[libcxx-commits] [libcxx] [libc++] constexpr atomic and atomic_ref (PR #98765)

[Nikolas Klauser via libcxx-commits]

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@@ -105,23 +107,37 @@ struct __atomic_base // false
       volatile _NOEXCEPT {
     std::__atomic_wait(*this, __v, __m);
   }
-  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void
+  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void
   wait(_Tp __v, memory_order __m = memory_order_seq_cst) const _NOEXCEPT {
-    std::__atomic_wait(*this, __v, __m);
+    if (__libcpp_is_constant_evaluated()) {
+      if (this->load(__m) != __v) {
+        __builtin_trap();
+      }
+    } else {
+      std::__atomic_wait(*this, __v, __m);
+    }
   }
   _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void notify_one() volatile _NOEXCEPT {
     std::__atomic_notify_one(*this);
   }
-  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void notify_one() _NOEXCEPT { std::__atomic_notify_one(*this); }
+  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void notify_one() _NOEXCEPT {
+    if !consteval {
+      std::__atomic_notify_one(*this);
+    }
+  }
   _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void notify_all() volatile _NOEXCEPT {
     std::__atomic_notify_all(*this);
   }
-  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI void notify_all() _NOEXCEPT { std::__atomic_notify_all(*this); }
+  _LIBCPP_AVAILABILITY_SYNC _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX26 void notify_all() _NOEXCEPT {
+    if !consteval {
+      std::__atomic_notify_all(*this);
+    }
+  }
 
 #if _LIBCPP_STD_VER >= 20
   _LIBCPP_HIDE_FROM_ABI constexpr __atomic_base() noexcept(is_nothrow_default_constructible_v<_Tp>) : __a_(_Tp()) {}
 #else
-  _LIBCPP_HIDE_FROM_ABI __atomic_base() _NOEXCEPT = default;
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __atomic_base() _NOEXCEPT = default;
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philnik777 wrote:

Unrelated change?

https://github.com/llvm/llvm-project/pull/98765