Merge pull request #5775 from ethereum/codeAccess

Provide access to code of contract types.

6 files changed, 134 insertions, 3 deletions

diff --git a/libsolidity/analysis/GlobalContext.cpp b/libsolidity/analysis/GlobalContext.cpp
index cd5fe07d..2276d783 100644
--- a/libsolidity/analysis/GlobalContext.cpp
+++ b/libsolidity/analysis/GlobalContext.cpp
@@ -61,7 +61,14 @@ m_magicVariables(vector<shared_ptr<MagicVariableDeclaration const>>{
 	make_shared<MagicVariableDeclaration>("sha256", make_shared<FunctionType>(strings{"bytes memory"}, strings{"bytes32"}, FunctionType::Kind::SHA256, false, StateMutability::Pure)),
 	make_shared<MagicVariableDeclaration>("sha3", make_shared<FunctionType>(strings{"bytes memory"}, strings{"bytes32"}, FunctionType::Kind::KECCAK256, false, StateMutability::Pure)),
 	make_shared<MagicVariableDeclaration>("suicide", make_shared<FunctionType>(strings{"address payable"}, strings{}, FunctionType::Kind::Selfdestruct)),
-	make_shared<MagicVariableDeclaration>("tx", make_shared<MagicType>(MagicType::Kind::Transaction))
+	make_shared<MagicVariableDeclaration>("tx", make_shared<MagicType>(MagicType::Kind::Transaction)),
+	make_shared<MagicVariableDeclaration>("type", make_shared<FunctionType>(
+		strings{"address"} /* accepts any contract type, handled by the type checker */,
+		strings{} /* returns a MagicType, handled by the type checker */,
+		FunctionType::Kind::MetaType,
+		false,
+		StateMutability::Pure
+	)),
 })
 {
 }
diff --git a/libsolidity/analysis/StaticAnalyzer.cpp b/libsolidity/analysis/StaticAnalyzer.cpp
index aaaa4f9f..11ed6a4f 100644
--- a/libsolidity/analysis/StaticAnalyzer.cpp
+++ b/libsolidity/analysis/StaticAnalyzer.cpp
@@ -32,6 +32,56 @@ using namespace dev;
 using namespace langutil;
 using namespace dev::solidity;
 
+/**
+ * Helper class that determines whether a contract's constructor uses inline assembly.
+ */
+class dev::solidity::ConstructorUsesAssembly
+{
+public:
+	/// @returns true if and only if the contract's or any of its bases' constructors
+	/// use inline assembly.
+	bool check(ContractDefinition const& _contract)
+	{
+		for (auto const* base: _contract.annotation().linearizedBaseContracts)
+			if (checkInternal(*base))
+				return true;
+		return false;
+	}
+
+
+private:
+	class Checker: public ASTConstVisitor
+	{
+	public:
+		Checker(FunctionDefinition const& _f) { _f.accept(*this); }
+		bool visit(InlineAssembly const&) override { assemblySeen = true; return false; }
+		bool assemblySeen = false;
+	};
+
+	bool checkInternal(ContractDefinition const& _contract)
+	{
+		if (!m_usesAssembly.count(&_contract))
+		{
+			bool usesAssembly = false;
+			if (_contract.constructor())
+				usesAssembly = Checker{*_contract.constructor()}.assemblySeen;
+			m_usesAssembly[&_contract] = usesAssembly;
+		}
+		return m_usesAssembly[&_contract];
+	}
+
+	map<ContractDefinition const*, bool> m_usesAssembly;
+};
+
+StaticAnalyzer::StaticAnalyzer(ErrorReporter& _errorReporter):
+	m_errorReporter(_errorReporter)
+{
+}
+
+StaticAnalyzer::~StaticAnalyzer()
+{
+}
+
 bool StaticAnalyzer::analyze(SourceUnit const& _sourceUnit)
 {
 	_sourceUnit.accept(*this);
@@ -152,6 +202,18 @@ bool StaticAnalyzer::visit(MemberAccess const& _memberAccess)
 				_memberAccess.location(),
 				"\"block.blockhash()\" has been deprecated in favor of \"blockhash()\""
 			);
+		else if (type->kind() == MagicType::Kind::MetaType && _memberAccess.memberName() == "runtimeCode")
+		{
+			if (!m_constructorUsesAssembly)
+				m_constructorUsesAssembly = make_unique<ConstructorUsesAssembly>();
+			ContractType const& contract = dynamic_cast<ContractType const&>(*type->typeArgument());
+			if (m_constructorUsesAssembly->check(contract.contractDefinition()))
+				m_errorReporter.warning(
+					_memberAccess.location(),
+					"The constructor of the contract (or its base) uses inline assembly. "
+					"Because of that, it might be that the deployed bytecode is different from type(...).runtimeCode."
+				);
+		}
 	}
 
 	if (_memberAccess.memberName() == "callcode")
diff --git a/libsolidity/analysis/StaticAnalyzer.h b/libsolidity/analysis/StaticAnalyzer.h
index ff33fa3a..3daf83b3 100644
--- a/libsolidity/analysis/StaticAnalyzer.h
+++ b/libsolidity/analysis/StaticAnalyzer.h
@@ -38,6 +38,8 @@ namespace dev
 namespace solidity
 {
 
+class ConstructorUsesAssembly;
+
 
 /**
  * The module that performs static analysis on the AST.
@@ -49,7 +51,8 @@ class StaticAnalyzer: private ASTConstVisitor
 {
 public:
 	/// @param _errorReporter provides the error logging functionality.
-	explicit StaticAnalyzer(langutil::ErrorReporter& _errorReporter): m_errorReporter(_errorReporter) {}
+	explicit StaticAnalyzer(langutil::ErrorReporter& _errorReporter);
+	~StaticAnalyzer();
 
 	/// Performs static analysis on the given source unit and all of its sub-nodes.
 	/// @returns true iff all checks passed. Note even if all checks passed, errors() can still contain warnings
@@ -85,6 +88,10 @@ private:
 	/// when traversing.
 	std::map<std::pair<size_t, VariableDeclaration const*>, int> m_localVarUseCount;
 
+	/// Cache that holds information about whether a contract's constructor
+	/// uses inline assembly.
+	std::unique_ptr<ConstructorUsesAssembly> m_constructorUsesAssembly;
+
 	FunctionDefinition const* m_currentFunction = nullptr;
 
 	/// Flag that indicates a constructor.
diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index 7fa9933c..d038233c 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -199,6 +199,38 @@ TypePointers TypeChecker::typeCheckABIDecodeAndRetrieveReturnType(FunctionCall c
 	return components;
 }
 
+TypePointers TypeChecker::typeCheckMetaTypeFunctionAndRetrieveReturnType(FunctionCall const& _functionCall)
+{
+	vector<ASTPointer<Expression const>> arguments = _functionCall.arguments();
+	if (arguments.size() != 1)
+	{
+		m_errorReporter.typeError(
+			_functionCall.location(),
+			"This function takes one argument, but " +
+			toString(arguments.size()) +
+			" were provided."
+		);
+		return {};
+	}
+	TypePointer firstArgType = type(*arguments.front());
+	if (
+		firstArgType->category() != Type::Category::TypeType ||
+		dynamic_cast<TypeType const&>(*firstArgType).actualType()->category() != TypeType::Category::Contract
+	)
+	{
+		m_errorReporter.typeError(
+			arguments.front()->location(),
+			"Invalid type for argument in function call. "
+			"Contract type required, but " +
+			type(*arguments.front())->toString(true) +
+			" provided."
+		);
+		return {};
+	}
+
+	return {MagicType::metaType(dynamic_cast<TypeType const&>(*firstArgType).actualType())};
+}
+
 void TypeChecker::endVisit(InheritanceSpecifier const& _inheritance)
 {
 	auto base = dynamic_cast<ContractDefinition const*>(&dereference(_inheritance.name()));
@@ -1831,6 +1863,9 @@ bool TypeChecker::visit(FunctionCall const& _functionCall)
 			returnTypes = functionType->returnParameterTypes();
 			break;
 		}
+		case FunctionType::Kind::MetaType:
+			returnTypes = typeCheckMetaTypeFunctionAndRetrieveReturnType(_functionCall);
+			break;
 		default:
 		{
 			typeCheckFunctionCall(_functionCall, functionType);
@@ -2071,8 +2106,24 @@ bool TypeChecker::visit(MemberAccess const& _memberAccess)
 		if (tt->actualType()->category() == Type::Category::Enum)
 			annotation.isPure = true;
 	if (auto magicType = dynamic_cast<MagicType const*>(exprType.get()))
+	{
 		if (magicType->kind() == MagicType::Kind::ABI)
 			annotation.isPure = true;
+		else if (magicType->kind() == MagicType::Kind::MetaType && (
+			memberName == "creationCode" || memberName == "runtimeCode"
+		))
+		{
+			annotation.isPure = true;
+			m_scope->annotation().contractDependencies.insert(
+				&dynamic_cast<ContractType const&>(*magicType->typeArgument()).contractDefinition()
+			);
+			if (contractDependenciesAreCyclic(*m_scope))
+				m_errorReporter.typeError(
+					_memberAccess.location(),
+					"Circular reference for contract code access."
+				);
+		}
+	}
 
 	return false;
 }
diff --git a/libsolidity/analysis/TypeChecker.h b/libsolidity/analysis/TypeChecker.h
index b60c571a..d5f3645c 100644
--- a/libsolidity/analysis/TypeChecker.h
+++ b/libsolidity/analysis/TypeChecker.h
@@ -81,6 +81,8 @@ private:
 		bool _abiEncoderV2
 	);
 
+	TypePointers typeCheckMetaTypeFunctionAndRetrieveReturnType(FunctionCall const& _functionCall);
+
 	/// Performs type checks and determines result types for type conversion FunctionCall nodes.
 	TypePointer typeCheckTypeConversionAndRetrieveReturnType(
 		FunctionCall const& _functionCall
diff --git a/libsolidity/analysis/ViewPureChecker.cpp b/libsolidity/analysis/ViewPureChecker.cpp
index eb019481..7df7ac17 100644
--- a/libsolidity/analysis/ViewPureChecker.cpp
+++ b/libsolidity/analysis/ViewPureChecker.cpp
@@ -338,7 +338,9 @@ void ViewPureChecker::endVisit(MemberAccess const& _memberAccess)
 			{MagicType::Kind::ABI, "encodeWithSignature"},
 			{MagicType::Kind::Block, "blockhash"},
 			{MagicType::Kind::Message, "data"},
-			{MagicType::Kind::Message, "sig"}
+			{MagicType::Kind::Message, "sig"},
+			{MagicType::Kind::MetaType, "creationCode"},
+			{MagicType::Kind::MetaType, "runtimeCode"}
 		};
 		set<MagicMember> static const payableMembers{
 			{MagicType::Kind::Message, "value"}