From 8d7f36d2589b073dab4356d6a08020579470a6bc Mon Sep 17 00:00:00 2001
From: Vadim Sadokhov <v.sadokhov@vk.team>
Date: Fri, 31 Oct 2025 16:27:51 +0300
Subject: [PATCH 1/5] solve some runtime-light issues

---
 runtime-light/coroutine/detail/when-any.h     | 12 ++++--
 runtime-light/coroutine/io-scheduler.h        | 39 ++++++++++++-------
 runtime-light/runtime-light.cmake             |  1 -
 .../diagnostics}/php-assert.cpp               |  0
 .../operators}/null_coalesce.h                |  0
 runtime-light/stdlib/stdlib.cmake             |  1 +
 runtime-light/stdlib/string/regex-state.h     |  4 +-
 runtime-light/tl/tl-core.h                    |  6 +--
 .../{utils => type-traits}/concepts.h         |  4 ++
 runtime-light/type-traits/functions.h         | 25 ++++++++++++
 runtime-light/utils/utils.cmake               |  1 -
 11 files changed, 69 insertions(+), 24 deletions(-)
 rename runtime-light/{utils => stdlib/diagnostics}/php-assert.cpp (100%)
 rename runtime-light/{utils => stdlib/operators}/null_coalesce.h (100%)
 rename runtime-light/{utils => type-traits}/concepts.h (88%)
 create mode 100644 runtime-light/type-traits/functions.h
 delete mode 100644 runtime-light/utils/utils.cmake

diff --git a/runtime-light/coroutine/detail/when-any.h b/runtime-light/coroutine/detail/when-any.h
index 085c1f3200..2c3bc7c7b4 100644
--- a/runtime-light/coroutine/detail/when-any.h
+++ b/runtime-light/coroutine/detail/when-any.h
@@ -16,6 +16,7 @@
 #include "runtime-light/coroutine/type-traits.h"
 #include "runtime-light/coroutine/void-value.h"
 #include "runtime-light/stdlib/diagnostics/logs.h"
+#include "runtime-light/type-traits/functions.h"
 
 namespace kphp::coro::detail::when_any {
 
@@ -120,7 +121,9 @@ class when_any_ready_awaitable<std::tuple<task_types...>> {
 
       const auto task_result_processor{[&result = m_awaitable.m_result](auto&& task) noexcept {
         if (auto task_result{std::forward<decltype(task)>(task).result()}; !result.has_value() && task_result.has_value()) {
-          result = std::move(task_result);
+          using result_variant_type = std::remove_cvref<decltype(result)>::type::value_type;
+          using task_result_type = decltype(task_result)::value_type;
+          result = result_variant_type(std::in_place_index<kphp::type_traits::variant_index<result_variant_type, task_result_type>()>, *std::move(task_result));
         }
       }};
       std::apply([&task_result_processor](auto&&... tasks) noexcept { (std::invoke(task_result_processor, std::forward<decltype(tasks)>(tasks)), ...); },
@@ -290,8 +293,11 @@ class when_any_task {
 
 template<kphp::coro::concepts::awaitable awaitable_type>
 auto make_when_any_task(awaitable_type awaitable) noexcept -> when_any_task<typename kphp::coro::awaitable_traits<awaitable_type>::awaiter_return_type> {
-  co_yield co_await std::move(awaitable);
-  co_return;
+  if constexpr (std::is_void_v<typename kphp::coro::awaitable_traits<awaitable_type>::awaiter_return_type>) {
+    co_await std::move(awaitable);
+  } else {
+    co_yield co_await std::move(awaitable);
+  }
 }
 
 } // namespace kphp::coro::detail::when_any
diff --git a/runtime-light/coroutine/io-scheduler.h b/runtime-light/coroutine/io-scheduler.h
index 241c518014..8adf8a7e09 100644
--- a/runtime-light/coroutine/io-scheduler.h
+++ b/runtime-light/coroutine/io-scheduler.h
@@ -16,6 +16,7 @@
 #include <memory>
 #include <optional>
 #include <ranges>
+#include <type_traits>
 #include <utility>
 #include <variant>
 
@@ -63,11 +64,11 @@ class io_scheduler {
   auto process_accept(k2::descriptor descriptor) noexcept -> void;
 
   auto update_timer() noexcept -> void;
-  [[nodiscard]] auto add_timer_token(k2::TimePoint time_point,
-                                     kphp::coro::detail::poll_info& poll_info) noexcept -> kphp::coro::detail::poll_info::timed_events::iterator;
+  [[nodiscard]] auto add_timer_token(k2::TimePoint time_point, kphp::coro::detail::poll_info& poll_info) noexcept
+      -> kphp::coro::detail::poll_info::timed_events::iterator;
   template<typename rep_type, typename period_type>
-  [[nodiscard]] auto add_timer_token(std::chrono::duration<rep_type, period_type> timeout,
-                                     kphp::coro::detail::poll_info& poll_info) noexcept -> kphp::coro::detail::poll_info::timed_events::iterator;
+  [[nodiscard]] auto add_timer_token(std::chrono::duration<rep_type, period_type> timeout, kphp::coro::detail::poll_info& poll_info) noexcept
+      -> kphp::coro::detail::poll_info::timed_events::iterator;
   auto remove_timer_token(kphp::coro::detail::poll_info::timed_events::iterator pos) noexcept -> void;
 
 public:
@@ -161,8 +162,8 @@ class io_scheduler {
    * @param timeout Maximum duration to wait for the event (0 means no timeout).
    * @return A task that yields the poll status when completed.
    */
-  [[nodiscard]] auto poll(k2::descriptor descriptor, kphp::coro::poll_op poll_op,
-                          std::chrono::nanoseconds timeout = std::chrono::nanoseconds{0}) noexcept -> kphp::coro::task<poll_status>;
+  [[nodiscard]] auto poll(k2::descriptor descriptor, kphp::coro::poll_op poll_op, std::chrono::nanoseconds timeout = std::chrono::nanoseconds{0}) noexcept
+      -> kphp::coro::task<poll_status>;
 
   /**
    * @brief Accepts an incoming connection with optional timeout.
@@ -329,8 +330,8 @@ inline auto io_scheduler::update_timer() noexcept -> void {
   }
 }
 
-inline auto io_scheduler::add_timer_token(k2::TimePoint time_point,
-                                          kphp::coro::detail::poll_info& poll_info) noexcept -> kphp::coro::detail::poll_info::timed_events::iterator {
+inline auto io_scheduler::add_timer_token(k2::TimePoint time_point, kphp::coro::detail::poll_info& poll_info) noexcept
+    -> kphp::coro::detail::poll_info::timed_events::iterator {
   const auto pos{m_timed_events.emplace(time_point, poll_info)};
   if (pos == m_timed_events.begin()) {
     update_timer();
@@ -339,8 +340,8 @@ inline auto io_scheduler::add_timer_token(k2::TimePoint time_point,
 }
 
 template<typename rep_type, typename period_type>
-auto io_scheduler::add_timer_token(std::chrono::duration<rep_type, period_type> timeout,
-                                   kphp::coro::detail::poll_info& poll_info) noexcept -> kphp::coro::detail::poll_info::timed_events::iterator {
+auto io_scheduler::add_timer_token(std::chrono::duration<rep_type, period_type> timeout, kphp::coro::detail::poll_info& poll_info) noexcept
+    -> kphp::coro::detail::poll_info::timed_events::iterator {
   k2::TimePoint time_point{};
   k2::instant(std::addressof(time_point));
   time_point.time_point_ns += std::chrono::duration_cast<std::chrono::nanoseconds>(timeout).count();
@@ -463,13 +464,23 @@ auto io_scheduler::schedule(coroutine_type coroutine, std::chrono::duration<rep_
   using expected_return_type = typename kphp::coro::coroutine_traits<coroutine_type>::return_type;
 
   if (timeout <= std::chrono::duration<rep_type, period_type>{0}) [[unlikely]] {
-    co_return std::expected<expected_return_type, timeout_status>{co_await schedule(std::move(coroutine))};
+    if constexpr (std::is_void_v<expected_return_type>) {
+      co_await schedule(std::move(coroutine));
+      co_return std::expected<expected_return_type, timeout_status>{};
+    } else {
+      co_return std::expected<expected_return_type, timeout_status>{co_await schedule(std::move(coroutine))};
+    }
   }
   auto result{co_await kphp::coro::when_any(std::move(coroutine), make_timeout_task(timeout))};
   if (std::holds_alternative<timeout_status>(result)) [[unlikely]] {
     co_return std::unexpected{std::move(std::get<1>(result))};
   }
-  co_return std::expected<expected_return_type, timeout_status>{std::move(std::get<0>(result))};
+
+  if constexpr (std::is_void_v<expected_return_type>) {
+    co_return std::expected<expected_return_type, timeout_status>{};
+  } else {
+    co_return std::expected<expected_return_type, timeout_status>{std::move(std::get<0>(result))};
+  }
 }
 
 template<typename rep_type, typename period_type>
@@ -494,8 +505,8 @@ auto io_scheduler::yield_for(std::chrono::duration<rep_type, period_type> amount
   co_await schedule_after(amount);
 }
 
-inline auto io_scheduler::poll(k2::descriptor descriptor, kphp::coro::poll_op poll_op,
-                               std::chrono::nanoseconds timeout) noexcept -> kphp::coro::task<poll_status> {
+inline auto io_scheduler::poll(k2::descriptor descriptor, kphp::coro::poll_op poll_op, std::chrono::nanoseconds timeout) noexcept
+    -> kphp::coro::task<poll_status> {
   k2::StreamStatus stream_status{};
   k2::stream_status(descriptor, std::addressof(stream_status));
   if (stream_status.libc_errno != k2::errno_ok) [[unlikely]] {
diff --git a/runtime-light/runtime-light.cmake b/runtime-light/runtime-light.cmake
index 3cc64e6e03..cbb74d4d38 100644
--- a/runtime-light/runtime-light.cmake
+++ b/runtime-light/runtime-light.cmake
@@ -22,7 +22,6 @@ include(${RUNTIME_LIGHT_DIR}/coroutine/coroutine.cmake)
 include(${RUNTIME_LIGHT_DIR}/server/server.cmake)
 include(${RUNTIME_LIGHT_DIR}/stdlib/stdlib.cmake)
 include(${RUNTIME_LIGHT_DIR}/tl/tl.cmake)
-include(${RUNTIME_LIGHT_DIR}/utils/utils.cmake)
 include(${RUNTIME_LIGHT_DIR}/state/state.cmake)
 include(${RUNTIME_LIGHT_DIR}/memory-resource-impl/memory-resource-impl.cmake)
 
diff --git a/runtime-light/utils/php-assert.cpp b/runtime-light/stdlib/diagnostics/php-assert.cpp
similarity index 100%
rename from runtime-light/utils/php-assert.cpp
rename to runtime-light/stdlib/diagnostics/php-assert.cpp
diff --git a/runtime-light/utils/null_coalesce.h b/runtime-light/stdlib/operators/null_coalesce.h
similarity index 100%
rename from runtime-light/utils/null_coalesce.h
rename to runtime-light/stdlib/operators/null_coalesce.h
diff --git a/runtime-light/stdlib/stdlib.cmake b/runtime-light/stdlib/stdlib.cmake
index a176dac8f5..22ceaece1f 100644
--- a/runtime-light/stdlib/stdlib.cmake
+++ b/runtime-light/stdlib/stdlib.cmake
@@ -8,6 +8,7 @@ prepend(
   diagnostics/backtrace.cpp
   diagnostics/contextual-logger.cpp
   diagnostics/error-handling-state.cpp
+  diagnostics/php-assert.cpp
   file/resource.cpp
   fork/fork-state.cpp
   fork/wait-queue-state.cpp
diff --git a/runtime-light/stdlib/string/regex-state.h b/runtime-light/stdlib/string/regex-state.h
index d7ebee625d..50b43312c8 100644
--- a/runtime-light/stdlib/string/regex-state.h
+++ b/runtime-light/stdlib/string/regex-state.h
@@ -11,10 +11,10 @@
 #include "runtime-common/core/allocator/script-allocator.h"
 #include "runtime-common/core/std/containers.h"
 #include "runtime-light/stdlib/string/regex-include.h"
-#include "runtime-light/utils/concepts.h"
+#include "runtime-light/type-traits/concepts.h"
 
 struct RegexInstanceState final : private vk::not_copyable {
-  template<hashable Key, typename Value>
+  template<kphp::type_traits::hashable Key, typename Value>
   using unordered_map = kphp::stl::unordered_map<Key, Value, kphp::memory::script_allocator>;
 
   static constexpr size_t MAX_SUBPATTERNS_COUNT = 512;
diff --git a/runtime-light/tl/tl-core.h b/runtime-light/tl/tl-core.h
index 9c9d378d28..ccaf95e986 100644
--- a/runtime-light/tl/tl-core.h
+++ b/runtime-light/tl/tl-core.h
@@ -16,7 +16,7 @@
 #include "runtime-common/core/allocator/script-allocator.h"
 #include "runtime-common/core/std/containers.h"
 #include "runtime-light/stdlib/diagnostics/logs.h"
-#include "runtime-light/utils/concepts.h"
+#include "runtime-light/type-traits/concepts.h"
 
 namespace tl {
 
@@ -66,7 +66,7 @@ class storer {
     m_buffer.append_range(bytes);
   }
 
-  template<standard_layout T, standard_layout U>
+  template<kphp::type_traits::standard_layout T, kphp::type_traits::standard_layout U>
   requires std::convertible_to<U, T>
   void store_trivial(const U& t) noexcept {
     store_bytes({reinterpret_cast<const std::byte*>(std::addressof(t)), sizeof(T)});
@@ -136,7 +136,7 @@ class fetcher {
     return bytes;
   }
 
-  template<standard_layout T>
+  template<kphp::type_traits::standard_layout T>
   std::optional<T> fetch_trivial() noexcept {
     if (m_remaining < sizeof(T)) {
       return std::nullopt;
diff --git a/runtime-light/utils/concepts.h b/runtime-light/type-traits/concepts.h
similarity index 88%
rename from runtime-light/utils/concepts.h
rename to runtime-light/type-traits/concepts.h
index a2db5a90fe..56f125e20d 100644
--- a/runtime-light/utils/concepts.h
+++ b/runtime-light/type-traits/concepts.h
@@ -8,6 +8,8 @@
 #include <cstddef>
 #include <functional>
 
+namespace kphp::type_traits {
+
 template<typename T>
 concept standard_layout = std::is_standard_layout_v<T>;
 
@@ -18,3 +20,5 @@ concept hashable = requires(T t) {
 
 template<typename type, typename... types>
 concept in_types = (std::same_as<type, types> || ...);
+
+} // namespace kphp::type_traits
diff --git a/runtime-light/type-traits/functions.h b/runtime-light/type-traits/functions.h
new file mode 100644
index 0000000000..0f92bd7de1
--- /dev/null
+++ b/runtime-light/type-traits/functions.h
@@ -0,0 +1,25 @@
+//  Compiler for PHP (aka KPHP)
+//  Copyright (c) 2025 LLC «V Kontakte»
+//  Distributed under the GPL v3 License, see LICENSE.notice.txt
+
+#pragma once
+
+#include <cstddef>
+#include <variant>
+
+namespace kphp::type_traits {
+
+template<typename variant_type, typename T, size_t index = 0>
+constexpr size_t variant_index() noexcept {
+  static_assert(index < std::variant_size_v<variant_type>, "Type not found in variant");
+  if constexpr (index == std::variant_size_v<variant_type>) {
+    // To prevent the error of substituting an index that is too large in variant_alternative_t
+    return index;
+  } else if constexpr (std::is_same_v<std::variant_alternative_t<index, variant_type>, T>) {
+    return index;
+  } else {
+    return variant_index<variant_type, T, index + 1>();
+  }
+}
+
+} // namespace kphp::type_traits
diff --git a/runtime-light/utils/utils.cmake b/runtime-light/utils/utils.cmake
deleted file mode 100644
index 911086ea12..0000000000
--- a/runtime-light/utils/utils.cmake
+++ /dev/null
@@ -1 +0,0 @@
-prepend(RUNTIME_LIGHT_UTILS_SRC utils/ php-assert.cpp)

From 10f5b05d5504f713e16fead8ae983689a201e6c3 Mon Sep 17 00:00:00 2001
From: Vadim Sadokhov <v.sadokhov@vk.team>
Date: Fri, 31 Oct 2025 16:31:19 +0300
Subject: [PATCH 2/5] small fix

---
 runtime-light/coroutine/detail/when-any.h |  2 +-
 runtime-light/coroutine/io-scheduler.h    | 24 +++++++++++------------
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/runtime-light/coroutine/detail/when-any.h b/runtime-light/coroutine/detail/when-any.h
index 2c3bc7c7b4..a73796a210 100644
--- a/runtime-light/coroutine/detail/when-any.h
+++ b/runtime-light/coroutine/detail/when-any.h
@@ -123,7 +123,7 @@ class when_any_ready_awaitable<std::tuple<task_types...>> {
         if (auto task_result{std::forward<decltype(task)>(task).result()}; !result.has_value() && task_result.has_value()) {
           using result_variant_type = std::remove_cvref<decltype(result)>::type::value_type;
           using task_result_type = decltype(task_result)::value_type;
-          result = result_variant_type(std::in_place_index<kphp::type_traits::variant_index<result_variant_type, task_result_type>()>, *std::move(task_result));
+          result = result_variant_type{std::in_place_index<kphp::type_traits::variant_index<result_variant_type, task_result_type>()>, *std::move(task_result)};
         }
       }};
       std::apply([&task_result_processor](auto&&... tasks) noexcept { (std::invoke(task_result_processor, std::forward<decltype(tasks)>(tasks)), ...); },
diff --git a/runtime-light/coroutine/io-scheduler.h b/runtime-light/coroutine/io-scheduler.h
index 8adf8a7e09..b096deeea5 100644
--- a/runtime-light/coroutine/io-scheduler.h
+++ b/runtime-light/coroutine/io-scheduler.h
@@ -64,11 +64,11 @@ class io_scheduler {
   auto process_accept(k2::descriptor descriptor) noexcept -> void;
 
   auto update_timer() noexcept -> void;
-  [[nodiscard]] auto add_timer_token(k2::TimePoint time_point, kphp::coro::detail::poll_info& poll_info) noexcept
-      -> kphp::coro::detail::poll_info::timed_events::iterator;
+  [[nodiscard]] auto add_timer_token(k2::TimePoint time_point,
+                                     kphp::coro::detail::poll_info& poll_info) noexcept -> kphp::coro::detail::poll_info::timed_events::iterator;
   template<typename rep_type, typename period_type>
-  [[nodiscard]] auto add_timer_token(std::chrono::duration<rep_type, period_type> timeout, kphp::coro::detail::poll_info& poll_info) noexcept
-      -> kphp::coro::detail::poll_info::timed_events::iterator;
+  [[nodiscard]] auto add_timer_token(std::chrono::duration<rep_type, period_type> timeout,
+                                     kphp::coro::detail::poll_info& poll_info) noexcept -> kphp::coro::detail::poll_info::timed_events::iterator;
   auto remove_timer_token(kphp::coro::detail::poll_info::timed_events::iterator pos) noexcept -> void;
 
 public:
@@ -162,8 +162,8 @@ class io_scheduler {
    * @param timeout Maximum duration to wait for the event (0 means no timeout).
    * @return A task that yields the poll status when completed.
    */
-  [[nodiscard]] auto poll(k2::descriptor descriptor, kphp::coro::poll_op poll_op, std::chrono::nanoseconds timeout = std::chrono::nanoseconds{0}) noexcept
-      -> kphp::coro::task<poll_status>;
+  [[nodiscard]] auto poll(k2::descriptor descriptor, kphp::coro::poll_op poll_op,
+                          std::chrono::nanoseconds timeout = std::chrono::nanoseconds{0}) noexcept -> kphp::coro::task<poll_status>;
 
   /**
    * @brief Accepts an incoming connection with optional timeout.
@@ -330,8 +330,8 @@ inline auto io_scheduler::update_timer() noexcept -> void {
   }
 }
 
-inline auto io_scheduler::add_timer_token(k2::TimePoint time_point, kphp::coro::detail::poll_info& poll_info) noexcept
-    -> kphp::coro::detail::poll_info::timed_events::iterator {
+inline auto io_scheduler::add_timer_token(k2::TimePoint time_point,
+                                          kphp::coro::detail::poll_info& poll_info) noexcept -> kphp::coro::detail::poll_info::timed_events::iterator {
   const auto pos{m_timed_events.emplace(time_point, poll_info)};
   if (pos == m_timed_events.begin()) {
     update_timer();
@@ -340,8 +340,8 @@ inline auto io_scheduler::add_timer_token(k2::TimePoint time_point, kphp::coro::
 }
 
 template<typename rep_type, typename period_type>
-auto io_scheduler::add_timer_token(std::chrono::duration<rep_type, period_type> timeout, kphp::coro::detail::poll_info& poll_info) noexcept
-    -> kphp::coro::detail::poll_info::timed_events::iterator {
+auto io_scheduler::add_timer_token(std::chrono::duration<rep_type, period_type> timeout,
+                                   kphp::coro::detail::poll_info& poll_info) noexcept -> kphp::coro::detail::poll_info::timed_events::iterator {
   k2::TimePoint time_point{};
   k2::instant(std::addressof(time_point));
   time_point.time_point_ns += std::chrono::duration_cast<std::chrono::nanoseconds>(timeout).count();
@@ -505,8 +505,8 @@ auto io_scheduler::yield_for(std::chrono::duration<rep_type, period_type> amount
   co_await schedule_after(amount);
 }
 
-inline auto io_scheduler::poll(k2::descriptor descriptor, kphp::coro::poll_op poll_op, std::chrono::nanoseconds timeout) noexcept
-    -> kphp::coro::task<poll_status> {
+inline auto io_scheduler::poll(k2::descriptor descriptor, kphp::coro::poll_op poll_op,
+                               std::chrono::nanoseconds timeout) noexcept -> kphp::coro::task<poll_status> {
   k2::StreamStatus stream_status{};
   k2::stream_status(descriptor, std::addressof(stream_status));
   if (stream_status.libc_errno != k2::errno_ok) [[unlikely]] {

From 3955ff726094ac41e0cc23deebdb7f7d4a8832a1 Mon Sep 17 00:00:00 2001
From: Vadim Sadokhov <v.sadokhov@vk.team>
Date: Fri, 31 Oct 2025 17:22:36 +0300
Subject: [PATCH 3/5] small fix

---
 runtime-light/coroutine/detail/when-any.h                   | 4 ++--
 runtime-light/coroutine/io-scheduler.h                      | 1 +
 runtime-light/{type-traits => metaprogramming}/concepts.h   | 4 ++--
 .../functions.h => metaprogramming/type-functions.h}        | 6 +++---
 runtime-light/stdlib/string/regex-state.h                   | 4 ++--
 runtime-light/tl/tl-core.h                                  | 6 +++---
 6 files changed, 13 insertions(+), 12 deletions(-)
 rename runtime-light/{type-traits => metaprogramming}/concepts.h (89%)
 rename runtime-light/{type-traits/functions.h => metaprogramming/type-functions.h} (86%)

diff --git a/runtime-light/coroutine/detail/when-any.h b/runtime-light/coroutine/detail/when-any.h
index a73796a210..1ba1f892ed 100644
--- a/runtime-light/coroutine/detail/when-any.h
+++ b/runtime-light/coroutine/detail/when-any.h
@@ -15,8 +15,8 @@
 #include "runtime-light/coroutine/concepts.h"
 #include "runtime-light/coroutine/type-traits.h"
 #include "runtime-light/coroutine/void-value.h"
+#include "runtime-light/metaprogramming/type-functions.h"
 #include "runtime-light/stdlib/diagnostics/logs.h"
-#include "runtime-light/type-traits/functions.h"
 
 namespace kphp::coro::detail::when_any {
 
@@ -123,7 +123,7 @@ class when_any_ready_awaitable<std::tuple<task_types...>> {
         if (auto task_result{std::forward<decltype(task)>(task).result()}; !result.has_value() && task_result.has_value()) {
           using result_variant_type = std::remove_cvref<decltype(result)>::type::value_type;
           using task_result_type = decltype(task_result)::value_type;
-          result = result_variant_type{std::in_place_index<kphp::type_traits::variant_index<result_variant_type, task_result_type>()>, *std::move(task_result)};
+          result = result_variant_type{std::in_place_index<kphp::type_functions::variant_index<result_variant_type, task_result_type>()>, *std::move(task_result)};
         }
       }};
       std::apply([&task_result_processor](auto&&... tasks) noexcept { (std::invoke(task_result_processor, std::forward<decltype(tasks)>(tasks)), ...); },
diff --git a/runtime-light/coroutine/io-scheduler.h b/runtime-light/coroutine/io-scheduler.h
index b096deeea5..657dae1539 100644
--- a/runtime-light/coroutine/io-scheduler.h
+++ b/runtime-light/coroutine/io-scheduler.h
@@ -471,6 +471,7 @@ auto io_scheduler::schedule(coroutine_type coroutine, std::chrono::duration<rep_
       co_return std::expected<expected_return_type, timeout_status>{co_await schedule(std::move(coroutine))};
     }
   }
+
   auto result{co_await kphp::coro::when_any(std::move(coroutine), make_timeout_task(timeout))};
   if (std::holds_alternative<timeout_status>(result)) [[unlikely]] {
     co_return std::unexpected{std::move(std::get<1>(result))};
diff --git a/runtime-light/type-traits/concepts.h b/runtime-light/metaprogramming/concepts.h
similarity index 89%
rename from runtime-light/type-traits/concepts.h
rename to runtime-light/metaprogramming/concepts.h
index 56f125e20d..0912acd607 100644
--- a/runtime-light/type-traits/concepts.h
+++ b/runtime-light/metaprogramming/concepts.h
@@ -8,7 +8,7 @@
 #include <cstddef>
 #include <functional>
 
-namespace kphp::type_traits {
+namespace kphp::concepts {
 
 template<typename T>
 concept standard_layout = std::is_standard_layout_v<T>;
@@ -21,4 +21,4 @@ concept hashable = requires(T t) {
 template<typename type, typename... types>
 concept in_types = (std::same_as<type, types> || ...);
 
-} // namespace kphp::type_traits
+} // namespace kphp::concepts
diff --git a/runtime-light/type-traits/functions.h b/runtime-light/metaprogramming/type-functions.h
similarity index 86%
rename from runtime-light/type-traits/functions.h
rename to runtime-light/metaprogramming/type-functions.h
index 0f92bd7de1..620ddf1969 100644
--- a/runtime-light/type-traits/functions.h
+++ b/runtime-light/metaprogramming/type-functions.h
@@ -7,10 +7,10 @@
 #include <cstddef>
 #include <variant>
 
-namespace kphp::type_traits {
+namespace kphp::type_functions {
 
 template<typename variant_type, typename T, size_t index = 0>
-constexpr size_t variant_index() noexcept {
+consteval size_t variant_index() noexcept {
   static_assert(index < std::variant_size_v<variant_type>, "Type not found in variant");
   if constexpr (index == std::variant_size_v<variant_type>) {
     // To prevent the error of substituting an index that is too large in variant_alternative_t
@@ -22,4 +22,4 @@ constexpr size_t variant_index() noexcept {
   }
 }
 
-} // namespace kphp::type_traits
+} // namespace kphp::type_functions
diff --git a/runtime-light/stdlib/string/regex-state.h b/runtime-light/stdlib/string/regex-state.h
index 50b43312c8..6d6fb64b1e 100644
--- a/runtime-light/stdlib/string/regex-state.h
+++ b/runtime-light/stdlib/string/regex-state.h
@@ -10,11 +10,11 @@
 #include "common/mixin/not_copyable.h"
 #include "runtime-common/core/allocator/script-allocator.h"
 #include "runtime-common/core/std/containers.h"
+#include "runtime-light/metaprogramming/concepts.h"
 #include "runtime-light/stdlib/string/regex-include.h"
-#include "runtime-light/type-traits/concepts.h"
 
 struct RegexInstanceState final : private vk::not_copyable {
-  template<kphp::type_traits::hashable Key, typename Value>
+  template<kphp::concepts::hashable Key, typename Value>
   using unordered_map = kphp::stl::unordered_map<Key, Value, kphp::memory::script_allocator>;
 
   static constexpr size_t MAX_SUBPATTERNS_COUNT = 512;
diff --git a/runtime-light/tl/tl-core.h b/runtime-light/tl/tl-core.h
index ccaf95e986..6be470c403 100644
--- a/runtime-light/tl/tl-core.h
+++ b/runtime-light/tl/tl-core.h
@@ -15,8 +15,8 @@
 #include "common/algorithms/find.h"
 #include "runtime-common/core/allocator/script-allocator.h"
 #include "runtime-common/core/std/containers.h"
+#include "runtime-light/metaprogramming/concepts.h"
 #include "runtime-light/stdlib/diagnostics/logs.h"
-#include "runtime-light/type-traits/concepts.h"
 
 namespace tl {
 
@@ -66,7 +66,7 @@ class storer {
     m_buffer.append_range(bytes);
   }
 
-  template<kphp::type_traits::standard_layout T, kphp::type_traits::standard_layout U>
+  template<kphp::concepts::standard_layout T, kphp::concepts::standard_layout U>
   requires std::convertible_to<U, T>
   void store_trivial(const U& t) noexcept {
     store_bytes({reinterpret_cast<const std::byte*>(std::addressof(t)), sizeof(T)});
@@ -136,7 +136,7 @@ class fetcher {
     return bytes;
   }
 
-  template<kphp::type_traits::standard_layout T>
+  template<kphp::concepts::standard_layout T>
   std::optional<T> fetch_trivial() noexcept {
     if (m_remaining < sizeof(T)) {
       return std::nullopt;

From 610c2040e6b505b9d6a582d0910bd8b43535377b Mon Sep 17 00:00:00 2001
From: Vadim Sadokhov <v.sadokhov@vk.team>
Date: Fri, 31 Oct 2025 17:25:09 +0300
Subject: [PATCH 4/5] small fix

---
 runtime-light/coroutine/detail/when-any.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/runtime-light/coroutine/detail/when-any.h b/runtime-light/coroutine/detail/when-any.h
index 1ba1f892ed..f124f5928e 100644
--- a/runtime-light/coroutine/detail/when-any.h
+++ b/runtime-light/coroutine/detail/when-any.h
@@ -123,7 +123,8 @@ class when_any_ready_awaitable<std::tuple<task_types...>> {
         if (auto task_result{std::forward<decltype(task)>(task).result()}; !result.has_value() && task_result.has_value()) {
           using result_variant_type = std::remove_cvref<decltype(result)>::type::value_type;
           using task_result_type = decltype(task_result)::value_type;
-          result = result_variant_type{std::in_place_index<kphp::type_functions::variant_index<result_variant_type, task_result_type>()>, *std::move(task_result)};
+          result =
+              result_variant_type{std::in_place_index<kphp::type_functions::variant_index<result_variant_type, task_result_type>()>, *std::move(task_result)};
         }
       }};
       std::apply([&task_result_processor](auto&&... tasks) noexcept { (std::invoke(task_result_processor, std::forward<decltype(tasks)>(tasks)), ...); },

From 168c2fdbed0e3f705dd9eb6b6d86f5c53b28b165 Mon Sep 17 00:00:00 2001
From: Vadim Sadokhov <v.sadokhov@vk.team>
Date: Wed, 5 Nov 2025 17:31:12 +0300
Subject: [PATCH 5/5] small fix

---
 runtime-light/metaprogramming/type-functions.h | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/runtime-light/metaprogramming/type-functions.h b/runtime-light/metaprogramming/type-functions.h
index 620ddf1969..350fa453d7 100644
--- a/runtime-light/metaprogramming/type-functions.h
+++ b/runtime-light/metaprogramming/type-functions.h
@@ -5,17 +5,15 @@
 #pragma once
 
 #include <cstddef>
+#include <type_traits>
 #include <variant>
 
 namespace kphp::type_functions {
 
 template<typename variant_type, typename T, size_t index = 0>
+requires(index < std::variant_size_v<variant_type>)
 consteval size_t variant_index() noexcept {
-  static_assert(index < std::variant_size_v<variant_type>, "Type not found in variant");
-  if constexpr (index == std::variant_size_v<variant_type>) {
-    // To prevent the error of substituting an index that is too large in variant_alternative_t
-    return index;
-  } else if constexpr (std::is_same_v<std::variant_alternative_t<index, variant_type>, T>) {
+  if constexpr (std::is_same_v<std::variant_alternative_t<index, variant_type>, T>) {
     return index;
   } else {
     return variant_index<variant_type, T, index + 1>();