From 52ab85be9ec91ee9dbe46161fa8cb987d1702cb6 Mon Sep 17 00:00:00 2001
From: Mingxin Wang <mingxwa@microsoft.com>
Date: Mon, 14 Oct 2024 13:58:20 +0800
Subject: [PATCH] Add assertion for `proxy_invoke()` and `proxy_reflect()`
 (#175)

---
 proxy.h | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/proxy.h b/proxy.h
index 92b3556..f54b139 100644
--- a/proxy.h
+++ b/proxy.h
@@ -4,6 +4,7 @@
 #ifndef _MSFT_PROXY_
 #define _MSFT_PROXY_
 
+#include <cassert>
 #include <cstddef>
 #include <bit>
 #include <concepts>
@@ -565,12 +566,14 @@ struct meta_ptr_reset_guard {
 
 template <class F>
 struct proxy_helper {
-  static inline const auto& get_meta(const proxy<F>& p) noexcept
-      { return *p.meta_.operator->(); }
+  static inline const auto& get_meta(const proxy<F>& p) noexcept {
+    assert(p.has_value());
+    return *p.meta_.operator->();
+  }
   template <class C, class O, qualifier_type Q, class... Args>
   static decltype(auto) invoke(add_qualifier_t<proxy<F>, Q> p, Args&&... args) {
-    auto dispatcher = p.meta_
-        ->template dispatcher_meta<typename overload_traits<O>
+    auto dispatcher = get_meta(p)
+        .template dispatcher_meta<typename overload_traits<O>
         ::template meta_provider<C::is_direct, typename C::dispatch_type>>
         ::dispatcher;
     if constexpr (C::is_direct &&
@@ -788,9 +791,12 @@ class proxy : public details::facade_traits<F>::direct_accessor {
  private:
   template <class P, class... Args>
   P& initialize(Args&&... args) {
-    std::construct_at(reinterpret_cast<P*>(ptr_), std::forward<Args>(args)...);
+    P& result = *std::construct_at(
+        reinterpret_cast<P*>(ptr_), std::forward<Args>(args)...);
+    if constexpr (requires { (bool)result; })
+        { assert((bool)result); }
     meta_ = details::meta_ptr<typename _Traits::meta>{std::in_place_type<P>};
-    return *std::launder(reinterpret_cast<P*>(ptr_));
+    return result;
   }
 
   [[___PRO_NO_UNIQUE_ADDRESS_ATTRIBUTE]]