Parse "virtual" keyword

libsolidity/ast/AST.h

@@ -604,13 +604,15 @@ public:
 		ASTPointer<ASTString> const& _name,
 		Declaration::Visibility _visibility,
 		ASTPointer<ParameterList> const& _parameters,
+		bool _isVirtual = false,
 		ASTPointer<OverrideSpecifier> const& _overrides = nullptr,
 		ASTPointer<ParameterList> const& _returnParameters = ASTPointer<ParameterList>()
 	):
 		Declaration(_location, _name, _visibility),
 		m_parameters(_parameters),
 		m_overrides(_overrides),
-		m_returnParameters(_returnParameters)
+		m_returnParameters(_returnParameters),
+		m_isVirtual(_isVirtual)
 	{
 	}
 
@@ -624,6 +626,7 @@ protected:
 	ASTPointer<ParameterList> m_parameters;
 	ASTPointer<OverrideSpecifier> m_overrides;
 	ASTPointer<ParameterList> m_returnParameters;
+	bool m_isVirtual;
 };
 
 /**
@@ -661,6 +664,7 @@ public:
 		Declaration::Visibility _visibility,
 		StateMutability _stateMutability,
 		Token _kind,
+		bool _isVirtual,
 		ASTPointer<OverrideSpecifier> const& _overrides,
 		ASTPointer<ASTString> const& _documentation,
 		ASTPointer<ParameterList> const& _parameters,
@@ -668,7 +672,7 @@ public:
 		ASTPointer<ParameterList> const& _returnParameters,
 		ASTPointer<Block> const& _body
 	):
-		CallableDeclaration(_location, _name, _visibility, _parameters, _overrides, _returnParameters),
+		CallableDeclaration(_location, _name, _visibility, _parameters, _isVirtual, _overrides, _returnParameters),
 		Documented(_documentation),
 		ImplementationOptional(_body != nullptr),
 		m_stateMutability(_stateMutability),
@@ -738,6 +742,7 @@ public:
 		bool _isStateVar = false,
 		bool _isIndexed = false,
 		bool _isConstant = false,
+		bool _isVirtual = false,
 		ASTPointer<OverrideSpecifier> const& _overrides = nullptr,
 		Location _referenceLocation = Location::Unspecified
 	):
@@ -747,9 +752,11 @@ public:
 		m_isStateVariable(_isStateVar),
 		m_isIndexed(_isIndexed),
 		m_isConstant(_isConstant),
+		m_isVirtual(_isVirtual),
 		m_overrides(_overrides),
 		m_location(_referenceLocation) {}
 
+
 	void accept(ASTVisitor& _visitor) override;
 	void accept(ASTConstVisitor& _visitor) const override;
 
@@ -791,6 +798,7 @@ public:
 	bool isIndexed() const { return m_isIndexed; }
 	bool isConstant() const { return m_isConstant; }
 	ASTPointer<OverrideSpecifier> const& overrides() const { return m_overrides; }
+	bool isVirtual() const { return m_isVirtual; }
 	Location referenceLocation() const { return m_location; }
 	/// @returns a set of allowed storage locations for the variable.
 	std::set<Location> allowedDataLocations() const;
@@ -814,6 +822,7 @@ private:
 	bool m_isStateVariable; ///< Whether or not this is a contract state variable
 	bool m_isIndexed; ///< Whether this is an indexed variable (used by events).
 	bool m_isConstant; ///< Whether the variable is a compile-time constant.
+	bool m_isVirtual; ///< Whether the variable is virtual and can be overridden
 	ASTPointer<OverrideSpecifier> m_overrides; ///< Contains the override specifier node
 	Location m_location; ///< Location of the variable if it is of reference type.
 };
@@ -829,10 +838,11 @@ public:
 		ASTPointer<ASTString> const& _name,
 		ASTPointer<ASTString> const& _documentation,
 		ASTPointer<ParameterList> const& _parameters,
+		bool _isVirtual,
 		ASTPointer<OverrideSpecifier> const& _overrides,
 		ASTPointer<Block> const& _body
 	):
-		CallableDeclaration(_location, _name, Visibility::Internal, _parameters, _overrides),
+		CallableDeclaration(_location, _name, Visibility::Internal, _parameters, _isVirtual, _overrides),
 		Documented(_documentation),
 		m_body(_body)
 	{

libsolidity/parsing/Parser.cpp

@@ -466,6 +466,7 @@ Parser::FunctionHeaderParserResult Parser::parseFunctionHeader(bool _isStateVari
 	RecursionGuard recursionGuard(*this);
 	FunctionHeaderParserResult result;
 
+	result.isVirtual = false;
 	result.overrides = nullptr;
 
 	VarDeclParserOptions options;
@@ -515,6 +516,14 @@ Parser::FunctionHeaderParserResult Parser::parseFunctionHeader(bool _isStateVari
 
 			result.overrides = parseOverrideSpecifier();
 		}
+		else if (!_isStateVariable && token == Token::Virtual)
+		{
+			if (result.isVirtual)
+				parserError("Virtual already specified.");
+
+			result.isVirtual = true;
+			m_scanner->next();
+		}
 		else
 			break;
 	}
@@ -591,6 +600,7 @@ ASTPointer<ASTNode> Parser::parseFunctionDefinition()
 		header.visibility,
 		header.stateMutability,
 		kind,
+		header.isVirtual,
 		header.overrides,
 		docstring,
 		header.parameters,
@@ -679,6 +689,7 @@ ASTPointer<VariableDeclaration> Parser::parseVariableDeclaration(
 
 	bool isIndexed = false;
 	bool isDeclaredConst = false;
+	bool isVirtual = false;
 	ASTPointer<OverrideSpecifier> overrides = nullptr;
 	Declaration::Visibility visibility(Declaration::Visibility::Default);
 	VariableDeclaration::Location location = VariableDeclaration::Location::Unspecified;
@@ -709,6 +720,14 @@ ASTPointer<VariableDeclaration> Parser::parseVariableDeclaration(
 
 			overrides = parseOverrideSpecifier();
 		}
+		else if (_options.isStateVariable && token == Token::Virtual)
+		{
+			if (isVirtual)
+				parserError("Virtual already specified.");
+
+			isVirtual = true;
+			m_scanner->next();
+		}
 		else
 		{
 			if (_options.allowIndexed && token == Token::Indexed)
@@ -774,6 +793,7 @@ ASTPointer<VariableDeclaration> Parser::parseVariableDeclaration(
 		_options.isStateVariable,
 		isIndexed,
 		isDeclaredConst,
+		isVirtual,
 		overrides,
 		location
 	);
@@ -804,13 +824,32 @@ ASTPointer<ModifierDefinition> Parser::parseModifierDefinition()
 		parameters = createEmptyParameterList();
 
 	ASTPointer<OverrideSpecifier> overrides;
+	bool isVirtual = false;
+
+	while(true)
+	{
+		if (m_scanner->currentToken() == Token::Override)
+		{
+			if (overrides)
+				parserError("Override already specified.");
+			overrides = parseOverrideSpecifier();
+		}
+		else if (m_scanner->currentToken() == Token::Virtual)
+		{
+			if (isVirtual)
+				parserError("Virtual already specified.");
+
+			isVirtual = true;
+			m_scanner->next();
+		}
+		else
+			break;
+	}
 
-	if (m_scanner->currentToken() == Token::Override)
-		overrides = parseOverrideSpecifier();
 
 	ASTPointer<Block> block = parseBlock();
 	nodeFactory.setEndPositionFromNode(block);
-	return nodeFactory.createNode<ModifierDefinition>(name, docstring, parameters, overrides, block);
+	return nodeFactory.createNode<ModifierDefinition>(name, docstring, parameters, isVirtual, overrides, block);
 }
 
 ASTPointer<EventDefinition> Parser::parseEventDefinition()

libsolidity/parsing/Parser.h

@@ -70,6 +70,7 @@ private:
 	/// This struct is shared for parsing a function header and a function type.
 	struct FunctionHeaderParserResult
 	{
+		bool isVirtual;
 		ASTPointer<OverrideSpecifier> overrides;
 		ASTPointer<ParameterList> parameters;
 		ASTPointer<ParameterList> returnParameters;