Merge pull request #2688 from chriseth/toBytesConversion

Allow explicit conversions bytes <-> string.

libsolidity/AST.cpp

@@ -844,9 +844,15 @@ void FunctionCall::checkTypeRequirements(TypePointers const*)
 			BOOST_THROW_EXCEPTION(createTypeError("Exactly one argument expected for explicit type conversion."));
 		if (!isPositionalCall)
 			BOOST_THROW_EXCEPTION(createTypeError("Type conversion cannot allow named arguments."));
-		if (!m_arguments.front()->getType()->isExplicitlyConvertibleTo(*type.getActualType()))
-			BOOST_THROW_EXCEPTION(createTypeError("Explicit type conversion not allowed."));
 		m_type = type.getActualType();
+		auto argType = m_arguments.front()->getType();
+		if (auto argRefType = dynamic_cast<ReferenceType const*>(argType.get()))
+			// do not change the data location when converting
+			// (data location cannot yet be specified for type conversions)
+			m_type = ReferenceType::copyForLocationIfReference(argRefType->location(), m_type);
+		if (!argType->isExplicitlyConvertibleTo(*m_type))
+			BOOST_THROW_EXCEPTION(createTypeError("Explicit type conversion not allowed."));
+
 		return;
 	}
 

libsolidity/CompilerUtils.cpp

@@ -404,7 +404,7 @@ void CompilerUtils::convertType(Type const& _typeOnStack, Type const& _targetTyp
 		case DataLocation::Storage:
 			// Other cases are done explicitly in LValue::storeValue, and only possible by assignment.
 			solAssert(
-				targetType.isPointer() &&
+				(targetType.isPointer() || (typeOnStack.isByteArray() && targetType.isByteArray())) &&
 				typeOnStack.location() == DataLocation::Storage,
 				"Invalid conversion to storage type."
 			);
@@ -469,6 +469,13 @@ void CompilerUtils::convertType(Type const& _typeOnStack, Type const& _targetTyp
 			}
 			break;
 		}
+		case DataLocation::CallData:
+			solAssert(
+					targetType.isByteArray() &&
+					typeOnStack.isByteArray() &&
+					typeOnStack.location() == DataLocation::CallData,
+				"Invalid conversion to calldata type.");
+			break;
 		default:
 			solAssert(
 				false,

libsolidity/Types.cpp

@@ -789,6 +789,21 @@ bool ArrayType::isImplicitlyConvertibleTo(const Type& _convertTo) const
 	}
 }
 
+bool ArrayType::isExplicitlyConvertibleTo(const Type& _convertTo) const
+{
+	if (isImplicitlyConvertibleTo(_convertTo))
+		return true;
+	// allow conversion bytes <-> string
+	if (_convertTo.getCategory() != getCategory())
+		return false;
+	auto& convertTo = dynamic_cast<ArrayType const&>(_convertTo);
+	if (convertTo.location() != location())
+		return false;
+	if (!isByteArray() || !convertTo.isByteArray())
+		return false;
+	return true;
+}
+
 bool ArrayType::operator==(Type const& _other) const
 {
 	if (_other.getCategory() != getCategory())

libsolidity/Types.h

@@ -477,6 +477,7 @@ public:
 	{}
 
 	virtual bool isImplicitlyConvertibleTo(Type const& _convertTo) const override;
+	virtual bool isExplicitlyConvertibleTo(Type const& _convertTo) const override;
 	virtual bool operator==(const Type& _other) const override;
 	virtual unsigned getCalldataEncodedSize(bool _padded) const override;
 	virtual bool isDynamicallySized() const override { return m_hasDynamicLength; }

test/libsolidity/SolidityEndToEndTest.cpp

@@ -5099,6 +5099,31 @@ BOOST_AUTO_TEST_CASE(memory_structs_with_mappings)
 	BOOST_CHECK(callContractFunction("f()") == encodeArgs(u256(0)));
 }
 
+BOOST_AUTO_TEST_CASE(string_bytes_conversion)
+{
+	char const* sourceCode = R"(
+		contract Test {
+			string s;
+			bytes b;
+			function f(string _s, uint n) returns (byte) {
+				b = bytes(_s);
+				s = string(b);
+				return bytes(s)[n];
+			}
+			function l() returns (uint) { return bytes(s).length; }
+		}
+	)";
+	compileAndRun(sourceCode, 0, "Test");
+	BOOST_CHECK(callContractFunction(
+		"f(string,uint256)",
+		u256(0x40),
+		u256(2),
+		u256(6),
+		string("abcdef")
+	) == encodeArgs("c"));
+	BOOST_CHECK(callContractFunction("l()") == encodeArgs(u256(6)));
+}
+
 BOOST_AUTO_TEST_CASE(string_as_mapping_key)
 {
 	char const* sourceCode = R"(

test/libsolidity/SolidityNameAndTypeResolution.cpp

@@ -2149,6 +2149,23 @@ BOOST_AUTO_TEST_CASE(memory_structs_with_mappings)
 	BOOST_CHECK_THROW(parseTextAndResolveNames(text), TypeError);
 }
 
+BOOST_AUTO_TEST_CASE(string_bytes_conversion)
+{
+	char const* text = R"(
+		contract Test {
+			string s;
+			bytes b;
+			function h(string _s) external { bytes(_s).length; }
+			function i(string _s) internal { bytes(_s).length; }
+			function j() internal { bytes(s).length; }
+			function k(bytes _b) external { string(_b); }
+			function l(bytes _b) internal { string(_b); }
+			function m() internal { string(b); }
+		}
+	)";
+	BOOST_CHECK_NO_THROW(parseTextAndResolveNames(text));
+}
+
 BOOST_AUTO_TEST_SUITE_END()
 
 }