From 5d56ef759f0e3b28c27972b8f361aa36e422479b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=9C=A8=E5=A4=B4=E4=BA=91?= <orz@orzz.org>
Date: Mon, 1 Dec 2025 09:58:53 +0000
Subject: [PATCH] refactor(uninitialized): Improve construct() overload
 resolution

IMPROVEMENTS:
1. Add explicit zero-argument overload to avoid SFINAE ambiguity
2. Require at least one argument (A1) for parameterized overloads
3. Better separation between direct initialization and aggregate initialization

BENEFITS:
- Clearer intent: zero-argument construction is explicitly handled
- Avoids potential SFINAE ambiguity when empty parameter pack is used
- More maintainable: easier to understand which overload is selected
- Consistent with modern C++ best practices for variadic templates

TECHNICAL DETAILS:
- Zero-arg overload: Always uses T() for value initialization
- One-or-more-arg overload: Uses SFINAE to choose between:
  * T(args...) for types with matching constructor
  * T{args...} for aggregate types or types with initializer_list ctor

This is a code quality improvement and does not fix any compilation issues,
but provides better template overload resolution.
---
 include/libipc/imp/uninitialized.h | 30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/include/libipc/imp/uninitialized.h b/include/libipc/imp/uninitialized.h
index 01b69c8..dd7b109 100644
--- a/include/libipc/imp/uninitialized.h
+++ b/include/libipc/imp/uninitialized.h
@@ -21,20 +21,32 @@ namespace ipc {
  * \see https://en.cppreference.com/w/cpp/memory/construct_at
 */
 
-template <typename T, typename... A>
-auto construct(void *p, A &&...args)
-  -> std::enable_if_t<::std::is_constructible<T, A...>::value, T *> {
+// Overload for zero arguments - use value initialization
+template <typename T>
+T* construct(void *p) {
 #if defined(LIBIPC_CPP_20)
-  return std::construct_at(static_cast<T *>(p), std::forward<A>(args)...);
+  return std::construct_at(static_cast<T *>(p));
 #else
-  return ::new (p) T(std::forward<A>(args)...);
+  return ::new (p) T();
 #endif
 }
 
-template <typename T, typename... A>
-auto construct(void *p, A &&...args)
-  -> std::enable_if_t<!::std::is_constructible<T, A...>::value, T *> {
-  return ::new (p) T{std::forward<A>(args)...};
+// Overload for one or more arguments - prefer direct initialization
+template <typename T, typename A1, typename... A>
+auto construct(void *p, A1 &&arg1, A &&...args)
+  -> std::enable_if_t<::std::is_constructible<T, A1, A...>::value, T *> {
+#if defined(LIBIPC_CPP_20)
+  return std::construct_at(static_cast<T *>(p), std::forward<A1>(arg1), std::forward<A>(args)...);
+#else
+  return ::new (p) T(std::forward<A1>(arg1), std::forward<A>(args)...);
+#endif
+}
+
+// Overload for non-constructible types - use aggregate initialization
+template <typename T, typename A1, typename... A>
+auto construct(void *p, A1 &&arg1, A &&...args)
+  -> std::enable_if_t<!::std::is_constructible<T, A1, A...>::value, T *> {
+  return ::new (p) T{std::forward<A1>(arg1), std::forward<A>(args)...};
 }
 
 /**