4 files changed, 50 insertions, 11 deletions

diff --git a/libsolidity/analysis/SyntaxChecker.cpp b/libsolidity/analysis/SyntaxChecker.cpp
index b595c4d1..343b4ba8 100644
--- a/libsolidity/analysis/SyntaxChecker.cpp
+++ b/libsolidity/analysis/SyntaxChecker.cpp
@@ -216,7 +216,22 @@ bool SyntaxChecker::visit(FunctionDefinition const& _function)
 
 	if (v050 && _function.noVisibilitySpecified())
 		m_errorReporter.syntaxError(_function.location(), "No visibility specified.");
-			
+
+	if (_function.isOldStyleConstructor())
+	{
+		if (v050)
+			m_errorReporter.syntaxError(
+				_function.location(),
+				"Functions are not allowed to have the same name as the contract. "
+				"If you intend this to be a constructor, use \"constructor(...) { ... }\" to define it."
+			);
+		else
+			m_errorReporter.warning(
+				_function.location(),
+				"Defining constructors as functions with the same name as the contract is deprecated. "
+				"Use \"constructor(...) { ... }\" instead."
+			);
+	}
 	return true;
 }
 
diff --git a/libsolidity/ast/AST.h b/libsolidity/ast/AST.h
index 9c67d354..56bb412c 100644
--- a/libsolidity/ast/AST.h
+++ b/libsolidity/ast/AST.h
@@ -607,7 +607,8 @@ public:
 
 	StateMutability stateMutability() const { return m_stateMutability; }
 	bool isConstructor() const { return m_isConstructor; }
-	bool isFallback() const { return name().empty(); }
+	bool isOldStyleConstructor() const { return m_isConstructor && !name().empty(); }
+	bool isFallback() const { return !m_isConstructor && name().empty(); }
 	bool isPayable() const { return m_stateMutability == StateMutability::Payable; }
 	std::vector<ASTPointer<ModifierInvocation>> const& modifiers() const { return m_functionModifiers; }
 	std::vector<ASTPointer<VariableDeclaration>> const& returnParameters() const { return m_returnParameters->parameters(); }
diff --git a/libsolidity/parsing/Parser.cpp b/libsolidity/parsing/Parser.cpp
index 8c97f55f..3dbd4c8f 100644
--- a/libsolidity/parsing/Parser.cpp
+++ b/libsolidity/parsing/Parser.cpp
@@ -238,7 +238,10 @@ ASTPointer<ContractDefinition> Parser::parseContractDefinition(Token::Value _exp
 		Token::Value currentTokenValue = m_scanner->currentToken();
 		if (currentTokenValue == Token::RBrace)
 			break;
-		else if (currentTokenValue == Token::Function)
+		else if (
+			currentTokenValue == Token::Function ||
+			(currentTokenValue == Token::Identifier && m_scanner->currentLiteral() == "constructor")
+		)
 			// This can be a function or a state variable of function type (especially
 			// complicated to distinguish fallback function from function type state variable)
 			subNodes.push_back(parseFunctionDefinitionOrFunctionTypeStateVariable(name.get()));
@@ -329,15 +332,31 @@ StateMutability Parser::parseStateMutability(Token::Value _token)
 	return stateMutability;
 }
 
-Parser::FunctionHeaderParserResult Parser::parseFunctionHeader(bool _forceEmptyName, bool _allowModifiers)
+Parser::FunctionHeaderParserResult Parser::parseFunctionHeader(
+	bool _forceEmptyName,
+	bool _allowModifiers,
+	ASTString const* _contractName
+)
 {
 	RecursionGuard recursionGuard(*this);
 	FunctionHeaderParserResult result;
-	expectToken(Token::Function);
-	if (_forceEmptyName || m_scanner->currentToken() == Token::LParen)
-		result.name = make_shared<ASTString>(); // anonymous function
+
+	result.isConstructor = false;
+
+	if (m_scanner->currentToken() == Token::Identifier && m_scanner->currentLiteral() == "constructor")
+		result.isConstructor = true;
+	else if (m_scanner->currentToken() != Token::Function)
+		solAssert(false, "Function or constructor expected.");
+	m_scanner->next();
+
+	if (result.isConstructor || _forceEmptyName || m_scanner->currentToken() == Token::LParen)
+		result.name = make_shared<ASTString>();
 	else
 		result.name = expectIdentifierToken();
+
+	if (!result.name->empty() && _contractName && *result.name == *_contractName)
+		result.isConstructor = true;
+
 	VarDeclParserOptions options;
 	options.allowLocationSpecifier = true;
 	result.parameters = parseParameterList(options);
@@ -407,7 +426,7 @@ ASTPointer<ASTNode> Parser::parseFunctionDefinitionOrFunctionTypeStateVariable(A
 	if (m_scanner->currentCommentLiteral() != "")
 		docstring = make_shared<ASTString>(m_scanner->currentCommentLiteral());
 
-	FunctionHeaderParserResult header = parseFunctionHeader(false, true);
+	FunctionHeaderParserResult header = parseFunctionHeader(false, true, _contractName);
 
 	if (
 		!header.modifiers.empty() ||
@@ -426,12 +445,11 @@ ASTPointer<ASTNode> Parser::parseFunctionDefinitionOrFunctionTypeStateVariable(A
 		}
 		else
 			m_scanner->next(); // just consume the ';'
-		bool const c_isConstructor = (_contractName && *header.name == *_contractName);
 		return nodeFactory.createNode<FunctionDefinition>(
 			header.name,
 			header.visibility,
 			header.stateMutability,
-			c_isConstructor,
+			header.isConstructor,
 			docstring,
 			header.parameters,
 			header.modifiers,
diff --git a/libsolidity/parsing/Parser.h b/libsolidity/parsing/Parser.h
index 3f780af9..eb120a61 100644
--- a/libsolidity/parsing/Parser.h
+++ b/libsolidity/parsing/Parser.h
@@ -56,6 +56,7 @@ private:
 	/// This struct is shared for parsing a function header and a function type.
 	struct FunctionHeaderParserResult
 	{
+		bool isConstructor;
 		ASTPointer<ASTString> name;
 		ASTPointer<ParameterList> parameters;
 		ASTPointer<ParameterList> returnParameters;
@@ -73,7 +74,11 @@ private:
 	ASTPointer<InheritanceSpecifier> parseInheritanceSpecifier();
 	Declaration::Visibility parseVisibilitySpecifier(Token::Value _token);
 	StateMutability parseStateMutability(Token::Value _token);
-	FunctionHeaderParserResult parseFunctionHeader(bool _forceEmptyName, bool _allowModifiers);
+	FunctionHeaderParserResult parseFunctionHeader(
+		bool _forceEmptyName,
+		bool _allowModifiers,
+		ASTString const* _contractName = nullptr
+	);
 	ASTPointer<ASTNode> parseFunctionDefinitionOrFunctionTypeStateVariable(ASTString const* _contractName);
 	ASTPointer<FunctionDefinition> parseFunctionDefinition(ASTString const* _contractName);
 	ASTPointer<StructDefinition> parseStructDefinition();