From f5665aa7c105b3f8ece6adf047de980d2e98617c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=B6nke=20Ludwig?= <sludwig@rejectedsoftware.com>
Date: Sat, 27 Oct 2018 16:31:59 +0200
Subject: [PATCH] Fix compilation on older DMD frontends.

---
 source/vibe/core/core.d | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/source/vibe/core/core.d b/source/vibe/core/core.d
index e40db1d..abdfa12 100644
--- a/source/vibe/core/core.d
+++ b/source/vibe/core/core.d
@@ -1039,7 +1039,7 @@ struct Timer {
 
 		if (callback) {
 			m_driver.timers.userData!Callback(m_id) = callback;
-			m_driver.timers.wait(m_id, timerCallbackHandler);
+			m_driver.timers.wait(m_id, &TimerCallbackHandler.instance.handle);
 		}
 	}
 
@@ -1094,15 +1094,19 @@ struct Timer {
 	}
 }
 
-private immutable TimerCallback2 timerCallbackHandler = (TimerID timer, bool fired) {
-	if (fired) {
-		auto cb = eventDriver.timers.userData!(Timer.Callback)(timer);
-		cb();
-	}
+struct TimerCallbackHandler {
+	static TimerCallbackHandler instance;
+	void handle(TimerID timer, bool fired)
+	@safe nothrow {
+		if (fired) {
+			auto cb = eventDriver.timers.userData!(Timer.Callback)(timer);
+			cb();
+		}
 
-	if (!eventDriver.timers.isUnique(timer))
-		eventDriver.timers.wait(timer, timerCallbackHandler);
-};
+		if (!eventDriver.timers.isUnique(timer))
+			eventDriver.timers.wait(timer, &handle);
+	}
+}
 
 
 /** Returns an object that ensures that no task switches happen during its life time.