Deprecate throw.

libsolidity/analysis/SyntaxChecker.cpp

@@ -135,6 +135,16 @@ bool SyntaxChecker::visit(Break const& _breakStatement)
 	return true;
 }
 
+bool SyntaxChecker::visit(Throw const& _throwStatement)
+{
+	m_errorReporter.warning(
+		_throwStatement.location(),
+		"\"throw\" is deprecated in favour of \"revert()\", \"require()\" and \"assert()\"."
+	);
+
+	return true;
+}
+
 bool SyntaxChecker::visit(UnaryOperation const& _operation)
 {
 	if (_operation.getOperator() == Token::Add)

libsolidity/analysis/SyntaxChecker.h

@@ -33,6 +33,7 @@ namespace solidity
  *  - whether continue/break is in a for/while loop.
  *  - whether a modifier contains at least one '_'
  *  - issues deprecation warnings for unary '+'
+ *  - issues deprecation warning for throw
  */
 class SyntaxChecker: private ASTConstVisitor
 {
@@ -59,6 +60,8 @@ private:
 	virtual bool visit(Continue const& _continueStatement) override;
 	virtual bool visit(Break const& _breakStatement) override;
 
+	virtual bool visit(Throw const& _throwStatement) override;
+
 	virtual bool visit(UnaryOperation const& _operation) override;
 
 	virtual bool visit(PlaceholderStatement const& _placeholderStatement) override;