From 61450335a5f6621d25669f452d6fd45a057805e3 Mon Sep 17 00:00:00 2001
From: Nekotekina <nekotekina@gmail.com>
Date: Wed, 21 Apr 2021 17:19:53 +0300
Subject: [PATCH] named_thread: use concepts, improve constructors

Better default thread name detection.
---
 Utilities/Thread.h | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/Utilities/Thread.h b/Utilities/Thread.h
index e881d6081c..7360d7b2d6 100644
--- a/Utilities/Thread.h
+++ b/Utilities/Thread.h
@@ -42,7 +42,7 @@ class named_thread;
 
 class thread_base;
 
-template <typename Ctx, typename X = void, typename... Args>
+template <typename Ctx, typename... Args>
 struct result_storage
 {
 	static constexpr bool empty = true;
@@ -50,8 +50,8 @@ struct result_storage
 	using type = void;
 };
 
-template <typename Ctx, typename... Args>
-struct result_storage<Ctx, std::enable_if_t<!std::is_void_v<std::invoke_result_t<Ctx, Args&&...>>>, Args...>
+template <typename Ctx, typename... Args> requires (!std::is_void_v<std::invoke_result_t<Ctx, Args&&...>>)
+struct result_storage<Ctx, Args...>
 {
 	using T = std::invoke_result_t<Ctx, Args&&...>;
 
@@ -84,6 +84,12 @@ struct result_storage<Ctx, std::enable_if_t<!std::is_void_v<std::invoke_result_t
 	}
 };
 
+template <typename T>
+concept NamedThreadName = requires (T& t)
+{
+	std::string_view(t.thread_name);
+};
+
 // Base class for task queue (linked list)
 class thread_future
 {
@@ -110,12 +116,6 @@ public:
 	}
 };
 
-template <typename T, typename = void>
-struct thread_thread_name : std::bool_constant<false> {};
-
-template <typename T>
-struct thread_thread_name<T, std::void_t<decltype(named_thread<T>::thread_name)>> : std::bool_constant<true> {};
-
 // Thread base class
 class thread_base
 {
@@ -479,16 +479,17 @@ class named_thread final : public Context, result_storage<Context>, thread_base
 	friend class thread_ctrl;
 
 public:
-	// Default constructor
-	named_thread() requires (std::is_default_constructible_v<Context>) && (thread_thread_name<Context>::value)
-		: Context()
+	// Forwarding constructor with default name (also potentially the default constructor)
+	template <typename... Args> requires (std::is_constructible_v<Context, Args&&...>) && (NamedThreadName<Context>)
+	named_thread(Args&&... args)
+		: Context(std::forward<Args>(args)...)
 		, thread(trampoline, Context::thread_name)
 	{
 		thread::start();
 	}
 
 	// Normal forwarding constructor
-	template <typename... Args, typename = std::enable_if_t<std::is_constructible_v<Context, Args&&...>>>
+	template <typename... Args> requires (std::is_constructible_v<Context, Args&&...>) && (!NamedThreadName<Context>)
 	named_thread(std::string_view name, Args&&... args)
 		: Context(std::forward<Args>(args)...)
 		, thread(trampoline, name)