From 4669b06ab448b61350bff23db12da1a8e9fff5fa Mon Sep 17 00:00:00 2001
From: chriseth <chris@ethereum.org>
Date: Tue, 15 Jan 2019 22:49:15 +0100
Subject: [PATCH] Warn if type(..).runtimeCode is used with assembly in the
 constructor.

---
 libsolidity/analysis/StaticAnalyzer.cpp       | 62 +++++++++++++++++++
 libsolidity/analysis/StaticAnalyzer.h         |  9 ++-
 .../metaTypes/runtimeCodeWarningAssembly.sol  | 17 +++++
 3 files changed, 87 insertions(+), 1 deletion(-)
 create mode 100644 test/libsolidity/syntaxTests/metaTypes/runtimeCodeWarningAssembly.sol

diff --git a/libsolidity/analysis/StaticAnalyzer.cpp b/libsolidity/analysis/StaticAnalyzer.cpp
index aaaa4f9f5..11ed6a4fe 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 ff33fa3a4..3daf83b31 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/test/libsolidity/syntaxTests/metaTypes/runtimeCodeWarningAssembly.sol b/test/libsolidity/syntaxTests/metaTypes/runtimeCodeWarningAssembly.sol
new file mode 100644
index 000000000..ec8d97842
--- /dev/null
+++ b/test/libsolidity/syntaxTests/metaTypes/runtimeCodeWarningAssembly.sol
@@ -0,0 +1,17 @@
+contract Test {
+    function f() public pure returns (uint) {
+        return type(C).runtimeCode.length +
+            type(D).runtimeCode.length +
+            type(C).creationCode.length +
+            type(D).creationCode.length;
+    }
+}
+contract C {
+    constructor() public { assembly {} }
+}
+contract D is C {
+    constructor() public {}
+}
+// ----
+// Warning: (77-96): 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.
+// Warning: (118-137): 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.