Merge pull request #2848 from ethereum/checkViewPure

Enforce view and pure.

6 files changed, 398 insertions, 4 deletions

diff --git a/libsolidity/analysis/StaticAnalyzer.cpp b/libsolidity/analysis/StaticAnalyzer.cpp
index d012c25d..ffa538b6 100644
--- a/libsolidity/analysis/StaticAnalyzer.cpp
+++ b/libsolidity/analysis/StaticAnalyzer.cpp
@@ -57,8 +57,6 @@ bool StaticAnalyzer::visit(FunctionDefinition const& _function)
 	solAssert(m_localVarUseCount.empty(), "");
 	m_nonPayablePublic = _function.isPublic() && !_function.isPayable();
 	m_constructor = _function.isConstructor();
-	if (_function.stateMutability() == StateMutability::Pure)
-		m_errorReporter.warning(_function.location(), "Function is marked pure. Be careful, pureness is not enforced yet.");
 	return true;
 }
 
diff --git a/libsolidity/analysis/StaticAnalyzer.h b/libsolidity/analysis/StaticAnalyzer.h
index a3080b42..24ed119f 100644
--- a/libsolidity/analysis/StaticAnalyzer.h
+++ b/libsolidity/analysis/StaticAnalyzer.h
@@ -37,8 +37,8 @@ namespace solidity
 /**
  * The module that performs static analysis on the AST.
  * In this context, static analysis is anything that can produce warnings which can help
- * programmers write cleaner code. For every warning generated eher, it has to be possible to write
- * equivalent code that does generate the warning.
+ * programmers write cleaner code. For every warning generated here, it has to be possible to write
+ * equivalent code that does not generate the warning.
  */
 class StaticAnalyzer: private ASTConstVisitor
 {
diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index c54f4c87..26529c22 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -339,6 +339,9 @@ void TypeChecker::checkFunctionOverride(FunctionDefinition const& function, Func
 	if (!functionType.hasEqualArgumentTypes(superType))
 		return;
 
+	if (!function.annotation().superFunction)
+		function.annotation().superFunction = &super;
+
 	if (function.visibility() != super.visibility())
 		overrideError(function, super, "Overriding function visibility differs.");
 
diff --git a/libsolidity/analysis/TypeChecker.h b/libsolidity/analysis/TypeChecker.h
index f2e13765..0c6f54d3 100644
--- a/libsolidity/analysis/TypeChecker.h
+++ b/libsolidity/analysis/TypeChecker.h
@@ -63,6 +63,7 @@ private:
 	void checkContractDuplicateFunctions(ContractDefinition const& _contract);
 	void checkContractIllegalOverrides(ContractDefinition const& _contract);
 	/// Reports a type error with an appropiate message if overriden function signature differs.
+	/// Also stores the direct super function in the AST annotations.
 	void checkFunctionOverride(FunctionDefinition const& function, FunctionDefinition const& super);
 	void overrideError(FunctionDefinition const& function, FunctionDefinition const& super, std::string message);
 	void checkContractAbstractFunctions(ContractDefinition const& _contract);
diff --git a/libsolidity/analysis/ViewPureChecker.cpp b/libsolidity/analysis/ViewPureChecker.cpp
new file mode 100644
index 00000000..8f9d41c9
--- /dev/null
+++ b/libsolidity/analysis/ViewPureChecker.cpp
@@ -0,0 +1,313 @@
+/*
+	This file is part of solidity.
+
+	solidity is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	solidity is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with solidity.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <libsolidity/analysis/ViewPureChecker.h>
+
+#include <libevmasm/SemanticInformation.h>
+
+#include <libsolidity/inlineasm/AsmData.h>
+
+#include <functional>
+
+using namespace std;
+using namespace dev;
+using namespace dev::solidity;
+
+namespace
+{
+
+class AssemblyViewPureChecker: public boost::static_visitor<void>
+{
+public:
+	explicit AssemblyViewPureChecker(std::function<void(StateMutability, SourceLocation const&)> _reportMutability):
+		m_reportMutability(_reportMutability) {}
+
+	void operator()(assembly::Label const&) { }
+	void operator()(assembly::Instruction const& _instruction)
+	{
+		if (eth::SemanticInformation::invalidInViewFunctions(_instruction.instruction))
+			m_reportMutability(StateMutability::NonPayable, _instruction.location);
+		else if (eth::SemanticInformation::invalidInPureFunctions(_instruction.instruction))
+			m_reportMutability(StateMutability::View, _instruction.location);
+	}
+	void operator()(assembly::Literal const&) {}
+	void operator()(assembly::Identifier const&) {}
+	void operator()(assembly::FunctionalInstruction const& _instr)
+	{
+		(*this)(_instr.instruction);
+		for (auto const& arg: _instr.arguments)
+			boost::apply_visitor(*this, arg);
+	}
+	void operator()(assembly::StackAssignment const&) {}
+	void operator()(assembly::Assignment const& _assignment)
+	{
+		boost::apply_visitor(*this, *_assignment.value);
+	}
+	void operator()(assembly::VariableDeclaration const& _varDecl)
+	{
+		if (_varDecl.value)
+			boost::apply_visitor(*this, *_varDecl.value);
+	}
+	void operator()(assembly::FunctionDefinition const& _funDef)
+	{
+		(*this)(_funDef.body);
+	}
+	void operator()(assembly::FunctionCall const& _funCall)
+	{
+		for (auto const& arg: _funCall.arguments)
+			boost::apply_visitor(*this, arg);
+	}
+	void operator()(assembly::Switch const& _switch)
+	{
+		boost::apply_visitor(*this, *_switch.expression);
+		for (auto const& _case: _switch.cases)
+		{
+			if (_case.value)
+				(*this)(*_case.value);
+			(*this)(_case.body);
+		}
+	}
+	void operator()(assembly::ForLoop const& _for)
+	{
+		(*this)(_for.pre);
+		boost::apply_visitor(*this, *_for.condition);
+		(*this)(_for.body);
+		(*this)(_for.post);
+	}
+	void operator()(assembly::Block const& _block)
+	{
+		for (auto const& s: _block.statements)
+			boost::apply_visitor(*this, s);
+	}
+
+private:
+	std::function<void(StateMutability, SourceLocation const&)> m_reportMutability;
+};
+
+}
+
+bool ViewPureChecker::check()
+{
+	vector<ContractDefinition const*> contracts;
+
+	for (auto const& node: m_ast)
+	{
+		SourceUnit const* source = dynamic_cast<SourceUnit const*>(node.get());
+		solAssert(source, "");
+		contracts += source->filteredNodes<ContractDefinition>(source->nodes());
+	}
+
+	// Check modifiers first to infer their state mutability.
+	for (auto const* contract: contracts)
+		for (ModifierDefinition const* mod: contract->functionModifiers())
+			mod->accept(*this);
+
+	for (auto const* contract: contracts)
+		contract->accept(*this);
+
+	return !m_errors;
+}
+
+
+
+bool ViewPureChecker::visit(FunctionDefinition const& _funDef)
+{
+	solAssert(!m_currentFunction, "");
+	m_currentFunction = &_funDef;
+	m_currentBestMutability = StateMutability::Pure;
+	return true;
+}
+
+void ViewPureChecker::endVisit(FunctionDefinition const& _funDef)
+{
+	solAssert(m_currentFunction == &_funDef, "");
+	if (
+		m_currentBestMutability < _funDef.stateMutability() &&
+		_funDef.stateMutability() != StateMutability::Payable &&
+		_funDef.isImplemented() &&
+		!_funDef.isConstructor() &&
+		!_funDef.isFallback() &&
+		!_funDef.annotation().superFunction
+	)
+		m_errorReporter.warning(
+			_funDef.location(),
+			"Function state mutability can be restricted to " + stateMutabilityToString(m_currentBestMutability)
+		);
+	m_currentFunction = nullptr;
+}
+
+bool ViewPureChecker::visit(ModifierDefinition const&)
+{
+	solAssert(m_currentFunction == nullptr, "");
+	m_currentBestMutability = StateMutability::Pure;
+	return true;
+}
+
+void ViewPureChecker::endVisit(ModifierDefinition const& _modifierDef)
+{
+	solAssert(m_currentFunction == nullptr, "");
+	m_inferredMutability[&_modifierDef] = m_currentBestMutability;
+}
+
+void ViewPureChecker::endVisit(Identifier const& _identifier)
+{
+	Declaration const* declaration = _identifier.annotation().referencedDeclaration;
+	solAssert(declaration, "");
+
+	StateMutability mutability = StateMutability::Pure;
+
+	bool writes = _identifier.annotation().lValueRequested;
+	if (VariableDeclaration const* varDecl = dynamic_cast<VariableDeclaration const*>(declaration))
+	{
+		if (varDecl->isStateVariable() && !varDecl->isConstant())
+			mutability = writes ? StateMutability::NonPayable : StateMutability::View;
+	}
+	else if (MagicVariableDeclaration const* magicVar = dynamic_cast<MagicVariableDeclaration const*>(declaration))
+	{
+		switch (magicVar->type()->category())
+		{
+		case Type::Category::Contract:
+			solAssert(_identifier.name() == "this" || _identifier.name() == "super", "");
+			if (!dynamic_cast<ContractType const&>(*magicVar->type()).isSuper())
+				// reads the address
+				mutability = StateMutability::View;
+			break;
+		case Type::Category::Integer:
+			solAssert(_identifier.name() == "now", "");
+			mutability = StateMutability::View;
+			break;
+		default:
+			break;
+		}
+	}
+
+	reportMutability(mutability, _identifier.location());
+}
+
+void ViewPureChecker::endVisit(InlineAssembly const& _inlineAssembly)
+{
+	AssemblyViewPureChecker{
+		[=](StateMutability _mutability, SourceLocation const& _location) { reportMutability(_mutability, _location); }
+	}(_inlineAssembly.operations());
+}
+
+void ViewPureChecker::reportMutability(StateMutability _mutability, SourceLocation const& _location)
+{
+	if (m_currentFunction && m_currentFunction->stateMutability() < _mutability)
+	{
+		string text;
+		if (_mutability == StateMutability::View)
+			text =
+				"Function declared as pure, but this expression (potentially) reads from the "
+				"environment or state and thus requires \"view\".";
+		else if (_mutability == StateMutability::NonPayable)
+			text =
+				"Function declared as " +
+				stateMutabilityToString(m_currentFunction->stateMutability()) +
+				", but this expression (potentially) modifies the state and thus "
+				"requires non-payable (the default) or payable.";
+		else
+			solAssert(false, "");
+
+		if (m_currentFunction->stateMutability() == StateMutability::View)
+			// TODO Change this to error with 0.5.0
+			m_errorReporter.warning(_location, text);
+		else if (m_currentFunction->stateMutability() == StateMutability::Pure)
+		{
+			m_errors = true;
+			m_errorReporter.typeError(_location, text);
+		}
+		else
+			solAssert(false, "");
+	}
+	if (_mutability > m_currentBestMutability)
+		m_currentBestMutability = _mutability;
+}
+
+void ViewPureChecker::endVisit(FunctionCall const& _functionCall)
+{
+	if (_functionCall.annotation().kind != FunctionCallKind::FunctionCall)
+		return;
+
+	StateMutability mut = dynamic_cast<FunctionType const&>(*_functionCall.expression().annotation().type).stateMutability();
+	// We only require "nonpayable" to call a payble function.
+	if (mut == StateMutability::Payable)
+		mut = StateMutability::NonPayable;
+	reportMutability(mut, _functionCall.location());
+}
+
+void ViewPureChecker::endVisit(MemberAccess const& _memberAccess)
+{
+	StateMutability mutability = StateMutability::Pure;
+	bool writes = _memberAccess.annotation().lValueRequested;
+
+	ASTString const& member = _memberAccess.memberName();
+	switch (_memberAccess.expression().annotation().type->category())
+	{
+	case Type::Category::Contract:
+	case Type::Category::Integer:
+		if (member == "balance" && !_memberAccess.annotation().referencedDeclaration)
+			mutability = StateMutability::View;
+		break;
+	case Type::Category::Magic:
+		// we can ignore the kind of magic and only look at the name of the member
+		if (member != "data" && member != "sig" && member != "blockhash")
+			mutability = StateMutability::View;
+		break;
+	case Type::Category::Struct:
+	{
+		if (_memberAccess.expression().annotation().type->dataStoredIn(DataLocation::Storage))
+			mutability = writes ? StateMutability::NonPayable : StateMutability::View;
+		break;
+	}
+	case Type::Category::Array:
+	{
+		auto const& type = dynamic_cast<ArrayType const&>(*_memberAccess.expression().annotation().type);
+		if (member == "length" && type.isDynamicallySized() && type.dataStoredIn(DataLocation::Storage))
+			mutability = writes ? StateMutability::NonPayable : StateMutability::View;
+		break;
+	}
+	default:
+		break;
+	}
+	reportMutability(mutability, _memberAccess.location());
+}
+
+void ViewPureChecker::endVisit(IndexAccess const& _indexAccess)
+{
+	if (!_indexAccess.indexExpression())
+		solAssert(_indexAccess.annotation().type->category() == Type::Category::TypeType, "");
+	else
+	{
+		bool writes = _indexAccess.annotation().lValueRequested;
+		if (_indexAccess.baseExpression().annotation().type->dataStoredIn(DataLocation::Storage))
+			reportMutability(writes ? StateMutability::NonPayable : StateMutability::View, _indexAccess.location());
+	}
+}
+
+void ViewPureChecker::endVisit(ModifierInvocation const& _modifier)
+{
+	solAssert(_modifier.name(), "");
+	if (ModifierDefinition const* mod = dynamic_cast<decltype(mod)>(_modifier.name()->annotation().referencedDeclaration))
+	{
+		solAssert(m_inferredMutability.count(mod), "");
+		reportMutability(m_inferredMutability.at(mod), _modifier.location());
+	}
+	else
+		solAssert(dynamic_cast<ContractDefinition const*>(_modifier.name()->annotation().referencedDeclaration), "");
+}
+
diff --git a/libsolidity/analysis/ViewPureChecker.h b/libsolidity/analysis/ViewPureChecker.h
new file mode 100644
index 00000000..ae303533
--- /dev/null
+++ b/libsolidity/analysis/ViewPureChecker.h
@@ -0,0 +1,79 @@
+/*
+	This file is part of solidity.
+
+	solidity is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	solidity is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with solidity.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#pragma once
+
+#include <libsolidity/ast/ASTEnums.h>
+#include <libsolidity/ast/ASTForward.h>
+#include <libsolidity/ast/ASTVisitor.h>
+
+#include <libsolidity/interface/ErrorReporter.h>
+
+#include <map>
+#include <memory>
+
+namespace dev
+{
+namespace solidity
+{
+
+class ASTNode;
+class FunctionDefinition;
+class ModifierDefinition;
+class Identifier;
+class MemberAccess;
+class IndexAccess;
+class ModifierInvocation;
+class FunctionCall;
+class InlineAssembly;
+
+class ViewPureChecker: private ASTConstVisitor
+{
+public:
+	ViewPureChecker(std::vector<std::shared_ptr<ASTNode>> const& _ast, ErrorReporter& _errorReporter):
+		m_ast(_ast), m_errorReporter(_errorReporter) {}
+
+	bool check();
+
+private:
+
+	virtual bool visit(FunctionDefinition const& _funDef) override;
+	virtual void endVisit(FunctionDefinition const& _funDef) override;
+	virtual bool visit(ModifierDefinition const& _modifierDef) override;
+	virtual void endVisit(ModifierDefinition const& _modifierDef) override;
+	virtual void endVisit(Identifier const& _identifier) override;
+	virtual void endVisit(MemberAccess const& _memberAccess) override;
+	virtual void endVisit(IndexAccess const& _indexAccess) override;
+	virtual void endVisit(ModifierInvocation const& _modifier) override;
+	virtual void endVisit(FunctionCall const& _functionCall) override;
+	virtual void endVisit(InlineAssembly const& _inlineAssembly) override;
+
+	/// Called when an element of mutability @a _mutability is encountered.
+	/// Creates appropriate warnings and errors and sets @a m_currentBestMutability.
+	void reportMutability(StateMutability _mutability, SourceLocation const& _location);
+
+	std::vector<std::shared_ptr<ASTNode>> const& m_ast;
+	ErrorReporter& m_errorReporter;
+
+	bool m_errors = false;
+	StateMutability m_currentBestMutability = StateMutability::Payable;
+	FunctionDefinition const* m_currentFunction = nullptr;
+	std::map<ModifierDefinition const*, StateMutability> m_inferredMutability;
+};
+
+}
+}