[Yul] More accurate error messages for break/continue

libyul/AsmParser.cpp

@@ -105,31 +105,19 @@ Statement Parser::parseStatement()
 	case Token::For:
 		return parseForLoop();
 	case Token::Break:
-		if (m_insideForLoopBody)
-		{
-			auto stmt = Statement{ createWithLocation<Break>() };
-			m_scanner->next();
-			return stmt;
-		}
-		else
-		{
-			m_errorReporter.syntaxError(location(), "Keyword break outside for-loop body is not allowed.");
-			m_scanner->next();
-			return {};
-		}
+	{
+		Statement stmt{createWithLocation<Break>()};
+		checkBreakContinuePosition("break");
+		m_scanner->next();
+		return stmt;
+	}
 	case Token::Continue:
-		if (m_insideForLoopBody)
-		{
-			auto stmt = Statement{ createWithLocation<Continue>() };
-			m_scanner->next();
-			return stmt;
-		}
-		else
-		{
-			m_errorReporter.syntaxError(location(), "Keyword continue outside for-loop body is not allowed.");
-			m_scanner->next();
-			return {};
-		}
+	{
+		Statement stmt{createWithLocation<Continue>()};
+		checkBreakContinuePosition("continue");
+		m_scanner->next();
+		return stmt;
+	}
 	case Token::Assign:
 	{
 		if (m_dialect->flavour != AsmFlavour::Loose)
@@ -269,20 +257,24 @@ Case Parser::parseCase()
 
 ForLoop Parser::parseForLoop()
 {
-	bool outerForLoopBody = m_insideForLoopBody;
-	m_insideForLoopBody = false;
-
 	RecursionGuard recursionGuard(*this);
+
+	ForLoopComponent outerForLoopComponent = m_currentForLoopComponent;
+
 	ForLoop forLoop = createWithLocation<ForLoop>();
 	expectToken(Token::For);
+	m_currentForLoopComponent = ForLoopComponent::ForLoopPre;
 	forLoop.pre = parseBlock();
+	m_currentForLoopComponent = ForLoopComponent::None;
 	forLoop.condition = make_unique<Expression>(parseExpression());
+	m_currentForLoopComponent = ForLoopComponent::ForLoopPost;
 	forLoop.post = parseBlock();
-
-	m_insideForLoopBody = true;
+	m_currentForLoopComponent = ForLoopComponent::ForLoopBody;
 	forLoop.body = parseBlock();
-	m_insideForLoopBody = outerForLoopBody;
 	forLoop.location.end = forLoop.body.location.end;
+
+	m_currentForLoopComponent = outerForLoopComponent;
+
 	return forLoop;
 }
 
@@ -487,9 +479,9 @@ VariableDeclaration Parser::parseVariableDeclaration()
 FunctionDefinition Parser::parseFunctionDefinition()
 {
 	RecursionGuard recursionGuard(*this);
-	auto outerForLoopBody = m_insideForLoopBody;
-	m_insideForLoopBody = false;
-	ScopeGuard restoreInsideForLoopBody{[&]() { m_insideForLoopBody = outerForLoopBody; }};
+	ForLoopComponent outerForLoopComponent = m_currentForLoopComponent;
+	m_currentForLoopComponent = ForLoopComponent::None;
+
 	FunctionDefinition funDef = createWithLocation<FunctionDefinition>();
 	expectToken(Token::Function);
 	funDef.name = expectAsmIdentifier();
@@ -516,6 +508,8 @@ FunctionDefinition Parser::parseFunctionDefinition()
 	}
 	funDef.body = parseBlock();
 	funDef.location.end = funDef.body.location.end;
+
+	m_currentForLoopComponent = outerForLoopComponent;
 	return funDef;
 }
 
@@ -642,6 +636,24 @@ YulString Parser::expectAsmIdentifier()
 	return name;
 }
 
+void Parser::checkBreakContinuePosition(string const& _which)
+{
+	switch (m_currentForLoopComponent)
+	{
+	case ForLoopComponent::None:
+		m_errorReporter.syntaxError(location(), "Keyword \"" + _which + "\" needs to be inside a for-loop body.");
+		break;
+	case ForLoopComponent::ForLoopPre:
+		m_errorReporter.syntaxError(location(), "Keyword \"" + _which + "\" in for-loop init block is not allowed.");
+		break;
+	case ForLoopComponent::ForLoopPost:
+		m_errorReporter.syntaxError(location(), "Keyword \"" + _which + "\" in for-loop post block is not allowed.");
+		break;
+	case ForLoopComponent::ForLoopBody:
+		break;
+	}
+}
+
 bool Parser::isValidNumberLiteral(string const& _literal)
 {
 	try

libyul/AsmParser.h

@@ -32,14 +32,20 @@
 #include <memory>
 #include <vector>
 
+
 namespace yul
 {
 
 class Parser: public langutil::ParserBase
 {
 public:
+	enum class ForLoopComponent
+	{
+		None, ForLoopPre, ForLoopPost, ForLoopBody
+	};
+
 	explicit Parser(langutil::ErrorReporter& _errorReporter, std::shared_ptr<Dialect> _dialect):
-		ParserBase(_errorReporter), m_dialect(std::move(_dialect)), m_insideForLoopBody{false} {}
+		ParserBase(_errorReporter), m_dialect(std::move(_dialect)) {}
 
 	/// Parses an inline assembly block starting with `{` and ending with `}`.
 	/// @param _reuseScanner if true, do check for end of input after the `}`.
@@ -83,11 +89,14 @@ protected:
 	TypedName parseTypedName();
 	YulString expectAsmIdentifier();
 
+	/// Reports an error if we are currently not inside the body part of a for loop.
+	void checkBreakContinuePosition(std::string const& _which);
+
 	static bool isValidNumberLiteral(std::string const& _literal);
 
 private:
 	std::shared_ptr<Dialect> m_dialect;
-	bool m_insideForLoopBody;
+	ForLoopComponent m_currentForLoopComponent = ForLoopComponent::None;
 };
 
 }