Merge pull request #5552 from 0yi0/5551-rational-convertible-to-fixed-point

Fix conversions from rational number literals to fixed-point types.

5 files changed, 86 insertions, 55 deletions

diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index 1c9f1956..d41415c0 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -935,30 +935,32 @@ bool TypeChecker::visit(VariableDeclarationStatement const& _statement)
 			var.accept(*this);
 			if (!valueComponentType->isImplicitlyConvertibleTo(*var.annotation().type))
 			{
+				auto errorMsg = "Type " +
+					valueComponentType->toString() +
+					" is not implicitly convertible to expected type " +
+					var.annotation().type->toString();
 				if (
 					valueComponentType->category() == Type::Category::RationalNumber &&
 					dynamic_cast<RationalNumberType const&>(*valueComponentType).isFractional() &&
 					valueComponentType->mobileType()
 				)
-					m_errorReporter.typeError(
-						_statement.location(),
-						"Type " +
-						valueComponentType->toString() +
-						" is not implicitly convertible to expected type " +
-						var.annotation().type->toString() +
-						". Try converting to type " +
-						valueComponentType->mobileType()->toString() +
-						" or use an explicit conversion."
-					);
+				{
+					if (var.annotation().type->operator==(*valueComponentType->mobileType()))
+						m_errorReporter.typeError(
+							_statement.location(),
+							errorMsg + ", but it can be explicitly converted."
+						);
+					else
+						m_errorReporter.typeError(
+							_statement.location(),
+							errorMsg +
+							". Try converting to type " +
+							valueComponentType->mobileType()->toString() +
+							" or use an explicit conversion."
+						);
+				}
 				else
-					m_errorReporter.typeError(
-						_statement.location(),
-						"Type " +
-						valueComponentType->toString() +
-						" is not implicitly convertible to expected type " +
-						var.annotation().type->toString() +
-						"."
-					);
+					m_errorReporter.typeError(_statement.location(), errorMsg + ".");
 			}
 		}
 	}
@@ -2331,30 +2333,32 @@ bool TypeChecker::expectType(Expression const& _expression, Type const& _expecte
 	_expression.accept(*this);
 	if (!type(_expression)->isImplicitlyConvertibleTo(_expectedType))
 	{
+		auto errorMsg = "Type " +
+			type(_expression)->toString() +
+			" is not implicitly convertible to expected type " +
+			_expectedType.toString();
 		if (
 			type(_expression)->category() == Type::Category::RationalNumber &&
 			dynamic_pointer_cast<RationalNumberType const>(type(_expression))->isFractional() &&
 			type(_expression)->mobileType()
 		)
-			m_errorReporter.typeError(
-				_expression.location(),
-				"Type " +
-				type(_expression)->toString() +
-				" is not implicitly convertible to expected type " +
-				_expectedType.toString() +
-				". Try converting to type " +
-				type(_expression)->mobileType()->toString() +
-				" or use an explicit conversion."
-			);
+		{
+			if (_expectedType.operator==(*type(_expression)->mobileType()))
+				m_errorReporter.typeError(
+					_expression.location(),
+					errorMsg + ", but it can be explicitly converted."
+				);
+			else
+				m_errorReporter.typeError(
+					_expression.location(),
+					errorMsg +
+					". Try converting to type " +
+					type(_expression)->mobileType()->toString() +
+					" or use an explicit conversion."
+				);
+		}
 		else
-			m_errorReporter.typeError(
-				_expression.location(),
-				"Type " +
-				type(_expression)->toString() +
-				" is not implicitly convertible to expected type " +
-				_expectedType.toString() +
-				"."
-			);
+			m_errorReporter.typeError(_expression.location(), errorMsg + ".");
 		return false;
 	}
 	return true;
diff --git a/libsolidity/ast/Types.cpp b/libsolidity/ast/Types.cpp
index f5a38747..621e6513 100644
--- a/libsolidity/ast/Types.cpp
+++ b/libsolidity/ast/Types.cpp
@@ -125,6 +125,22 @@ bool fitsPrecisionBase2(bigint const& _mantissa, uint32_t _expBase2)
 	return fitsPrecisionBaseX(_mantissa, 1.0, _expBase2);
 }
 
+/// Checks whether _value fits into IntegerType _type.
+bool fitsIntegerType(bigint const& _value, IntegerType const& _type)
+{
+	return (_type.minValue() <= _value) && (_value <= _type.maxValue());
+}
+
+/// Checks whether _value fits into _bits bits when having 1 bit as the sign bit
+/// if _signed is true.
+bool fitsIntoBits(bigint const& _value, unsigned _bits, bool _signed)
+{
+	return fitsIntegerType(_value, IntegerType(
+		_bits,
+		_signed ? IntegerType::Modifier::Signed : IntegerType::Modifier::Unsigned
+	));
+}
+
 }
 
 void StorageOffsets::computeOffsets(TypePointers const& _types)
@@ -963,27 +979,21 @@ BoolResult RationalNumberType::isImplicitlyConvertibleTo(Type const& _convertTo)
 		if (isFractional())
 			return false;
 		IntegerType const& targetType = dynamic_cast<IntegerType const&>(_convertTo);
-		if (m_value == rational(0))
-			return true;
-		unsigned forSignBit = (targetType.isSigned() ? 1 : 0);
-		if (m_value > rational(0))
-		{
-			if (m_value.numerator() <= (u256(-1) >> (256 - targetType.numBits() + forSignBit)))
-				return true;
-			return false;
-		}
-		if (targetType.isSigned())
-		{
-			if (-m_value.numerator() <= (u256(1) << (targetType.numBits() - forSignBit)))
-				return true;
-		}
-		return false;
+		return fitsIntegerType(m_value.numerator(), targetType);
 	}
 	case Category::FixedPoint:
 	{
-		if (auto fixed = fixedPointType())
-			return fixed->isImplicitlyConvertibleTo(_convertTo);
-		return false;
+		FixedPointType const& targetType = dynamic_cast<FixedPointType const&>(_convertTo);
+		// Store a negative number into an unsigned.
+		if (isNegative() && !targetType.isSigned())
+			return false;
+		if (!isFractional())
+			return (targetType.minIntegerValue() <= m_value) && (m_value <= targetType.maxIntegerValue());
+		rational value = m_value * pow(bigint(10), targetType.fractionalDigits());
+		// Need explicit conversion since truncation will occur.
+		if (value.denominator() != 1)
+			return false;
+		return fitsIntoBits(value.numerator(), targetType.numBits(), targetType.isSigned());
 	}
 	case Category::FixedBytes:
 		return (m_value == rational(0)) || (m_compatibleBytesType && *m_compatibleBytesType == _convertTo);
diff --git a/test/libsolidity/syntaxTests/nameAndTypeResolution/313_fixed_type_size_capabilities.sol b/test/libsolidity/syntaxTests/nameAndTypeResolution/313_fixed_type_size_capabilities.sol
index 441cf81e..295cf4ea 100644
--- a/test/libsolidity/syntaxTests/nameAndTypeResolution/313_fixed_type_size_capabilities.sol
+++ b/test/libsolidity/syntaxTests/nameAndTypeResolution/313_fixed_type_size_capabilities.sol
@@ -10,4 +10,5 @@ contract test {
     }
 }
 // ----
-// Warning: (20-707): Function state mutability can be restricted to pure
+// TypeError: (153-250): Type rational_const 9208...(70 digits omitted)...7637 / 1000...(71 digits omitted)...0000 is not implicitly convertible to expected type ufixed256x77, but it can be explicitly converted.
+// TypeError: (470-566): Type rational_const -933...(70 digits omitted)...0123 / 1000...(70 digits omitted)...0000 is not implicitly convertible to expected type fixed256x76, but it can be explicitly converted.
diff --git a/test/libsolidity/syntaxTests/types/rational_number_literal_to_fixed_implicit.sol b/test/libsolidity/syntaxTests/types/rational_number_literal_to_fixed_implicit.sol
new file mode 100644
index 00000000..ca50e03b
--- /dev/null
+++ b/test/libsolidity/syntaxTests/types/rational_number_literal_to_fixed_implicit.sol
@@ -0,0 +1,15 @@
+contract C {
+    function literalToUFixed() public pure {
+        ufixed8x2 a = 0.10;
+        ufixed8x2 b = 0.00;
+        ufixed8x2 c = 2.55;
+        a; b; c;
+    }
+    function literalToFixed() public pure {
+        fixed8x1 a =   0.1;
+        fixed8x1 b =  12.7;
+        fixed8x1 c = -12.8;
+        a; b; c;
+    }
+}
+// ----
diff --git a/test/libsolidity/syntaxTests/types/too_small_negative_numbers.sol b/test/libsolidity/syntaxTests/types/too_small_negative_numbers.sol
index 66bd9a8e..f86ffcdd 100644
--- a/test/libsolidity/syntaxTests/types/too_small_negative_numbers.sol
+++ b/test/libsolidity/syntaxTests/types/too_small_negative_numbers.sol
@@ -2,3 +2,4 @@ contract C {
   fixed8x80 a = -1e-100;
 }
 // ----
+// TypeError: (29-36): Type rational_const -1 / 1000...(93 digits omitted)...0000 is not implicitly convertible to expected type fixed8x80, but it can be explicitly converted.