From 5f2a90b0c79ecca2499802d81d7f37709d69fa61 Mon Sep 17 00:00:00 2001
From: Ben Deane <ben@elbeno.com>
Date: Thu, 10 Jul 2025 16:19:35 -0600
Subject: [PATCH] :bug: Small fixes for `CX_VALUE` and friends

Problem:
- `CX_VALUE` without a capture clause is important for use cases where the
  lambda has to be default constructible.
- Naming the function type in the `CX_WRAP` macro causes shadowing warnings.

Solution:
- Remove the default capture clause from `CX_VALUE`.
- Leave the function unnamed in `CX_WRAP`.
---
 include/stdx/utility.hpp | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/include/stdx/utility.hpp b/include/stdx/utility.hpp
index 9afcce9..1478f97 100644
--- a/include/stdx/utility.hpp
+++ b/include/stdx/utility.hpp
@@ -234,7 +234,7 @@ template <typename T> constexpr auto is_ct_v<T const> = is_ct_v<T>;
 
 #ifndef CX_VALUE
 #define CX_VALUE(...)                                                          \
-    [&]() constexpr {                                                          \
+    []() constexpr {                                                           \
         STDX_PRAGMA(diagnostic push)                                           \
         STDX_PRAGMA(diagnostic ignored "-Wold-style-cast")                     \
         STDX_PRAGMA(diagnostic ignored "-Wunused-value")                       \
@@ -274,7 +274,10 @@ template <typename T> constexpr auto is_ct_v<T const> = is_ct_v<T>;
     }([&] { return X; })
 
 #ifdef __clang__
-#define CX_DETECT(X) std::is_empty_v<decltype(CX_VALUE(X))>
+#define CX_DETECT(X)                                                           \
+    std::is_empty_v<decltype([&] {                                             \
+        return (X) + ::stdx::cxv_detail::type_val{};                           \
+    })>
 #else
 namespace stdx {
 inline namespace v1 {
@@ -290,10 +293,11 @@ constexpr auto cx_detect1(auto) { return 0; }
 #endif
 
 #define CX_WRAP(X)                                                             \
-    [&]<typename F>(F f) {                                                     \
+    [&](auto f) {                                                              \
         STDX_PRAGMA(diagnostic push)                                           \
         STDX_PRAGMA(diagnostic ignored "-Wold-style-cast")                     \
-        if constexpr (::stdx::is_cx_value_v<std::invoke_result_t<F>>) {        \
+        if constexpr (::stdx::is_cx_value_v<                                   \
+                          std::invoke_result_t<decltype(f)>>) {                \
             return f();                                                        \
         } else if constexpr (CX_DETECT(X)) {                                   \
             if constexpr (decltype(::stdx::cxv_detail::is_type<                \