Reimplement constant evaluator.

libsolidity/analysis/ConstantEvaluator.cpp

@@ -32,6 +32,8 @@ using namespace solidity;
 using namespace solidity::frontend;
 using namespace solidity::langutil;
 
+using TypedRational = ConstantEvaluator::TypedRational;
+
 namespace
 {
 
@@ -227,85 +229,162 @@ optional<rational> ConstantEvaluator::evaluateUnaryOperator(Token _operator, rat
 	}
 }
 
+optional<TypedRational> convertType(rational const& _value, Type const& _type)
+{
+	if (_type.category() == Type::Category::RationalNumber)
+		return TypedRational{TypeProvider::rationalNumber(_value), _value};
+	else if (auto const* integerType = dynamic_cast<IntegerType const*>(&_type))
+	{
+		if (_value > integerType->maxValue() || _value < integerType->minValue())
+			return nullopt;
+		else
+			return TypedRational{&_type, _value.numerator() / _value.denominator()};
+	}
+	else
+		return nullopt;
+}
+
+optional<TypedRational> convertType(optional<TypedRational> const& _value, Type const& _type)
+{
+	return _value ? convertType(_value->value, _type) : nullopt;
+}
+
+optional<TypedRational> constantToTypedValue(Type const& _type)
+{
+	if (_type.category() == Type::Category::RationalNumber)
+		return TypedRational{&_type, dynamic_cast<RationalNumberType const&>(_type).value()};
+	else
+		return nullopt;
+}
+
+optional<TypedRational> ConstantEvaluator::evaluate(
+	langutil::ErrorReporter& _errorReporter,
+	Expression const& _expr
+)
+{
+	return ConstantEvaluator{_errorReporter}.evaluate(_expr);
+}
+
+
+optional<TypedRational> ConstantEvaluator::evaluate(ASTNode const& _node)
+{
+	if (!m_values.count(&_node))
+	{
+		if (auto const* varDecl = dynamic_cast<VariableDeclaration const*>(&_node))
+		{
+			solAssert(varDecl->isConstant(), "");
+			if (!varDecl->value())
+				m_values[&_node] = nullopt;
+			else
+			{
+				m_depth++;
+				if (m_depth > 32)
+					m_errorReporter.fatalTypeError(
+						5210_error,
+						varDecl->location(),
+						"Cyclic constant definition (or maximum recursion depth exhausted)."
+					);
+				m_values[&_node] = convertType(evaluate(*varDecl->value()), *varDecl->type());
+				m_depth--;
+			}
+		}
+		else if (auto const* expression = dynamic_cast<Expression const*>(&_node))
+		{
+			expression->accept(*this);
+			if (!m_values.count(&_node))
+				m_values[&_node] = nullopt;
+		}
+	}
+	return m_values.at(&_node);
+}
+
 void ConstantEvaluator::endVisit(UnaryOperation const& _operation)
 {
-	auto sub = type(_operation.subExpression());
-	if (sub)
-		setType(_operation, sub->unaryOperatorResult(_operation.getOperator()));
+	optional<TypedRational> value = evaluate(_operation.subExpression());
+	if (!value)
+		return;
+
+	TypePointer resultType = value->type->unaryOperatorResult(_operation.getOperator());
+	if (!resultType)
+		return;
+	value = convertType(value, *resultType);
+	if (!value)
+		return;
+
+	if (optional<rational> result = evaluateUnaryOperator(_operation.getOperator(), value->value))
+	{
+		optional<TypedRational> convertedValue = convertType(*result, *resultType);
+		if (!convertedValue)
+			m_errorReporter.fatalTypeError(
+				3667_error,
+				_operation.location(),
+				"Arithmetic error when computing constant value."
+			);
+		m_values[&_operation] = convertedValue;
+	}
 }
 
 void ConstantEvaluator::endVisit(BinaryOperation const& _operation)
 {
-	auto left = type(_operation.leftExpression());
-	auto right = type(_operation.rightExpression());
-	if (left && right)
+	optional<TypedRational> left = evaluate(_operation.leftExpression());
+	optional<TypedRational> right = evaluate(_operation.rightExpression());
+	if (!left || !right)
+		return;
+
+	// If this is implemented in the future: Comparison operators have a "binaryOperatorResult"
+	// that is non-bool, but the result has to be bool.
+	if (TokenTraits::isCompareOp(_operation.getOperator()))
+		return;
+
+	TypePointer resultType = left->type->binaryOperatorResult(_operation.getOperator(), right->type);
+	if (!resultType)
 	{
-		TypePointer commonType = left->binaryOperatorResult(_operation.getOperator(), right);
-		if (!commonType)
-			m_errorReporter.fatalTypeError(
-				6020_error,
-				_operation.location(),
-				"Operator " +
-				string(TokenTraits::toString(_operation.getOperator())) +
-				" not compatible with types " +
-				left->toString() +
-				" and " +
-				right->toString()
+		m_errorReporter.fatalTypeError(
+			6020_error,
+			_operation.location(),
+			"Operator " +
+			string(TokenTraits::toString(_operation.getOperator())) +
+			" not compatible with types " +
+			left->type->toString() +
+			" and " +
+			right->type->toString()
 			);
-		setType(
-			_operation,
-			TokenTraits::isCompareOp(_operation.getOperator()) ?
-			TypeProvider::boolean() :
-			commonType
-		);
+		return;
+	}
+
+	left = convertType(left, *resultType);
+	right = convertType(right, *resultType);
+	if (!left || !right)
+		return;
+
+	if (optional<rational> value = evaluateBinaryOperator(_operation.getOperator(), left->value, right->value))
+	{
+		optional<TypedRational> convertedValue = convertType(*value, *resultType);
+		if (!convertedValue)
+			m_errorReporter.fatalTypeError(
+				2643_error,
+				_operation.location(),
+				"Arithmetic error when computing constant value."
+			);
+		m_values[&_operation] = convertedValue;
 	}
 }
 
 void ConstantEvaluator::endVisit(Literal const& _literal)
 {
-	setType(_literal, TypeProvider::forLiteral(_literal));
+	if (Type const* literalType = TypeProvider::forLiteral(_literal))
+		m_values[&_literal] = constantToTypedValue(*literalType);
 }
 
 void ConstantEvaluator::endVisit(Identifier const& _identifier)
 {
 	VariableDeclaration const* variableDeclaration = dynamic_cast<VariableDeclaration const*>(_identifier.annotation().referencedDeclaration);
-	if (!variableDeclaration)
-		return;
-	if (!variableDeclaration->isConstant())
-		return;
-
-	ASTPointer<Expression> const& value = variableDeclaration->value();
-	if (!value)
-		return;
-	else if (!m_types->count(value.get()))
-	{
-		if (m_depth > 32)
-			m_errorReporter.fatalTypeError(5210_error, _identifier.location(), "Cyclic constant definition (or maximum recursion depth exhausted).");
-		ConstantEvaluator(m_errorReporter, m_depth + 1, m_types).evaluate(*value);
-	}
-
-	setType(_identifier, type(*value));
+	if (variableDeclaration && variableDeclaration->isConstant())
+		m_values[&_identifier] = evaluate(*variableDeclaration);
 }
 
 void ConstantEvaluator::endVisit(TupleExpression const& _tuple)
 {
 	if (!_tuple.isInlineArray() && _tuple.components().size() == 1)
-		setType(_tuple, type(*_tuple.components().front()));
-}
-
-void ConstantEvaluator::setType(ASTNode const& _node, TypePointer const& _type)
-{
-	if (_type && _type->category() == Type::Category::RationalNumber)
-		(*m_types)[&_node] = _type;
-}
-
-TypePointer ConstantEvaluator::type(ASTNode const& _node)
-{
-	return (*m_types)[&_node];
-}
-
-TypePointer ConstantEvaluator::evaluate(Expression const& _expr)
-{
-	_expr.accept(*this);
-	return type(_expr);
+		m_values[&_tuple] = evaluate(*_tuple.components().front());
 }

libsolidity/analysis/ConstantEvaluator.h

@@ -39,22 +39,23 @@ class TypeChecker;
 
 /**
  * Small drop-in replacement for TypeChecker to evaluate simple expressions of integer constants.
+ *
+ * Note: This always use "checked arithmetic" in the sense that any over- or underflow
+ * results in "unknown" value.
  */
 class ConstantEvaluator: private ASTConstVisitor
 {
 public:
-	ConstantEvaluator(
-		langutil::ErrorReporter& _errorReporter,
-		size_t _newDepth = 0,
-		std::shared_ptr<std::map<ASTNode const*, TypePointer>> _types = std::make_shared<std::map<ASTNode const*, TypePointer>>()
-	):
-		m_errorReporter(_errorReporter),
-		m_depth(_newDepth),
-		m_types(std::move(_types))
+	struct TypedRational
 	{
-	}
+		TypePointer type;
+		rational value;
+	};
 
-	TypePointer evaluate(Expression const& _expr);
+	static std::optional<TypedRational> evaluate(
+		langutil::ErrorReporter& _errorReporter,
+		Expression const& _expr
+	);
 
 	/// Performs arbitrary-precision evaluation of a binary operator. Returns nullopt on cases like
 	/// division by zero or e.g. bit operators applied to fractional values.
@@ -65,19 +66,21 @@ public:
 	static std::optional<rational> evaluateUnaryOperator(Token _operator, rational const& _input);
 
 private:
+	explicit ConstantEvaluator(langutil::ErrorReporter& _errorReporter): m_errorReporter(_errorReporter) {}
+
+	std::optional<TypedRational> evaluate(ASTNode const& _node);
+
 	void endVisit(BinaryOperation const& _operation) override;
 	void endVisit(UnaryOperation const& _operation) override;
 	void endVisit(Literal const& _literal) override;
 	void endVisit(Identifier const& _identifier) override;
 	void endVisit(TupleExpression const& _tuple) override;
 
-	void setType(ASTNode const& _node, TypePointer const& _type);
-	TypePointer type(ASTNode const& _node);
-
 	langutil::ErrorReporter& m_errorReporter;
 	/// Current recursion depth.
 	size_t m_depth = 0;
-	std::shared_ptr<std::map<ASTNode const*, TypePointer>> m_types;
+	/// Values of sub-expressions and variable declarations.
+	std::map<ASTNode const*, std::optional<TypedRational>> m_values;
 };
 
 }

libsolidity/analysis/DeclarationTypeChecker.cpp

@@ -265,26 +265,30 @@ void DeclarationTypeChecker::endVisit(ArrayTypeName const& _typeName)
 	solAssert(baseType->storageBytes() != 0, "Illegal base type of storage size zero for array.");
 	if (Expression const* length = _typeName.length())
 	{
-		TypePointer& lengthTypeGeneric = length->annotation().type;
-		if (!lengthTypeGeneric)
-			lengthTypeGeneric = ConstantEvaluator(m_errorReporter).evaluate(*length);
-		RationalNumberType const* lengthType = dynamic_cast<RationalNumberType const*>(lengthTypeGeneric);
-		u256 lengthValue = 0;
-		if (!lengthType || !lengthType->mobileType())
+		optional<rational> lengthValue;
+		if (length->annotation().type && length->annotation().type->category() == Type::Category::RationalNumber)
+			lengthValue = dynamic_cast<RationalNumberType const&>(*length->annotation().type).value();
+		else if (optional<ConstantEvaluator::TypedRational> value = ConstantEvaluator::evaluate(m_errorReporter, *length))
+			lengthValue = value->value;
+
+		if (!lengthValue || lengthValue > TypeProvider::uint256()->max())
 			m_errorReporter.typeError(
 				5462_error,
 				length->location(),
 				"Invalid array length, expected integer literal or constant expression."
 			);
-		else if (lengthType->isZero())
+		else if (*lengthValue == 0)
 			m_errorReporter.typeError(1406_error, length->location(), "Array with zero length specified.");
-		else if (lengthType->isFractional())
+		else if (lengthValue->denominator() != 1)
 			m_errorReporter.typeError(3208_error, length->location(), "Array with fractional length specified.");
-		else if (lengthType->isNegative())
+		else if (*lengthValue < 0)
 			m_errorReporter.typeError(3658_error, length->location(), "Array with negative length specified.");
-		else
-			lengthValue = lengthType->literalValue(nullptr);
-		_typeName.annotation().type = TypeProvider::array(DataLocation::Storage, baseType, lengthValue);
+
+		_typeName.annotation().type = TypeProvider::array(
+			DataLocation::Storage,
+			baseType,
+			lengthValue ? u256(lengthValue->numerator()) : u256(0)
+		);
 	}
 	else
 		_typeName.annotation().type = TypeProvider::array(DataLocation::Storage, baseType);

libsolidity/analysis/StaticAnalyzer.cpp

@@ -290,10 +290,8 @@ bool StaticAnalyzer::visit(BinaryOperation const& _operation)
 		*_operation.rightExpression().annotation().isPure &&
 		(_operation.getOperator() == Token::Div || _operation.getOperator() == Token::Mod)
 	)
-		if (auto rhs = dynamic_cast<RationalNumberType const*>(
-			ConstantEvaluator(m_errorReporter).evaluate(_operation.rightExpression())
-		))
-			if (rhs->isZero())
+		if (auto rhs = ConstantEvaluator::evaluate(m_errorReporter, _operation.rightExpression()))
+			if (rhs->value == 0)
 				m_errorReporter.typeError(
 					1211_error,
 					_operation.location(),
@@ -313,10 +311,8 @@ bool StaticAnalyzer::visit(FunctionCall const& _functionCall)
 		{
 			solAssert(_functionCall.arguments().size() == 3, "");
 			if (*_functionCall.arguments()[2]->annotation().isPure)
-				if (auto lastArg = dynamic_cast<RationalNumberType const*>(
-					ConstantEvaluator(m_errorReporter).evaluate(*(_functionCall.arguments())[2])
-				))
-					if (lastArg->isZero())
+				if (auto lastArg = ConstantEvaluator::evaluate(m_errorReporter, *(_functionCall.arguments())[2]))
+					if (lastArg->value == 0)
 						m_errorReporter.typeError(
 							4195_error,
 							_functionCall.location(),

libsolidity/ast/Types.h

@@ -568,6 +568,11 @@ public:
 	u256 literalValue(Literal const* _literal) const override;
 	TypePointer mobileType() const override;
 
+	/// @returns the underlying raw literal value.
+	///
+	/// @see literalValue(Literal const*))
+	rational const& value() const noexcept { return m_value; }
+
 	/// @returns the smallest integer type that can hold the value or an empty pointer if not possible.
 	IntegerType const* integerType() const;
 	/// @returns the smallest fixed type that can hold the value or incurs the least precision loss,

libsolutil/CMakeLists.txt

@@ -2,8 +2,8 @@ set(sources
 	Algorithms.h
 	AnsiColorized.h
 	Assertions.h
-	Common.h
 	Common.cpp
+	Common.h
 	CommonData.cpp
 	CommonData.h
 	CommonIO.cpp

test/libsolidity/semanticTests/constantEvaluator/rounding.sol

@@ -0,0 +1,15 @@
+contract C {
+    int constant a = 7;
+    int constant b = 3;
+    int constant c = a / b;
+    int constant d = (-a) / b;
+    function f() public pure returns (uint, int, uint, int) {
+        uint[c] memory x;
+        uint[-d] memory y;
+        return (x.length, c, y.length, -d);
+    }
+}
+// ====
+// compileViaYul: also
+// ----
+// f() -> 2, 2, 2, 2

test/libsolidity/semanticTests/constants/consteval_array_length.sol

@@ -0,0 +1,14 @@
+contract C {
+    uint constant a = 12;
+    uint constant b = 10;
+
+    function f() public pure returns (uint, uint) {
+        uint[(a / b) * b] memory x;
+        return (x.length, (a / b) * b);
+    }
+}
+// ====
+// compileViaYul: true
+// ----
+// constructor() ->
+// f() -> 0x0a, 0x0a

test/libsolidity/syntaxTests/array/length/complex_cyclic_constant.sol

@@ -7,4 +7,4 @@ contract C {
     }
 }
 // ----
-// TypeError 5210: (36-39): Cyclic constant definition (or maximum recursion depth exhausted).
+// TypeError 5210: (17-44): Cyclic constant definition (or maximum recursion depth exhausted).

test/libsolidity/syntaxTests/array/length/const_cannot_be_fractional.sol

@@ -3,4 +3,4 @@ contract C {
     uint[L] ids;
 }
 // ----
-// TypeError 3208: (51-52): Array with fractional length specified.
+// TypeError 5462: (51-52): Invalid array length, expected integer literal or constant expression.

test/libsolidity/syntaxTests/array/length/cyclic_constant.sol

@@ -5,4 +5,4 @@ contract C {
     }
 }
 // ----
-// TypeError 5210: (37-40): Cyclic constant definition (or maximum recursion depth exhausted).
+// TypeError 5210: (17-40): Cyclic constant definition (or maximum recursion depth exhausted).

test/libsolidity/syntaxTests/constantEvaluator/overflow.sol

@@ -0,0 +1,9 @@
+contract C {
+    uint8 constant a = 255;
+    uint16 constant b = a + 2;
+    function f() public pure {
+        uint[b] memory x;
+    }
+}
+// ----
+// TypeError 2643: (65-70): Arithmetic error when computing constant value.

test/libsolidity/syntaxTests/constantEvaluator/unary_fine.sol

@@ -0,0 +1,8 @@
+contract C {
+    int8 constant a = -7;
+    function f() public pure {
+        uint[-a] memory x;
+        x[0] = 2;
+    }
+}
+// ----

test/libsolidity/syntaxTests/constantEvaluator/underflow.sol

@@ -0,0 +1,8 @@
+contract C {
+    uint8 constant a = 0;
+    function f() public pure {
+        uint[a - 1] memory x;
+    }
+}
+// ----
+// TypeError 2643: (83-88): Arithmetic error when computing constant value.

test/libsolidity/syntaxTests/constantEvaluator/underflow_unary.sol

@@ -0,0 +1,8 @@
+contract C {
+    int8 constant a = -128;
+    function f() public pure {
+        uint[-a] memory x;
+    }
+}
+// ----
+// TypeError 3667: (85-87): Arithmetic error when computing constant value.