM(result.ptr(), counter++, entry.release().ptr());
+        }
         return result.release();
     }
 
@@ -676,8 +707,9 @@ public:
 protected:
     friend class type_caster_generic;
     void check_holder_compat() {
-        if (typeinfo->default_holder)
+        if (typeinfo->default_holder) {
             throw cast_error("Unable to load a custom holder type from a default-holder instance");
+        }
     }
 
     bool load_value(value_and_holder &&v_h) {
@@ -793,8 +825,9 @@ struct pyobject_caster {
             return true;
         }
 #endif
-        if (!isinstance<type>(src))
+        if (!isinstance<type>(src)) {
             return false;
+        }
         value = reinterpret_borrow<type>(src);
         return true;
     }
@@ -901,12 +934,14 @@ template <typename T, detail::enable_if_t<!detail::is_pyobject<T>::value, int> =
 object cast(T &&value, return_value_policy policy = return_value_policy::automatic_reference,
             handle parent = handle()) {
     using no_ref_T = typename std::remove_reference<T>::type;
-    if (policy == return_value_policy::automatic)
+    if (policy == return_value_policy::automatic) {
         policy = std::is_pointer<no_ref_T>::value ? return_value_policy::take_ownership :
                  std::is_lvalue_reference<T>::value ? return_value_policy::copy : return_value_policy::move;
-    else if (policy == return_value_policy::automatic_reference)
-        policy = std::is_pointer<no_ref_T>::value ? return_value_policy::reference :
-                 std::is_lvalue_reference<T>::value ? return_value_policy::copy : return_value_policy::move;
+    } else if (policy == return_value_policy::automatic_reference) {
+        policy = std::is_pointer<no_ref_T>::value     ? return_value_policy::reference
+                 : std::is_lvalue_reference<T>::value ? return_value_policy::copy
+                                                      : return_value_policy::move;
+    }
     return reinterpret_steal<object>(detail::make_caster<T>::cast(std::forward<T>(value), policy, parent));
 }
 
@@ -939,8 +974,9 @@ template <typename T> detail::enable_if_t<detail::move_always<T>::value, T> cast
     return move<T>(std::move(object));
 }
 template <typename T> detail::enable_if_t<detail::move_if_unreferenced<T>::value, T> cast(object &&object) {
-    if (object.ref_count() > 1)
+    if (object.ref_count() > 1) {
         return cast<T>(object);
+    }
     return move<T>(std::move(object));
 }
 template <typename T> detail::enable_if_t<detail::move_never<T>::value, T> cast(object &&object) {
@@ -1018,8 +1054,9 @@ template <return_value_policy policy = return_value_policy::automatic_reference,
     }
     tuple result(size);
     int counter = 0;
-    for (auto &arg_value : args)
+    for (auto &arg_value : args) {
         PyTuple_SET_ITEM(result.ptr(), counter++, arg_value.release().ptr());
+    }
     return result;
 }
 
@@ -1231,8 +1268,9 @@ public:
     /// Call a Python function and pass the collected arguments
     object call(PyObject *ptr) const {
         PyObject *result = PyObject_CallObject(ptr, m_args.ptr());
-        if (!result)
+        if (!result) {
             throw error_already_set();
+        }
         return reinterpret_steal<object>(result);
     }
 
@@ -1264,8 +1302,9 @@ public:
     /// Call a Python function and pass the collected arguments
     object call(PyObject *ptr) const {
         PyObject *result = PyObject_Call(ptr, m_args.ptr(), m_kwargs.ptr());
-        if (!result)
+        if (!result) {
             throw error_already_set();
+        }
         return reinterpret_steal<object>(result);
     }
 
@@ -1285,8 +1324,9 @@ private:
     }
 
     void process(list &args_list, detail::args_proxy ap) {
-        for (auto a : ap)
+        for (auto a : ap) {
             args_list.append(a);
+        }
     }
 
     void process(list &/*args_list*/, arg_v a) {
@@ -1315,8 +1355,9 @@ private:
     }
 
     void process(list &/*args_list*/, detail::kwargs_proxy kp) {
-        if (!kp)
+        if (!kp) {
             return;
+        }
         for (auto k : reinterpret_borrow<dict>(kp)) {
             if (m_kwargs.contains(k.first)) {
 #if defined(NDEBUG)
diff --git a/include/pybind11/chrono.h b/include/pybind11/chrono.h
index 460a28fa..b24533b9 100644
--- a/include/pybind11/chrono.h
+++ b/include/pybind11/chrono.h
@@ -46,7 +46,9 @@ public:
         // Lazy initialise the PyDateTime import
         if (!PyDateTimeAPI) { PyDateTime_IMPORT; }
 
-        if (!src) return false;
+        if (!src) {
+            return false;
+        }
         // If invoked with datetime.delta object
         if (PyDelta_Check(src.ptr())) {
             value = type(duration_cast<duration<rep, period>>(
@@ -124,7 +126,9 @@ public:
         // Lazy initialise the PyDateTime import
         if (!PyDateTimeAPI) { PyDateTime_IMPORT; }
 
-        if (!src) return false;
+        if (!src) {
+            return false;
+        }
 
         std::tm cal;
         microseconds msecs;
@@ -156,8 +160,9 @@ public:
             cal.tm_year  = 70;  // earliest available date for Python's datetime
             cal.tm_isdst = -1;
             msecs        = microseconds(PyDateTime_TIME_GET_MICROSECOND(src.ptr()));
+        } else {
+            return false;
         }
-        else return false;
 
         value = time_point_cast<Duration>(system_clock::from_time_t(std::mktime(&cal)) + msecs);
         return true;
@@ -173,8 +178,9 @@ public:
         // (cfr. https://github.com/pybind/pybind11/issues/2417)
         using us_t = duration<int, std::micro>;
         auto us = duration_cast<us_t>(src.time_since_epoch() % seconds(1));
-        if (us.count() < 0)
+        if (us.count() < 0) {
             us += seconds(1);
+        }
 
         // Subtract microseconds BEFORE `system_clock::to_time_t`, because:
         // > If std::time_t has lower precision, it is implementation-defined whether the value is rounded or truncated.
@@ -183,8 +189,9 @@ public:
 
         std::tm localtime;
         std::tm *localtime_ptr = localtime_thread_safe(&tt, &localtime);
-        if (!localtime_ptr)
+        if (!localtime_ptr) {
             throw cast_error("Unable to represent system_clock in local time");
+        }
         return PyDateTime_FromDateAndTime(localtime.tm_year + 1900,
                                           localtime.tm_mon + 1,
                                           localtime.tm_mday,
diff --git a/include/pybind11/complex.h b/include/pybind11/complex.h
index e1ecf435..72c87359 100644
--- a/include/pybind11/complex.h
+++ b/include/pybind11/complex.h
@@ -42,10 +42,12 @@ template <typename T> struct is_fmt_numeric<std::complex<T>, detail::enable_if_t
 template <typename T> class type_caster<std::complex<T>> {
 public:
     bool load(handle src, bool convert) {
-        if (!src)
+        if (!src) {
             return false;
-        if (!convert && !PyComplex_Check(src.ptr()))
+        }
+        if (!convert && !PyComplex_Check(src.ptr())) {
             return false;
+        }
         Py_complex result = PyComplex_AsCComplex(src.ptr());
         if (result.real == -1.0 && PyErr_Occurred()) {
             PyErr_Clear();
diff --git a/include/pybind11/detail/class.h b/include/pybind11/detail/class.h
index dd8c60ba..28edc129 100644
--- a/include/pybind11/detail/class.h
+++ b/include/pybind11/detail/class.h
@@ -66,8 +66,9 @@ inline PyTypeObject *make_static_property_type() {
        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);
-    if (!heap_type)
+    if (!heap_type) {
         pybind11_fail("make_static_property_type(): error allocating type!");
+    }
 
     heap_type->ht_name = name_obj.inc_ref().ptr();
 #ifdef PYBIND11_BUILTIN_QUALNAME
@@ -81,8 +82,9 @@ inline PyTypeObject *make_static_property_type() {
     type->tp_descr_get = pybind11_static_get;
     type->tp_descr_set = pybind11_static_set;
 
-    if (PyType_Ready(type) < 0)
+    if (PyType_Ready(type) < 0) {
         pybind11_fail("make_static_property_type(): failure in PyType_Ready()!");
+    }
 
     setattr((PyObject *) type, "__module__", str("pybind11_builtins"));
     PYBIND11_SET_OLDPY_QUALNAME(type, name_obj);
@@ -209,19 +211,21 @@ extern "C" inline void pybind11_meta_dealloc(PyObject *obj) {
         auto tindex = std::type_index(*tinfo->cpptype);
         internals.direct_conversions.erase(tindex);
 
-        if (tinfo->module_local)
+        if (tinfo->module_local) {
             get_local_internals().registered_types_cpp.erase(tindex);
-        else
+        } else {
             internals.registered_types_cpp.erase(tindex);
+        }
         internals.registered_types_py.erase(tinfo->type);
 
         // Actually just `std::erase_if`, but that's only available in C++20
         auto &cache = internals.inactive_override_cache;
         for (auto it = cache.begin(), last = cache.end(); it != last; ) {
-            if (it->first == (PyObject *) tinfo->type)
+            if (it->first == (PyObject *) tinfo->type) {
                 it = cache.erase(it);
-            else
+            } else {
                 ++it;
+            }
         }
 
         delete tinfo;
@@ -242,8 +246,9 @@ inline PyTypeObject* make_default_metaclass() {
        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);
-    if (!heap_type)
+    if (!heap_type) {
         pybind11_fail("make_default_metaclass(): error allocating metaclass!");
+    }
 
     heap_type->ht_name = name_obj.inc_ref().ptr();
 #ifdef PYBIND11_BUILTIN_QUALNAME
@@ -264,8 +269,9 @@ inline PyTypeObject* make_default_metaclass() {
 
     type->tp_dealloc = pybind11_meta_dealloc;
 
-    if (PyType_Ready(type) < 0)
+    if (PyType_Ready(type) < 0) {
         pybind11_fail("make_default_metaclass(): failure in PyType_Ready()!");
+    }
 
     setattr((PyObject *) type, "__module__", str("pybind11_builtins"));
     PYBIND11_SET_OLDPY_QUALNAME(type, name_obj);
@@ -283,8 +289,9 @@ inline void traverse_offset_bases(void *valueptr, const detail::type_info *tinfo
             for (auto &c : parent_tinfo->implicit_casts) {
                 if (c.first == tinfo->cpptype) {
                     auto *parentptr = c.second(valueptr);
-                    if (parentptr != valueptr)
+                    if (parentptr != valueptr) {
                         f(parentptr, self);
+                    }
                     traverse_offset_bases(parentptr, parent_tinfo, self, f);
                     break;
                 }
@@ -311,14 +318,16 @@ inline bool deregister_instance_impl(void *ptr, instance *self) {
 
 inline void register_instance(instance *self, void *valptr, const type_info *tinfo) {
     register_instance_impl(valptr, self);
-    if (!tinfo->simple_ancestors)
+    if (!tinfo->simple_ancestors) {
         traverse_offset_bases(valptr, tinfo, self, register_instance_impl);
+    }
 }
 
 inline bool deregister_instance(instance *self, void *valptr, const type_info *tinfo) {
     bool ret = deregister_instance_impl(valptr, self);
-    if (!tinfo->simple_ancestors)
+    if (!tinfo->simple_ancestors) {
         traverse_offset_bases(valptr, tinfo, self, deregister_instance_impl);
+    }
     return ret;
 }
 
@@ -377,8 +386,9 @@ inline void clear_patients(PyObject *self) {
     auto patients = std::move(pos->second);
     internals.patients.erase(pos);
     instance->has_patients = false;
-    for (PyObject *&patient : patients)
+    for (PyObject *&patient : patients) {
         Py_CLEAR(patient);
+    }
 }
 
 /// Clears all internal data from the instance and removes it from registered instances in
@@ -392,25 +402,32 @@ inline void clear_instance(PyObject *self) {
 
             // We have to deregister before we call dealloc because, for virtual MI types, we still
             // need to be able to get the parent pointers.
-            if (v_h.instance_registered() && !deregister_instance(instance, v_h.value_ptr(), v_h.type))
-                pybind11_fail("pybind11_object_dealloc(): Tried to deallocate unregistered instance!");
+            if (v_h.instance_registered()
+                && !deregister_instance(instance, v_h.value_ptr(), v_h.type)) {
+                pybind11_fail(
+                    "pybind11_object_dealloc(): Tried to deallocate unregistered instance!");
+            }
 
-            if (instance->owned || v_h.holder_constructed())
+            if (instance->owned || v_h.holder_constructed()) {
                 v_h.type->dealloc(v_h);
+            }
         }
     }
     // Deallocate the value/holder layout internals:
     instance->deallocate_layout();
 
-    if (instance->weakrefs)
+    if (instance->weakrefs) {
         PyObject_ClearWeakRefs(self);
+    }
 
     PyObject **dict_ptr = _PyObject_GetDictPtr(self);
-    if (dict_ptr)
+    if (dict_ptr) {
         Py_CLEAR(*dict_ptr);
+    }
 
-    if (instance->has_patients)
+    if (instance->has_patients) {
         clear_patients(self);
+    }
 }
 
 /// Instance destructor function for all pybind11 types. It calls `type_info.dealloc`
@@ -448,8 +465,9 @@ inline PyObject *make_object_base_type(PyTypeObject *metaclass) {
        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);
-    if (!heap_type)
+    if (!heap_type) {
         pybind11_fail("make_object_base_type(): error allocating type!");
+    }
 
     heap_type->ht_name = name_obj.inc_ref().ptr();
 #ifdef PYBIND11_BUILTIN_QUALNAME
@@ -469,8 +487,9 @@ inline PyObject *make_object_base_type(PyTypeObject *metaclass) {
     /* Support weak references (needed for the keep_alive feature) */
     type->tp_weaklistoffset = offsetof(instance, weakrefs);
 
-    if (PyType_Ready(type) < 0)
+    if (PyType_Ready(type) < 0) {
         pybind11_fail("PyType_Ready failed in make_object_base_type():" + error_string());
+    }
 
     setattr((PyObject *) type, "__module__", str("pybind11_builtins"));
     PYBIND11_SET_OLDPY_QUALNAME(type, name_obj);
@@ -482,8 +501,9 @@ inline PyObject *make_object_base_type(PyTypeObject *metaclass) {
 /// dynamic_attr: Support for `d = instance.__dict__`.
 extern "C" inline PyObject *pybind11_get_dict(PyObject *self, void *) {
     PyObject *&dict = *_PyObject_GetDictPtr(self);
-    if (!dict)
+    if (!dict) {
         dict = PyDict_New();
+    }
     Py_XINCREF(dict);
     return dict;
 }
@@ -538,12 +558,14 @@ extern "C" inline int pybind11_getbuffer(PyObject *obj, Py_buffer *view, int fla
     type_info *tinfo = nullptr;
     for (auto type : reinterpret_borrow<tuple>(Py_TYPE(obj)->tp_mro)) {
         tinfo = get_type_info((PyTypeObject *) type.ptr());
-        if (tinfo && tinfo->get_buffer)
+        if (tinfo && tinfo->get_buffer) {
             break;
+        }
     }
     if (view == nullptr || !tinfo || !tinfo->get_buffer) {
-        if (view)
+        if (view) {
             view->obj = nullptr;
+        }
         PyErr_SetString(PyExc_BufferError, "pybind11_getbuffer(): Internal error");
         return -1;
     }
@@ -561,11 +583,13 @@ extern "C" inline int pybind11_getbuffer(PyObject *obj, Py_buffer *view, int fla
     view->buf = info->ptr;
     view->itemsize = info->itemsize;
     view->len = view->itemsize;
-    for (auto s : info->shape)
+    for (auto s : info->shape) {
         view->len *= s;
+    }
     view->readonly = static_cast<int>(info->readonly);
-    if ((flags & PyBUF_FORMAT) == PyBUF_FORMAT)
+    if ((flags & PyBUF_FORMAT) == PyBUF_FORMAT) {
         view->format = const_cast<char *>(info->format.c_str());
+    }
     if ((flags & PyBUF_STRIDES) == PyBUF_STRIDES) {
         view->ndim = (int) info->ndim;
         view->strides = info->strides.data();
@@ -608,10 +632,11 @@ inline PyObject* make_new_python_type(const type_record &rec) {
 
     object module_;
     if (rec.scope) {
-        if (hasattr(rec.scope, "__module__"))
+        if (hasattr(rec.scope, "__module__")) {
             module_ = rec.scope.attr("__module__");
-        else if (hasattr(rec.scope, "__name__"))
+        } else if (hasattr(rec.scope, "__name__")) {
             module_ = rec.scope.attr("__name__");
+        }
     }
 
     auto full_name = c_str(
@@ -642,8 +667,9 @@ inline PyObject* make_new_python_type(const type_record &rec) {
                                          : internals.default_metaclass;
 
     auto heap_type = (PyHeapTypeObject *) metaclass->tp_alloc(metaclass, 0);
-    if (!heap_type)
+    if (!heap_type) {
         pybind11_fail(std::string(rec.name) + ": Unable to create type object!");
+    }
 
     heap_type->ht_name = name.release().ptr();
 #ifdef PYBIND11_BUILTIN_QUALNAME
@@ -655,8 +681,9 @@ inline PyObject* make_new_python_type(const type_record &rec) {
     type->tp_doc = tp_doc;
     type->tp_base = type_incref((PyTypeObject *)base);
     type->tp_basicsize = static_cast<ssize_t>(sizeof(instance));
-    if (!bases.empty())
+    if (!bases.empty()) {
         type->tp_bases = bases.release().ptr();
+    }
 
     /* Don't inherit base __init__ */
     type->tp_init = pybind11_object_init;
@@ -674,31 +701,38 @@ inline PyObject* make_new_python_type(const type_record &rec) {
 #if PY_MAJOR_VERSION < 3
     type->tp_flags |= Py_TPFLAGS_CHECKTYPES;
 #endif
-    if (!rec.is_final)
+    if (!rec.is_final) {
         type->tp_flags |= Py_TPFLAGS_BASETYPE;
+    }
 
-    if (rec.dynamic_attr)
+    if (rec.dynamic_attr) {
         enable_dynamic_attributes(heap_type);
+    }
 
-    if (rec.buffer_protocol)
+    if (rec.buffer_protocol) {
         enable_buffer_protocol(heap_type);
+    }
 
-    if (rec.custom_type_setup_callback)
+    if (rec.custom_type_setup_callback) {
         rec.custom_type_setup_callback(heap_type);
+    }
 
-    if (PyType_Ready(type) < 0)
+    if (PyType_Ready(type) < 0) {
         pybind11_fail(std::string(rec.name) + ": PyType_Ready failed (" + error_string() + ")!");
+    }
 
     assert(!rec.dynamic_attr || PyType_HasFeature(type, Py_TPFLAGS_HAVE_GC));
 
     /* Register type with the parent scope */
-    if (rec.scope)
+    if (rec.scope) {
         setattr(rec.scope, rec.name, (PyObject *) type);
-    else
+    } else {
         Py_INCREF(type); // Keep it alive forever (reference leak)
+    }
 
-    if (module_) // Needed by pydoc
+    if (module_) { // Needed by pydoc
         setattr((PyObject *) type, "__module__", module_);
+    }
 
     PYBIND11_SET_OLDPY_QUALNAME(type, qualname);
 
diff --git a/include/pybind11/detail/init.h b/include/pybind11/detail/init.h
index 65b823e5..ba408d76 100644
--- a/include/pybind11/detail/init.h
+++ b/include/pybind11/detail/init.h
@@ -33,7 +33,9 @@ private:
 PYBIND11_NAMESPACE_BEGIN(initimpl)
 
 inline void no_nullptr(void *ptr) {
-    if (!ptr) throw type_error("pybind11::init(): factory function returned nullptr");
+    if (!ptr) {
+        throw type_error("pybind11::init(): factory function returned nullptr");
+    }
 }
 
 // Implementing functions for all forms of py::init<...> and py::init(...)
@@ -136,9 +138,10 @@ void construct(value_and_holder &v_h, Holder<Class> holder, bool need_alias) {
     auto *ptr = holder_helper<Holder<Class>>::get(holder);
     no_nullptr(ptr);
     // If we need an alias, check that the held pointer is actually an alias instance
-    if (PYBIND11_SILENCE_MSVC_C4127(Class::has_alias) && need_alias && !is_alias<Class>(ptr))
+    if (PYBIND11_SILENCE_MSVC_C4127(Class::has_alias) && need_alias && !is_alias<Class>(ptr)) {
         throw type_error("pybind11::init(): construction failed: returned holder-wrapped instance "
                          "is not an alias instance");
+    }
 
     v_h.value_ptr() = ptr;
     v_h.type->init_instance(v_h.inst, &holder);
@@ -153,10 +156,11 @@ void construct(value_and_holder &v_h, Cpp<Class> &&result, bool need_alias) {
     PYBIND11_WORKAROUND_INCORRECT_MSVC_C4100(need_alias);
     static_assert(std::is_move_constructible<Cpp<Class>>::value,
         "pybind11::init() return-by-value factory function requires a movable class");
-    if (PYBIND11_SILENCE_MSVC_C4127(Class::has_alias) && need_alias)
+    if (PYBIND11_SILENCE_MSVC_C4127(Class::has_alias) && need_alias) {
         construct_alias_from_cpp<Class>(is_alias_constructible<Class>{}, v_h, std::move(result));
-    else
+    } else {
         v_h.value_ptr() = new Cpp<Class>(std::move(result));
+    }
 }
 
 // return-by-value version 2: returning a value of the alias type itself.  We move-construct an
@@ -183,12 +187,19 @@ struct constructor {
               enable_if_t<Class::has_alias &&
                           std::is_constructible<Cpp<Class>, Args...>::value, int> = 0>
     static void execute(Class &cl, const Extra&... extra) {
-        cl.def("__init__", [](value_and_holder &v_h, Args... args) {
-            if (Py_TYPE(v_h.inst) == v_h.type->type)
-                v_h.value_ptr() = construct_or_initialize<Cpp<Class>>(std::forward<Args>(args)...);
-            else
-                v_h.value_ptr() = construct_or_initialize<Alias<Class>>(std::forward<Args>(args)...);
-        }, is_new_style_constructor(), extra...);
+        cl.def(
+            "__init__",
+            [](value_and_holder &v_h, Args... args) {
+                if (Py_TYPE(v_h.inst) == v_h.type->type) {
+                    v_h.value_ptr()
+                        = construct_or_initialize<Cpp<Class>>(std::forward<Args>(args)...);
+                } else {
+                    v_h.value_ptr()
+                        = construct_or_initialize<Alias<Class>>(std::forward<Args>(args)...);
+                }
+            },
+            is_new_style_constructor(),
+            extra...);
     }
 
     template <typename Class, typename... Extra,
diff --git a/include/pybind11/detail/internals.h b/include/pybind11/detail/internals.h
index 9edb9492..661acf5d 100644
--- a/include/pybind11/detail/internals.h
+++ b/include/pybind11/detail/internals.h
@@ -398,8 +398,9 @@ inline void translate_local_exception(std::exception_ptr p) {
 /// Return a reference to the current `internals` data
 PYBIND11_NOINLINE internals &get_internals() {
     auto **&internals_pp = get_internals_pp();
-    if (internals_pp && *internals_pp)
+    if (internals_pp && *internals_pp) {
         return **internals_pp;
+    }
 
     // Ensure that the GIL is held since we will need to make Python calls.
     // Cannot use py::gil_scoped_acquire here since that constructor calls get_internals.
@@ -425,7 +426,9 @@ PYBIND11_NOINLINE internals &get_internals() {
         (*internals_pp)->registered_exception_translators.push_front(&translate_local_exception);
 #endif
     } else {
-        if (!internals_pp) internals_pp = new internals*();
+        if (!internals_pp) {
+            internals_pp = new internals *();
+        }
         auto *&internals_ptr = *internals_pp;
         internals_ptr = new internals();
 #if defined(WITH_THREAD)
diff --git a/include/pybind11/detail/type_caster_base.h b/include/pybind11/detail/type_caster_base.h
index 87a4087a..212a944a 100644
--- a/include/pybind11/detail/type_caster_base.h
+++ b/include/pybind11/detail/type_caster_base.h
@@ -69,11 +69,13 @@ public:
 
     /// ... and destroyed after it returns
     ~loader_life_support() {
-        if (get_stack_top() != this)
+        if (get_stack_top() != this) {
             pybind11_fail("loader_life_support: internal error");
+        }
         set_stack_top(parent);
-        for (auto* item : keep_alive)
+        for (auto *item : keep_alive) {
             Py_DECREF(item);
+        }
     }
 
     /// This can only be used inside a pybind11-bound function, either by `argument_loader`
@@ -90,8 +92,9 @@ public:
                              "of temporary values");
         }
 
-        if (frame->keep_alive.insert(h.ptr()).second)
+        if (frame->keep_alive.insert(h.ptr()).second) {
             Py_INCREF(h.ptr());
+        }
     }
 };
 
@@ -103,14 +106,17 @@ inline std::pair<decltype(internals::registered_types_py)::iterator, bool> all_t
 // Populates a just-created cache entry.
 PYBIND11_NOINLINE void all_type_info_populate(PyTypeObject *t, std::vector<type_info *> &bases) {
     std::vector<PyTypeObject *> check;
-    for (handle parent : reinterpret_borrow<tuple>(t->tp_bases))
+    for (handle parent : reinterpret_borrow<tuple>(t->tp_bases)) {
         check.push_back((PyTypeObject *) parent.ptr());
+    }
 
     auto const &type_dict = get_internals().registered_types_py;
     for (size_t i = 0; i < check.size(); i++) {
         auto type = check[i];
         // Ignore Python2 old-style class super type:
-        if (!PyType_Check((PyObject *) type)) continue;
+        if (!PyType_Check((PyObject *) type)) {
+            continue;
+        }
 
         // Check `type` in the current set of registered python types:
         auto it = type_dict.find(type);
@@ -127,7 +133,9 @@ PYBIND11_NOINLINE void all_type_info_populate(PyTypeObject *t, std::vector<type_
                 for (auto *known : bases) {
                     if (known == tinfo) { found = true; break; }
                 }
-                if (!found) bases.push_back(tinfo);
+                if (!found) {
+                    bases.push_back(tinfo);
+                }
             }
         }
         else if (type->tp_bases) {
@@ -140,8 +148,9 @@ PYBIND11_NOINLINE void all_type_info_populate(PyTypeObject *t, std::vector<type_
                 check.pop_back();
                 i--;
             }
-            for (handle parent : reinterpret_borrow<tuple>(type->tp_bases))
+            for (handle parent : reinterpret_borrow<tuple>(type->tp_bases)) {
                 check.push_back((PyTypeObject *) parent.ptr());
+            }
         }
     }
 }
@@ -158,9 +167,10 @@ PYBIND11_NOINLINE void all_type_info_populate(PyTypeObject *t, std::vector<type_
  */
 inline const std::vector<detail::type_info *> &all_type_info(PyTypeObject *type) {
     auto ins = all_type_info_get_cache(type);
-    if (ins.second)
+    if (ins.second) {
         // New cache entry: populate it
         all_type_info_populate(type, ins.first->second);
+    }
 
     return ins.first->second;
 }
@@ -172,36 +182,43 @@ inline const std::vector<detail::type_info *> &all_type_info(PyTypeObject *type)
  */
 PYBIND11_NOINLINE detail::type_info* get_type_info(PyTypeObject *type) {
     auto &bases = all_type_info(type);
-    if (bases.empty())
+    if (bases.empty()) {
         return nullptr;
-    if (bases.size() > 1)
-        pybind11_fail("pybind11::detail::get_type_info: type has multiple pybind11-registered bases");
+    }
+    if (bases.size() > 1) {
+        pybind11_fail(
+            "pybind11::detail::get_type_info: type has multiple pybind11-registered bases");
+    }
     return bases.front();
 }
 
 inline detail::type_info *get_local_type_info(const std::type_index &tp) {
     auto &locals = get_local_internals().registered_types_cpp;
     auto it = locals.find(tp);
-    if (it != locals.end())
+    if (it != locals.end()) {
         return it->second;
+    }
     return nullptr;
 }
 
 inline detail::type_info *get_global_type_info(const std::type_index &tp) {
     auto &types = get_internals().registered_types_cpp;
     auto it = types.find(tp);
-    if (it != types.end())
+    if (it != types.end()) {
         return it->second;
+    }
     return nullptr;
 }
 
 /// Return the type info for a given C++ type; on lookup failure can either throw or return nullptr.
 PYBIND11_NOINLINE detail::type_info *get_type_info(const std::type_index &tp,
                                                           bool throw_if_missing = false) {
-    if (auto ltype = get_local_type_info(tp))
+    if (auto ltype = get_local_type_info(tp)) {
         return ltype;
-    if (auto gtype = get_global_type_info(tp))
+    }
+    if (auto gtype = get_global_type_info(tp)) {
         return gtype;
+    }
 
     if (throw_if_missing) {
         std::string tname = tp.name();
@@ -222,8 +239,9 @@ PYBIND11_NOINLINE handle find_registered_python_instance(void *src,
     auto it_instances = get_internals().registered_instances.equal_range(src);
     for (auto it_i = it_instances.first; it_i != it_instances.second; ++it_i) {
         for (auto instance_type : detail::all_type_info(Py_TYPE(it_i->second))) {
-            if (instance_type && same_type(*instance_type->cpptype, *tinfo->cpptype))
+            if (instance_type && same_type(*instance_type->cpptype, *tinfo->cpptype)) {
                 return handle((PyObject *) it_i->second).inc_ref();
+            }
         }
     }
     return handle();
@@ -263,12 +281,13 @@ struct value_and_holder {
     }
     // NOLINTNEXTLINE(readability-make-member-function-const)
     void set_holder_constructed(bool v = true) {
-        if (inst->simple_layout)
+        if (inst->simple_layout) {
             inst->simple_holder_constructed = v;
-        else if (v)
+        } else if (v) {
             inst->nonsimple.status[index] |= instance::status_holder_constructed;
-        else
+        } else {
             inst->nonsimple.status[index] &= (std::uint8_t) ~instance::status_holder_constructed;
+        }
     }
     bool instance_registered() const {
         return inst->simple_layout
@@ -277,12 +296,13 @@ struct value_and_holder {
     }
     // NOLINTNEXTLINE(readability-make-member-function-const)
     void set_instance_registered(bool v = true) {
-        if (inst->simple_layout)
+        if (inst->simple_layout) {
             inst->simple_instance_registered = v;
-        else if (v)
+        } else if (v) {
             inst->nonsimple.status[index] |= instance::status_instance_registered;
-        else
+        } else {
             inst->nonsimple.status[index] &= (std::uint8_t) ~instance::status_instance_registered;
+        }
     }
 };
 
@@ -317,8 +337,9 @@ public:
         bool operator==(const iterator &other) const { return curr.index == other.curr.index; }
         bool operator!=(const iterator &other) const { return curr.index != other.curr.index; }
         iterator &operator++() {
-            if (!inst->simple_layout)
+            if (!inst->simple_layout) {
                 curr.vh += 1 + (*types)[curr.index]->holder_size_in_ptrs;
+            }
             ++curr.index;
             curr.type = curr.index < types->size() ? (*types)[curr.index] : nullptr;
             return *this;
@@ -332,7 +353,9 @@ public:
 
     iterator find(const type_info *find_type) {
         auto it = begin(), endit = end();
-        while (it != endit && it->type != find_type) ++it;
+        while (it != endit && it->type != find_type) {
+            ++it;
+        }
         return it;
     }
 
@@ -351,16 +374,19 @@ public:
  */
 PYBIND11_NOINLINE value_and_holder instance::get_value_and_holder(const type_info *find_type /*= nullptr default in common.h*/, bool throw_if_missing /*= true in common.h*/) {
     // Optimize common case:
-    if (!find_type || Py_TYPE(this) == find_type->type)
+    if (!find_type || Py_TYPE(this) == find_type->type) {
         return value_and_holder(this, find_type, 0, 0);
+    }
 
     detail::values_and_holders vhs(this);
     auto it = vhs.find(find_type);
-    if (it != vhs.end())
+    if (it != vhs.end()) {
         return *it;
+    }
 
-    if (!throw_if_missing)
+    if (!throw_if_missing) {
         return value_and_holder();
+    }
 
 #if defined(NDEBUG)
     pybind11_fail("pybind11::detail::instance::get_value_and_holder: "
@@ -378,8 +404,10 @@ PYBIND11_NOINLINE void instance::allocate_layout() {
 
     const size_t n_types = tinfo.size();
 
-    if (n_types == 0)
-        pybind11_fail("instance allocation failed: new instance has no pybind11-registered base types");
+    if (n_types == 0) {
+        pybind11_fail(
+            "instance allocation failed: new instance has no pybind11-registered base types");
+    }
 
     simple_layout =
         n_types == 1 && tinfo.front()->holder_size_in_ptrs <= instance_simple_holder_in_ptrs();
@@ -410,7 +438,9 @@ PYBIND11_NOINLINE void instance::allocate_layout() {
         // just wrappers around malloc.
 #if PY_VERSION_HEX >= 0x03050000
         nonsimple.values_and_holders = (void **) PyMem_Calloc(space, sizeof(void *));
-        if (!nonsimple.values_and_holders) throw std::bad_alloc();
+        if (!nonsimple.values_and_holders) {
+            throw std::bad_alloc();
+        }
 #else
         nonsimple.values_and_holders = (void **) PyMem_New(void *, space);
         if (!nonsimple.values_and_holders) throw std::bad_alloc();
@@ -423,14 +453,16 @@ PYBIND11_NOINLINE void instance::allocate_layout() {
 
 // NOLINTNEXTLINE(readability-make-member-function-const)
 PYBIND11_NOINLINE void instance::deallocate_layout() {
-    if (!simple_layout)
+    if (!simple_layout) {
         PyMem_Free(nonsimple.values_and_holders);
+    }
 }
 
 PYBIND11_NOINLINE bool isinstance_generic(handle obj, const std::type_info &tp) {
     handle type = detail::get_type_handle(tp, false);
-    if (!type)
+    if (!type) {
         return false;
+    }
     return isinstance(obj, type);
 }
 
@@ -447,14 +479,16 @@ PYBIND11_NOINLINE std::string error_string() {
         errorString += handle(scope.type).attr("__name__").cast<std::string>();
         errorString += ": ";
     }
-    if (scope.value)
+    if (scope.value) {
         errorString += (std::string) str(scope.value);
+    }
 
     PyErr_NormalizeException(&scope.type, &scope.value, &scope.trace);
 
 #if PY_MAJOR_VERSION >= 3
-    if (scope.trace != nullptr)
+    if (scope.trace != nullptr) {
         PyException_SetTraceback(scope.value, scope.trace);
+    }
 #endif
 
 #if !defined(PYPY_VERSION)
@@ -462,8 +496,9 @@ PYBIND11_NOINLINE std::string error_string() {
         auto *trace = (PyTracebackObject *) scope.trace;
 
         /* Get the deepest trace possible */
-        while (trace->tb_next)
+        while (trace->tb_next) {
             trace = trace->tb_next;
+        }
 
         PyFrameObject *frame = trace->tb_frame;
         errorString += "\n\nAt:\n";
@@ -493,8 +528,9 @@ PYBIND11_NOINLINE handle get_object_handle(const void *ptr, const detail::type_i
     auto range = instances.equal_range(ptr);
     for (auto it = range.first; it != range.second; ++it) {
         for (const auto &vh : values_and_holders(it->second)) {
-            if (vh.type == type)
+            if (vh.type == type) {
                 return handle((PyObject *) it->second);
+            }
         }
     }
     return handle();
@@ -535,15 +571,18 @@ public:
                                          void *(*copy_constructor)(const void *),
                                          void *(*move_constructor)(const void *),
                                          const void *existing_holder = nullptr) {
-        if (!tinfo) // no type info: error will be set already
+        if (!tinfo) { // no type info: error will be set already
             return handle();
+        }
 
         void *src = const_cast<void *>(_src);
-        if (src == nullptr)
+        if (src == nullptr) {
             return none().release();
+        }
 
-        if (handle registered_inst = find_registered_python_instance(src, tinfo))
+        if (handle registered_inst = find_registered_python_instance(src, tinfo)) {
             return registered_inst;
+        }
 
         auto inst = reinterpret_steal<object>(make_new_instance(tinfo->type));
         auto wrapper = reinterpret_cast<instance *>(inst.ptr());
@@ -564,9 +603,9 @@ public:
                 break;
 
             case return_value_policy::copy:
-                if (copy_constructor)
+                if (copy_constructor) {
                     valueptr = copy_constructor(src);
-                else {
+                } else {
 #if defined(NDEBUG)
                     throw cast_error("return_value_policy = copy, but type is "
                                      "non-copyable! (compile in debug mode for details)");
@@ -581,11 +620,11 @@ public:
                 break;
 
             case return_value_policy::move:
-                if (move_constructor)
+                if (move_constructor) {
                     valueptr = move_constructor(src);
-                else if (copy_constructor)
+                } else if (copy_constructor) {
                     valueptr = copy_constructor(src);
-                else {
+                } else {
 #if defined(NDEBUG)
                     throw cast_error("return_value_policy = move, but type is neither "
                                      "movable nor copyable! "
@@ -650,8 +689,9 @@ public:
     }
     bool try_direct_conversions(handle src) {
         for (auto &converter : *typeinfo->direct_conversions) {
-            if (converter(src.ptr(), value))
+            if (converter(src.ptr(), value)) {
                 return true;
+            }
         }
         return false;
     }
@@ -659,8 +699,9 @@ public:
 
     PYBIND11_NOINLINE static void *local_load(PyObject *src, const type_info *ti) {
         auto caster = type_caster_generic(ti);
-        if (caster.load(src, false))
+        if (caster.load(src, false)) {
             return caster.value;
+        }
         return nullptr;
     }
 
@@ -669,14 +710,16 @@ public:
     PYBIND11_NOINLINE bool try_load_foreign_module_local(handle src) {
         constexpr auto *local_key = PYBIND11_MODULE_LOCAL_ID;
         const auto pytype = type::handle_of(src);
-        if (!hasattr(pytype, local_key))
+        if (!hasattr(pytype, local_key)) {
             return false;
+        }
 
         type_info *foreign_typeinfo = reinterpret_borrow<capsule>(getattr(pytype, local_key));
         // Only consider this foreign loader if actually foreign and is a loader of the correct cpp type
         if (foreign_typeinfo->module_local_load == &local_load
-            || (cpptype && !same_type(*cpptype, *foreign_typeinfo->cpptype)))
+            || (cpptype && !same_type(*cpptype, *foreign_typeinfo->cpptype))) {
             return false;
+        }
 
         if (auto result = foreign_typeinfo->module_local_load(src.ptr(), foreign_typeinfo)) {
             value = result;
@@ -690,8 +733,12 @@ public:
     // logic (without having to resort to virtual inheritance).
     template <typename ThisT>
     PYBIND11_NOINLINE bool load_impl(handle src, bool convert) {
-        if (!src) return false;
-        if (!typeinfo) return try_load_foreign_module_local(src);
+        if (!src) {
+            return false;
+        }
+        if (!typeinfo) {
+            return try_load_foreign_module_local(src);
+        }
 
         auto &this_ = static_cast<ThisT &>(*this);
         this_.check_holder_compat();
@@ -734,8 +781,9 @@ public:
             // Case 2c: C++ multiple inheritance is involved and we couldn't find an exact type match
             // in the registered bases, above, so try implicit casting (needed for proper C++ casting
             // when MI is involved).
-            if (this_.try_implicit_casts(src, convert))
+            if (this_.try_implicit_casts(src, convert)) {
                 return true;
+            }
         }
 
         // Perform an implicit conversion
@@ -747,8 +795,9 @@ public:
                     return true;
                 }
             }
-            if (this_.try_direct_conversions(src))
+            if (this_.try_direct_conversions(src)) {
                 return true;
+            }
         }
 
         // Failed to match local typeinfo. Try again with global.
@@ -767,7 +816,9 @@ public:
         // Custom converters didn't take None, now we convert None to nullptr.
         if (src.is_none()) {
            // Defer accepting None to other overloads (if we aren't in convert mode):
-           if (!convert) return false;
+           if (!convert) {
+               return false;
+           }
            value = nullptr;
            return true;
         }
@@ -907,8 +958,10 @@ public:
     explicit type_caster_base(const std::type_info &info) : type_caster_generic(info) { }
 
     static handle cast(const itype &src, return_value_policy policy, handle parent) {
-        if (policy == return_value_policy::automatic || policy == return_value_policy::automatic_reference)
+        if (policy == return_value_policy::automatic
+            || policy == return_value_policy::automatic_reference) {
             policy = return_value_policy::copy;
+        }
         return cast(&src, policy, parent);
     }
 
@@ -960,7 +1013,12 @@ public:
     // NOLINTNEXTLINE(google-explicit-constructor)
     operator itype*() { return (type *) value; }
     // NOLINTNEXTLINE(google-explicit-constructor)
-    operator itype&() { if (!value) throw reference_cast_error(); return *((itype *) value); }
+    operator itype&() {
+        if (!value) {
+            throw reference_cast_error();
+        }
+        return *((itype *) value);
+    }
 
 protected:
     using Constructor = void *(*)(const void *);
diff --git a/include/pybind11/detail/typeid.h b/include/pybind11/detail/typeid.h
index 39ba8ce0..53c166be 100644
--- a/include/pybind11/detail/typeid.h
+++ b/include/pybind11/detail/typeid.h
@@ -24,7 +24,9 @@ PYBIND11_NAMESPACE_BEGIN(detail)
 inline void erase_all(std::string &string, const std::string &search) {
     for (size_t pos = 0;;) {
         pos = string.find(search, pos);
-        if (pos == std::string::npos) break;
+        if (pos == std::string::npos) {
+            break;
+        }
         string.erase(pos, search.length());
     }
 }
@@ -34,8 +36,9 @@ PYBIND11_NOINLINE void clean_type_id(std::string &name) {
     int status = 0;
     std::unique_ptr<char, void (*)(void *)> res {
         abi::__cxa_demangle(name.c_str(), nullptr, nullptr, &status), std::free };
-    if (status == 0)
+    if (status == 0) {
         name = res.get();
+    }
 #else
     detail::erase_all(name, "class ");
     detail::erase_all(name, "struct ");
diff --git a/include/pybind11/eigen.h b/include/pybind11/eigen.h
index 696099fa..87f4e9f8 100644
--- a/include/pybind11/eigen.h
+++ b/include/pybind11/eigen.h
@@ -145,8 +145,9 @@ template <typename Type_> struct EigenProps {
     // (preferring the latter if it will fit in either, i.e. for a fully dynamic matrix type).
     static EigenConformable<row_major> conformable(const array &a) {
         const auto dims = a.ndim();
-        if (dims < 1 || dims > 2)
+        if (dims < 1 || dims > 2) {
             return false;
+        }
 
         if (dims == 2) { // Matrix type: require exact match (or dynamic)
 
@@ -155,9 +156,10 @@ template <typename Type_> struct EigenProps {
                 np_cols = a.shape(1),
                 np_rstride = a.strides(0) / static_cast<ssize_t>(sizeof(Scalar)),
                 np_cstride = a.strides(1) / static_cast<ssize_t>(sizeof(Scalar));
-            if ((PYBIND11_SILENCE_MSVC_C4127(fixed_rows) && np_rows != rows) ||
-                (PYBIND11_SILENCE_MSVC_C4127(fixed_cols) && np_cols != cols))
+            if ((PYBIND11_SILENCE_MSVC_C4127(fixed_rows) && np_rows != rows)
+                || (PYBIND11_SILENCE_MSVC_C4127(fixed_cols) && np_cols != cols)) {
                 return false;
+            }
 
             return {np_rows, np_cols, np_rstride, np_cstride};
         }
@@ -168,8 +170,9 @@ template <typename Type_> struct EigenProps {
               stride = a.strides(0) / static_cast<ssize_t>(sizeof(Scalar));
 
         if (vector) { // Eigen type is a compile-time vector
-            if (PYBIND11_SILENCE_MSVC_C4127(fixed) && size != n)
+            if (PYBIND11_SILENCE_MSVC_C4127(fixed) && size != n) {
                 return false; // Vector size mismatch
+            }
             return {rows == 1 ? 1 : n, cols == 1 ? 1 : n, stride};
         }
         if (fixed) {
@@ -179,10 +182,14 @@ template <typename Type_> struct EigenProps {
         if (fixed_cols) {
             // Since this isn't a vector, cols must be != 1.  We allow this only if it exactly
             // equals the number of elements (rows is Dynamic, and so 1 row is allowed).
-            if (cols != n) return false;
+            if (cols != n) {
+                return false;
+            }
             return {1, n, stride};
         } // Otherwise it's either fully dynamic, or column dynamic; both become a column vector
-            if (PYBIND11_SILENCE_MSVC_C4127(fixed_rows) && rows != n) return false;
+        if (PYBIND11_SILENCE_MSVC_C4127(fixed_rows) && rows != n) {
+            return false;
+        }
             return {n, 1, stride};
     }
 
@@ -213,14 +220,18 @@ template <typename Type_> struct EigenProps {
 template <typename props> handle eigen_array_cast(typename props::Type const &src, handle base = handle(), bool writeable = true) {
     constexpr ssize_t elem_size = sizeof(typename props::Scalar);
     array a;
-    if (props::vector)
+    if (props::vector) {
         a = array({ src.size() }, { elem_size * src.innerStride() }, src.data(), base);
-    else
-        a = array({ src.rows(), src.cols() }, { elem_size * src.rowStride(), elem_size * src.colStride() },
-                  src.data(), base);
+    } else {
+        a = array({src.rows(), src.cols()},
+                  {elem_size * src.rowStride(), elem_size * src.colStride()},
+                  src.data(),
+                  base);
+    }
 
-    if (!writeable)
+    if (!writeable) {
         array_proxy(a.ptr())->flags &= ~detail::npy_api::NPY_ARRAY_WRITEABLE_;
+    }
 
     return a.release();
 }
@@ -255,28 +266,35 @@ struct type_caster<Type, enable_if_t<is_eigen_dense_plain<Type>::value>> {
 
     bool load(handle src, bool convert) {
         // If we're in no-convert mode, only load if given an array of the correct type
-        if (!convert && !isinstance<array_t<Scalar>>(src))
+        if (!convert && !isinstance<array_t<Scalar>>(src)) {
             return false;
+        }
 
         // Coerce into an array, but don't do type conversion yet; the copy below handles it.
         auto buf = array::ensure(src);
 
-        if (!buf)
+        if (!buf) {
             return false;
+        }
 
         auto dims = buf.ndim();
-        if (dims < 1 || dims > 2)
+        if (dims < 1 || dims > 2) {
             return false;
+        }
 
         auto fits = props::conformable(buf);
-        if (!fits)
+        if (!fits) {
             return false;
+        }
 
         // Allocate the new type, then build a numpy reference into it
         value = Type(fits.rows, fits.cols);
         auto ref = reinterpret_steal<array>(eigen_ref_array<props>(value));
-        if (dims == 1) ref = ref.squeeze();
-        else if (ref.ndim() == 1) buf = buf.squeeze();
+        if (dims == 1) {
+            ref = ref.squeeze();
+        } else if (ref.ndim() == 1) {
+            buf = buf.squeeze();
+        }
 
         int result = detail::npy_api::get().PyArray_CopyInto_(ref.ptr(), buf.ptr());
 
@@ -323,14 +341,18 @@ public:
     }
     // lvalue reference return; default (automatic) becomes copy
     static handle cast(Type &src, return_value_policy policy, handle parent) {
-        if (policy == return_value_policy::automatic || policy == return_value_policy::automatic_reference)
+        if (policy == return_value_policy::automatic
+            || policy == return_value_policy::automatic_reference) {
             policy = return_value_policy::copy;
+        }
         return cast_impl(&src, policy, parent);
     }
     // const lvalue reference return; default (automatic) becomes copy
     static handle cast(const Type &src, return_value_policy policy, handle parent) {
-        if (policy == return_value_policy::automatic || policy == return_value_policy::automatic_reference)
+        if (policy == return_value_policy::automatic
+            || policy == return_value_policy::automatic_reference) {
             policy = return_value_policy::copy;
+        }
         return cast(&src, policy, parent);
     }
     // non-const pointer return
@@ -439,11 +461,14 @@ public:
 
             if (aref && (!need_writeable || aref.writeable())) {
                 fits = props::conformable(aref);
-                if (!fits) return false; // Incompatible dimensions
-                if (!fits.template stride_compatible<props>())
+                if (!fits) {
+                    return false; // Incompatible dimensions
+                }
+                if (!fits.template stride_compatible<props>()) {
                     need_copy = true;
-                else
+                } else {
                     copy_or_ref = std::move(aref);
+                }
             }
             else {
                 need_copy = true;
@@ -454,13 +479,18 @@ public:
             // We need to copy: If we need a mutable reference, or we're not supposed to convert
             // (either because we're in the no-convert overload pass, or because we're explicitly
             // instructed not to copy (via `py::arg().noconvert()`) we have to fail loading.
-            if (!convert || need_writeable) return false;
+            if (!convert || need_writeable) {
+                return false;
+            }
 
             Array copy = Array::ensure(src);
-            if (!copy) return false;
-            fits = props::conformable(copy);
-            if (!fits || !fits.template stride_compatible<props>())
+            if (!copy) {
                 return false;
+            }
+            fits = props::conformable(copy);
+            if (!fits || !fits.template stride_compatible<props>()) {
+                return false;
+            }
             copy_or_ref = std::move(copy);
             loader_life_support::add_patient(copy_or_ref);
         }
@@ -550,8 +580,9 @@ struct type_caster<Type, enable_if_t<is_eigen_sparse<Type>::value>> {
     static constexpr bool rowMajor = Type::IsRowMajor;
 
     bool load(handle src, bool) {
-        if (!src)
+        if (!src) {
             return false;
+        }
 
         auto obj = reinterpret_borrow<object>(src);
         object sparse_module = module_::import("scipy.sparse");
@@ -572,8 +603,9 @@ struct type_caster<Type, enable_if_t<is_eigen_sparse<Type>::value>> {
         auto shape = pybind11::tuple((pybind11::object) obj.attr("shape"));
         auto nnz = obj.attr("nnz").cast<Index>();
 
-        if (!values || !innerIndices || !outerIndices)
+        if (!values || !innerIndices || !outerIndices) {
             return false;
+        }
 
         value = EigenMapSparseMatrix<Scalar,
                                      Type::Flags & (Eigen::RowMajor | Eigen::ColMajor),
diff --git a/include/pybind11/embed.h b/include/pybind11/embed.h
index 9ab1ce9c..9da2862f 100644
--- a/include/pybind11/embed.h
+++ b/include/pybind11/embed.h
@@ -77,12 +77,14 @@ struct embedded_module {
     using init_t = void (*)();
 #endif
     embedded_module(const char *name, init_t init) {
-        if (Py_IsInitialized() != 0)
+        if (Py_IsInitialized() != 0) {
             pybind11_fail("Can't add new modules after the interpreter has been initialized");
+        }
 
         auto result = PyImport_AppendInittab(name, init);
-        if (result == -1)
+        if (result == -1) {
             pybind11_fail("Insufficient memory to add a new module");
+        }
     }
 };
 
@@ -135,8 +137,9 @@ inline void set_interpreter_argv(int argc, const char *const *argv, bool add_pro
 
     const char *const empty_argv[]{"\0"};
     const char *const *safe_argv = special_case ? empty_argv : argv;
-    if (special_case)
+    if (special_case) {
         argc = 1;
+    }
 
     auto argv_size = static_cast<size_t>(argc);
 #if PY_MAJOR_VERSION >= 3
@@ -192,8 +195,9 @@ inline void initialize_interpreter(bool init_signal_handlers = true,
                                    int argc = 0,
                                    const char *const *argv = nullptr,
                                    bool add_program_dir_to_path = true) {
-    if (Py_IsInitialized() != 0)
+    if (Py_IsInitialized() != 0) {
         pybind11_fail("The interpreter is already running");
+    }
 
     Py_InitializeEx(init_signal_handlers ? 1 : 0);
 
@@ -244,8 +248,9 @@ inline void finalize_interpreter() {
     // during destruction), so we get the pointer-pointer here and check it after Py_Finalize().
     detail::internals **internals_ptr_ptr = detail::get_internals_pp();
     // It could also be stashed in builtins, so look there too:
-    if (builtins.contains(id) && isinstance<capsule>(builtins[id]))
+    if (builtins.contains(id) && isinstance<capsule>(builtins[id])) {
         internals_ptr_ptr = capsule(builtins[id]);
+    }
 
     Py_Finalize();
 
@@ -285,8 +290,9 @@ public:
     scoped_interpreter &operator=(scoped_interpreter &&) = delete;
 
     ~scoped_interpreter() {
-        if (is_valid)
+        if (is_valid) {
             finalize_interpreter();
+        }
     }
 
 private:
diff --git a/include/pybind11/eval.h b/include/pybind11/eval.h
index 4248551e..8009fbde 100644
--- a/include/pybind11/eval.h
+++ b/include/pybind11/eval.h
@@ -46,8 +46,9 @@ enum eval_mode {
 
 template <eval_mode mode = eval_expr>
 object eval(const str &expr, object global = globals(), object local = object()) {
-    if (!local)
+    if (!local) {
         local = global;
+    }
 
     detail::ensure_builtins_in_globals(global);
 
@@ -64,8 +65,9 @@ object eval(const str &expr, object global = globals(), object local = object())
     }
 
     PyObject *result = PyRun_String(buffer.c_str(), start, global.ptr(), local.ptr());
-    if (!result)
+    if (!result) {
         throw error_already_set();
+    }
     return reinterpret_steal<object>(result);
 }
 
@@ -102,8 +104,9 @@ object eval_file(str) {
 #else
 template <eval_mode mode = eval_statements>
 object eval_file(str fname, object global = globals(), object local = object()) {
-    if (!local)
+    if (!local) {
         local = global;
+    }
 
     detail::ensure_builtins_in_globals(global);
 
@@ -154,8 +157,9 @@ object eval_file(str fname, object global = globals(), object local = object())
                                     local.ptr(), closeFile);
 #endif
 
-    if (!result)
+    if (!result) {
         throw error_already_set();
+    }
     return reinterpret_steal<object>(result);
 }
 #endif
diff --git a/include/pybind11/functional.h b/include/pybind11/functional.h
index 7912aef1..9e2f0b5b 100644
--- a/include/pybind11/functional.h
+++ b/include/pybind11/functional.h
@@ -25,12 +25,15 @@ public:
     bool load(handle src, bool convert) {
         if (src.is_none()) {
             // Defer accepting None to other overloads (if we aren't in convert mode):
-            if (!convert) return false;
+            if (!convert) {
+                return false;
+            }
             return true;
         }
 
-        if (!isinstance<function>(src))
+        if (!isinstance<function>(src)) {
             return false;
+        }
 
         auto func = reinterpret_borrow<function>(src);
 
@@ -104,12 +107,14 @@ public:
 
     template <typename Func>
     static handle cast(Func &&f_, return_value_policy policy, handle /* parent */) {
-        if (!f_)
+        if (!f_) {
             return none().inc_ref();
+        }
 
         auto result = f_.template target<function_type>();
-        if (result)
+        if (result) {
             return cpp_function(*result, policy).release();
+        }
         return cpp_function(std::forward<Func>(f_), policy).release();
     }
 
diff --git a/include/pybind11/gil.h b/include/pybind11/gil.h
index b73aaa3f..b493fd14 100644
--- a/include/pybind11/gil.h
+++ b/include/pybind11/gil.h
@@ -99,8 +99,9 @@ public:
                     pybind11_fail("scoped_acquire::dec_ref(): internal error!");
             #endif
             PyThreadState_Clear(tstate);
-            if (active)
+            if (active) {
                 PyThreadState_DeleteCurrent();
+            }
             PYBIND11_TLS_DELETE_VALUE(detail::get_internals().tstate);
             release = false;
         }
@@ -117,8 +118,9 @@ public:
 
     PYBIND11_NOINLINE ~gil_scoped_acquire() {
         dec_ref();
-        if (release)
-           PyEval_SaveThread();
+        if (release) {
+            PyEval_SaveThread();
+        }
     }
 private:
     PyThreadState *tstate = nullptr;
@@ -150,11 +152,13 @@ public:
     }
 
     ~gil_scoped_release() {
-        if (!tstate)
+        if (!tstate) {
             return;
+        }
         // `PyEval_RestoreThread()` should not be called if runtime is finalizing
-        if (active)
+        if (active) {
             PyEval_RestoreThread(tstate);
+        }
         if (disassoc) {
             auto key = detail::get_internals().tstate;
             PYBIND11_TLS_REPLACE_VALUE(key, tstate);
diff --git a/include/pybind11/iostream.h b/include/pybind11/iostream.h
index 95449a07..8c0772c2 100644
--- a/include/pybind11/iostream.h
+++ b/include/pybind11/iostream.h
@@ -71,23 +71,26 @@ private:
             return static_cast<unsigned char>(c) <= 0xEF;
         };
         // If the last character is ASCII, there are no incomplete code points
-        if (is_ascii(*rpptr))
+        if (is_ascii(*rpptr)) {
             return 0;
+        }
         // Otherwise, work back from the end of the buffer and find the first
         // UTF-8 leading byte
         const auto rpend   = rbase - rpptr >= 3 ? rpptr + 3 : rbase;
         const auto leading = std::find_if(rpptr, rpend, is_leading);
-        if (leading == rbase)
+        if (leading == rbase) {
             return 0;
+        }
         const auto dist    = static_cast<size_t>(leading - rpptr);
         size_t remainder   = 0;
 
-        if (dist == 0)
+        if (dist == 0) {
             remainder = 1; // 1-byte code point is impossible
-        else if (dist == 1)
+        } else if (dist == 1) {
             remainder = is_leading_2b(*leading) ? 0 : dist + 1;
-        else if (dist == 2)
+        } else if (dist == 2) {
             remainder = is_leading_3b(*leading) ? 0 : dist + 1;
+        }
         // else if (dist >= 3), at least 4 bytes before encountering an UTF-8
         // leading byte, either no remainder or invalid UTF-8.
         // Invalid UTF-8 will cause an exception later when converting
@@ -110,8 +113,9 @@ private:
             }
 
             // Copy the remainder at the end of the buffer to the beginning:
-            if (remainder > 0)
+            if (remainder > 0) {
                 std::memmove(pbase(), pptr() - remainder, remainder);
+            }
             setp(pbase(), epptr());
             pbump(static_cast<int>(remainder));
         }
@@ -223,10 +227,12 @@ public:
         : do_stdout_(do_stdout), do_stderr_(do_stderr) {}
 
     void enter() {
-        if (do_stdout_)
+        if (do_stdout_) {
             redirect_stdout.reset(new scoped_ostream_redirect());
-        if (do_stderr_)
+        }
+        if (do_stderr_) {
             redirect_stderr.reset(new scoped_estream_redirect());
+        }
     }
 
     void exit() {
diff --git a/include/pybind11/numpy.h b/include/pybind11/numpy.h
index 95a743ac..40bbff8e 100644
--- a/include/pybind11/numpy.h
+++ b/include/pybind11/numpy.h
@@ -87,10 +87,12 @@ struct numpy_internals {
 
     numpy_type_info *get_type_info(const std::type_info& tinfo, bool throw_if_missing = true) {
         auto it = registered_dtypes.find(std::type_index(tinfo));
-        if (it != registered_dtypes.end())
+        if (it != registered_dtypes.end()) {
             return &(it->second);
-        if (throw_if_missing)
+        }
+        if (throw_if_missing) {
             pybind11_fail(std::string("NumPy type info missing for ") + tinfo.name());
+        }
         return nullptr;
     }
 
@@ -105,8 +107,9 @@ PYBIND11_NOINLINE void load_numpy_internals(numpy_internals* &ptr) {
 
 inline numpy_internals& get_numpy_internals() {
     static numpy_internals* ptr = nullptr;
-    if (!ptr)
+    if (!ptr) {
         load_numpy_internals(ptr);
+    }
     return *ptr;
 }
 
@@ -235,8 +238,9 @@ private:
         npy_api api;
 #define DECL_NPY_API(Func) api.Func##_ = (decltype(api.Func##_)) api_ptr[API_##Func];
         DECL_NPY_API(PyArray_GetNDArrayCFeatureVersion);
-        if (api.PyArray_GetNDArrayCFeatureVersion_() < 0x7)
+        if (api.PyArray_GetNDArrayCFeatureVersion_() < 0x7) {
             pybind11_fail("pybind11 numpy support requires numpy >= 1.7.0");
+        }
         DECL_NPY_API(PyArray_Type);
         DECL_NPY_API(PyVoidArrType_Type);
         DECL_NPY_API(PyArrayDescr_Type);
@@ -491,8 +495,9 @@ public:
     /// This is essentially the same as calling numpy.dtype(args) in Python.
     static dtype from_args(object args) {
         PyObject *ptr = nullptr;
-        if ((detail::npy_api::get().PyArray_DescrConverter_(args.ptr(), &ptr) == 0) || !ptr)
+        if ((detail::npy_api::get().PyArray_DescrConverter_(args.ptr(), &ptr) == 0) || !ptr) {
             throw error_already_set();
+        }
         return reinterpret_steal<dtype>(ptr);
     }
 
@@ -536,8 +541,9 @@ private:
     dtype strip_padding(ssize_t itemsize) {
         // Recursively strip all void fields with empty names that are generated for
         // padding fields (as of NumPy v1.11).
-        if (!has_fields())
+        if (!has_fields()) {
             return *this;
+        }
 
         struct field_descr { PYBIND11_STR_TYPE name; object format; pybind11::int_ offset; };
         std::vector<field_descr> field_descriptors;
@@ -547,8 +553,9 @@ private:
             auto name = spec[0].cast<pybind11::str>();
             auto format = spec[1].cast<tuple>()[0].cast<dtype>();
             auto offset = spec[1].cast<tuple>()[1].cast<pybind11::int_>();
-            if ((len(name) == 0u) && format.kind() == 'V')
+            if ((len(name) == 0u) && format.kind() == 'V') {
                 continue;
+            }
             field_descriptors.push_back({(PYBIND11_STR_TYPE) name, format.strip_padding(format.itemsize()), offset});
         }
 
@@ -586,22 +593,25 @@ public:
     array(const pybind11::dtype &dt, ShapeContainer shape, StridesContainer strides,
           const void *ptr = nullptr, handle base = handle()) {
 
-        if (strides->empty())
+        if (strides->empty()) {
             *strides = detail::c_strides(*shape, dt.itemsize());
+        }
 
         auto ndim = shape->size();
-        if (ndim != strides->size())
+        if (ndim != strides->size()) {
             pybind11_fail("NumPy: shape ndim doesn't match strides ndim");
+        }
         auto descr = dt;
 
         int flags = 0;
         if (base && ptr) {
-            if (isinstance<array>(base))
+            if (isinstance<array>(base)) {
                 /* Copy flags from base (except ownership bit) */
                 flags = reinterpret_borrow<array>(base).flags() & ~detail::npy_api::NPY_ARRAY_OWNDATA_;
-            else
+            } else {
                 /* Writable by default, easy to downgrade later on if needed */
                 flags = detail::npy_api::NPY_ARRAY_WRITEABLE_;
+            }
         }
 
         auto &api = detail::npy_api::get();
@@ -611,8 +621,9 @@ public:
             reinterpret_cast<Py_intptr_t*>(shape->data()),
             reinterpret_cast<Py_intptr_t*>(strides->data()),
             const_cast<void *>(ptr), flags, nullptr));
-        if (!tmp)
+        if (!tmp) {
             throw error_already_set();
+        }
         if (ptr) {
             if (base) {
                 api.PyArray_SetBaseObject_(tmp.ptr(), base.inc_ref().ptr());
@@ -681,8 +692,9 @@ public:
 
     /// Dimension along a given axis
     ssize_t shape(ssize_t dim) const {
-        if (dim >= ndim())
+        if (dim >= ndim()) {
             fail_dim_check(dim, "invalid axis");
+        }
         return shape()[dim];
     }
 
@@ -693,8 +705,9 @@ public:
 
     /// Stride along a given axis
     ssize_t strides(ssize_t dim) const {
-        if (dim >= ndim())
+        if (dim >= ndim()) {
             fail_dim_check(dim, "invalid axis");
+        }
         return strides()[dim];
     }
 
@@ -730,8 +743,9 @@ public:
     /// Byte offset from beginning of the array to a given index (full or partial).
     /// May throw if the index would lead to out of bounds access.
     template<typename... Ix> ssize_t offset_at(Ix... index) const {
-        if ((ssize_t) sizeof...(index) > ndim())
+        if ((ssize_t) sizeof...(index) > ndim()) {
             fail_dim_check(sizeof...(index), "too many indices for an array");
+        }
         return byte_offset(ssize_t(index)...);
     }
 
@@ -750,9 +764,11 @@ public:
      * and the caller must take care not to access invalid dimensions or dimension indices.
      */
     template <typename T, ssize_t Dims = -1> detail::unchecked_mutable_reference<T, Dims> mutable_unchecked() & {
-        if (PYBIND11_SILENCE_MSVC_C4127(Dims >= 0) && ndim() != Dims)
-            throw std::domain_error("array has incorrect number of dimensions: " + std::to_string(ndim()) +
-                    "; expected " + std::to_string(Dims));
+        if (PYBIND11_SILENCE_MSVC_C4127(Dims >= 0) && ndim() != Dims) {
+            throw std::domain_error("array has incorrect number of dimensions: "
+                                    + std::to_string(ndim()) + "; expected "
+                                    + std::to_string(Dims));
+        }
         return detail::unchecked_mutable_reference<T, Dims>(mutable_data(), shape(), strides(), ndim());
     }
 
@@ -764,9 +780,11 @@ public:
      * invalid dimensions or dimension indices.
      */
     template <typename T, ssize_t Dims = -1> detail::unchecked_reference<T, Dims> unchecked() const & {
-        if (PYBIND11_SILENCE_MSVC_C4127(Dims >= 0) && ndim() != Dims)
-            throw std::domain_error("array has incorrect number of dimensions: " + std::to_string(ndim()) +
-                    "; expected " + std::to_string(Dims));
+        if (PYBIND11_SILENCE_MSVC_C4127(Dims >= 0) && ndim() != Dims) {
+            throw std::domain_error("array has incorrect number of dimensions: "
+                                    + std::to_string(ndim()) + "; expected "
+                                    + std::to_string(Dims));
+        }
         return detail::unchecked_reference<T, Dims>(data(), shape(), strides(), ndim());
     }
 
@@ -789,7 +807,9 @@ public:
         auto new_array = reinterpret_steal<object>(
             detail::npy_api::get().PyArray_Resize_(m_ptr, &d, int(refcheck), -1)
         );
-        if (!new_array) throw error_already_set();
+        if (!new_array) {
+            throw error_already_set();
+        }
         if (isinstance<array>(new_array)) { *this = std::move(new_array); }
     }
 
@@ -824,8 +844,9 @@ public:
     /// In case of an error, nullptr is returned and the Python error is cleared.
     static array ensure(handle h, int ExtraFlags = 0) {
         auto result = reinterpret_steal<array>(raw_array(h.ptr(), ExtraFlags));
-        if (!result)
+        if (!result) {
             PyErr_Clear();
+        }
         return result;
     }
 
@@ -843,8 +864,9 @@ protected:
     }
 
     void check_writeable() const {
-        if (!writeable())
+        if (!writeable()) {
             throw std::domain_error("array is not writeable");
+        }
     }
 
     template<typename... Ix> void check_dimensions(Ix... index) const {
@@ -890,13 +912,19 @@ public:
 
     PYBIND11_DEPRECATED("Use array_t<T>::ensure() instead")
     array_t(handle h, bool is_borrowed) : array(raw_array_t(h.ptr()), stolen_t{}) {
-        if (!m_ptr) PyErr_Clear();
-        if (!is_borrowed) Py_XDECREF(h.ptr());
+        if (!m_ptr) {
+            PyErr_Clear();
+        }
+        if (!is_borrowed) {
+            Py_XDECREF(h.ptr());
+        }
     }
 
     // NOLINTNEXTLINE(google-explicit-constructor)
     array_t(const object &o) : array(raw_array_t(o.ptr()), stolen_t{}) {
-        if (!m_ptr) throw error_already_set();
+        if (!m_ptr) {
+            throw error_already_set();
+        }
     }
 
     explicit array_t(const buffer_info& info, handle base = handle()) : array(info, base) { }
@@ -933,15 +961,17 @@ public:
 
     // Reference to element at a given index
     template<typename... Ix> const T& at(Ix... index) const {
-        if ((ssize_t) sizeof...(index) != ndim())
+        if ((ssize_t) sizeof...(index) != ndim()) {
             fail_dim_check(sizeof...(index), "index dimension mismatch");
+        }
         return *(static_cast<const T*>(array::data()) + byte_offset(ssize_t(index)...) / itemsize());
     }
 
     // Mutable reference to element at a given index
     template<typename... Ix> T& mutable_at(Ix... index) {
-        if ((ssize_t) sizeof...(index) != ndim())
+        if ((ssize_t) sizeof...(index) != ndim()) {
             fail_dim_check(sizeof...(index), "index dimension mismatch");
+        }
         return *(static_cast<T*>(array::mutable_data()) + byte_offset(ssize_t(index)...) / itemsize());
     }
 
@@ -970,8 +1000,9 @@ public:
     /// it).  In case of an error, nullptr is returned and the Python error is cleared.
     static array_t ensure(handle h) {
         auto result = reinterpret_steal<array_t>(raw_array_t(h.ptr()));
-        if (!result)
+        if (!result) {
             PyErr_Clear();
+        }
         return result;
     }
 
@@ -1032,8 +1063,9 @@ struct pyobject_caster<array_t<T, ExtraFlags>> {
     using type = array_t<T, ExtraFlags>;
 
     bool load(handle src, bool convert) {
-        if (!convert && !type::check_(src))
+        if (!convert && !type::check_(src)) {
             return false;
+        }
         value = type::ensure(src);
         return static_cast<bool>(value);
     }
@@ -1098,8 +1130,9 @@ public:
     static constexpr int value = values[detail::is_fmt_numeric<T>::index];
 
     static pybind11::dtype dtype() {
-        if (auto ptr = npy_api::get().PyArray_DescrFromType_(value))
+        if (auto ptr = npy_api::get().PyArray_DescrFromType_(value)) {
             return reinterpret_steal<pybind11::dtype>(ptr);
+        }
         pybind11_fail("Unsupported buffer format!");
     }
 };
@@ -1147,8 +1180,9 @@ PYBIND11_NOINLINE void register_structured_dtype(
     bool (*direct_converter)(PyObject *, void *&)) {
 
     auto& numpy_internals = get_numpy_internals();
-    if (numpy_internals.get_type_info(tinfo, false))
+    if (numpy_internals.get_type_info(tinfo, false)) {
         pybind11_fail("NumPy: dtype is already registered");
+    }
 
     // Use ordered fields because order matters as of NumPy 1.14:
     // https://docs.scipy.org/doc/numpy/release.html#multiple-field-indexing-assignment-of-structured-arrays
@@ -1158,9 +1192,10 @@ PYBIND11_NOINLINE void register_structured_dtype(
 
     list names, formats, offsets;
     for (auto& field : ordered_fields) {
-        if (!field.descr)
-            pybind11_fail(std::string("NumPy: unsupported field dtype: `") +
-                            field.name + "` @ " + tinfo.name());
+        if (!field.descr) {
+            pybind11_fail(std::string("NumPy: unsupported field dtype: `") + field.name + "` @ "
+                          + tinfo.name());
+        }
         names.append(PYBIND11_STR_TYPE(field.name));
         formats.append(field.descr);
         offsets.append(pybind11::int_(field.offset));
@@ -1186,21 +1221,24 @@ PYBIND11_NOINLINE void register_structured_dtype(
     // isn't guaranteed to work due to https://github.com/numpy/numpy/issues/9049
     oss << "^T{";
     for (auto& field : ordered_fields) {
-        if (field.offset > offset)
+        if (field.offset > offset) {
             oss << (field.offset - offset) << 'x';
+        }
         oss << field.format << ':' << field.name << ':';
         offset = field.offset + field.size;
     }
-    if (itemsize > offset)
+    if (itemsize > offset) {
         oss << (itemsize - offset) << 'x';
+    }
     oss << '}';
     auto format_str = oss.str();
 
     // Sanity check: verify that NumPy properly parses our buffer format string
     auto& api = npy_api::get();
     auto arr =  array(buffer_info(nullptr, itemsize, format_str, 1));
-    if (!api.PyArray_EquivTypes_(dtype_ptr, arr.dtype().ptr()))
+    if (!api.PyArray_EquivTypes_(dtype_ptr, arr.dtype().ptr())) {
         pybind11_fail("NumPy: invalid buffer descriptor!");
+    }
 
     auto tindex = std::type_index(tinfo);
     numpy_internals.registered_dtypes[tindex] = { dtype_ptr, format_str };
@@ -1234,8 +1272,9 @@ private:
 
     static bool direct_converter(PyObject *obj, void*& value) {
         auto& api = npy_api::get();
-        if (!PyObject_TypeCheck(obj, api.PyVoidArrType_Type_))
+        if (!PyObject_TypeCheck(obj, api.PyVoidArrType_Type_)) {
             return false;
+        }
         if (auto descr = reinterpret_steal<object>(api.PyArray_DescrFromScalar_(obj))) {
             if (api.PyArray_EquivTypes_(dtype_ptr(), descr.ptr())) {
                 value = ((PyVoidScalarObject_Proxy *) obj)->obval;
@@ -1363,12 +1402,14 @@ public:
           m_common_iterator() {
 
         // Manual copy to avoid conversion warning if using std::copy
-        for (size_t i = 0; i < shape.size(); ++i)
+        for (size_t i = 0; i < shape.size(); ++i) {
             m_shape[i] = shape[i];
+        }
 
         container_type strides(shape.size());
-        for (size_t i = 0; i < N; ++i)
+        for (size_t i = 0; i < N; ++i) {
             init_common_iterator(buffers[i], shape, m_common_iterator[i], strides);
+        }
     }
 
     multi_array_iterator& operator++() {
@@ -1401,10 +1442,11 @@ private:
         auto strides_iter = strides.rbegin();
 
         while (buffer_shape_iter != buffer.shape.rend()) {
-            if (*shape_iter == *buffer_shape_iter)
+            if (*shape_iter == *buffer_shape_iter) {
                 *strides_iter = *buffer_strides_iter;
-            else
+            } else {
                 *strides_iter = 0;
+            }
 
             ++buffer_shape_iter;
             ++buffer_strides_iter;
@@ -1417,8 +1459,9 @@ private:
     }
 
     void increment_common_iterator(size_t dim) {
-        for (auto &iter : m_common_iterator)
+        for (auto &iter : m_common_iterator) {
             iter.increment(dim);
+        }
     }
 
     container_type m_shape;
@@ -1451,26 +1494,30 @@ broadcast_trivial broadcast(const std::array<buffer_info, N> &buffers, ssize_t &
             auto &dim_size_out = *res_iter;
 
             // Each input dimension can either be 1 or `n`, but `n` values must match across buffers
-            if (dim_size_out == 1)
+            if (dim_size_out == 1) {
                 dim_size_out = dim_size_in;
-            else if (dim_size_in != 1 && dim_size_in != dim_size_out)
+            } else if (dim_size_in != 1 && dim_size_in != dim_size_out) {
                 pybind11_fail("pybind11::vectorize: incompatible size/dimension of inputs!");
+            }
         }
     }
 
     bool trivial_broadcast_c = true;
     bool trivial_broadcast_f = true;
     for (size_t i = 0; i < N && (trivial_broadcast_c || trivial_broadcast_f); ++i) {
-        if (buffers[i].size == 1)
+        if (buffers[i].size == 1) {
             continue;
+        }
 
         // Require the same number of dimensions:
-        if (buffers[i].ndim != ndim)
+        if (buffers[i].ndim != ndim) {
             return broadcast_trivial::non_trivial;
+        }
 
         // Require all dimensions be full-size:
-        if (!std::equal(buffers[i].shape.cbegin(), buffers[i].shape.cend(), shape.cbegin()))
+        if (!std::equal(buffers[i].shape.cbegin(), buffers[i].shape.cend(), shape.cbegin())) {
             return broadcast_trivial::non_trivial;
+        }
 
         // Check for C contiguity (but only if previous inputs were also C contiguous)
         if (trivial_broadcast_c) {
@@ -1478,10 +1525,11 @@ broadcast_trivial broadcast(const std::array<buffer_info, N> &buffers, ssize_t &
             auto end = buffers[i].shape.crend();
             for (auto shape_iter = buffers[i].shape.crbegin(), stride_iter = buffers[i].strides.crbegin();
                     trivial_broadcast_c && shape_iter != end; ++shape_iter, ++stride_iter) {
-                if (expect_stride == *stride_iter)
+                if (expect_stride == *stride_iter) {
                     expect_stride *= *shape_iter;
-                else
+                } else {
                     trivial_broadcast_c = false;
+                }
             }
         }
 
@@ -1491,10 +1539,11 @@ broadcast_trivial broadcast(const std::array<buffer_info, N> &buffers, ssize_t &
             auto end = buffers[i].shape.cend();
             for (auto shape_iter = buffers[i].shape.cbegin(), stride_iter = buffers[i].strides.cbegin();
                     trivial_broadcast_f && shape_iter != end; ++shape_iter, ++stride_iter) {
-                if (expect_stride == *stride_iter)
+                if (expect_stride == *stride_iter) {
                     expect_stride *= *shape_iter;
-                else
+                } else {
                     trivial_broadcast_f = false;
+                }
             }
         }
     }
@@ -1527,8 +1576,9 @@ struct vectorize_returned_array {
     using Type = array_t<Return>;
 
     static Type create(broadcast_trivial trivial, const std::vector<ssize_t> &shape) {
-        if (trivial == broadcast_trivial::f_trivial)
+        if (trivial == broadcast_trivial::f_trivial) {
             return array_t<Return, array::f_style>(shape);
+        }
         return array_t<Return>(shape);
     }
 
@@ -1644,14 +1694,17 @@ private:
 
         auto result = returned_array::create(trivial, shape);
 
-        if (size == 0) return std::move(result);
+        if (size == 0) {
+            return std::move(result);
+        }
 
         /* Call the function */
         auto mutable_data = returned_array::mutable_data(result);
-        if (trivial == broadcast_trivial::non_trivial)
+        if (trivial == broadcast_trivial::non_trivial) {
             apply_broadcast(buffers, params, mutable_data, size, shape, i_seq, vi_seq, bi_seq);
-        else
+        } else {
             apply_trivial(buffers, params, mutable_data, size, i_seq, vi_seq, bi_seq);
+        }
 
         return std::move(result);
     }
@@ -1675,7 +1728,9 @@ private:
 
         for (size_t i = 0; i < size; ++i) {
             returned_array::call(out, i, f, *reinterpret_cast<param_n_t<Index> *>(params[Index])...);
-            for (auto &x : vecparams) x.first += x.second;
+            for (auto &x : vecparams) {
+                x.first += x.second;
+            }
         }
     }
 
diff --git a/include/pybind11/pybind11.h b/include/pybind11/pybind11.h
index b64d4268..14e84513 100644
--- a/include/pybind11/pybind11.h
+++ b/include/pybind11/pybind11.h
@@ -212,8 +212,9 @@ protected:
             cast_in args_converter;
 
             /* Try to cast the function arguments into the C++ domain */
-            if (!args_converter.load_args(call))
+            if (!args_converter.load_args(call)) {
                 return PYBIND11_TRY_NEXT_OVERLOAD;
+            }
 
             /* Invoke call policy pre-call hook */
             process_attributes<Extra...>::precall(call);
@@ -286,8 +287,9 @@ protected:
     class strdup_guard {
     public:
         ~strdup_guard() {
-            for (auto s : strings)
+            for (auto s : strings) {
                 std::free(s);
+            }
         }
         char *operator()(const char *s) {
             auto t = PYBIND11_COMPAT_STRDUP(s);
@@ -318,14 +320,18 @@ protected:
 
         /* Create copies of all referenced C-style strings */
         rec->name = guarded_strdup(rec->name ? rec->name : "");
-        if (rec->doc) rec->doc = guarded_strdup(rec->doc);
+        if (rec->doc) {
+            rec->doc = guarded_strdup(rec->doc);
+        }
         for (auto &a: rec->args) {
-            if (a.name)
+            if (a.name) {
                 a.name = guarded_strdup(a.name);
-            if (a.descr)
+            }
+            if (a.descr) {
                 a.descr = guarded_strdup(a.descr);
-            else if (a.value)
+            } else if (a.value) {
                 a.descr = guarded_strdup(repr(a.value).cast<std::string>().c_str());
+            }
         }
 
         rec->is_constructor = (std::strcmp(rec->name, "__init__") == 0)
@@ -355,12 +361,14 @@ protected:
             if (c == '{') {
                 // Write arg name for everything except *args and **kwargs.
                 is_starred = *(pc + 1) == '*';
-                if (is_starred)
+                if (is_starred) {
                     continue;
+                }
                 // Separator for keyword-only arguments, placed before the kw
                 // arguments start (unless we are already putting an *args)
-                if (!rec->has_args && arg_index == rec->nargs_pos)
+                if (!rec->has_args && arg_index == rec->nargs_pos) {
                     signature += "*, ";
+                }
                 if (arg_index < rec->args.size() && rec->args[arg_index].name) {
                     signature += rec->args[arg_index].name;
                 } else if (arg_index == 0 && rec->is_method) {
@@ -377,14 +385,17 @@ protected:
                 }
                 // Separator for positional-only arguments (placed after the
                 // argument, rather than before like *
-                if (rec->nargs_pos_only > 0 && (arg_index + 1) == rec->nargs_pos_only)
+                if (rec->nargs_pos_only > 0 && (arg_index + 1) == rec->nargs_pos_only) {
                     signature += ", /";
-                if (!is_starred)
+                }
+                if (!is_starred) {
                     arg_index++;
+                }
             } else if (c == '%') {
                 const std::type_info *t = types[type_index++];
-                if (!t)
+                if (!t) {
                     pybind11_fail("Internal error while parsing type signature (1)");
+                }
                 if (auto tinfo = detail::get_type_info(*t)) {
                     handle th((PyObject *) tinfo->type);
                     signature +=
@@ -406,8 +417,9 @@ protected:
             }
         }
 
-        if (arg_index != args - rec->has_args - rec->has_kwargs || types[type_index] != nullptr)
+        if (arg_index != args - rec->has_args - rec->has_kwargs || types[type_index] != nullptr) {
             pybind11_fail("Internal error while parsing type signature (2)");
+        }
 
 #if PY_MAJOR_VERSION < 3
         if (std::strcmp(rec->name, "__next__") == 0) {
@@ -422,8 +434,9 @@ protected:
         rec->args.shrink_to_fit();
         rec->nargs = (std::uint16_t) args;
 
-        if (rec->sibling && PYBIND11_INSTANCE_METHOD_CHECK(rec->sibling.ptr()))
+        if (rec->sibling && PYBIND11_INSTANCE_METHOD_CHECK(rec->sibling.ptr())) {
             rec->sibling = PYBIND11_INSTANCE_METHOD_GET_FUNCTION(rec->sibling.ptr());
+        }
 
         detail::function_record *chain = nullptr, *chain_start = rec;
         if (rec->sibling) {
@@ -433,13 +446,16 @@ protected:
                 chain = (detail::function_record *) rec_capsule;
                 /* Never append a method to an overload chain of a parent class;
                    instead, hide the parent's overloads in this case */
-                if (!chain->scope.is(rec->scope))
+                if (!chain->scope.is(rec->scope)) {
                     chain = nullptr;
+                }
+            }
+            // Don't trigger for things like the default __init__, which are wrapper_descriptors
+            // that we are intentionally replacing
+            else if (!rec->sibling.is_none() && rec->name[0] != '_') {
+                pybind11_fail("Cannot overload existing non-function object \""
+                              + std::string(rec->name) + "\" with a function of the same name");
             }
-            // Don't trigger for things like the default __init__, which are wrapper_descriptors that we are intentionally replacing
-            else if (!rec->sibling.is_none() && rec->name[0] != '_')
-                pybind11_fail("Cannot overload existing non-function object \"" + std::string(rec->name) +
-                        "\" with a function of the same name");
         }
 
         if (!chain) {
@@ -466,21 +482,26 @@ protected:
             }
 
             m_ptr = PyCFunction_NewEx(rec->def, rec_capsule.ptr(), scope_module.ptr());
-            if (!m_ptr)
+            if (!m_ptr) {
                 pybind11_fail("cpp_function::cpp_function(): Could not allocate function object");
+            }
         } else {
             /* Append at the beginning or end of the overload chain */
             m_ptr = rec->sibling.ptr();
             inc_ref();
-            if (chain->is_method != rec->is_method)
-                pybind11_fail("overloading a method with both static and instance methods is not supported; "
-                    #if defined(NDEBUG)
-                        "compile in debug mode for more details"
+            if (chain->is_method != rec->is_method) {
+                pybind11_fail(
+                    "overloading a method with both static and instance methods is not supported; "
+#if defined(NDEBUG)
+                    "compile in debug mode for more details"
                     #else
-                        "error while attempting to bind " + std::string(rec->is_method ? "instance" : "static") + " method " +
-                        std::string(pybind11::str(rec->scope.attr("__name__"))) + "." + std::string(rec->name) + signature
+                    "error while attempting to bind "
+                    + std::string(rec->is_method ? "instance" : "static") + " method "
+                    + std::string(pybind11::str(rec->scope.attr("__name__"))) + "."
+                    + std::string(rec->name) + signature
                     #endif
                 );
+            }
 
             if (rec->prepend) {
                 // Beginning of chain; we need to replace the capsule's current head-of-the-chain
@@ -494,8 +515,9 @@ protected:
             } else {
                 // Or end of chain (normal behavior)
                 chain_start = chain;
-                while (chain->next)
+                while (chain->next) {
                     chain = chain->next;
+                }
                 chain->next = unique_rec.release();
                 guarded_strdup.release();
             }
@@ -515,9 +537,12 @@ protected:
         bool first_user_def = true;
         for (auto it = chain_start; it != nullptr; it = it->next) {
             if (options::show_function_signatures()) {
-                if (index > 0) signatures += "\n";
-                if (chain)
+                if (index > 0) {
+                    signatures += "\n";
+                }
+                if (chain) {
                     signatures += std::to_string(++index) + ". ";
+                }
                 signatures += rec->name;
                 signatures += it->signature;
                 signatures += "\n";
@@ -526,12 +551,19 @@ protected:
                 // If we're appending another docstring, and aren't printing function signatures, we
                 // need to append a newline first:
                 if (!options::show_function_signatures()) {
-                    if (first_user_def) first_user_def = false;
-                    else signatures += "\n";
+                    if (first_user_def) {
+                        first_user_def = false;
+                    } else {
+                        signatures += "\n";
+                    }
+                }
+                if (options::show_function_signatures()) {
+                    signatures += "\n";
                 }
-                if (options::show_function_signatures()) signatures += "\n";
                 signatures += it->doc;
-                if (options::show_function_signatures()) signatures += "\n";
+                if (options::show_function_signatures()) {
+                    signatures += "\n";
+                }
             }
         }
 
@@ -544,8 +576,10 @@ protected:
 
         if (rec->is_method) {
             m_ptr = PYBIND11_INSTANCE_METHOD_NEW(m_ptr, rec->scope.ptr());
-            if (!m_ptr)
-                pybind11_fail("cpp_function::cpp_function(): Could not allocate instance method object");
+            if (!m_ptr) {
+                pybind11_fail(
+                    "cpp_function::cpp_function(): Could not allocate instance method object");
+            }
             Py_DECREF(func);
         }
     }
@@ -560,8 +594,9 @@ protected:
 
         while (rec) {
             detail::function_record *next = rec->next;
-            if (rec->free_data)
+            if (rec->free_data) {
                 rec->free_data(rec);
+            }
             // During initialization, these strings might not have been copied yet,
             // so they cannot be freed. Once the function has been created, they can.
             // Check `make_function_record` for more details.
@@ -574,17 +609,19 @@ protected:
                     std::free(const_cast<char *>(arg.descr));
                 }
             }
-            for (auto &arg: rec->args)
+            for (auto &arg : rec->args) {
                 arg.value.dec_ref();
+            }
             if (rec->def) {
                 std::free(const_cast<char *>(rec->def->ml_doc));
                 // Python 3.9.0 decref's these in the wrong order; rec->def
                 // If loaded on 3.9.0, let these leak (use Python 3.9.1 at runtime to fix)
                 // See https://github.com/python/cpython/pull/22670
                 #if !defined(PYPY_VERSION) && PY_MAJOR_VERSION == 3 && PY_MINOR_VERSION == 9
-                    if (!is_zero)
-                        delete rec->def;
-                #else
+                if (!is_zero) {
+                    delete rec->def;
+                }
+#else
                     delete rec->def;
                 #endif
             }
@@ -621,8 +658,9 @@ protected:
 
             // If this value is already registered it must mean __init__ is invoked multiple times;
             // we really can't support that in C++, so just ignore the second __init__.
-            if (self_value_and_holder.instance_registered())
+            if (self_value_and_holder.instance_registered()) {
                 return none().release().ptr();
+            }
         }
 
         try {
@@ -658,15 +696,22 @@ protected:
 
                 const function_record &func = *it;
                 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
-                if (func.has_kwargs) --num_args; //  or py::kwargs)
+                if (func.has_args) {
+                    --num_args; // (but don't count py::args
+                }
+                if (func.has_kwargs) {
+                    --num_args; //  or py::kwargs)
+                }
                 size_t pos_args = func.nargs_pos;
 
-                if (!func.has_args && n_args_in > pos_args)
+                if (!func.has_args && n_args_in > pos_args) {
                     continue; // Too many positional arguments for this overload
+                }
 
-                if (n_args_in < pos_args && func.args.size() < pos_args)
-                    continue; // Not enough positional arguments given, and not enough defaults to fill in the blanks
+                if (n_args_in < pos_args && func.args.size() < pos_args) {
+                    continue; // Not enough positional arguments given, and not enough defaults to
+                              // fill in the blanks
+                }
 
                 function_call call(func, parent);
 
@@ -677,8 +722,9 @@ protected:
                 if (func.is_new_style_constructor) {
                     // The `value` may have been preallocated by an old-style `__init__`
                     // if it was a preceding candidate for overload resolution.
-                    if (self_value_and_holder)
+                    if (self_value_and_holder) {
                         self_value_and_holder.type->dealloc(self_value_and_holder);
+                    }
 
                     call.init_self = PyTuple_GET_ITEM(args_in, 0);
                     call.args.emplace_back(reinterpret_cast<PyObject *>(&self_value_and_holder));
@@ -703,8 +749,9 @@ protected:
                     call.args.push_back(arg);
                     call.args_convert.push_back(arg_rec ? arg_rec->convert : true);
                 }
-                if (bad_arg)
+                if (bad_arg) {
                     continue; // Maybe it was meant for another overload (issue #688)
+                }
 
                 // Keep track of how many position args we copied out in case we need to come back
                 // to copy the rest into a py::args argument.
@@ -725,12 +772,14 @@ protected:
                         if (value) {
                             call.args.push_back(value);
                             call.args_convert.push_back(arg_rec.convert);
-                        } else
+                        } else {
                             break;
+                        }
                     }
 
-                    if (args_copied < func.nargs_pos_only)
+                    if (args_copied < func.nargs_pos_only) {
                         continue; // Not enough defaults to fill the positional arguments
+                    }
                 }
 
                 // 2. Check kwargs and, failing that, defaults that may help complete the list
@@ -741,8 +790,9 @@ protected:
                         const auto &arg_rec = func.args[args_copied];
 
                         handle value;
-                        if (kwargs_in && arg_rec.name)
+                        if (kwargs_in && arg_rec.name) {
                             value = dict_getitemstring(kwargs.ptr(), arg_rec.name);
+                        }
 
                         if (value) {
                             // Consume a kwargs value
@@ -763,23 +813,27 @@ protected:
 
                         if (value) {
                             // If we're at the py::args index then first insert a stub for it to be replaced later
-                            if (func.has_args && call.args.size() == func.nargs_pos)
+                            if (func.has_args && call.args.size() == func.nargs_pos) {
                                 call.args.push_back(none());
+                            }
 
                             call.args.push_back(value);
                             call.args_convert.push_back(arg_rec.convert);
-                        }
-                        else
+                        } else {
                             break;
+                        }
                     }
 
-                    if (args_copied < num_args)
-                        continue; // Not enough arguments, defaults, or kwargs to fill the positional arguments
+                    if (args_copied < num_args) {
+                        continue; // Not enough arguments, defaults, or kwargs to fill the
+                                  // positional arguments
+                    }
                 }
 
                 // 3. Check everything was consumed (unless we have a kwargs arg)
-                if (kwargs && !kwargs.empty() && !func.has_kwargs)
+                if (kwargs && !kwargs.empty() && !func.has_kwargs) {
                     continue; // Unconsumed kwargs, but no py::kwargs argument to accept them
+                }
 
                 // 4a. If we have a py::args argument, create a new tuple with leftovers
                 if (func.has_args) {
@@ -797,18 +851,20 @@ protected:
                             extra_args[i] = PyTuple_GET_ITEM(args_in, positional_args_copied + i);
                         }
                     }
-                    if (call.args.size() <= func.nargs_pos)
+                    if (call.args.size() <= func.nargs_pos) {
                         call.args.push_back(extra_args);
-                    else
+                    } else {
                         call.args[func.nargs_pos] = extra_args;
+                    }
                     call.args_convert.push_back(false);
                     call.args_ref = std::move(extra_args);
                 }
 
                 // 4b. If we have a py::kwargs, pass on any remaining kwargs
                 if (func.has_kwargs) {
-                    if (!kwargs.ptr())
+                    if (!kwargs.ptr()) {
                         kwargs = dict(); // If we didn't get one, send an empty one
+                    }
                     call.args.push_back(kwargs);
                     call.args_convert.push_back(false);
                     call.kwargs_ref = std::move(kwargs);
@@ -838,8 +894,9 @@ protected:
                     result = PYBIND11_TRY_NEXT_OVERLOAD;
                 }
 
-                if (result.ptr() != PYBIND11_TRY_NEXT_OVERLOAD)
+                if (result.ptr() != PYBIND11_TRY_NEXT_OVERLOAD) {
                     break;
+                }
 
                 if (overloaded) {
                     // The (overloaded) call failed; if the call has at least one argument that
@@ -870,8 +927,9 @@ 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.
-                        if (!result)
+                        if (!result) {
                             it = &call.func;
+                        }
                         break;
                     }
                 }
@@ -923,8 +981,9 @@ protected:
         };
 
         if (result.ptr() == PYBIND11_TRY_NEXT_OVERLOAD) {
-            if (overloads->is_operator)
+            if (overloads->is_operator) {
                 return handle(Py_NotImplemented).inc_ref().ptr();
+            }
 
             std::string msg = std::string(overloads->name) + "(): incompatible " +
                 std::string(overloads->is_constructor ? "constructor" : "function") +
@@ -944,7 +1003,9 @@ protected:
                         size_t end = sig.find(", "), next = end + 2;
                         size_t ret = sig.rfind(" -> ");
                         // Or the ), if there is no comma:
-                        if (end >= sig.size()) next = end = sig.find(')');
+                        if (end >= sig.size()) {
+                            next = end = sig.find(')');
+                        }
                         if (start < end && next < sig.size()) {
                             msg.append(sig, start, end - start);
                             msg += '(';
@@ -953,7 +1014,9 @@ protected:
                         }
                     }
                 }
-                if (!wrote_sig) msg += it2->signature;
+                if (!wrote_sig) {
+                    msg += it2->signature;
+                }
 
                 msg += "\n";
             }
@@ -961,8 +1024,11 @@ protected:
             auto args_ = reinterpret_borrow<tuple>(args_in);
             bool some_args = false;
             for (size_t ti = overloads->is_constructor ? 1 : 0; ti < args_.size(); ++ti) {
-                if (!some_args) some_args = true;
-                else msg += ", ";
+                if (!some_args) {
+                    some_args = true;
+                } else {
+                    msg += ", ";
+                }
                 try {
                     msg += pybind11::repr(args_[ti]);
                 } catch (const error_already_set&) {
@@ -972,12 +1038,17 @@ protected:
             if (kwargs_in) {
                 auto kwargs = reinterpret_borrow<dict>(kwargs_in);
                 if (!kwargs.empty()) {
-                    if (some_args) msg += "; ";
+                    if (some_args) {
+                        msg += "; ";
+                    }
                     msg += "kwargs: ";
                     bool first = true;
                     for (auto kwarg : kwargs) {
-                        if (first) first = false;
-                        else msg += ", ";
+                        if (first) {
+                            first = false;
+                        } else {
+                            msg += ", ";
+                        }
                         msg += pybind11::str("{}=").format(kwarg.first);
                         try {
                             msg += pybind11::repr(kwarg.second);
@@ -1068,8 +1139,9 @@ public:
         std::string full_name = std::string(PyModule_GetName(m_ptr))
             + std::string(".") + std::string(name);
         auto result = reinterpret_borrow<module_>(PyImport_AddModule(full_name.c_str()));
-        if (doc && options::show_user_defined_docstrings())
+        if (doc && options::show_user_defined_docstrings()) {
             result.attr("__doc__") = pybind11::str(doc);
+        }
         attr(name) = result;
         return result;
     }
@@ -1077,16 +1149,18 @@ public:
     /// Import and return a module or throws `error_already_set`.
     static module_ import(const char *name) {
         PyObject *obj = PyImport_ImportModule(name);
-        if (!obj)
+        if (!obj) {
             throw error_already_set();
+        }
         return reinterpret_steal<module_>(obj);
     }
 
     /// Reload the module or throws `error_already_set`.
     void reload() {
         PyObject *obj = PyImport_ReloadModule(ptr());
-        if (!obj)
+        if (!obj) {
             throw error_already_set();
+        }
         *this = reinterpret_steal<module_>(obj);
     }
 
@@ -1098,9 +1172,11 @@ public:
         established will, in most cases, break things.
     \endrst */
     PYBIND11_NOINLINE void add_object(const char *name, handle obj, bool overwrite = false) {
-        if (!overwrite && hasattr(*this, name))
-            pybind11_fail("Error during initialization: multiple incompatible definitions with name \"" +
-                    std::string(name) + "\"");
+        if (!overwrite && hasattr(*this, name)) {
+            pybind11_fail(
+                "Error during initialization: multiple incompatible definitions with name \""
+                + std::string(name) + "\"");
+        }
 
         PyModule_AddObject(ptr(), name, obj.inc_ref().ptr() /* steals a reference */);
     }
@@ -1138,8 +1214,9 @@ public:
         auto m = Py_InitModule3(name, nullptr, options::show_user_defined_docstrings() ? doc : nullptr);
 #endif
         if (m == nullptr) {
-            if (PyErr_Occurred())
+            if (PyErr_Occurred()) {
                 throw error_already_set();
+            }
             pybind11_fail("Internal error in module_::create_extension_module()");
         }
         // TODO: Should be reinterpret_steal for Python 3, but Python also steals it again when returned from PyInit_...
@@ -1177,14 +1254,17 @@ public:
     PYBIND11_OBJECT_DEFAULT(generic_type, object, PyType_Check)
 protected:
     void initialize(const type_record &rec) {
-        if (rec.scope && hasattr(rec.scope, "__dict__") && rec.scope.attr("__dict__").contains(rec.name))
-            pybind11_fail("generic_type: cannot initialize type \"" + std::string(rec.name) +
-                          "\": an object with that name is already defined");
+        if (rec.scope && hasattr(rec.scope, "__dict__")
+            && rec.scope.attr("__dict__").contains(rec.name)) {
+            pybind11_fail("generic_type: cannot initialize type \"" + std::string(rec.name)
+                          + "\": an object with that name is already defined");
+        }
 
         if ((rec.module_local ? get_local_type_info(*rec.type) : get_global_type_info(*rec.type))
-            != nullptr)
-            pybind11_fail("generic_type: type \"" + std::string(rec.name) +
-                          "\" is already registered!");
+            != nullptr) {
+            pybind11_fail("generic_type: type \"" + std::string(rec.name)
+                          + "\" is already registered!");
+        }
 
         m_ptr = make_new_python_type(rec);
 
@@ -1206,10 +1286,11 @@ protected:
         auto &internals = get_internals();
         auto tindex = std::type_index(*rec.type);
         tinfo->direct_conversions = &internals.direct_conversions[tindex];
-        if (rec.module_local)
+        if (rec.module_local) {
             get_local_internals().registered_types_cpp[tindex] = tinfo;
-        else
+        } else {
             internals.registered_types_cpp[tindex] = tinfo;
+        }
         internals.registered_types_py[(PyTypeObject *) m_ptr] = { tinfo };
 
         if (rec.bases.size() > 1 || rec.multiple_inheritance) {
@@ -1237,8 +1318,9 @@ protected:
         auto t = reinterpret_borrow<tuple>(value->tp_bases);
         for (handle h : t) {
             auto tinfo2 = get_type_info((PyTypeObject *) h.ptr());
-            if (tinfo2)
+            if (tinfo2) {
                 tinfo2->simple_type = false;
+            }
             mark_parents_nonsimple((PyTypeObject *) h.ptr());
         }
     }
@@ -1249,12 +1331,12 @@ protected:
         auto *type = (PyHeapTypeObject*) m_ptr;
         auto tinfo = detail::get_type_info(&type->ht_type);
 
-        if (!type->ht_type.tp_as_buffer)
-            pybind11_fail(
-                "To be able to register buffer protocol support for the type '" +
-                get_fully_qualified_tp_name(tinfo->type) +
-                "' the associated class<>(..) invocation must "
-                "include the pybind11::buffer_protocol() annotation!");
+        if (!type->ht_type.tp_as_buffer) {
+            pybind11_fail("To be able to register buffer protocol support for the type '"
+                          + get_fully_qualified_tp_name(tinfo->type)
+                          + "' the associated class<>(..) invocation must "
+                            "include the pybind11::buffer_protocol() annotation!");
+        }
 
         tinfo->get_buffer = get_buffer;
         tinfo->get_buffer_data = get_buffer_data;
@@ -1475,8 +1557,9 @@ public:
         auto *ptr = new capture { std::forward<Func>(func) };
         install_buffer_funcs([](PyObject *obj, void *ptr) -> buffer_info* {
             detail::make_caster<type> caster;
-            if (!caster.load(obj, false))
+            if (!caster.load(obj, false)) {
                 return nullptr;
+            }
             return new buffer_info(((capture *) ptr)->func(caster));
         }, ptr);
         weakref(m_ptr, cpp_function([ptr](handle wr) {
@@ -1598,7 +1681,9 @@ public:
                 std::free(doc_prev);
                 rec_fset->doc = PYBIND11_COMPAT_STRDUP(rec_fset->doc);
             }
-            if (! rec_active) rec_active = rec_fset;
+            if (!rec_active) {
+                rec_active = rec_fset;
+            }
         }
         def_property_static_impl(name, fget, fset, rec_active);
         return *this;
@@ -1716,8 +1801,9 @@ PYBIND11_NAMESPACE_BEGIN(detail)
 inline str enum_name(handle arg) {
     dict entries = arg.get_type().attr("__entries");
     for (auto kv : entries) {
-        if (handle(kv.second[int_(0)]).equal(arg))
+        if (handle(kv.second[int_(0)]).equal(arg)) {
             return pybind11::str(kv.first);
+        }
     }
     return "???";
 }
@@ -1752,15 +1838,17 @@ struct enum_base {
             [](handle arg) -> std::string {
                 std::string docstring;
                 dict entries = arg.attr("__entries");
-                if (((PyTypeObject *) arg.ptr())->tp_doc)
+                if (((PyTypeObject *) arg.ptr())->tp_doc) {
                     docstring += std::string(((PyTypeObject *) arg.ptr())->tp_doc) + "\n\n";
+                }
                 docstring += "Members:";
                 for (auto kv : entries) {
                     auto key = std::string(pybind11::str(kv.first));
                     auto comment = kv.second[int_(1)];
                     docstring += "\n\n  " + key;
-                    if (!comment.is_none())
+                    if (!comment.is_none()) {
                         docstring += " : " + (std::string) pybind11::str(comment);
+                    }
                 }
                 return docstring;
             }, name("__doc__")
@@ -1769,8 +1857,9 @@ struct enum_base {
         m_base.attr("__members__") = static_property(cpp_function(
             [](handle arg) -> dict {
                 dict entries = arg.attr("__entries"), m;
-                for (auto kv : entries)
+                for (auto kv : entries) {
                     m[kv.first] = kv.second[int_(0)];
+                }
                 return m;
             }, name("__members__")), none(), none(), ""
         );
@@ -1865,8 +1954,9 @@ struct enum_base {
 
     PYBIND11_NOINLINE void export_values() {
         dict entries = m_base.attr("__entries");
-        for (auto kv : entries)
+        for (auto kv : entries) {
             m_parent.attr(kv.first) = kv.second[int_(0)];
+        }
     }
 
     handle m_base;
@@ -1944,11 +2034,13 @@ PYBIND11_NAMESPACE_BEGIN(detail)
 
 
 PYBIND11_NOINLINE void keep_alive_impl(handle nurse, handle patient) {
-    if (!nurse || !patient)
+    if (!nurse || !patient) {
         pybind11_fail("Could not activate keep_alive!");
+    }
 
-    if (patient.is_none() || nurse.is_none())
+    if (patient.is_none() || nurse.is_none()) {
         return; /* Nothing to keep alive or nothing to be kept alive by */
+    }
 
     auto tinfo = all_type_info(Py_TYPE(nurse.ptr()));
     if (!tinfo.empty()) {
@@ -1972,12 +2064,15 @@ PYBIND11_NOINLINE void keep_alive_impl(handle nurse, handle patient) {
 
 PYBIND11_NOINLINE void keep_alive_impl(size_t Nurse, size_t Patient, function_call &call, handle ret) {
     auto get_arg = [&](size_t n) {
-        if (n == 0)
+        if (n == 0) {
             return ret;
-        if (n == 1 && call.init_self)
+        }
+        if (n == 1 && call.init_self) {
             return call.init_self;
-        if (n <= call.args.size())
+        }
+        if (n <= call.args.size()) {
             return call.args[n - 1];
+        }
         return handle();
     };
 
@@ -2000,10 +2095,11 @@ inline std::pair<decltype(internals::registered_types_py)::iterator, bool> all_t
             // TODO consolidate the erasure code in pybind11_meta_dealloc() in class.h
             auto &cache = get_internals().inactive_override_cache;
             for (auto it = cache.begin(), last = cache.end(); it != last; ) {
-                if (it->first == reinterpret_cast<PyObject *>(type))
+                if (it->first == reinterpret_cast<PyObject *>(type)) {
                     it = cache.erase(it);
-                else
+                } else {
                     ++it;
+                }
             }
 
             wr.dec_ref();
@@ -2089,19 +2185,24 @@ iterator make_iterator_impl(Iterator first, Sentinel last, Extra &&... extra) {
 
     if (!detail::get_type_info(typeid(state), false)) {
         class_<state>(handle(), "iterator", pybind11::module_local())
-            .def("__iter__", [](state &s) -> state& { return s; })
-            .def("__next__", [](state &s) -> ValueType {
-                if (!s.first_or_done)
-                    ++s.it;
-                else
-                    s.first_or_done = false;
-                if (s.it == s.end) {
-                    s.first_or_done = true;
-                    throw stop_iteration();
-                }
-                return Access()(s.it);
-            // NOLINTNEXTLINE(readability-const-return-type) // PR #3263
-            }, std::forward<Extra>(extra)..., Policy);
+            .def("__iter__", [](state &s) -> state & { return s; })
+            .def(
+                "__next__",
+                [](state &s) -> ValueType {
+                    if (!s.first_or_done) {
+                        ++s.it;
+                    } else {
+                        s.first_or_done = false;
+                    }
+                    if (s.it == s.end) {
+                        s.first_or_done = true;
+                        throw stop_iteration();
+                    }
+                    return Access()(s.it);
+                    // NOLINTNEXTLINE(readability-const-return-type) // PR #3263
+                },
+                std::forward<Extra>(extra)...,
+                Policy);
     }
 
     return cast(state{first, last, true});
@@ -2187,23 +2288,27 @@ template <typename InputType, typename OutputType> void implicitly_convertible()
     };
     auto implicit_caster = [](PyObject *obj, PyTypeObject *type) -> PyObject * {
         static bool currently_used = false;
-        if (currently_used) // implicit conversions are non-reentrant
+        if (currently_used) { // implicit conversions are non-reentrant
             return nullptr;
+        }
         set_flag flag_helper(currently_used);
-        if (!detail::make_caster<InputType>().load(obj, false))
+        if (!detail::make_caster<InputType>().load(obj, false)) {
             return nullptr;
+        }
         tuple args(1);
         args[0] = obj;
         PyObject *result = PyObject_Call((PyObject *) type, args.ptr(), nullptr);
-        if (result == nullptr)
+        if (result == nullptr) {
             PyErr_Clear();
+        }
         return result;
     };
 
-    if (auto tinfo = detail::get_type_info(typeid(OutputType)))
+    if (auto tinfo = detail::get_type_info(typeid(OutputType))) {
         tinfo->implicit_conversions.push_back(implicit_caster);
-    else
+    } else {
         pybind11_fail("implicitly_convertible: Unable to find type " + type_id<OutputType>());
+    }
 }
 
 
@@ -2239,9 +2344,11 @@ public:
         std::string full_name = scope.attr("__name__").cast<std::string>() +
                                 std::string(".") + name;
         m_ptr = PyErr_NewException(const_cast<char *>(full_name.c_str()), base.ptr(), NULL);
-        if (hasattr(scope, "__dict__") && scope.attr("__dict__").contains(name))
+        if (hasattr(scope, "__dict__") && scope.attr("__dict__").contains(name)) {
             pybind11_fail("Error during initialization: multiple incompatible "
-                          "definitions with name \"" + std::string(name) + "\"");
+                          "definitions with name \""
+                          + std::string(name) + "\"");
+        }
         scope.attr(name) = *this;
     }
 
@@ -2265,13 +2372,17 @@ exception<CppException> &register_exception_impl(handle scope,
                                                 handle base,
                                                 bool isLocal) {
     auto &ex = detail::get_exception_object<CppException>();
-    if (!ex) ex = exception<CppException>(scope, name, base);
+    if (!ex) {
+        ex = exception<CppException>(scope, name, base);
+    }
 
     auto register_func = isLocal ? &register_local_exception_translator
                                  : &register_exception_translator;
 
     register_func([](std::exception_ptr p) {
-        if (!p) return;
+        if (!p) {
+            return;
+        }
         try {
             std::rethrow_exception(p);
         } catch (const CppException &e) {
@@ -2339,8 +2450,9 @@ PYBIND11_NOINLINE void print(const tuple &args, const dict &kwargs) {
     write(line);
     write(kwargs.contains("end") ? kwargs["end"] : cast("\n"));
 
-    if (kwargs.contains("flush") && kwargs["flush"].cast<bool>())
+    if (kwargs.contains("flush") && kwargs["flush"].cast<bool>()) {
         file.attr("flush")();
+    }
 }
 PYBIND11_NAMESPACE_END(detail)
 
@@ -2363,16 +2475,18 @@ error_already_set::~error_already_set() {
 PYBIND11_NAMESPACE_BEGIN(detail)
 inline function get_type_override(const void *this_ptr, const type_info *this_type, const char *name)  {
     handle self = get_object_handle(this_ptr, this_type);
-    if (!self)
+    if (!self) {
         return function();
+    }
     handle type = type::handle_of(self);
     auto key = std::make_pair(type.ptr(), name);
 
     /* Cache functions that aren't overridden in Python to avoid
        many costly Python dictionary lookups below */
     auto &cache = get_internals().inactive_override_cache;
-    if (cache.find(key) != cache.end())
+    if (cache.find(key) != cache.end()) {
         return function();
+    }
 
     function override = getattr(self, name, function());
     if (override.is_cpp_function()) {
diff --git a/include/pybind11/pytypes.h b/include/pybind11/pytypes.h
index 902fb1f0..74388349 100644
--- a/include/pybind11/pytypes.h
+++ b/include/pybind11/pytypes.h
@@ -242,7 +242,11 @@ class object : public handle {
 public:
     object() = default;
     PYBIND11_DEPRECATED("Use reinterpret_borrow<object>() or reinterpret_steal<object>()")
-    object(handle h, bool is_borrowed) : handle(h) { if (is_borrowed) inc_ref(); }
+    object(handle h, bool is_borrowed) : handle(h) {
+        if (is_borrowed) {
+            inc_ref();
+        }
+    }
     /// Copy constructor; always increases the reference count
     object(const object &o) : handle(o) { inc_ref(); }
     /// Move constructor; steals the object from ``other`` and preserves its reference count
@@ -458,8 +462,9 @@ template <> inline bool isinstance<object>(handle obj) { return obj.ptr() != nul
 /// Return true if ``obj`` is an instance of the ``type``.
 inline bool isinstance(handle obj, handle type) {
     const auto result = PyObject_IsInstance(obj.ptr(), type.ptr());
-    if (result == -1)
+    if (result == -1) {
         throw error_already_set();
+    }
     return result != 0;
 }
 
@@ -529,12 +534,13 @@ PYBIND11_NAMESPACE_BEGIN(detail)
 inline handle get_function(handle value) {
     if (value) {
 #if PY_MAJOR_VERSION >= 3
-        if (PyInstanceMethod_Check(value.ptr()))
+        if (PyInstanceMethod_Check(value.ptr())) {
             value = PyInstanceMethod_GET_FUNCTION(value.ptr());
-        else
+        } else
 #endif
-        if (PyMethod_Check(value.ptr()))
+            if (PyMethod_Check(value.ptr())) {
             value = PyMethod_GET_FUNCTION(value.ptr());
+        }
     }
     return value;
 }
@@ -1076,14 +1082,18 @@ public:
     template <typename SzType, detail::enable_if_t<std::is_integral<SzType>::value, int> = 0>
     str(const char *c, const SzType &n)
         : object(PyUnicode_FromStringAndSize(c, ssize_t_cast(n)), stolen_t{}) {
-        if (!m_ptr) pybind11_fail("Could not allocate string object!");
+        if (!m_ptr) {
+            pybind11_fail("Could not allocate string object!");
+        }
     }
 
     // 'explicit' is explicitly omitted from the following constructors to allow implicit conversion to py::str from C++ string-like objects
     // NOLINTNEXTLINE(google-explicit-constructor)
     str(const char *c = "")
         : object(PyUnicode_FromString(c), stolen_t{}) {
-        if (!m_ptr) pybind11_fail("Could not allocate string object!");
+        if (!m_ptr) {
+            pybind11_fail("Could not allocate string object!");
+        }
     }
 
     // NOLINTNEXTLINE(google-explicit-constructor)
@@ -1109,20 +1119,26 @@ public:
         Return a string representation of the object. This is analogous to
         the ``str()`` function in Python.
     \endrst */
-    explicit str(handle h) : object(raw_str(h.ptr()), stolen_t{}) { if (!m_ptr) throw error_already_set(); }
+    explicit str(handle h) : object(raw_str(h.ptr()), stolen_t{}) {
+        if (!m_ptr) {
+            throw error_already_set();
+        }
+    }
 
     // NOLINTNEXTLINE(google-explicit-constructor)
     operator std::string() const {
         object temp = *this;
         if (PyUnicode_Check(m_ptr)) {
             temp = reinterpret_steal<object>(PyUnicode_AsUTF8String(m_ptr));
-            if (!temp)
+            if (!temp) {
                 throw error_already_set();
+            }
         }
         char *buffer = nullptr;
         ssize_t length = 0;
-        if (PYBIND11_BYTES_AS_STRING_AND_SIZE(temp.ptr(), &buffer, &length))
+        if (PYBIND11_BYTES_AS_STRING_AND_SIZE(temp.ptr(), &buffer, &length)) {
             pybind11_fail("Unable to extract string contents! (invalid type)");
+        }
         return std::string(buffer, (size_t) length);
     }
 
@@ -1162,13 +1178,17 @@ public:
     // NOLINTNEXTLINE(google-explicit-constructor)
     bytes(const char *c = "")
         : object(PYBIND11_BYTES_FROM_STRING(c), stolen_t{}) {
-        if (!m_ptr) pybind11_fail("Could not allocate bytes object!");
+        if (!m_ptr) {
+            pybind11_fail("Could not allocate bytes object!");
+        }
     }
 
     template <typename SzType, detail::enable_if_t<std::is_integral<SzType>::value, int> = 0>
     bytes(const char *c, const SzType &n)
         : object(PYBIND11_BYTES_FROM_STRING_AND_SIZE(c, ssize_t_cast(n)), stolen_t{}) {
-        if (!m_ptr) pybind11_fail("Could not allocate bytes object!");
+        if (!m_ptr) {
+            pybind11_fail("Could not allocate bytes object!");
+        }
     }
 
     // Allow implicit conversion:
@@ -1181,8 +1201,9 @@ public:
     operator std::string() const {
         char *buffer = nullptr;
         ssize_t length = 0;
-        if (PYBIND11_BYTES_AS_STRING_AND_SIZE(m_ptr, &buffer, &length))
+        if (PYBIND11_BYTES_AS_STRING_AND_SIZE(m_ptr, &buffer, &length)) {
             pybind11_fail("Unable to extract bytes contents!");
+        }
         return std::string(buffer, (size_t) length);
     }
 
@@ -1199,8 +1220,9 @@ public:
     operator std::string_view() const {
         char *buffer = nullptr;
         ssize_t length = 0;
-        if (PYBIND11_BYTES_AS_STRING_AND_SIZE(m_ptr, &buffer, &length))
+        if (PYBIND11_BYTES_AS_STRING_AND_SIZE(m_ptr, &buffer, &length)) {
             pybind11_fail("Unable to extract bytes contents!");
+        }
         return {buffer, static_cast<size_t>(length)};
     }
 #endif
@@ -1214,27 +1236,32 @@ inline bytes::bytes(const pybind11::str &s) {
     object temp = s;
     if (PyUnicode_Check(s.ptr())) {
         temp = reinterpret_steal<object>(PyUnicode_AsUTF8String(s.ptr()));
-        if (!temp)
+        if (!temp) {
             pybind11_fail("Unable to extract string contents! (encoding issue)");
+        }
     }
     char *buffer = nullptr;
     ssize_t length = 0;
-    if (PYBIND11_BYTES_AS_STRING_AND_SIZE(temp.ptr(), &buffer, &length))
+    if (PYBIND11_BYTES_AS_STRING_AND_SIZE(temp.ptr(), &buffer, &length)) {
         pybind11_fail("Unable to extract string contents! (invalid type)");
+    }
     auto obj = reinterpret_steal<object>(PYBIND11_BYTES_FROM_STRING_AND_SIZE(buffer, length));
-    if (!obj)
+    if (!obj) {
         pybind11_fail("Could not allocate bytes object!");
+    }
     m_ptr = obj.release().ptr();
 }
 
 inline str::str(const bytes& b) {
     char *buffer = nullptr;
     ssize_t length = 0;
-    if (PYBIND11_BYTES_AS_STRING_AND_SIZE(b.ptr(), &buffer, &length))
+    if (PYBIND11_BYTES_AS_STRING_AND_SIZE(b.ptr(), &buffer, &length)) {
         pybind11_fail("Unable to extract bytes contents!");
+    }
     auto obj = reinterpret_steal<object>(PyUnicode_FromStringAndSize(buffer, length));
-    if (!obj)
+    if (!obj) {
         pybind11_fail("Could not allocate string object!");
+    }
     m_ptr = obj.release().ptr();
 }
 
@@ -1247,7 +1274,9 @@ public:
     template <typename SzType, detail::enable_if_t<std::is_integral<SzType>::value, int> = 0>
     bytearray(const char *c, const SzType &n)
         : object(PyByteArray_FromStringAndSize(c, ssize_t_cast(n)), stolen_t{}) {
-        if (!m_ptr) pybind11_fail("Could not allocate bytearray object!");
+        if (!m_ptr) {
+            pybind11_fail("Could not allocate bytearray object!");
+        }
     }
 
     bytearray()
@@ -1295,7 +1324,9 @@ private:
     /// Return the truth value of an object -- always returns a new reference
     static PyObject *raw_bool(PyObject *op) {
         const auto value = PyObject_IsTrue(op);
-        if (value == -1) return nullptr;
+        if (value == -1) {
+            return nullptr;
+        }
         return handle(value != 0 ? Py_True : Py_False).inc_ref().ptr();
     }
 };
@@ -1330,17 +1361,21 @@ public:
     // NOLINTNEXTLINE(google-explicit-constructor)
     int_(T value) {
         if (PYBIND11_SILENCE_MSVC_C4127(sizeof(T) <= sizeof(long))) {
-            if (std::is_signed<T>::value)
+            if (std::is_signed<T>::value) {
                 m_ptr = PyLong_FromLong((long) value);
-            else
+            } else {
                 m_ptr = PyLong_FromUnsignedLong((unsigned long) value);
+            }
         } else {
-            if (std::is_signed<T>::value)
+            if (std::is_signed<T>::value) {
                 m_ptr = PyLong_FromLongLong((long long) value);
-            else
+            } else {
                 m_ptr = PyLong_FromUnsignedLongLong((unsigned long long) value);
+            }
+        }
+        if (!m_ptr) {
+            pybind11_fail("Could not allocate int object!");
         }
-        if (!m_ptr) pybind11_fail("Could not allocate int object!");
     }
 
     template <typename T,
@@ -1361,11 +1396,15 @@ public:
     // Allow implicit conversion from float/double:
     // NOLINTNEXTLINE(google-explicit-constructor)
     float_(float value) : object(PyFloat_FromDouble((double) value), stolen_t{}) {
-        if (!m_ptr) pybind11_fail("Could not allocate float object!");
+        if (!m_ptr) {
+            pybind11_fail("Could not allocate float object!");
+        }
     }
     // NOLINTNEXTLINE(google-explicit-constructor)
     float_(double value = .0) : object(PyFloat_FromDouble((double) value), stolen_t{}) {
-        if (!m_ptr) pybind11_fail("Could not allocate float object!");
+        if (!m_ptr) {
+            pybind11_fail("Could not allocate float object!");
+        }
     }
     // NOLINTNEXTLINE(google-explicit-constructor)
     operator float() const { return (float) PyFloat_AsDouble(m_ptr); }
@@ -1378,7 +1417,9 @@ public:
     PYBIND11_OBJECT_CVT_DEFAULT(weakref, object, PyWeakref_Check, raw_weakref)
     explicit weakref(handle obj, handle callback = {})
         : object(PyWeakref_NewRef(obj.ptr(), callback.ptr()), stolen_t{}) {
-        if (!m_ptr) pybind11_fail("Could not allocate weak reference!");
+        if (!m_ptr) {
+            pybind11_fail("Could not allocate weak reference!");
+        }
     }
 
 private:
@@ -1392,8 +1433,9 @@ public:
     PYBIND11_OBJECT_DEFAULT(slice, object, PySlice_Check)
     slice(handle start, handle stop, handle step) {
         m_ptr = PySlice_New(start.ptr(), stop.ptr(), step.ptr());
-        if (!m_ptr)
+        if (!m_ptr) {
             pybind11_fail("Could not allocate slice object!");
+        }
     }
 
 #ifdef PYBIND11_HAS_OPTIONAL
@@ -1434,15 +1476,17 @@ public:
 
     explicit capsule(const void *value, const char *name = nullptr, void (*destructor)(PyObject *) = nullptr)
         : object(PyCapsule_New(const_cast<void *>(value), name, destructor), stolen_t{}) {
-        if (!m_ptr)
+        if (!m_ptr) {
             pybind11_fail("Could not allocate capsule object!");
+        }
     }
 
     PYBIND11_DEPRECATED("Please pass a destructor that takes a void pointer as input")
     capsule(const void *value, void (*destruct)(PyObject *))
         : object(PyCapsule_New(const_cast<void*>(value), nullptr, destruct), stolen_t{}) {
-        if (!m_ptr)
+        if (!m_ptr) {
             pybind11_fail("Could not allocate capsule object!");
+        }
     }
 
     capsule(const void *value, void (*destructor)(void *)) {
@@ -1452,11 +1496,13 @@ public:
             destructor(ptr);
         });
 
-        if (!m_ptr)
+        if (!m_ptr) {
             pybind11_fail("Could not allocate capsule object!");
+        }
 
-        if (PyCapsule_SetContext(m_ptr, (void *) destructor) != 0)
+        if (PyCapsule_SetContext(m_ptr, (void *) destructor) != 0) {
             pybind11_fail("Could not set capsule context!");
+        }
     }
 
     explicit capsule(void (*destructor)()) {
@@ -1465,8 +1511,9 @@ public:
             destructor();
         });
 
-        if (!m_ptr)
+        if (!m_ptr) {
             pybind11_fail("Could not allocate capsule object!");
+        }
     }
 
     // NOLINTNEXTLINE(google-explicit-constructor)
@@ -1504,7 +1551,9 @@ public:
               detail::enable_if_t<std::is_integral<SzType>::value, int> = 0>
     // Some compilers generate link errors when using `const SzType &` here:
     explicit tuple(SzType size = 0) : object(PyTuple_New(ssize_t_cast(size)), stolen_t{}) {
-        if (!m_ptr) pybind11_fail("Could not allocate tuple object!");
+        if (!m_ptr) {
+            pybind11_fail("Could not allocate tuple object!");
+        }
     }
     size_t size() const { return (size_t) PyTuple_Size(m_ptr); }
     bool empty() const { return size() == 0; }
@@ -1527,7 +1576,9 @@ class dict : public object {
 public:
     PYBIND11_OBJECT_CVT(dict, object, PyDict_Check, raw_dict)
     dict() : object(PyDict_New(), stolen_t{}) {
-        if (!m_ptr) pybind11_fail("Could not allocate dict object!");
+        if (!m_ptr) {
+            pybind11_fail("Could not allocate dict object!");
+        }
     }
     template <typename... Args,
               typename = detail::enable_if_t<args_are_all_keyword_or_ds<Args...>()>,
@@ -1547,8 +1598,9 @@ public:
 private:
     /// Call the `dict` Python type -- always returns a new reference
     static PyObject *raw_dict(PyObject *op) {
-        if (PyDict_Check(op))
+        if (PyDict_Check(op)) {
             return handle(op).inc_ref().ptr();
+        }
         return PyObject_CallFunctionObjArgs((PyObject *) &PyDict_Type, op, nullptr);
     }
 };
@@ -1558,8 +1610,9 @@ public:
     PYBIND11_OBJECT_DEFAULT(sequence, object, PySequence_Check)
     size_t size() const {
         ssize_t result = PySequence_Size(m_ptr);
-        if (result == -1)
+        if (result == -1) {
             throw error_already_set();
+        }
         return (size_t) result;
     }
     bool empty() const { return size() == 0; }
@@ -1576,7 +1629,9 @@ public:
               detail::enable_if_t<std::is_integral<SzType>::value, int> = 0>
     // Some compilers generate link errors when using `const SzType &` here:
     explicit list(SzType size = 0) : object(PyList_New(ssize_t_cast(size)), stolen_t{}) {
-        if (!m_ptr) pybind11_fail("Could not allocate list object!");
+        if (!m_ptr) {
+            pybind11_fail("Could not allocate list object!");
+        }
     }
     size_t size() const { return (size_t) PyList_Size(m_ptr); }
     bool empty() const { return size() == 0; }
@@ -1603,7 +1658,9 @@ class set : public object {
 public:
     PYBIND11_OBJECT_CVT(set, object, PySet_Check, PySet_New)
     set() : object(PySet_New(nullptr), stolen_t{}) {
-        if (!m_ptr) pybind11_fail("Could not allocate set object!");
+        if (!m_ptr) {
+            pybind11_fail("Could not allocate set object!");
+        }
     }
     size_t size() const { return (size_t) PySet_Size(m_ptr); }
     bool empty() const { return size() == 0; }
@@ -1621,8 +1678,9 @@ public:
     PYBIND11_OBJECT_DEFAULT(function, object, PyCallable_Check)
     handle cpp_function() const {
         handle fun = detail::get_function(m_ptr);
-        if (fun && PyCFunction_Check(fun.ptr()))
+        if (fun && PyCFunction_Check(fun.ptr())) {
             return fun;
+        }
         return handle();
     }
     bool is_cpp_function() const { return (bool) cpp_function(); }
@@ -1639,7 +1697,9 @@ public:
 
     buffer_info request(bool writable = false) const {
         int flags = PyBUF_STRIDES | PyBUF_FORMAT;
-        if (writable) flags |= PyBUF_WRITABLE;
+        if (writable) {
+            flags |= PyBUF_WRITABLE;
+        }
         auto *view = new Py_buffer();
         if (PyObject_GetBuffer(m_ptr, view, flags) != 0) {
             delete view;
@@ -1663,14 +1723,16 @@ public:
         use ``memoryview(const object& obj)`` instead of this constructor.
      \endrst */
     explicit memoryview(const buffer_info& info) {
-        if (!info.view())
+        if (!info.view()) {
             pybind11_fail("Prohibited to create memoryview without Py_buffer");
+        }
         // Note: PyMemoryView_FromBuffer never increments obj reference.
         m_ptr = (info.view()->obj) ?
             PyMemoryView_FromObject(info.view()->obj) :
             PyMemoryView_FromBuffer(info.view());
-        if (!m_ptr)
+        if (!m_ptr) {
             pybind11_fail("Unable to create memoryview from buffer descriptor");
+        }
     }
 
     /** \rst
@@ -1744,8 +1806,9 @@ public:
         PyObject* ptr = PyMemoryView_FromMemory(
             reinterpret_cast<char*>(mem), size,
             (readonly) ? PyBUF_READ : PyBUF_WRITE);
-        if (!ptr)
+        if (!ptr) {
             pybind11_fail("Could not allocate memoryview object!");
+        }
         return memoryview(object(ptr, stolen_t{}));
     }
 
@@ -1768,11 +1831,13 @@ inline memoryview memoryview::from_buffer(
     detail::any_container<ssize_t> shape,
     detail::any_container<ssize_t> strides, bool readonly) {
     size_t ndim = shape->size();
-    if (ndim != strides->size())
+    if (ndim != strides->size()) {
         pybind11_fail("memoryview: shape length doesn't match strides length");
+    }
     ssize_t size = ndim != 0u ? 1 : 0;
-    for (size_t i = 0; i < ndim; ++i)
+    for (size_t i = 0; i < ndim; ++i) {
         size *= (*shape)[i];
+    }
     Py_buffer view;
     view.buf = ptr;
     view.obj = nullptr;
@@ -1786,8 +1851,9 @@ inline memoryview memoryview::from_buffer(
     view.suboffsets = nullptr;
     view.internal = nullptr;
     PyObject* obj = PyMemoryView_FromBuffer(&view);
-    if (!obj)
+    if (!obj) {
         throw error_already_set();
+    }
     return memoryview(object(obj, stolen_t{}));
 }
 /// @endcond
@@ -1799,8 +1865,9 @@ inline memoryview memoryview::from_buffer(
 /// Get the length of a Python object.
 inline size_t len(handle h) {
     ssize_t result = PyObject_Length(h.ptr());
-    if (result < 0)
+    if (result < 0) {
         throw error_already_set();
+    }
     return (size_t) result;
 }
 
@@ -1823,7 +1890,9 @@ inline size_t len_hint(handle h) {
 
 inline str repr(handle h) {
     PyObject *str_value = PyObject_Repr(h.ptr());
-    if (!str_value) throw error_already_set();
+    if (!str_value) {
+        throw error_already_set();
+    }
 #if PY_MAJOR_VERSION < 3
     PyObject *unicode = PyUnicode_FromEncodedObject(str_value, "utf-8", nullptr);
     Py_XDECREF(str_value); str_value = unicode;
@@ -1873,8 +1942,9 @@ handle object_api<D>::get_type() const { return type::handle_of(derived()); }
 template <typename D>
 bool object_api<D>::rich_compare(object_api const &other, int value) const {
     int rv = PyObject_RichCompareBool(derived().ptr(), other.derived().ptr(), value);
-    if (rv == -1)
+    if (rv == -1) {
         throw error_already_set();
+    }
     return rv == 1;
 }
 
diff --git a/include/pybind11/stl.h b/include/pybind11/stl.h
index 43034948..fb1eea67 100644
--- a/include/pybind11/stl.h
+++ b/include/pybind11/stl.h
@@ -52,14 +52,16 @@ template <typename Type, typename Key> struct set_caster {
     using key_conv = make_caster<Key>;
 
     bool load(handle src, bool convert) {
-        if (!isinstance<pybind11::set>(src))
+        if (!isinstance<pybind11::set>(src)) {
             return false;
+        }
         auto s = reinterpret_borrow<pybind11::set>(src);
         value.clear();
         for (auto entry : s) {
             key_conv conv;
-            if (!conv.load(entry, convert))
+            if (!conv.load(entry, convert)) {
                 return false;
+            }
             value.insert(cast_op<Key &&>(std::move(conv)));
         }
         return true;
@@ -67,13 +69,15 @@ template <typename Type, typename Key> struct set_caster {
 
     template <typename T>
     static handle cast(T &&src, return_value_policy policy, handle parent) {
-        if (!std::is_lvalue_reference<T>::value)
+        if (!std::is_lvalue_reference<T>::value) {
             policy = return_value_policy_override<Key>::policy(policy);
+        }
         pybind11::set s;
         for (auto &&value : src) {
             auto value_ = reinterpret_steal<object>(key_conv::cast(forward_like<T>(value), policy, parent));
-            if (!value_ || !s.add(value_))
+            if (!value_ || !s.add(value_)) {
                 return handle();
+            }
         }
         return s.release();
     }
@@ -86,16 +90,17 @@ template <typename Type, typename Key, typename Value> struct map_caster {
     using value_conv = make_caster<Value>;
 
     bool load(handle src, bool convert) {
-        if (!isinstance<dict>(src))
+        if (!isinstance<dict>(src)) {
             return false;
+        }
         auto d = reinterpret_borrow<dict>(src);
         value.clear();
         for (auto it : d) {
             key_conv kconv;
             value_conv vconv;
-            if (!kconv.load(it.first.ptr(), convert) ||
-                !vconv.load(it.second.ptr(), convert))
+            if (!kconv.load(it.first.ptr(), convert) || !vconv.load(it.second.ptr(), convert)) {
                 return false;
+            }
             value.emplace(cast_op<Key &&>(std::move(kconv)), cast_op<Value &&>(std::move(vconv)));
         }
         return true;
@@ -113,8 +118,9 @@ template <typename Type, typename Key, typename Value> struct map_caster {
         for (auto &&kv : src) {
             auto key = reinterpret_steal<object>(key_conv::cast(forward_like<T>(kv.first), policy_key, parent));
             auto value = reinterpret_steal<object>(value_conv::cast(forward_like<T>(kv.second), policy_value, parent));
-            if (!key || !value)
+            if (!key || !value) {
                 return handle();
+            }
             d[key] = value;
         }
         return d.release();
@@ -127,15 +133,17 @@ template <typename Type, typename Value> struct list_caster {
     using value_conv = make_caster<Value>;
 
     bool load(handle src, bool convert) {
-        if (!isinstance<sequence>(src) || isinstance<bytes>(src) || isinstance<str>(src))
+        if (!isinstance<sequence>(src) || isinstance<bytes>(src) || isinstance<str>(src)) {
             return false;
+        }
         auto s = reinterpret_borrow<sequence>(src);
         value.clear();
         reserve_maybe(s, &value);
         for (auto it : s) {
             value_conv conv;
-            if (!conv.load(it, convert))
+            if (!conv.load(it, convert)) {
                 return false;
+            }
             value.push_back(cast_op<Value &&>(std::move(conv)));
         }
         return true;
@@ -153,14 +161,16 @@ private:
 public:
     template <typename T>
     static handle cast(T &&src, return_value_policy policy, handle parent) {
-        if (!std::is_lvalue_reference<T>::value)
+        if (!std::is_lvalue_reference<T>::value) {
             policy = return_value_policy_override<Value>::policy(policy);
+        }
         list l(src.size());
         ssize_t index = 0;
         for (auto &&value : src) {
             auto value_ = reinterpret_steal<object>(value_conv::cast(forward_like<T>(value), policy, parent));
-            if (!value_)
+            if (!value_) {
                 return handle();
+            }
             PyList_SET_ITEM(l.ptr(), index++, value_.release().ptr()); // steals a reference
         }
         return l.release();
@@ -184,8 +194,9 @@ template <typename ArrayType, typename Value, bool Resizable, size_t Size = 0> s
 private:
     template <bool R = Resizable>
     bool require_size(enable_if_t<R, size_t> size) {
-        if (value.size() != size)
+        if (value.size() != size) {
             value.resize(size);
+        }
         return true;
     }
     template <bool R = Resizable>
@@ -195,16 +206,19 @@ private:
 
 public:
     bool load(handle src, bool convert) {
-        if (!isinstance<sequence>(src))
+        if (!isinstance<sequence>(src)) {
             return false;
+        }
         auto l = reinterpret_borrow<sequence>(src);
-        if (!require_size(l.size()))
+        if (!require_size(l.size())) {
             return false;
+        }
         size_t ctr = 0;
         for (auto it : l) {
             value_conv conv;
-            if (!conv.load(it, convert))
+            if (!conv.load(it, convert)) {
                 return false;
+            }
             value[ctr++] = cast_op<Value &&>(std::move(conv));
         }
         return true;
@@ -216,8 +230,9 @@ public:
         ssize_t index = 0;
         for (auto &&value : src) {
             auto value_ = reinterpret_steal<object>(value_conv::cast(forward_like<T>(value), policy, parent));
-            if (!value_)
+            if (!value_) {
                 return handle();
+            }
             PyList_SET_ITEM(l.ptr(), index++, value_.release().ptr()); // steals a reference
         }
         return l.release();
@@ -250,8 +265,9 @@ template<typename Type, typename Value = typename Type::value_type> struct optio
 
     template <typename T>
     static handle cast(T &&src, return_value_policy policy, handle parent) {
-        if (!src)
+        if (!src) {
             return none().inc_ref();
+        }
         if (!std::is_lvalue_reference<T>::value) {
             policy = return_value_policy_override<Value>::policy(policy);
         }
@@ -266,8 +282,9 @@ template<typename Type, typename Value = typename Type::value_type> struct optio
             return true;  // default-constructed value is already empty
         }
         value_conv inner_caster;
-        if (!inner_caster.load(src, convert))
+        if (!inner_caster.load(src, convert)) {
             return false;
+        }
 
         value.emplace(cast_op<Value &&>(std::move(inner_caster)));
         return true;
@@ -341,8 +358,9 @@ struct variant_caster<V<Ts...>> {
         // E.g. `py::int_(1).cast<variant<double, int>>()` needs to fill the `int`
         // slot of the variant. Without two-pass loading `double` would be filled
         // because it appears first and a conversion is possible.
-        if (convert && load_alternative(src, false, type_list<Ts...>{}))
+        if (convert && load_alternative(src, false, type_list<Ts...>{})) {
             return true;
+        }
         return load_alternative(src, convert, type_list<Ts...>{});
     }
 
diff --git a/include/pybind11/stl_bind.h b/include/pybind11/stl_bind.h
index 050be83c..8ae68296 100644
--- a/include/pybind11/stl_bind.h
+++ b/include/pybind11/stl_bind.h
@@ -87,10 +87,11 @@ void vector_if_equal_operator(enable_if_t<is_comparable<Vector>::value, Class_>
 
     cl.def("remove", [](Vector &v, const T &x) {
             auto p = std::find(v.begin(), v.end(), x);
-            if (p != v.end())
+            if (p != v.end()) {
                 v.erase(p);
-            else
+            } else {
                 throw value_error();
+            }
         },
         arg("x"),
         "Remove the first item from the list whose value is x. "
@@ -116,10 +117,12 @@ void vector_modifiers(enable_if_t<is_copy_constructible<typename Vector::value_t
     using DiffType = typename Vector::difference_type;
 
     auto wrap_i = [](DiffType i, SizeType n) {
-        if (i < 0)
+        if (i < 0) {
             i += n;
-        if (i < 0 || (SizeType)i >= n)
+        }
+        if (i < 0 || (SizeType) i >= n) {
             throw index_error();
+        }
         return i;
     };
 
@@ -131,8 +134,9 @@ void vector_modifiers(enable_if_t<is_copy_constructible<typename Vector::value_t
     cl.def(init([](const iterable &it) {
         auto v = std::unique_ptr<Vector>(new Vector());
         v->reserve(len_hint(it));
-        for (handle h : it)
+        for (handle h : it) {
             v->push_back(h.cast<T>());
+        }
         return v.release();
     }));
 
@@ -177,26 +181,29 @@ void vector_modifiers(enable_if_t<is_copy_constructible<typename Vector::value_t
     cl.def("insert",
         [](Vector &v, DiffType i, const T &x) {
             // Can't use wrap_i; i == v.size() is OK
-            if (i < 0)
+            if (i < 0) {
                 i += v.size();
-            if (i < 0 || (SizeType)i > v.size())
+            }
+            if (i < 0 || (SizeType) i > v.size()) {
                 throw index_error();
+            }
             v.insert(v.begin() + i, x);
         },
         arg("i") , arg("x"),
         "Insert an item at a given position."
     );
 
-    cl.def("pop",
+    cl.def(
+        "pop",
         [](Vector &v) {
-            if (v.empty())
+            if (v.empty()) {
                 throw index_error();
+            }
             T t = std::move(v.back());
             v.pop_back();
             return t;
         },
-        "Remove and return the last item"
-    );
+        "Remove and return the last item");
 
     cl.def("pop",
         [wrap_i](Vector &v, DiffType i) {
@@ -222,8 +229,9 @@ void vector_modifiers(enable_if_t<is_copy_constructible<typename Vector::value_t
         [](const Vector &v, slice slice) -> Vector * {
             size_t start = 0, stop = 0, step = 0, slicelength = 0;
 
-            if (!slice.compute(v.size(), &start, &stop, &step, &slicelength))
+            if (!slice.compute(v.size(), &start, &stop, &step, &slicelength)) {
                 throw error_already_set();
+            }
 
             auto *seq = new Vector();
             seq->reserve((size_t) slicelength);
@@ -241,11 +249,14 @@ void vector_modifiers(enable_if_t<is_copy_constructible<typename Vector::value_t
         "__setitem__",
         [](Vector &v, slice slice, const Vector &value) {
             size_t start = 0, stop = 0, step = 0, slicelength = 0;
-            if (!slice.compute(v.size(), &start, &stop, &step, &slicelength))
+            if (!slice.compute(v.size(), &start, &stop, &step, &slicelength)) {
                 throw error_already_set();
+            }
 
-            if (slicelength != value.size())
-                throw std::runtime_error("Left and right hand size of slice assignment have different sizes!");
+            if (slicelength != value.size()) {
+                throw std::runtime_error(
+                    "Left and right hand size of slice assignment have different sizes!");
+            }
 
             for (size_t i=0; i<slicelength; ++i) {
                 v[start] = value[i];
@@ -267,8 +278,9 @@ void vector_modifiers(enable_if_t<is_copy_constructible<typename Vector::value_t
         [](Vector &v, slice slice) {
             size_t start = 0, stop = 0, step = 0, slicelength = 0;
 
-            if (!slice.compute(v.size(), &start, &stop, &step, &slicelength))
+            if (!slice.compute(v.size(), &start, &stop, &step, &slicelength)) {
                 throw error_already_set();
+            }
 
             if (step == 1 && false) {
                 v.erase(v.begin() + (DiffType) start, v.begin() + DiffType(start + slicelength));
@@ -296,10 +308,12 @@ void vector_accessor(enable_if_t<!vector_needs_copy<Vector>::value, Class_> &cl)
     using ItType   = typename Vector::iterator;
 
     auto wrap_i = [](DiffType i, SizeType n) {
-        if (i < 0)
+        if (i < 0) {
             i += n;
-        if (i < 0 || (SizeType)i >= n)
+        }
+        if (i < 0 || (SizeType) i >= n) {
             throw index_error();
+        }
         return i;
     };
 
@@ -328,15 +342,15 @@ void vector_accessor(enable_if_t<vector_needs_copy<Vector>::value, Class_> &cl)
     using SizeType = typename Vector::size_type;
     using DiffType = typename Vector::difference_type;
     using ItType   = typename Vector::iterator;
-    cl.def("__getitem__",
-        [](const Vector &v, DiffType i) -> T {
-            if (i < 0 && (i += v.size()) < 0)
-                throw index_error();
-            if ((SizeType)i >= v.size())
-                throw index_error();
-            return v[(SizeType)i];
+    cl.def("__getitem__", [](const Vector &v, DiffType i) -> T {
+        if (i < 0 && (i += v.size()) < 0) {
+            throw index_error();
         }
-    );
+        if ((SizeType) i >= v.size()) {
+            throw index_error();
+        }
+        return v[(SizeType) i];
+    });
 
     cl.def("__iter__",
            [](Vector &v) {
@@ -358,8 +372,9 @@ template <typename Vector, typename Class_> auto vector_if_insertion_operator(Cl
             s << name << '[';
             for (size_type i=0; i < v.size(); ++i) {
                 s << v[i];
-                if (i != v.size() - 1)
+                if (i != v.size() - 1) {
                     s << ", ";
+                }
             }
             s << ']';
             return s.str();
@@ -402,10 +417,14 @@ void vector_buffer_impl(Class_& cl, std::true_type) {
 
     cl.def(init([](const buffer &buf) {
         auto info = buf.request();
-        if (info.ndim != 1 || info.strides[0] % static_cast<ssize_t>(sizeof(T)))
+        if (info.ndim != 1 || info.strides[0] % static_cast<ssize_t>(sizeof(T))) {
             throw type_error("Only valid 1D buffers can be copied to a vector");
-        if (!detail::compare_buffer_info<T>::compare(info) || (ssize_t) sizeof(T) != info.itemsize)
-            throw type_error("Format mismatch (Python: " + info.format + " C++: " + format_descriptor<T>::format() + ")");
+        }
+        if (!detail::compare_buffer_info<T>::compare(info)
+            || (ssize_t) sizeof(T) != info.itemsize) {
+            throw type_error("Format mismatch (Python: " + info.format
+                             + " C++: " + format_descriptor<T>::format() + ")");
+        }
 
         T *p = static_cast<T*>(info.ptr);
         ssize_t step = info.strides[0] / static_cast<ssize_t>(sizeof(T));
@@ -415,8 +434,9 @@ void vector_buffer_impl(Class_& cl, std::true_type) {
         }
         Vector vec;
         vec.reserve((size_t) info.shape[0]);
-        for (; p != end; p += step)
+        for (; p != end; p += step) {
             vec.push_back(*p);
+        }
         return vec;
 
     }));
@@ -545,8 +565,11 @@ void map_assignment(enable_if_t<is_copy_assignable<typename Map::mapped_type>::v
     cl.def("__setitem__",
            [](Map &m, const KeyType &k, const MappedType &v) {
                auto it = m.find(k);
-               if (it != m.end()) it->second = v;
-               else m.emplace(k, v);
+               if (it != m.end()) {
+                   it->second = v;
+               } else {
+                   m.emplace(k, v);
+               }
            }
     );
 }
@@ -583,8 +606,9 @@ template <typename Map, typename Class_> auto map_if_insertion_operator(Class_ &
             s << name << '{';
             bool f = false;
             for (auto const &kv : m) {
-                if (f)
+                if (f) {
                     s << ", ";
+                }
                 s << kv.first << ": " << kv.second;
                 f = true;
             }
@@ -675,8 +699,9 @@ class_<Map, holder_type> bind_map(handle scope, const std::string &name, Args&&.
     cl.def("__getitem__",
         [](Map &m, const KeyType &k) -> MappedType & {
             auto it = m.find(k);
-            if (it == m.end())
-              throw key_error();
+            if (it == m.end()) {
+                throw key_error();
+            }
            return it->second;
         },
         return_value_policy::reference_internal // ref + keepalive
@@ -685,8 +710,9 @@ class_<Map, holder_type> bind_map(handle scope, const std::string &name, Args&&.
     cl.def("__contains__",
         [](Map &m, const KeyType &k) -> bool {
             auto it = m.find(k);
-            if (it == m.end())
-              return false;
+            if (it == m.end()) {
+                return false;
+            }
            return true;
         }
     );
@@ -699,8 +725,9 @@ class_<Map, holder_type> bind_map(handle scope, const std::string &name, Args&&.
     cl.def("__delitem__",
            [](Map &m, const KeyType &k) {
                auto it = m.find(k);
-               if (it == m.end())
+               if (it == m.end()) {
                    throw key_error();
+               }
                m.erase(it);
            }
     );
@@ -717,8 +744,9 @@ class_<Map, holder_type> bind_map(handle scope, const std::string &name, Args&&.
     keys_view.def("__contains__",
         [](KeysView &view, const KeyType &k) -> bool {
             auto it = view.map.find(k);
-            if (it == view.map.end())
+            if (it == view.map.end()) {
                 return false;
+            }
             return true;
         }
     );
diff --git a/tests/constructor_stats.h b/tests/constructor_stats.h
index 805968a0..8ee40479 100644
--- a/tests/constructor_stats.h
+++ b/tests/constructor_stats.h
@@ -101,10 +101,11 @@ public:
     }
 
     void destroyed(void *inst) {
-        if (--_instances[inst] < 0)
+        if (--_instances[inst] < 0) {
             throw std::runtime_error("cstats.destroyed() called with unknown "
                                      "instance; potential double-destruction "
                                      "or a missing cstats.created()");
+        }
     }
 
     static void gc() {
@@ -127,9 +128,11 @@ public:
     int alive() {
         gc();
         int total = 0;
-        for (const auto &p : _instances)
-            if (p.second > 0)
+        for (const auto &p : _instances) {
+            if (p.second > 0) {
                 total += p.second;
+            }
+        }
         return total;
     }
 
@@ -145,7 +148,9 @@ public:
     // Move out stored values
     py::list values() {
         py::list l;
-        for (const auto &v : _values) l.append(py::cast(v));
+        for (const auto &v : _values) {
+            l.append(py::cast(v));
+        }
         _values.clear();
         return l;
     }
@@ -181,7 +186,9 @@ public:
             }
         }
         catch (const std::out_of_range&) {}
-        if (!t1) throw std::runtime_error("Unknown class passed to ConstructorStats::get()");
+        if (!t1) {
+            throw std::runtime_error("Unknown class passed to ConstructorStats::get()");
+        }
         auto &cs1 = get(*t1);
         // If we have both a t1 and t2 match, one is probably the trampoline class; return whichever
         // has more constructions (typically one or the other will be 0)
@@ -189,7 +196,9 @@ public:
             auto &cs2 = get(*t2);
             int cs1_total = cs1.default_constructions + cs1.copy_constructions + cs1.move_constructions + (int) cs1._values.size();
             int cs2_total = cs2.default_constructions + cs2.copy_constructions + cs2.move_constructions + (int) cs2._values.size();
-            if (cs2_total > cs1_total) return cs2;
+            if (cs2_total > cs1_total) {
+                return cs2;
+            }
         }
         return cs1;
     }
diff --git a/tests/object.h b/tests/object.h
index be21bf63..6365457c 100644
--- a/tests/object.h
+++ b/tests/object.h
@@ -27,10 +27,11 @@ public:
      */
     void decRef(bool dealloc = true) const {
         --m_refCount;
-        if (m_refCount == 0 && dealloc)
+        if (m_refCount == 0 && dealloc) {
             delete this;
-        else if (m_refCount < 0)
+        } else if (m_refCount < 0) {
             throw std::runtime_error("Internal error: reference count < 0!");
+        }
     }
 
     virtual std::string toString() const = 0;
@@ -66,7 +67,9 @@ public:
 
     /// Construct a reference from a pointer
     explicit ref(T *ptr) : m_ptr(ptr) {
-        if (m_ptr) ((Object *) m_ptr)->incRef();
+        if (m_ptr) {
+            ((Object *) m_ptr)->incRef();
+        }
 
         print_created(this, "from pointer", m_ptr); track_created((ref_tag*) this, "from pointer");
 
@@ -74,8 +77,9 @@ public:
 
     /// Copy constructor
     ref(const ref &r) : m_ptr(r.m_ptr) {
-        if (m_ptr)
+        if (m_ptr) {
             ((Object *) m_ptr)->incRef();
+        }
 
         print_copy_created(this, "with pointer", m_ptr); track_copy_created((ref_tag*) this);
     }
@@ -89,8 +93,9 @@ public:
 
     /// Destroy this reference
     ~ref() {
-        if (m_ptr)
+        if (m_ptr) {
             ((Object *) m_ptr)->decRef();
+        }
 
         print_destroyed(this); track_destroyed((ref_tag*) this);
     }
@@ -99,10 +104,12 @@ public:
     ref &operator=(ref &&r) noexcept {
         print_move_assigned(this, "pointer", r.m_ptr); track_move_assigned((ref_tag*) this);
 
-        if (*this == r)
+        if (*this == r) {
             return *this;
-        if (m_ptr)
+        }
+        if (m_ptr) {
             ((Object *) m_ptr)->decRef();
+        }
         m_ptr = r.m_ptr;
         r.m_ptr = nullptr;
         return *this;
@@ -116,13 +123,16 @@ public:
         print_copy_assigned(this, "pointer", r.m_ptr);
         track_copy_assigned((ref_tag *) this);
 
-        if (m_ptr == r.m_ptr)
+        if (m_ptr == r.m_ptr) {
             return *this;
-        if (m_ptr)
+        }
+        if (m_ptr) {
             ((Object *) m_ptr)->decRef();
+        }
         m_ptr = r.m_ptr;
-        if (m_ptr)
+        if (m_ptr) {
             ((Object *) m_ptr)->incRef();
+        }
         return *this;
     }
 
@@ -130,13 +140,16 @@ public:
     ref& operator=(T *ptr) {
         print_values(this, "assigned pointer"); track_values((ref_tag*) this, "assigned pointer");
 
-        if (m_ptr == ptr)
+        if (m_ptr == ptr) {
             return *this;
-        if (m_ptr)
+        }
+        if (m_ptr) {
             ((Object *) m_ptr)->decRef();
+        }
         m_ptr = ptr;
-        if (m_ptr)
+        if (m_ptr) {
             ((Object *) m_ptr)->incRef();
+        }
         return *this;
     }
 
diff --git a/tests/pybind11_cross_module_tests.cpp b/tests/pybind11_cross_module_tests.cpp
index 5838cb27..82228a44 100644
--- a/tests/pybind11_cross_module_tests.cpp
+++ b/tests/pybind11_cross_module_tests.cpp
@@ -39,7 +39,9 @@ PYBIND11_MODULE(pybind11_cross_module_tests, m) {
     m.def("throw_local_simple_error", []() { throw LocalSimpleException("external mod"); });
     py::register_exception_translator([](std::exception_ptr p) {
       try {
-          if (p) std::rethrow_exception(p);
+          if (p) {
+              std::rethrow_exception(p);
+          }
       } catch (const shared_exception &e) {
           PyErr_SetString(PyExc_KeyError, e.what());
       }
diff --git a/tests/pybind11_tests.cpp b/tests/pybind11_tests.cpp
index 439cd401..ec4581ef 100644
--- a/tests/pybind11_tests.cpp
+++ b/tests/pybind11_tests.cpp
@@ -86,6 +86,7 @@ PYBIND11_MODULE(pybind11_tests, m) {
         .def(py::init<int>())
         .def("__repr__", [](const IncType& u) { return "IncType({})"_s.format(u.value()); });
 
-    for (const auto &initializer : initializers())
+    for (const auto &initializer : initializers()) {
         initializer(m);
+    }
 }
diff --git a/tests/test_buffers.cpp b/tests/test_buffers.cpp
index 3a8e3e7b..09203639 100644
--- a/tests/test_buffers.cpp
+++ b/tests/test_buffers.cpp
@@ -85,8 +85,9 @@ TEST_SUBMODULE(buffers, m) {
         /// Construct from a buffer
         .def(py::init([](const py::buffer &b) {
             py::buffer_info info = b.request();
-            if (info.format != py::format_descriptor<float>::format() || info.ndim != 2)
+            if (info.format != py::format_descriptor<float>::format() || info.ndim != 2) {
                 throw std::runtime_error("Incompatible buffer format!");
+            }
 
             auto v = new Matrix(info.shape[0], info.shape[1]);
             memcpy(v->data(), info.ptr, sizeof(float) * (size_t) (v->rows() * v->cols()));
@@ -99,14 +100,16 @@ TEST_SUBMODULE(buffers, m) {
         /// Bare bones interface
         .def("__getitem__",
              [](const Matrix &m, std::pair<py::ssize_t, py::ssize_t> i) {
-                 if (i.first >= m.rows() || i.second >= m.cols())
+                 if (i.first >= m.rows() || i.second >= m.cols()) {
                      throw py::index_error();
+                 }
                  return m(i.first, i.second);
              })
         .def("__setitem__",
              [](Matrix &m, std::pair<py::ssize_t, py::ssize_t> i, float v) {
-                 if (i.first >= m.rows() || i.second >= m.cols())
+                 if (i.first >= m.rows() || i.second >= m.cols()) {
                      throw py::index_error();
+                 }
                  m(i.first, i.second) = v;
              })
         /// Provide buffer access
diff --git a/tests/test_builtin_casters.cpp b/tests/test_builtin_casters.cpp
index 4a9f3383..5ff5a8fc 100644
--- a/tests/test_builtin_casters.cpp
+++ b/tests/test_builtin_casters.cpp
@@ -93,8 +93,11 @@ TEST_SUBMODULE(builtin_casters, m) {
 #if PY_MAJOR_VERSION >= 3
     // Under Python 2.7, invalid unicode UTF-32 characters don't appear to trigger UnicodeDecodeError
     m.def("bad_utf32_string", [=]() { return std::u32string({ a32, char32_t(0xd800), z32 }); });
-    if (PYBIND11_SILENCE_MSVC_C4127(sizeof(wchar_t) == 2))
-        m.def("bad_wchar_string", [=]() { return std::wstring({ wchar_t(0x61), wchar_t(0xd800) }); });
+    if (PYBIND11_SILENCE_MSVC_C4127(sizeof(wchar_t) == 2)) {
+        m.def("bad_wchar_string", [=]() {
+            return std::wstring({wchar_t(0x61), wchar_t(0xd800)});
+        });
+    }
 #endif
     m.def("u8_Z", []() -> char { return 'Z'; });
     m.def("u8_eacute", []() -> char { return '\xe9'; });
@@ -133,9 +136,21 @@ TEST_SUBMODULE(builtin_casters, m) {
     m.def("string_view_print",   [](std::string_view s)    { py::print(s, s.size()); });
     m.def("string_view16_print", [](std::u16string_view s) { py::print(s, s.size()); });
     m.def("string_view32_print", [](std::u32string_view s) { py::print(s, s.size()); });
-    m.def("string_view_chars",   [](std::string_view s)    { py::list l; for (auto c : s) l.append((std::uint8_t) c); return l; });
-    m.def("string_view16_chars", [](std::u16string_view s) { py::list l; for (auto c : s) l.append((int) c); return l; });
-    m.def("string_view32_chars", [](std::u32string_view s) { py::list l; for (auto c : s) l.append((int) c); return l; });
+    m.def("string_view_chars",   [](std::string_view s)    { py::list l;
+        for (auto c : s) {
+            l.append((std::uint8_t) c);
+        }
+        return l; });
+    m.def("string_view16_chars", [](std::u16string_view s) { py::list l;
+        for (auto c : s) {
+            l.append((int) c);
+        }
+        return l; });
+    m.def("string_view32_chars", [](std::u32string_view s) { py::list l;
+        for (auto c : s) {
+            l.append((int) c);
+        }
+        return l; });
     m.def("string_view_return",   []() { return std::string_view((const char*)u8"utf8 secret \U0001f382"); });
     m.def("string_view16_return", []() { return std::u16string_view(u"utf16 secret \U0001f382"); });
     m.def("string_view32_return", []() { return std::u32string_view(U"utf32 secret \U0001f382"); });
diff --git a/tests/test_call_policies.cpp b/tests/test_call_policies.cpp
index 7cb98d0d..cdbd9d42 100644
--- a/tests/test_call_policies.cpp
+++ b/tests/test_call_policies.cpp
@@ -95,8 +95,9 @@ TEST_SUBMODULE(call_policies, m) {
     // but it's unclear how to test it without `PyGILState_GetThisThreadState`.
     auto report_gil_status = []() {
         auto is_gil_held = false;
-        if (auto tstate = py::detail::get_thread_state_unchecked())
+        if (auto tstate = py::detail::get_thread_state_unchecked()) {
             is_gil_held = (tstate == PyGILState_GetThisThreadState());
+        }
 
         return is_gil_held ? "GIL held" : "GIL released";
     };
diff --git a/tests/test_callbacks.cpp b/tests/test_callbacks.cpp
index 58688b6e..b73a6237 100644
--- a/tests/test_callbacks.cpp
+++ b/tests/test_callbacks.cpp
@@ -136,11 +136,16 @@ TEST_SUBMODULE(callbacks, m) {
     m.def("dummy_function_overloaded", [](int i, int j) { return i + j; });
     m.def("dummy_function_overloaded", &dummy_function);
     m.def("dummy_function2", [](int i, int j) { return i + j; });
-    m.def("roundtrip", [](std::function<int(int)> f, bool expect_none = false) {
-        if (expect_none && f)
-            throw std::runtime_error("Expected None to be converted to empty std::function");
-        return f;
-    }, py::arg("f"), py::arg("expect_none")=false);
+    m.def(
+        "roundtrip",
+        [](std::function<int(int)> f, bool expect_none = false) {
+            if (expect_none && f) {
+                throw std::runtime_error("Expected None to be converted to empty std::function");
+            }
+            return f;
+        },
+        py::arg("f"),
+        py::arg("expect_none") = false);
     m.def("test_dummy_function", [](const std::function<int(int)> &f) -> std::string {
         using fn_type = int (*)(int);
         auto result = f.target<fn_type>();
@@ -215,8 +220,9 @@ TEST_SUBMODULE(callbacks, m) {
         };
 
         // spawn worker threads
-        for (auto i : work)
+        for (auto i : work) {
             start_f(py::cast<int>(i));
+        }
     });
 
     m.def("callback_num_times", [](const py::function &f, std::size_t num) {
diff --git a/tests/test_class.cpp b/tests/test_class.cpp
index 52a41a3b..977297e5 100644
--- a/tests/test_class.cpp
+++ b/tests/test_class.cpp
@@ -139,9 +139,13 @@ TEST_SUBMODULE(class_, m) {
 
     m.def("return_class_1", []() -> BaseClass* { return new DerivedClass1(); });
     m.def("return_class_2", []() -> BaseClass* { return new DerivedClass2(); });
-    m.def("return_class_n", [](int n) -> BaseClass* {
-        if (n == 1) return new DerivedClass1();
-        if (n == 2) return new DerivedClass2();
+    m.def("return_class_n", [](int n) -> BaseClass * {
+        if (n == 1) {
+            return new DerivedClass1();
+        }
+        if (n == 2) {
+            return new DerivedClass2();
+        }
         return new BaseClass();
     });
     m.def("return_none", []() -> BaseClass* { return nullptr; });
@@ -167,8 +171,9 @@ TEST_SUBMODULE(class_, m) {
         // See https://github.com/pybind/pybind11/issues/2486
         // if (category == 2)
         //     return py::type::of<int>();
-        if (category == 1)
+        if (category == 1) {
             return py::type::of<DerivedClass1>();
+        }
         return py::type::of<Invalid>();
     });
 
diff --git a/tests/test_copy_move.cpp b/tests/test_copy_move.cpp
index 4711a948..850edcb4 100644
--- a/tests/test_copy_move.cpp
+++ b/tests/test_copy_move.cpp
@@ -104,7 +104,9 @@ public:
     bool load(handle src, bool) { value = CopyOnlyInt(src.cast<int>()); return true; }
     static handle cast(const CopyOnlyInt &m, return_value_policy r, handle p) { return pybind11::cast(m.value, r, p); }
     static handle cast(const CopyOnlyInt *src, return_value_policy policy, handle parent) {
-        if (!src) return none().release();
+        if (!src) {
+            return none().release();
+        }
         return cast(*src, policy, parent);
     }
     explicit operator CopyOnlyInt *() { return &value; }
@@ -203,8 +205,9 @@ TEST_SUBMODULE(copy_move_policies, m) {
     private:
         void *operator new(size_t bytes) {
             void *ptr = std::malloc(bytes);
-            if (ptr)
+            if (ptr) {
                 return ptr;
+            }
             throw std::bad_alloc{};
         }
     };
diff --git a/tests/test_eigen.cpp b/tests/test_eigen.cpp
index d22a94a1..d7b62ef7 100644
--- a/tests/test_eigen.cpp
+++ b/tests/test_eigen.cpp
@@ -28,8 +28,11 @@ using MatrixXdR = Eigen::Matrix<double, Eigen::Dynamic, Eigen::Dynamic, Eigen::R
 // Sets/resets a testing reference matrix to have values of 10*r + c, where r and c are the
 // (1-based) row/column number.
 template <typename M> void reset_ref(M &x) {
-    for (int i = 0; i < x.rows(); i++) for (int j = 0; j < x.cols(); j++)
-        x(i, j) = 11 + 10*i + j;
+    for (int i = 0; i < x.rows(); i++) {
+        for (int j = 0; j < x.cols(); j++) {
+            x(i, j) = 11 + 10 * i + j;
+        }
+    }
 }
 
 // Returns a static, column-major matrix
@@ -63,9 +66,11 @@ double get_elem(const Eigen::Ref<const Eigen::MatrixXd> &m) { return m(2, 1); };
 // reference is referencing rows/columns correctly).
 template <typename MatrixArgType> Eigen::MatrixXd adjust_matrix(MatrixArgType m) {
     Eigen::MatrixXd ret(m);
-    for (int c = 0; c < m.cols(); c++)
-        for (int r = 0; r < m.rows(); r++)
-            ret(r, c) += 10*r + 100*c;  // NOLINT(clang-analyzer-core.uninitialized.Assign)
+    for (int c = 0; c < m.cols(); c++) {
+        for (int r = 0; r < m.rows(); r++) {
+            ret(r, c) += 10 * r + 100 * c; // NOLINT(clang-analyzer-core.uninitialized.Assign)
+        }
+    }
     return ret;
 }
 
@@ -225,7 +230,9 @@ TEST_SUBMODULE(eigen, m) {
     // Returns a DiagonalMatrix with diagonal (1,2,3,...)
     m.def("incr_diag", [](int k) {
         Eigen::DiagonalMatrix<int, Eigen::Dynamic> m(k);
-        for (int i = 0; i < k; i++) m.diagonal()[i] = i+1;
+        for (int i = 0; i < k; i++) {
+            m.diagonal()[i] = i + 1;
+        }
         return m;
     });
 
@@ -320,8 +327,9 @@ TEST_SUBMODULE(eigen, m) {
         "matrix_multiply",
         [](const py::EigenDRef<const Eigen::MatrixXd> &A,
            const py::EigenDRef<const Eigen::MatrixXd> &B) -> Eigen::MatrixXd {
-            if (A.cols() != B.rows())
+            if (A.cols() != B.rows()) {
                 throw std::domain_error("Nonconformable matrices!");
+            }
             return A * B;
         },
         py::arg("A"),
diff --git a/tests/test_embed/test_interpreter.cpp b/tests/test_embed/test_interpreter.cpp
index 508975eb..9ffc257b 100644
--- a/tests/test_embed/test_interpreter.cpp
+++ b/tests/test_embed/test_interpreter.cpp
@@ -307,7 +307,11 @@ TEST_CASE("Threads") {
 struct scope_exit {
     std::function<void()> f_;
     explicit scope_exit(std::function<void()> f) noexcept : f_(std::move(f)) {}
-    ~scope_exit() { if (f_) f_(); }
+    ~scope_exit() {
+        if (f_) {
+            f_();
+        }
+    }
 };
 
 TEST_CASE("Reload module from file") {
diff --git a/tests/test_eval.cpp b/tests/test_eval.cpp
index 29366f67..e40dde70 100644
--- a/tests/test_eval.cpp
+++ b/tests/test_eval.cpp
@@ -93,8 +93,9 @@ TEST_SUBMODULE(eval_, m) {
 
     // test_eval_empty_globals
     m.def("eval_empty_globals", [](py::object global) {
-        if (global.is_none())
+        if (global.is_none()) {
             global = py::dict();
+        }
         auto int_class = py::eval("isinstance(42, int)", global);
         return global;
     });
diff --git a/tests/test_exceptions.cpp b/tests/test_exceptions.cpp
index 3aa96738..ab7dfbf6 100644
--- a/tests/test_exceptions.cpp
+++ b/tests/test_exceptions.cpp
@@ -116,7 +116,9 @@ TEST_SUBMODULE(exceptions, m) {
     static py::exception<MyException> ex(m, "MyException");
     py::register_exception_translator([](std::exception_ptr p) {
         try {
-            if (p) std::rethrow_exception(p);
+            if (p) {
+                std::rethrow_exception(p);
+            }
         } catch (const MyException &e) {
             // Set MyException as the active python error
             ex(e.what());
@@ -128,7 +130,9 @@ TEST_SUBMODULE(exceptions, m) {
     // never by visible from Python
     py::register_exception_translator([](std::exception_ptr p) {
         try {
-            if (p) std::rethrow_exception(p);
+            if (p) {
+                std::rethrow_exception(p);
+            }
         } catch (const MyException2 &e) {
             // Translate this exception to a standard RuntimeError
             PyErr_SetString(PyExc_RuntimeError, e.what());
@@ -140,7 +144,9 @@ TEST_SUBMODULE(exceptions, m) {
     // translator for MyException by throwing a new exception
     py::register_exception_translator([](std::exception_ptr p) {
         try {
-            if (p) std::rethrow_exception(p);
+            if (p) {
+                std::rethrow_exception(p);
+            }
         } catch (const MyException4 &e) {
             throw MyException(e.what());
         }
@@ -181,7 +187,9 @@ TEST_SUBMODULE(exceptions, m) {
             py::object o = foo["bar"];
         }
         catch (py::error_already_set& ex) {
-            if (!ex.matches(PyExc_KeyError)) throw;
+            if (!ex.matches(PyExc_KeyError)) {
+                throw;
+            }
             return true;
         }
         return false;
@@ -193,7 +201,9 @@ TEST_SUBMODULE(exceptions, m) {
             py::object o = foo["bar"];
         }
         catch (py::error_already_set &ex) {
-            if (!ex.matches(PyExc_Exception)) throw;
+            if (!ex.matches(PyExc_Exception)) {
+                throw;
+            }
             return true;
         }
         return false;
@@ -204,15 +214,18 @@ TEST_SUBMODULE(exceptions, m) {
             py::module_::import("nonexistent");
         }
         catch (py::error_already_set &ex) {
-            if (!ex.matches(PyExc_ImportError)) throw;
+            if (!ex.matches(PyExc_ImportError)) {
+                throw;
+            }
             return true;
         }
         return false;
     });
 
     m.def("throw_already_set", [](bool err) {
-        if (err)
+        if (err) {
             PyErr_SetString(PyExc_ValueError, "foo");
+        }
         try {
             throw py::error_already_set();
         } catch (const std::runtime_error& e) {
@@ -224,8 +237,9 @@ TEST_SUBMODULE(exceptions, m) {
             }
         }
         PyErr_Clear();
-        if (err)
+        if (err) {
             PyErr_SetString(PyExc_ValueError, "foo");
+        }
         throw py::error_already_set();
     });
 
@@ -252,10 +266,11 @@ TEST_SUBMODULE(exceptions, m) {
               try {
                   f(*args);
               } catch (py::error_already_set &ex) {
-                  if (ex.matches(exc_type))
+                  if (ex.matches(exc_type)) {
                       py::print(ex.what());
-                  else
+                  } else {
                       throw;
+                  }
               }
           });
 
diff --git a/tests/test_iostream.cpp b/tests/test_iostream.cpp
index c620b594..ef54b0a1 100644
--- a/tests/test_iostream.cpp
+++ b/tests/test_iostream.cpp
@@ -22,8 +22,9 @@
 void noisy_function(const std::string &msg, bool flush) {
 
     std::cout << msg;
-    if (flush)
+    if (flush) {
         std::cout << std::flush;
+    }
 }
 
 void noisy_funct_dual(const std::string &msg, const std::string &emsg) {
diff --git a/tests/test_kwargs_and_defaults.cpp b/tests/test_kwargs_and_defaults.cpp
index 34ad2a86..0e262dad 100644
--- a/tests/test_kwargs_and_defaults.cpp
+++ b/tests/test_kwargs_and_defaults.cpp
@@ -26,8 +26,9 @@ TEST_SUBMODULE(kwargs_and_defaults, m) {
     std::vector<int> list{{13, 17}};
     m.def("kw_func4", [](const std::vector<int> &entries) {
         std::string ret = "{";
-        for (int i : entries)
+        for (int i : entries) {
             ret += std::to_string(i) + " ";
+        }
         ret.back() = '}';
         return ret;
     }, py::arg("myList") = list);
@@ -89,18 +90,20 @@ TEST_SUBMODULE(kwargs_and_defaults, m) {
     m.def("args_refcount", [](py::args a) {
         GC_IF_NEEDED;
         py::tuple t(a.size());
-        for (size_t i = 0; i < a.size(); i++)
+        for (size_t i = 0; i < a.size(); i++) {
             // Use raw Python API here to avoid an extra, intermediate incref on the tuple item:
             t[i] = (int) Py_REFCNT(PyTuple_GET_ITEM(a.ptr(), static_cast<py::ssize_t>(i)));
+        }
         return t;
     });
     m.def("mixed_args_refcount", [](const py::object &o, py::args a) {
         GC_IF_NEEDED;
         py::tuple t(a.size() + 1);
         t[0] = o.ref_count();
-        for (size_t i = 0; i < a.size(); i++)
+        for (size_t i = 0; i < a.size(); i++) {
             // Use raw Python API here to avoid an extra, intermediate incref on the tuple item:
             t[i + 1] = (int) Py_REFCNT(PyTuple_GET_ITEM(a.ptr(), static_cast<py::ssize_t>(i)));
+        }
         return t;
     });
 
diff --git a/tests/test_local_bindings.cpp b/tests/test_local_bindings.cpp
index a5808e2f..0fb3ecc1 100644
--- a/tests/test_local_bindings.cpp
+++ b/tests/test_local_bindings.cpp
@@ -47,8 +47,9 @@ TEST_SUBMODULE(local_bindings, m) {
         auto main = py::module_::import("pybind11_tests");
         if (py::hasattr(main, "class_")) {
             bind_local<LocalExternal, 7>(m, "LocalExternal", py::module_local());
+        } else {
+            throw std::runtime_error("test_class not enabled");
         }
-        else throw std::runtime_error("test_class not enabled");
     });
 
     // test_stl_bind_local
diff --git a/tests/test_numpy_array.cpp b/tests/test_numpy_array.cpp
index 30a71acc..4712c809 100644
--- a/tests/test_numpy_array.cpp
+++ b/tests/test_numpy_array.cpp
@@ -90,15 +90,17 @@ template<typename... Ix> arr data_t(const arr_t& a, Ix... index) {
 
 template<typename... Ix> arr& mutate_data(arr& a, Ix... index) {
     auto ptr = (uint8_t *) a.mutable_data(index...);
-    for (py::ssize_t i = 0; i < a.nbytes() - a.offset_at(index...); i++)
+    for (py::ssize_t i = 0; i < a.nbytes() - a.offset_at(index...); i++) {
         ptr[i] = (uint8_t) (ptr[i] * 2);
+    }
     return a;
 }
 
 template<typename... Ix> arr_t& mutate_data_t(arr_t& a, Ix... index) {
     auto ptr = a.mutable_data(index...);
-    for (py::ssize_t i = 0; i < a.size() - a.index_at(index...); i++)
+    for (py::ssize_t i = 0; i < a.size() - a.index_at(index...); i++) {
         ptr[i]++;
+    }
     return a;
 }
 
@@ -116,7 +118,9 @@ template<typename... Ix> arr_t& mutate_at_t(arr_t& a, Ix... idx) { a.mutable_at(
     sm.def(#name, [](type a, int i, int j, int k) { return name(a, i, j, k); });
 
 template <typename T, typename T2> py::handle auxiliaries(T &&r, T2 &&r2) {
-    if (r.ndim() != 2) throw std::domain_error("error: ndim != 2");
+    if (r.ndim() != 2) {
+        throw std::domain_error("error: ndim != 2");
+    }
     py::list l;
     l.append(*r.data(0, 0));
     l.append(*r2.mutable_data(0, 0));
@@ -292,34 +296,43 @@ TEST_SUBMODULE(numpy_array, sm) {
     // test_array_unchecked_fixed_dims
     sm.def("proxy_add2", [](py::array_t<double> a, double v) {
         auto r = a.mutable_unchecked<2>();
-        for (py::ssize_t i = 0; i < r.shape(0); i++)
-            for (py::ssize_t j = 0; j < r.shape(1); j++)
+        for (py::ssize_t i = 0; i < r.shape(0); i++) {
+            for (py::ssize_t j = 0; j < r.shape(1); j++) {
                 r(i, j) += v;
+            }
+        }
     }, py::arg{}.noconvert(), py::arg());
 
     sm.def("proxy_init3", [](double start) {
         py::array_t<double, py::array::c_style> a({ 3, 3, 3 });
         auto r = a.mutable_unchecked<3>();
-        for (py::ssize_t i = 0; i < r.shape(0); i++)
-        for (py::ssize_t j = 0; j < r.shape(1); j++)
-        for (py::ssize_t k = 0; k < r.shape(2); k++)
-            r(i, j, k) = start++;
+        for (py::ssize_t i = 0; i < r.shape(0); i++) {
+            for (py::ssize_t j = 0; j < r.shape(1); j++) {
+                for (py::ssize_t k = 0; k < r.shape(2); k++) {
+                    r(i, j, k) = start++;
+                }
+            }
+        }
         return a;
     });
     sm.def("proxy_init3F", [](double start) {
         py::array_t<double, py::array::f_style> a({ 3, 3, 3 });
         auto r = a.mutable_unchecked<3>();
-        for (py::ssize_t k = 0; k < r.shape(2); k++)
-        for (py::ssize_t j = 0; j < r.shape(1); j++)
-        for (py::ssize_t i = 0; i < r.shape(0); i++)
-            r(i, j, k) = start++;
+        for (py::ssize_t k = 0; k < r.shape(2); k++) {
+            for (py::ssize_t j = 0; j < r.shape(1); j++) {
+                for (py::ssize_t i = 0; i < r.shape(0); i++) {
+                    r(i, j, k) = start++;
+                }
+            }
+        }
         return a;
     });
     sm.def("proxy_squared_L2_norm", [](const py::array_t<double> &a) {
         auto r = a.unchecked<1>();
         double sumsq = 0;
-        for (py::ssize_t i = 0; i < r.shape(0); i++)
+        for (py::ssize_t i = 0; i < r.shape(0); i++) {
             sumsq += r[i] * r(i); // Either notation works for a 1D array
+        }
         return sumsq;
     });
 
@@ -345,19 +358,28 @@ TEST_SUBMODULE(numpy_array, sm) {
     // Same as the above, but without a compile-time dimensions specification:
     sm.def("proxy_add2_dyn", [](py::array_t<double> a, double v) {
         auto r = a.mutable_unchecked();
-        if (r.ndim() != 2) throw std::domain_error("error: ndim != 2");
-        for (py::ssize_t i = 0; i < r.shape(0); i++)
-            for (py::ssize_t j = 0; j < r.shape(1); j++)
+        if (r.ndim() != 2) {
+            throw std::domain_error("error: ndim != 2");
+        }
+        for (py::ssize_t i = 0; i < r.shape(0); i++) {
+            for (py::ssize_t j = 0; j < r.shape(1); j++) {
                 r(i, j) += v;
+            }
+        }
     }, py::arg{}.noconvert(), py::arg());
     sm.def("proxy_init3_dyn", [](double start) {
         py::array_t<double, py::array::c_style> a({ 3, 3, 3 });
         auto r = a.mutable_unchecked();
-        if (r.ndim() != 3) throw std::domain_error("error: ndim != 3");
-        for (py::ssize_t i = 0; i < r.shape(0); i++)
-        for (py::ssize_t j = 0; j < r.shape(1); j++)
-        for (py::ssize_t k = 0; k < r.shape(2); k++)
-            r(i, j, k) = start++;
+        if (r.ndim() != 3) {
+            throw std::domain_error("error: ndim != 3");
+        }
+        for (py::ssize_t i = 0; i < r.shape(0); i++) {
+            for (py::ssize_t j = 0; j < r.shape(1); j++) {
+                for (py::ssize_t k = 0; k < r.shape(2); k++) {
+                    r(i, j, k) = start++;
+                }
+            }
+        }
         return a;
     });
     sm.def("proxy_auxiliaries2_dyn", [](py::array_t<double> a) {
@@ -386,8 +408,10 @@ TEST_SUBMODULE(numpy_array, sm) {
     // reshape array to 2D without changing size
     sm.def("array_reshape2", [](py::array_t<double> a) {
         const auto dim_sz = (py::ssize_t)std::sqrt(a.size());
-        if (dim_sz * dim_sz != a.size())
-            throw std::domain_error("array_reshape2: input array total size is not a squared integer");
+        if (dim_sz * dim_sz != a.size()) {
+            throw std::domain_error(
+                "array_reshape2: input array total size is not a squared integer");
+        }
         a.resize({dim_sz, dim_sz});
     });
 
diff --git a/tests/test_numpy_dtypes.cpp b/tests/test_numpy_dtypes.cpp
index bf4f4cee..bd702e40 100644
--- a/tests/test_numpy_dtypes.cpp
+++ b/tests/test_numpy_dtypes.cpp
@@ -108,30 +108,35 @@ PYBIND11_PACKED(struct EnumStruct {
 
 std::ostream& operator<<(std::ostream& os, const StringStruct& v) {
     os << "a='";
-    for (size_t i = 0; i < 3 && (v.a[i] != 0); i++)
+    for (size_t i = 0; i < 3 && (v.a[i] != 0); i++) {
         os << v.a[i];
+    }
     os << "',b='";
-    for (size_t i = 0; i < 3 && (v.b[i] != 0); i++)
+    for (size_t i = 0; i < 3 && (v.b[i] != 0); i++) {
         os << v.b[i];
+    }
     return os << "'";
 }
 
 std::ostream& operator<<(std::ostream& os, const ArrayStruct& v) {
     os << "a={";
     for (int i = 0; i < 3; i++) {
-        if (i > 0)
+        if (i > 0) {
             os << ',';
+        }
         os << '{';
-        for (int j = 0; j < 3; j++)
+        for (int j = 0; j < 3; j++) {
             os << v.a[i][j] << ',';
+        }
         os << v.a[i][3] << '}';
     }
     os << "},b={" << v.b[0] << ',' << v.b[1];
     os << "},c={" << int(v.c[0]) << ',' << int(v.c[1]) << ',' << int(v.c[2]);
     os << "},d={";
     for (int i = 0; i < 4; i++) {
-        if (i > 0)
+        if (i > 0) {
             os << ',';
+        }
         os << '{' << v.d[i][0] << ',' << v.d[i][1] << '}';
     }
     return os << '}';
@@ -198,7 +203,9 @@ py::array_t<int32_t, 0> test_array_ctors(int i) {
 
     auto fill = [](py::array arr) {
         auto req = arr.request();
-        for (int i = 0; i < 6; i++) ((int32_t *) req.ptr)[i] = i + 1;
+        for (int i = 0; i < 6; i++) {
+            ((int32_t *) req.ptr)[i] = i + 1;
+        }
         return arr;
     };
 
@@ -373,32 +380,33 @@ TEST_SUBMODULE(numpy_dtypes, m) {
 
     m.def("print_dtypes", []() {
         py::list l;
-        for (const py::handle &d : {
-            py::dtype::of<SimpleStruct>(),
-            py::dtype::of<PackedStruct>(),
-            py::dtype::of<NestedStruct>(),
-            py::dtype::of<PartialStruct>(),
-            py::dtype::of<PartialNestedStruct>(),
-            py::dtype::of<StringStruct>(),
-            py::dtype::of<ArrayStruct>(),
-            py::dtype::of<EnumStruct>(),
-            py::dtype::of<StructWithUglyNames>(),
-            py::dtype::of<ComplexStruct>()
-        })
+        for (const py::handle &d : {py::dtype::of<SimpleStruct>(),
+                                    py::dtype::of<PackedStruct>(),
+                                    py::dtype::of<NestedStruct>(),
+                                    py::dtype::of<PartialStruct>(),
+                                    py::dtype::of<PartialNestedStruct>(),
+                                    py::dtype::of<StringStruct>(),
+                                    py::dtype::of<ArrayStruct>(),
+                                    py::dtype::of<EnumStruct>(),
+                                    py::dtype::of<StructWithUglyNames>(),
+                                    py::dtype::of<ComplexStruct>()}) {
             l.append(py::str(d));
+        }
         return l;
     });
     m.def("test_dtype_ctors", &test_dtype_ctors);
     m.def("test_dtype_kind", [dtype_names]() {
         py::list list;
-        for (auto& dt_name : dtype_names)
+        for (auto &dt_name : dtype_names) {
             list.append(py::dtype(dt_name).kind());
+        }
         return list;
     });
     m.def("test_dtype_char_", [dtype_names]() {
         py::list list;
-        for (auto& dt_name : dtype_names)
+        for (auto &dt_name : dtype_names) {
             list.append(py::dtype(dt_name).char_());
+        }
         return list;
     });
     m.def("test_dtype_methods", []() {
@@ -423,8 +431,9 @@ TEST_SUBMODULE(numpy_dtypes, m) {
         if (non_empty) {
             auto req = arr.request();
             auto ptr = static_cast<StringStruct*>(req.ptr);
-            for (py::ssize_t i = 0; i < req.size * req.itemsize; i++)
-                static_cast<char*>(req.ptr)[i] = 0;
+            for (py::ssize_t i = 0; i < req.size * req.itemsize; i++) {
+                static_cast<char *>(req.ptr)[i] = 0;
+            }
             ptr[1].a[0] = 'a'; ptr[1].b[0] = 'a';
             ptr[2].a[0] = 'a'; ptr[2].b[0] = 'a';
             ptr[3].a[0] = 'a'; ptr[3].b[0] = 'a';
@@ -443,16 +452,22 @@ TEST_SUBMODULE(numpy_dtypes, m) {
         py::array_t<ArrayStruct, 0> arr = mkarray_via_buffer<ArrayStruct>(n);
         auto ptr = (ArrayStruct *) arr.mutable_data();
         for (size_t i = 0; i < n; i++) {
-            for (size_t j = 0; j < 3; j++)
-                for (size_t k = 0; k < 4; k++)
+            for (size_t j = 0; j < 3; j++) {
+                for (size_t k = 0; k < 4; k++) {
                     ptr[i].a[j][k] = char('A' + (i * 100 + j * 10 + k) % 26);
-            for (size_t j = 0; j < 2; j++)
+                }
+            }
+            for (size_t j = 0; j < 2; j++) {
                 ptr[i].b[j] = int32_t(i * 1000 + j);
-            for (size_t j = 0; j < 3; j++)
+            }
+            for (size_t j = 0; j < 3; j++) {
                 ptr[i].c[j] = uint8_t(i * 10 + j);
-            for (size_t j = 0; j < 4; j++)
-                for (size_t k = 0; k < 2; k++)
+            }
+            for (size_t j = 0; j < 4; j++) {
+                for (size_t k = 0; k < 2; k++) {
                     ptr[i].d[j][k] = float(i) * 100.0f + float(j) * 10.0f + float(k);
+                }
+            }
         }
         return arr;
     });
diff --git a/tests/test_opaque_types.cpp b/tests/test_opaque_types.cpp
index 804de6d4..2da24574 100644
--- a/tests/test_opaque_types.cpp
+++ b/tests/test_opaque_types.cpp
@@ -45,8 +45,9 @@ TEST_SUBMODULE(opaque_types, m) {
         std::string ret = "Opaque list: [";
         bool first = true;
         for (const auto &entry : l) {
-            if (!first)
+            if (!first) {
                 ret += ", ";
+            }
             ret += entry;
             first = false;
         }
diff --git a/tests/test_pickling.cpp b/tests/test_pickling.cpp
index b77636dd..efe0463d 100644
--- a/tests/test_pickling.cpp
+++ b/tests/test_pickling.cpp
@@ -39,13 +39,15 @@ void wrap(py::module m) {
         .def(py::pickle(
             [](const py::object &self) {
                 py::dict d;
-                if (py::hasattr(self, "__dict__"))
+                if (py::hasattr(self, "__dict__")) {
                     d = self.attr("__dict__");
+                }
                 return py::make_tuple(self.attr("num"), d);
             },
             [](const py::tuple &t) {
-                if (t.size() != 2)
+                if (t.size() != 2) {
                     throw std::runtime_error("Invalid state!");
+                }
                 auto cpp_state = std::unique_ptr<SimpleBase>(new SimpleBaseTrampoline);
                 cpp_state->num = t[0].cast<int>();
                 auto py_state  = t[1].cast<py::dict>();
@@ -101,8 +103,9 @@ TEST_SUBMODULE(pickling, m) {
         });
     ignoreOldStyleInitWarnings([&pyPickleable]() {
         pyPickleable.def("__setstate__", [](Pickleable &p, const py::tuple &t) {
-            if (t.size() != 3)
+            if (t.size() != 3) {
                 throw std::runtime_error("Invalid state!");
+}
             /* Invoke the constructor (need to use in-place version) */
             new (&p) Pickleable(t[0].cast<std::string>());
 
@@ -119,8 +122,9 @@ TEST_SUBMODULE(pickling, m) {
                 return py::make_tuple(p.value(), p.extra1(), p.extra2());
             },
             [](const py::tuple &t) {
-                if (t.size() != 3)
+                if (t.size() != 3) {
                     throw std::runtime_error("Invalid state!");
+}
                 auto p = PickleableNew(t[0].cast<std::string>());
 
                 p.setExtra1(t[1].cast<int>());
@@ -153,8 +157,9 @@ TEST_SUBMODULE(pickling, m) {
         });
     ignoreOldStyleInitWarnings([&pyPickleableWithDict]() {
         pyPickleableWithDict.def("__setstate__", [](const py::object &self, const py::tuple &t) {
-            if (t.size() != 3)
+            if (t.size() != 3) {
                 throw std::runtime_error("Invalid state!");
+}
             /* Cast and construct */
             auto &p = self.cast<PickleableWithDict &>();
             new (&p) PickleableWithDict(t[0].cast<std::string>());
@@ -174,8 +179,9 @@ TEST_SUBMODULE(pickling, m) {
                 return py::make_tuple(self.attr("value"), self.attr("extra"), self.attr("__dict__"));
             },
             [](const py::tuple &t) {
-                if (t.size() != 3)
+                if (t.size() != 3) {
                     throw std::runtime_error("Invalid state!");
+}
 
                 auto cpp_state = PickleableWithDictNew(t[0].cast<std::string>());
                 cpp_state.extra = t[1].cast<int>();
diff --git a/tests/test_pytypes.cpp b/tests/test_pytypes.cpp
index 85cb98fc..3605ad8e 100644
--- a/tests/test_pytypes.cpp
+++ b/tests/test_pytypes.cpp
@@ -40,8 +40,9 @@ TEST_SUBMODULE(pytypes, m) {
     });
     m.def("print_list", [](const py::list &list) {
         int index = 0;
-        for (auto item : list)
+        for (auto item : list) {
             py::print("list item {}: {}"_s.format(index++, item));
+        }
     });
     // test_none
     m.def("get_none", []{return py::none();});
@@ -56,8 +57,9 @@ TEST_SUBMODULE(pytypes, m) {
         return set;
     });
     m.def("print_set", [](const py::set &set) {
-        for (auto item : set)
+        for (auto item : set) {
             py::print("key:", item);
+        }
     });
     m.def("set_contains",
           [](const py::set &set, const py::object &key) { return set.contains(key); });
@@ -66,8 +68,9 @@ TEST_SUBMODULE(pytypes, m) {
     // test_dict
     m.def("get_dict", []() { return py::dict("key"_a="value"); });
     m.def("print_dict", [](const py::dict &dict) {
-        for (auto item : dict)
+        for (auto item : dict) {
             py::print("key: {}, value={}"_s.format(item.first, item.second));
+        }
     });
     m.def("dict_keyword_constructor", []() {
         auto d1 = py::dict("x"_a=1, "y"_a=2);
@@ -405,9 +408,9 @@ TEST_SUBMODULE(pytypes, m) {
     m.def("test_memoryview_from_buffer", [](bool is_unsigned) {
         static const int16_t si16[] = { 3, 1, 4, 1, 5 };
         static const uint16_t ui16[] = { 2, 7, 1, 8 };
-        if (is_unsigned)
-            return py::memoryview::from_buffer(
-                ui16, { 4 }, { sizeof(uint16_t) });
+        if (is_unsigned) {
+            return py::memoryview::from_buffer(ui16, {4}, {sizeof(uint16_t)});
+        }
         return py::memoryview::from_buffer(si16, {5}, {sizeof(int16_t)});
     });
 
diff --git a/tests/test_sequences_and_iterators.cpp b/tests/test_sequences_and_iterators.cpp
index a378128a..a5b746ca 100644
--- a/tests/test_sequences_and_iterators.cpp
+++ b/tests/test_sequences_and_iterators.cpp
@@ -74,8 +74,9 @@ PYBIND11_MAKE_OPAQUE(std::vector<NonCopyableIntPair>);
 
 template <typename PythonType>
 py::list test_random_access_iterator(PythonType x) {
-    if (x.size() < 5)
+    if (x.size() < 5) {
         throw py::value_error("Please provide at least 5 elements for testing.");
+    }
 
     auto checks = py::list();
     auto assert_equal = [&checks](py::handle a, py::handle b) {
@@ -125,8 +126,9 @@ TEST_SUBMODULE(sequences_and_iterators, m) {
         .def(py::init<int>())
         .def("__getitem__", [](const Sliceable &s, const py::slice &slice) {
             py::ssize_t start = 0, stop = 0, step = 0, slicelength = 0;
-            if (!slice.compute(s.size, &start, &stop, &step, &slicelength))
+            if (!slice.compute(s.size, &start, &stop, &step, &slicelength)) {
                 throw py::error_already_set();
+            }
             int istart = static_cast<int>(start);
             int istop  = static_cast<int>(stop);
             int istep  = static_cast<int>(step);
@@ -195,10 +197,14 @@ TEST_SUBMODULE(sequences_and_iterators, m) {
         }
 
         bool operator==(const Sequence &s) const {
-            if (m_size != s.size()) return false;
-            for (size_t i = 0; i < m_size; ++i)
-                if (m_data[i] != s[i])
+            if (m_size != s.size()) {
+                return false;
+            }
+            for (size_t i = 0; i < m_size; ++i) {
+                if (m_data[i] != s[i]) {
                     return false;
+                }
+            }
             return true;
         }
         bool operator!=(const Sequence &s) const { return !operator==(s); }
@@ -207,16 +213,19 @@ TEST_SUBMODULE(sequences_and_iterators, m) {
         float &operator[](size_t index) { return m_data[index]; }
 
         bool contains(float v) const {
-            for (size_t i = 0; i < m_size; ++i)
-                if (v == m_data[i])
+            for (size_t i = 0; i < m_size; ++i) {
+                if (v == m_data[i]) {
                     return true;
+                }
+            }
             return false;
         }
 
         Sequence reversed() const {
             Sequence result(m_size);
-            for (size_t i = 0; i < m_size; ++i)
+            for (size_t i = 0; i < m_size; ++i) {
                 result[m_size - i - 1] = m_data[i];
+            }
             return result;
         }
 
@@ -235,14 +244,16 @@ TEST_SUBMODULE(sequences_and_iterators, m) {
         /// Bare bones interface
         .def("__getitem__",
              [](const Sequence &s, size_t i) {
-                 if (i >= s.size())
+                 if (i >= s.size()) {
                      throw py::index_error();
+                 }
                  return s[i];
              })
         .def("__setitem__",
              [](Sequence &s, size_t i, float v) {
-                 if (i >= s.size())
+                 if (i >= s.size()) {
                      throw py::index_error();
+                 }
                  s[i] = v;
              })
         .def("__len__", &Sequence::size)
@@ -257,8 +268,9 @@ TEST_SUBMODULE(sequences_and_iterators, m) {
         .def("__getitem__",
              [](const Sequence &s, const py::slice &slice) -> Sequence * {
                  size_t start = 0, stop = 0, step = 0, slicelength = 0;
-                 if (!slice.compute(s.size(), &start, &stop, &step, &slicelength))
+                 if (!slice.compute(s.size(), &start, &stop, &step, &slicelength)) {
                      throw py::error_already_set();
+                 }
                  auto *seq = new Sequence(slicelength);
                  for (size_t i = 0; i < slicelength; ++i) {
                      (*seq)[i] = s[start];
@@ -269,11 +281,13 @@ TEST_SUBMODULE(sequences_and_iterators, m) {
         .def("__setitem__",
              [](Sequence &s, const py::slice &slice, const Sequence &value) {
                  size_t start = 0, stop = 0, step = 0, slicelength = 0;
-                 if (!slice.compute(s.size(), &start, &stop, &step, &slicelength))
+                 if (!slice.compute(s.size(), &start, &stop, &step, &slicelength)) {
                      throw py::error_already_set();
-                 if (slicelength != value.size())
+                 }
+                 if (slicelength != value.size()) {
                      throw std::runtime_error(
                          "Left and right hand size of slice assignment have different sizes!");
+                 }
                  for (size_t i = 0; i < slicelength; ++i) {
                      s[start] = value[i];
                      start += step;
diff --git a/tests/test_smart_ptr.cpp b/tests/test_smart_ptr.cpp
index 94f04330..5bd77eae 100644
--- a/tests/test_smart_ptr.cpp
+++ b/tests/test_smart_ptr.cpp
@@ -113,8 +113,9 @@ public:
     static void cleanupAllInstances() {
         auto tmp = std::move(myobject4_instances);
         myobject4_instances.clear();
-        for (auto o : tmp)
+        for (auto o : tmp) {
             delete o;
+        }
     }
 private:
     ~MyObject4() {
@@ -140,8 +141,9 @@ public:
     static void cleanupAllInstances() {
         auto tmp = std::move(myobject4a_instances);
         myobject4a_instances.clear();
-        for (auto o : tmp)
+        for (auto o : tmp) {
             delete o;
+        }
     }
 protected:
     virtual ~MyObject4a() {
@@ -445,8 +447,9 @@ TEST_SUBMODULE(smart_ptr, m) {
         .def("add", &ElementList::add)
         .def("get", [](ElementList &el) {
             py::list list;
-            for (auto &e : el.l)
+            for (auto &e : el.l) {
                 list.append(py::cast(e));
+            }
             return list;
         });
 }
diff --git a/tests/test_stl_binders.cpp b/tests/test_stl_binders.cpp
index 6b23e352..7fb973ca 100644
--- a/tests/test_stl_binders.cpp
+++ b/tests/test_stl_binders.cpp
@@ -42,23 +42,27 @@ public:
 
 template <class Container> Container *one_to_n(int n) {
     auto v = new Container();
-    for (int i = 1; i <= n; i++)
+    for (int i = 1; i <= n; i++) {
         v->emplace_back(i);
+    }
     return v;
 }
 
 template <class Map> Map *times_ten(int n) {
     auto m = new Map();
-    for (int i = 1; i <= n; i++)
-        m->emplace(int(i), E_nc(10*i));
+    for (int i = 1; i <= n; i++) {
+        m->emplace(int(i), E_nc(10 * i));
+    }
     return m;
 }
 
 template <class NestMap> NestMap *times_hundred(int n) {
     auto m = new NestMap();
-    for (int i = 1; i <= n; i++)
-        for (int j = 1; j <= n; j++)
-            (*m)[i].emplace(int(j*10), E_nc(100*j));
+    for (int i = 1; i <= n; i++) {
+        for (int j = 1; j <= n; j++) {
+            (*m)[i].emplace(int(j * 10), E_nc(100 * j));
+        }
+    }
     return m;
 }
 
@@ -98,9 +102,11 @@ TEST_SUBMODULE(stl_binders, m) {
     m.def("get_nvnc", [](int n)
         {
             auto m = new std::map<int, std::vector<E_nc>>();
-            for (int i = 1; i <= n; i++)
-                for (int j = 1; j <= n; j++)
+            for (int i = 1; i <= n; i++) {
+                for (int j = 1; j <= n; j++) {
                     (*m)[i].emplace_back(j);
+                }
+            }
             return m;
         });
     py::bind_map<std::map<int, std::map<int, E_nc>>>(m, "MapMapENC");
diff --git a/tests/test_tagbased_polymorphic.cpp b/tests/test_tagbased_polymorphic.cpp
index 2c7bad8b..d54d1fd3 100644
--- a/tests/test_tagbased_polymorphic.cpp
+++ b/tests/test_tagbased_polymorphic.cpp
@@ -100,8 +100,12 @@ const std::type_info* Animal::type_of_kind(Kind kind)
         case Kind::LastCat: break;
     }
 
-    if (kind >= Kind::Dog && kind <= Kind::LastDog) return &typeid(Dog);
-    if (kind >= Kind::Cat && kind <= Kind::LastCat) return &typeid(Cat);
+    if (kind >= Kind::Dog && kind <= Kind::LastDog) {
+        return &typeid(Dog);
+    }
+    if (kind >= Kind::Cat && kind <= Kind::LastCat) {
+        return &typeid(Cat);
+    }
     return nullptr;
 }
 
diff --git a/tests/test_virtual_functions.cpp b/tests/test_virtual_functions.cpp
index d98b57f1..7fb90cc5 100644
--- a/tests/test_virtual_functions.cpp
+++ b/tests/test_virtual_functions.cpp
@@ -112,8 +112,9 @@ public:
     void operator=(const NonCopyable &) = delete;
     void operator=(NonCopyable &&) = delete;
     std::string get_value() const {
-        if (value)
+        if (value) {
             return std::to_string(*value);
+        }
         return "(null)";
     }
     ~NonCopyable() { print_destroyed(this); }