#pragma once
#include <gsl/gsl_byte>
#include <gsl/span>

namespace Halley
{
	class IMessage
	{
	public:
		virtual ~IMessage() {}

		virtual size_t getSerializedSize() = 0;
		virtual void serializeTo(gsl::span<gsl::byte> dst) = 0;
	};
}

#pragma once
#include <gsl/gsl>

namespace Halley
{
	class IMessage
	{
	public:
		virtual ~IMessage() {}

		virtual size_t getSerializedSize() = 0;
		virtual void serializeTo(gsl::span<gsl::byte> dst) = 0;
	};
}

Change include to fix compilation.
Change include  to fix compilation.
