Add ability to set the target EVM version.

libsolidity/interface/EVMVersion.h

@@ -0,0 +1,81 @@
+/*
+	This file is part of solidity.
+
+	solidity is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	solidity is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with solidity.  If not, see <http://www.gnu.org/licenses/>.
+*/
+/**
+ * EVM versioning.
+ */
+
+#pragma once
+
+#include <string>
+
+#include <boost/optional.hpp>
+
+namespace dev
+{
+namespace solidity
+{
+
+/**
+ * A version specifier of the EVM we want to compile to.
+ * Defaults to the latest version.
+ */
+class EVMVersion
+{
+public:
+	EVMVersion() {}
+
+	static EVMVersion homestead() { return {Version::Homestead}; }
+	static EVMVersion byzantium() { return {Version::Byzantium}; }
+
+	static boost::optional<EVMVersion> fromString(std::string const& _version)
+	{
+		if (_version == "homestead")
+			return homestead();
+		else if (_version == "byzantium")
+			return byzantium();
+		else
+			return {};
+	}
+
+	bool operator==(EVMVersion const& _other) const { return m_version == _other.m_version; }
+	bool operator!=(EVMVersion const& _other) const { return !this->operator==(_other); }
+
+	std::string name() const { return m_version == Version::Byzantium ? "byzantium" : "homestead"; }
+
+	/// Has the RETURNDATACOPY and RETURNDATASIZE opcodes.
+	bool supportsReturndata() const { return *this >= byzantium(); }
+	bool hasStaticCall() const { return *this >= byzantium(); }
+
+	/// Whether we have to retain the costs for the call opcode itself (false),
+	/// or whether we can just forward easily all remaining gas (true).
+	bool canOverchargeGasForCall() const
+	{
+		// @TODO when exactly was this introduced? Was together with the call stack fix.
+		return m_version == Version::Byzantium;
+	}
+
+private:
+	enum class Version { Homestead, Byzantium };
+
+	EVMVersion(Version _version): m_version(_version) {}
+
+	Version m_version = Version::Byzantium;
+};
+
+
+}
+}