Trying henryiii@ (void) expander idea.

Author: rwgk

include/pybind11/attr.h

@@ -518,26 +518,29 @@ template <typename... Args> struct process_attributes {
     static void init(const Args&... args, function_record *r) {
         PYBIND11_WORKAROUND_INCORRECT_MSVC_C4100(r);
         PYBIND11_WORKAROUND_INCORRECT_ALL_GCC_UNUSED_BUT_SET_PARAMETER(r);
-        PYBIND11_INT_ARRAY_WORKING_AROUND_MSVC_CLANG_ISSUES(
-            {0, (process_attribute<typename std::decay<Args>::type>::init(args, r), 0)...});
+        using expander = int[];
+        (void) expander{
+            0, ((void) process_attribute<typename std::decay<Args>::type>::init(args, r), 0)...};
     }
     static void init(const Args&... args, type_record *r) {
         PYBIND11_WORKAROUND_INCORRECT_MSVC_C4100(r);
         PYBIND11_WORKAROUND_INCORRECT_ALL_GCC_UNUSED_BUT_SET_PARAMETER(r);
-        PYBIND11_INT_ARRAY_WORKING_AROUND_MSVC_CLANG_ISSUES(
-            {0, (process_attribute<typename std::decay<Args>::type>::init(args, r), 0)...});
+        using expander = int[];
+        (void) expander{0,
+                        (process_attribute<typename std::decay<Args>::type>::init(args, r), 0)...};
     }
     static void precall(function_call &call) {
         PYBIND11_WORKAROUND_INCORRECT_MSVC_C4100(call);
-        PYBIND11_INT_ARRAY_WORKING_AROUND_MSVC_CLANG_ISSUES(
-            {0, (process_attribute<typename std::decay<Args>::type>::precall(call), 0)...});
+        using expander = int[];
+        (void) expander{0,
+                        (process_attribute<typename std::decay<Args>::type>::precall(call), 0)...};
     }
     static void postcall(function_call &call, handle fn_ret) {
         PYBIND11_WORKAROUND_INCORRECT_MSVC_C4100(call, fn_ret);
         PYBIND11_WORKAROUND_INCORRECT_ALL_GCC_UNUSED_BUT_SET_PARAMETER(fn_ret);
-        PYBIND11_INT_ARRAY_WORKING_AROUND_MSVC_CLANG_ISSUES(
-            {0,
-             (process_attribute<typename std::decay<Args>::type>::postcall(call, fn_ret), 0)...});
+        using expander = int[];
+        (void) expander{
+            0, (process_attribute<typename std::decay<Args>::type>::postcall(call, fn_ret), 0)...};
     }
 };
 

include/pybind11/cast.h

@@ -1236,8 +1236,8 @@ class unpacking_collector {
         // Tuples aren't (easily) resizable so a list is needed for collection,
         // but the actual function call strictly requires a tuple.
         auto args_list = list();
-        PYBIND11_INT_ARRAY_WORKING_AROUND_MSVC_CLANG_ISSUES(
-            {0, (process(args_list, std::forward<Ts>(values)), 0)...});
+        using expander = int[];
+        (void) expander{0, (process(args_list, std::forward<Ts>(values)), 0)...};
 
         m_args = std::move(args_list);
     }

include/pybind11/detail/common.h

@@ -954,17 +954,6 @@ inline void silence_unused_warnings(Args &&...) {}
 #    define PYBIND11_WORKAROUND_INCORRECT_OLD_GCC_UNUSED_BUT_SET_PARAMETER(...)
 #endif
 
-// MSVC error C4576: a parenthesized type followed by an initializer list is a
-//                   non-standard explicit type conversion syntax
-// clang: expression result unused [-Wunused-value]
-#if defined(_MSC_VER) || defined(__clang__) // All versions (as of July 2021).
-#    define PYBIND11_INT_ARRAY_WORKING_AROUND_MSVC_CLANG_ISSUES(...)                              \
-        int dummy[] = __VA_ARGS__;                                                                \
-        detail::silence_unused_warnings(dummy)
-#else
-#    define PYBIND11_INT_ARRAY_WORKING_AROUND_MSVC_CLANG_ISSUES(...) (int[]) __VA_ARGS__
-#endif
-
 #if defined(_MSC_VER) // All versions (as of July 2021).
 
 // warning C4127: Conditional expression is constant