From 84289a2ba996b41815f148f27aecc52a7864066d Mon Sep 17 00:00:00 2001
From: peterbell10 <peterbell10@live.co.uk>
Date: Sun, 10 May 2020 17:16:49 +0100
Subject: Cleanup some workarounds and warnings (#4735)

* Cleanup thread_local usage in FastRandom

* Use constexpr to avoid clang warning

* Fix more Wglobal-constructor warnings

* Make MSVC happy?
---
 src/FastRandom.cpp | 48 ++++++++++++------------------------------------
 1 file changed, 12 insertions(+), 36 deletions(-)

(limited to 'src/FastRandom.cpp')

diff --git a/src/FastRandom.cpp b/src/FastRandom.cpp
index 0cd44ace0..0ba5fb64a 100644
--- a/src/FastRandom.cpp
+++ b/src/FastRandom.cpp
@@ -5,38 +5,18 @@
 #include "Globals.h"
 #include "FastRandom.h"
 
-#if defined (__GNUC__)
-	#define ATTRIBUTE_TLS static __thread
-#elif defined (_MSC_VER)
-	#define ATTRIBUTE_TLS static __declspec(thread)
-#else
-	#define ATTRIBUTE_TLS thread_local
-#endif
-
 
 
 
 
 MTRand & GetRandomProvider()
 {
-	// Some compilers don't support thread_local for non-POD types, this is purely a work around for that restriction.
-	// There should be minimal overhead for the non-initializing case and all thread's instances are deleted properly.
-	ATTRIBUTE_TLS MTRand * LocalPtr = nullptr;
-	if (LocalPtr == nullptr)
-	{
-		// This list allows deletion of elements as if they had static storage duration
-		static std::mutex CSDeleteList;
-		static std::list<std::unique_ptr<MTRand>> DeleteList;
-
-		cRandomDeviceSeeder seeder;
-		auto NewInstance = cpp14::make_unique<MTRand>(seeder);
-		auto TempPtr = NewInstance.get();
-
-		std::lock_guard<std::mutex> Lock(CSDeleteList);
-		DeleteList.push_front(std::move(NewInstance));
-		LocalPtr = TempPtr;  // Set after push_back so LocalPtr won't dangle if it throws
-	}
-	return *LocalPtr;
+	thread_local MTRand Random = []
+		{
+			cRandomDeviceSeeder Seeder;
+			return MTRand(Seeder);
+		}();
+	return Random;
 }
 
 
@@ -45,15 +25,11 @@ MTRand & GetRandomProvider()
 
 UInt32 Detail::GetRandomSeed()
 {
-	ATTRIBUTE_TLS bool SeedCounterInitialized = false;
-	ATTRIBUTE_TLS UInt32 SeedCounter = 0;
-
-	if (!SeedCounterInitialized)
-	{
-		std::random_device rd;
-		std::uniform_int_distribution<UInt32> dist;
-		SeedCounter = dist(rd);
-		SeedCounterInitialized = true;
-	}
+	thread_local UInt32 SeedCounter = []
+		{
+			std::random_device rd;
+			std::uniform_int_distribution<UInt32> dist;
+			return dist(rd);
+		}();
 	return ++SeedCounter;
 }
-- 
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