Merge pull request #1673 from ethereum/structs

Returning structs

15 files changed, 894 insertions, 79 deletions

diff --git a/Changelog.md b/Changelog.md
index 0b9295d0..376494e0 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -5,6 +5,7 @@ Features:
  * Code Generator: Added ``.selector`` member on external function types to retrieve their signature.
  * Code Generator: Keep a single copy of encoding functions when using the experimental "ABIEncoderV2".
  * Optimizer: Add new optimization step to remove unused ``JUMPDEST``s.
+ * Code Generator: Support passing ``structs`` as arguments and return parameters (requires ``pragma experimental ABIEncoderV2`` for now).
  * Syntax Checker: Warn if no visibility is specified on contract functions.
  * Type Checker: Display helpful warning for unused function arguments/return parameters.
  * Type Checker: Do not show the same error multiple times for events.
diff --git a/docs/abi-spec.rst b/docs/abi-spec.rst
index f75a6885..97320c7f 100644
--- a/docs/abi-spec.rst
+++ b/docs/abi-spec.rst
@@ -68,13 +68,15 @@ The following non-fixed-size types exist:
 
 - ``<type>[]``: a variable-length array of the given fixed-length type.
 
-Types can be combined to anonymous structs by enclosing a finite non-negative number
+Types can be combined to a tuple by enclosing a finite non-negative number
 of them inside parentheses, separated by commas:
 
-- ``(T1,T2,...,Tn)``: anonymous struct (ordered tuple) consisting of the types ``T1``, ..., ``Tn``, ``n >= 0``
+- ``(T1,T2,...,Tn)``: tuple consisting of the types ``T1``, ..., ``Tn``, ``n >= 0``
 
-It is possible to form structs of structs, arrays of structs and so on.
+It is possible to form tuples of tuples, arrays of tuples and so on.
 
+.. note::
+    Solidity supports all the types presented above with the same names with the exception of tuples. The ABI tuple type is utilised for encoding Solidity ``structs``.
 
 Formal Specification of the Encoding
 ====================================
@@ -133,7 +135,7 @@ on the type of ``X`` being
 
   ``enc(X) = enc((X[0], ..., X[k-1]))``
   
-  i.e. it is encoded as if it were an anonymous struct with ``k`` elements
+  i.e. it is encoded as if it were a tuple with ``k`` elements
   of the same type.
   
 - ``T[]`` where ``X`` has ``k`` elements (``k`` is assumed to be of type ``uint256``):
@@ -176,7 +178,7 @@ and the return values ``v_1, ..., v_k`` of ``f`` are encoded as
 
   ``enc((v_1, ..., v_k))``
 
-i.e. the values are combined into an anonymous struct and encoded.
+i.e. the values are combined into a tuple and encoded.
 
 Examples
 ========
@@ -289,14 +291,16 @@ In effect, a log entry using this ABI is described as:
 JSON
 ====
 
-The JSON format for a contract's interface is given by an array of function and/or event descriptions. A function description is a JSON object with the fields:
+The JSON format for a contract's interface is given by an array of function and/or event descriptions.
+A function description is a JSON object with the fields:
 
 - ``type``: ``"function"``, ``"constructor"``, or ``"fallback"`` (the :ref:`unnamed "default" function <fallback-function>`);
 - ``name``: the name of the function;
 - ``inputs``: an array of objects, each of which contains:
 
   * ``name``: the name of the parameter;
-  * ``type``: the canonical type of the parameter.
+  * ``type``: the canonical type of the parameter (more below).
+  * ``components``: used for tuple types (more below).
 
 - ``outputs``: an array of objects similar to ``inputs``, can be omitted if function doesn't return anything;
 - ``payable``: ``true`` if function accepts ether, defaults to ``false``;
@@ -316,7 +320,8 @@ An event description is a JSON object with fairly similar fields:
 - ``inputs``: an array of objects, each of which contains:
 
   * ``name``: the name of the parameter;
-  * ``type``: the canonical type of the parameter.
+  * ``type``: the canonical type of the parameter (more below).
+  * ``components``: used for tuple types (more below).
   * ``indexed``: ``true`` if the field is part of the log's topics, ``false`` if it one of the log's data segment.
 
 - ``anonymous``: ``true`` if the event was declared as ``anonymous``.
@@ -353,3 +358,87 @@ would result in the JSON:
   "name":"foo",
   "outputs": []
   }]
+
+Handling tuple types
+--------------------
+
+Despite that names are intentionally not part of the ABI encoding they do make a lot of sense to be included
+in the JSON to enable displaying it to the end user. The structure is nested in the following way:
+
+An object with members ``name``, ``type`` and potentially ``components`` describes a typed variable.
+The canonical type is determined until a tuple type is reached and the string description up
+to that point is stored in ``type`` prefix with the word ``tuple``, i.e. it will be ``tuple`` followed by
+a sequence of ``[]`` and ``[k]`` with
+integers ``k``. The components of the tuple are then stored in the member ``components``,
+which is of array type and has the same structure as the top-level object except that
+``indexed`` is not allowed there.
+
+As an example, the code
+
+::
+
+  contract Test {
+    struct S { uint a; uint[] b; T[] c; }
+    struct T { uint x; uint y; }
+    function f(S s, T t, uint a) { }
+  }
+
+would result in the JSON:
+
+.. code:: json
+
+  [
+    {
+      "name": "f",
+      "type": "function",
+      "inputs": [
+        {
+          "name": "s",
+          "type": "tuple",
+          "components": [
+            {
+              "name": "a",
+              "type": "uint256"
+            },
+            {
+              "name": "b",
+              "type": "uint256[]"
+            },
+            {
+              "name": "c",
+              "type": "tuple[]",
+              "components": [
+                {
+                  "name": "x",
+                  "type": "uint256"
+                },
+                {
+                  "name": "y",
+                  "type": "uint256"
+                }
+              ]
+            }
+          ]
+        },
+        {
+          "name": "t",
+          "type": "tuple",
+          "components": [
+            {
+              "name": "x",
+              "type": "uint256"
+            },
+            {
+              "name": "y",
+              "type": "uint256"
+            }
+          ]
+        },
+        {
+          "name": "a",
+          "type": "uint256"
+        }
+      ],
+      "outputs": []
+    }
+  ]
diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index 26529c22..fe4207a3 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -546,7 +546,7 @@ bool TypeChecker::visit(FunctionDefinition const& _function)
 		if (!type(*var)->canLiveOutsideStorage())
 			m_errorReporter.typeError(var->location(), "Type is required to live outside storage.");
 		if (_function.visibility() >= FunctionDefinition::Visibility::Public && !(type(*var)->interfaceType(isLibraryFunction)))
-			m_errorReporter.fatalTypeError(var->location(), "Internal type is not allowed for public or external functions.");
+			m_errorReporter.fatalTypeError(var->location(), "Internal or recursive type is not allowed for public or external functions.");
 
 		var->accept(*this);
 	}
@@ -641,7 +641,7 @@ bool TypeChecker::visit(VariableDeclaration const& _variable)
 		_variable.visibility() >= VariableDeclaration::Visibility::Public &&
 		!FunctionType(_variable).interfaceFunctionType()
 	)
-		m_errorReporter.typeError(_variable.location(), "Internal type is not allowed for public state variables.");
+		m_errorReporter.typeError(_variable.location(), "Internal or recursive type is not allowed for public state variables.");
 
 	if (varType->category() == Type::Category::Array)
 		if (auto arrayType = dynamic_cast<ArrayType const*>(varType.get()))
@@ -728,7 +728,7 @@ bool TypeChecker::visit(EventDefinition const& _eventDef)
 		if (!type(*var)->canLiveOutsideStorage())
 			m_errorReporter.typeError(var->location(), "Type is required to live outside storage.");
 		if (!type(*var)->interfaceType(false))
-			m_errorReporter.typeError(var->location(), "Internal type is not allowed as event parameter type.");
+			m_errorReporter.typeError(var->location(), "Internal or recursive type is not allowed as event parameter type.");
 	}
 	if (_eventDef.isAnonymous() && numIndexed > 4)
 		m_errorReporter.typeError(_eventDef.location(), "More than 4 indexed arguments for anonymous event.");
diff --git a/libsolidity/ast/Types.cpp b/libsolidity/ast/Types.cpp
index 705d0f7f..83a5b465 100644
--- a/libsolidity/ast/Types.cpp
+++ b/libsolidity/ast/Types.cpp
@@ -33,6 +33,7 @@
 #include <boost/algorithm/string/replace.hpp>
 #include <boost/algorithm/string/predicate.hpp>
 #include <boost/range/adaptor/reversed.hpp>
+#include <boost/range/algorithm/copy.hpp>
 #include <boost/range/adaptor/sliced.hpp>
 #include <boost/range/adaptor/transformed.hpp>
 
@@ -1470,7 +1471,7 @@ string ArrayType::toString(bool _short) const
 	return ret;
 }
 
-string ArrayType::canonicalName(bool _addDataLocation) const
+string ArrayType::canonicalName() const
 {
 	string ret;
 	if (isString())
@@ -1479,16 +1480,29 @@ string ArrayType::canonicalName(bool _addDataLocation) const
 		ret = "bytes";
 	else
 	{
-		ret = baseType()->canonicalName(false) + "[";
+		ret = baseType()->canonicalName() + "[";
 		if (!isDynamicallySized())
 			ret += length().str();
 		ret += "]";
 	}
-	if (_addDataLocation && location() == DataLocation::Storage)
-		ret += " storage";
 	return ret;
 }
 
+string ArrayType::signatureInExternalFunction(bool _structsByName) const
+{
+	if (isByteArray())
+		return canonicalName();
+	else
+	{
+		solAssert(baseType(), "");
+		return
+			baseType()->signatureInExternalFunction(_structsByName) +
+			"[" +
+			(isDynamicallySized() ? "" : length().str()) +
+			"]";
+	}
+}
+
 MemberList::MemberMap ArrayType::nativeMembers(ContractDefinition const*) const
 {
 	MemberList::MemberMap members;
@@ -1597,7 +1611,7 @@ string ContractType::toString(bool) const
 		m_contract.name();
 }
 
-string ContractType::canonicalName(bool) const
+string ContractType::canonicalName() const
 {
 	return m_contract.annotation().canonicalName;
 }
@@ -1721,15 +1735,22 @@ unsigned StructType::calldataEncodedSize(bool _padded) const
 
 bool StructType::isDynamicallyEncoded() const
 {
-	solAssert(false, "Structs are not yet supported in the ABI.");
+	solAssert(!recursive(), "");
+	for (auto t: memoryMemberTypes())
+	{
+		solAssert(t, "Parameter should have external type.");
+		t = t->interfaceType(false);
+		if (t->isDynamicallyEncoded())
+			return true;
+	}
+	return false;
 }
 
 u256 StructType::memorySize() const
 {
 	u256 size;
-	for (auto const& member: members(nullptr))
-		if (member.type->canLiveOutsideStorage())
-			size += member.type->memoryHeadSize();
+	for (auto const& t: memoryMemberTypes())
+		size += t->memoryHeadSize();
 	return size;
 }
 
@@ -1767,10 +1788,33 @@ MemberList::MemberMap StructType::nativeMembers(ContractDefinition const*) const
 
 TypePointer StructType::interfaceType(bool _inLibrary) const
 {
+	if (!canBeUsedExternally(_inLibrary))
+		return TypePointer();
+
+	// Has to fulfill canBeUsedExternally(_inLibrary) == !!interfaceType(_inLibrary)
 	if (_inLibrary && location() == DataLocation::Storage)
 		return shared_from_this();
 	else
-		return TypePointer();
+		return copyForLocation(DataLocation::Memory, true);
+}
+
+bool StructType::canBeUsedExternally(bool _inLibrary) const
+{
+	if (_inLibrary && location() == DataLocation::Storage)
+		return true;
+	else if (recursive())
+		return false;
+	else
+	{
+		// Check that all members have interface types.
+		// We pass "false" to canBeUsedExternally (_inLibrary), because this struct will be
+		// passed by value and thus the encoding does not differ, but it will disallow
+		// mappings.
+		for (auto const& var: m_struct.members())
+			if (!var->annotation().type->canBeUsedExternally(false))
+				return false;
+	}
+	return true;
 }
 
 TypePointer StructType::copyForLocation(DataLocation _location, bool _isPointer) const
@@ -1780,12 +1824,27 @@ TypePointer StructType::copyForLocation(DataLocation _location, bool _isPointer)
 	return copy;
 }
 
-string StructType::canonicalName(bool _addDataLocation) const
+string StructType::signatureInExternalFunction(bool _structsByName) const
 {
-	string ret = m_struct.annotation().canonicalName;
-	if (_addDataLocation && location() == DataLocation::Storage)
-		ret += " storage";
-	return ret;
+	if (_structsByName)
+		return canonicalName();
+	else
+	{
+		TypePointers memberTypes = memoryMemberTypes();
+		auto memberTypeStrings = memberTypes | boost::adaptors::transformed([&](TypePointer _t) -> string
+		{
+			solAssert(_t, "Parameter should have external type.");
+			auto t = _t->interfaceType(_structsByName);
+			solAssert(t, "");
+			return t->signatureInExternalFunction(_structsByName);
+		});
+		return "(" + boost::algorithm::join(memberTypeStrings, ",") + ")";
+	}
+}
+
+string StructType::canonicalName() const
+{
+	return m_struct.annotation().canonicalName;
 }
 
 FunctionTypePointer StructType::constructorType() const
@@ -1827,6 +1886,15 @@ u256 StructType::memoryOffsetOfMember(string const& _name) const
 	return 0;
 }
 
+TypePointers StructType::memoryMemberTypes() const
+{
+	TypePointers types;
+	for (ASTPointer<VariableDeclaration> const& variable: m_struct.members())
+		if (variable->annotation().type->canLiveOutsideStorage())
+			types.push_back(variable->annotation().type);
+	return types;
+}
+
 set<string> StructType::membersMissingInMemory() const
 {
 	set<string> missing;
@@ -1836,6 +1904,33 @@ set<string> StructType::membersMissingInMemory() const
 	return missing;
 }
 
+bool StructType::recursive() const
+{
+	if (!m_recursive.is_initialized())
+	{
+		set<StructDefinition const*> structsSeen;
+		function<bool(StructType const*)> check = [&](StructType const* t) -> bool
+		{
+			StructDefinition const* str = &t->structDefinition();
+			if (structsSeen.count(str))
+				return true;
+			structsSeen.insert(str);
+			for (ASTPointer<VariableDeclaration> const& variable: str->members())
+			{
+				Type const* memberType = variable->annotation().type.get();
+				while (dynamic_cast<ArrayType const*>(memberType))
+					memberType = dynamic_cast<ArrayType const*>(memberType)->baseType().get();
+				if (StructType const* innerStruct = dynamic_cast<StructType const*>(memberType))
+					if (check(innerStruct))
+						return true;
+			}
+			return false;
+		};
+		m_recursive = check(this);
+	}
+	return *m_recursive;
+}
+
 TypePointer EnumType::unaryOperatorResult(Token::Value _operator) const
 {
 	return _operator == Token::Delete ? make_shared<TupleType>() : TypePointer();
@@ -1868,7 +1963,7 @@ string EnumType::toString(bool) const
 	return string("enum ") + m_enum.annotation().canonicalName;
 }
 
-string EnumType::canonicalName(bool) const
+string EnumType::canonicalName() const
 {
 	return m_enum.annotation().canonicalName;
 }
@@ -2295,7 +2390,7 @@ TypePointer FunctionType::binaryOperatorResult(Token::Value _operator, TypePoint
 	return TypePointer();
 }
 
-string FunctionType::canonicalName(bool) const
+string FunctionType::canonicalName() const
 {
 	solAssert(m_kind == Kind::External, "");
 	return "function";
@@ -2555,20 +2650,19 @@ string FunctionType::externalSignature() const
 	solAssert(m_declaration != nullptr, "External signature of function needs declaration");
 	solAssert(!m_declaration->name().empty(), "Fallback function has no signature.");
 
-	bool _inLibrary = dynamic_cast<ContractDefinition const&>(*m_declaration->scope()).isLibrary();
-
-	string ret = m_declaration->name() + "(";
-
+	bool const inLibrary = dynamic_cast<ContractDefinition const&>(*m_declaration->scope()).isLibrary();
 	FunctionTypePointer external = interfaceFunctionType();
 	solAssert(!!external, "External function type requested.");
-	TypePointers externalParameterTypes = external->parameterTypes();
-	for (auto it = externalParameterTypes.cbegin(); it != externalParameterTypes.cend(); ++it)
+	auto parameterTypes = external->parameterTypes();
+	auto typeStrings = parameterTypes | boost::adaptors::transformed([&](TypePointer _t) -> string
 	{
-		solAssert(!!(*it), "Parameter should have external type");
-		ret += (*it)->canonicalName(_inLibrary) + (it + 1 == externalParameterTypes.cend() ? "" : ",");
-	}
-
-	return ret + ")";
+		solAssert(_t, "Parameter should have external type.");
+		string typeName = _t->signatureInExternalFunction(inLibrary);
+		if (inLibrary && _t->dataStoredIn(DataLocation::Storage))
+			typeName += " storage";
+		return typeName;
+	});
+	return m_declaration->name() + "(" + boost::algorithm::join(typeStrings, ",") + ")";
 }
 
 u256 FunctionType::externalIdentifier() const
@@ -2699,9 +2793,9 @@ string MappingType::toString(bool _short) const
 	return "mapping(" + keyType()->toString(_short) + " => " + valueType()->toString(_short) + ")";
 }
 
-string MappingType::canonicalName(bool) const
+string MappingType::canonicalName() const
 {
-	return "mapping(" + keyType()->canonicalName(false) + " => " + valueType()->canonicalName(false) + ")";
+	return "mapping(" + keyType()->canonicalName() + " => " + valueType()->canonicalName() + ")";
 }
 
 string TypeType::identifier() const
diff --git a/libsolidity/ast/Types.h b/libsolidity/ast/Types.h
index d4d6da69..8ba55521 100644
--- a/libsolidity/ast/Types.h
+++ b/libsolidity/ast/Types.h
@@ -32,6 +32,7 @@
 
 #include <boost/noncopyable.hpp>
 #include <boost/rational.hpp>
+#include <boost/optional.hpp>
 
 #include <memory>
 #include <string>
@@ -245,9 +246,15 @@ public:
 
 	virtual std::string toString(bool _short) const = 0;
 	std::string toString() const { return toString(false); }
-	/// @returns the canonical name of this type for use in function signatures.
-	/// @param _addDataLocation if true, includes data location for reference types if it is "storage".
-	virtual std::string canonicalName(bool /*_addDataLocation*/) const { return toString(true); }
+	/// @returns the canonical name of this type for use in library function signatures.
+	virtual std::string canonicalName() const { return toString(true); }
+	/// @returns the signature of this type in external functions, i.e. `uint256` for integers
+	/// or `(uint256,bytes8)[2]` for an array of structs. If @a _structsByName,
+	/// structs are given by canonical name like `ContractName.StructName[2]`.
+	virtual std::string signatureInExternalFunction(bool /*_structsByName*/) const
+	{
+		return canonicalName();
+	}
 	virtual u256 literalValue(Literal const*) const
 	{
 		solAssert(false, "Literal value requested for type without literals.");
@@ -619,7 +626,8 @@ public:
 	virtual bool canLiveOutsideStorage() const override { return m_baseType->canLiveOutsideStorage(); }
 	virtual unsigned sizeOnStack() const override;
 	virtual std::string toString(bool _short) const override;
-	virtual std::string canonicalName(bool _addDataLocation) const override;
+	virtual std::string canonicalName() const override;
+	virtual std::string signatureInExternalFunction(bool _structsByName) const override;
 	virtual MemberList::MemberMap nativeMembers(ContractDefinition const* _currentScope) const override;
 	virtual TypePointer encodingType() const override;
 	virtual TypePointer decodingType() const override;
@@ -677,7 +685,7 @@ public:
 	virtual unsigned sizeOnStack() const override { return m_super ? 0 : 1; }
 	virtual bool isValueType() const override { return true; }
 	virtual std::string toString(bool _short) const override;
-	virtual std::string canonicalName(bool _addDataLocation) const override;
+	virtual std::string canonicalName() const override;
 
 	virtual MemberList::MemberMap nativeMembers(ContractDefinition const* _currentScope) const override;
 	virtual TypePointer encodingType() const override
@@ -738,13 +746,15 @@ public:
 	virtual MemberList::MemberMap nativeMembers(ContractDefinition const* _currentScope) const override;
 	virtual TypePointer encodingType() const override
 	{
-		return location() == DataLocation::Storage ? std::make_shared<IntegerType>(256) : TypePointer();
+		return location() == DataLocation::Storage ? std::make_shared<IntegerType>(256) : shared_from_this();
 	}
 	virtual TypePointer interfaceType(bool _inLibrary) const override;
+	virtual bool canBeUsedExternally(bool _inLibrary) const override;
 
 	TypePointer copyForLocation(DataLocation _location, bool _isPointer) const override;
 
-	virtual std::string canonicalName(bool _addDataLocation) const override;
+	virtual std::string canonicalName() const override;
+	virtual std::string signatureInExternalFunction(bool _structsByName) const override;
 
 	/// @returns a function that peforms the type conversion between a list of struct members
 	/// and a memory struct of this type.
@@ -755,11 +765,19 @@ public:
 
 	StructDefinition const& structDefinition() const { return m_struct; }
 
+	/// @returns the vector of types of members available in memory.
+	TypePointers memoryMemberTypes() const;
 	/// @returns the set of all members that are removed in the memory version (typically mappings).
 	std::set<std::string> membersMissingInMemory() const;
 
+	/// @returns true if the same struct is used recursively in one of its members. Only
+	/// analyses the "memory" representation, i.e. mappings are ignored in all structs.
+	bool recursive() const;
+
 private:
 	StructDefinition const& m_struct;
+	/// Cache for the recursive() function.
+	mutable boost::optional<bool> m_recursive;
 };
 
 /**
@@ -780,7 +798,7 @@ public:
 	virtual unsigned storageBytes() const override;
 	virtual bool canLiveOutsideStorage() const override { return true; }
 	virtual std::string toString(bool _short) const override;
-	virtual std::string canonicalName(bool _addDataLocation) const override;
+	virtual std::string canonicalName() const override;
 	virtual bool isValueType() const override { return true; }
 
 	virtual bool isExplicitlyConvertibleTo(Type const& _convertTo) const override;
@@ -951,7 +969,7 @@ public:
 	virtual bool isExplicitlyConvertibleTo(Type const& _convertTo) const override;
 	virtual TypePointer unaryOperatorResult(Token::Value _operator) const override;
 	virtual TypePointer binaryOperatorResult(Token::Value, TypePointer const&) const override;
-	virtual std::string canonicalName(bool /*_addDataLocation*/) const override;
+	virtual std::string canonicalName() const override;
 	virtual std::string toString(bool _short) const override;
 	virtual unsigned calldataEncodedSize(bool _padded) const override;
 	virtual bool canBeStored() const override { return m_kind == Kind::Internal || m_kind == Kind::External; }
@@ -1053,7 +1071,7 @@ public:
 	virtual std::string identifier() const override;
 	virtual bool operator==(Type const& _other) const override;
 	virtual std::string toString(bool _short) const override;
-	virtual std::string canonicalName(bool _addDataLocation) const override;
+	virtual std::string canonicalName() const override;
 	virtual bool canLiveOutsideStorage() const override { return false; }
 	virtual TypePointer binaryOperatorResult(Token::Value, TypePointer const&) const override { return TypePointer(); }
 	virtual TypePointer encodingType() const override
diff --git a/libsolidity/codegen/ABIFunctions.cpp b/libsolidity/codegen/ABIFunctions.cpp
index 3a9f1a48..9f6c55ba 100644
--- a/libsolidity/codegen/ABIFunctions.cpp
+++ b/libsolidity/codegen/ABIFunctions.cpp
@@ -404,9 +404,11 @@ string ABIFunctions::abiEncodingFunction(
 		else
 			solAssert(false, "");
 	}
-	else if (dynamic_cast<StructType const*>(&to))
+	else if (auto const* toStruct = dynamic_cast<StructType const*>(&to))
 	{
-		solUnimplementedAssert(false, "Structs not yet implemented.");
+		StructType const* fromStruct = dynamic_cast<StructType const*>(&_from);
+		solAssert(fromStruct, "");
+		return abiEncodingFunctionStruct(*fromStruct, *toStruct, _encodeAsLibraryTypes);
 	}
 	else if (_from.category() == Type::Category::Function)
 		return abiEncodingFunctionFunctionType(
@@ -534,7 +536,7 @@ string ABIFunctions::abiEncodingFunctionSimpleArray(
 					for { let i := 0 } lt(i, length) { i := add(i, 1) }
 					{
 						mstore(pos, sub(tail, headStart))
-						tail := <encodeToMemoryFun>(<arrayElementAccess>(srcPtr), tail)
+						tail := <encodeToMemoryFun>(<arrayElementAccess>, tail)
 						srcPtr := <nextArrayElement>(srcPtr)
 						pos := add(pos, <elementEncodedSize>)
 					}
@@ -549,7 +551,7 @@ string ABIFunctions::abiEncodingFunctionSimpleArray(
 					let srcPtr := <dataAreaFun>(value)
 					for { let i := 0 } lt(i, length) { i := add(i, 1) }
 					{
-						<encodeToMemoryFun>(<arrayElementAccess>(srcPtr), pos)
+						<encodeToMemoryFun>(<arrayElementAccess>, pos)
 						srcPtr := <nextArrayElement>(srcPtr)
 						pos := add(pos, <elementEncodedSize>)
 					}
@@ -573,7 +575,7 @@ string ABIFunctions::abiEncodingFunctionSimpleArray(
 			_encodeAsLibraryTypes,
 			true
 		));
-		templ("arrayElementAccess", inMemory ? "mload" : "sload");
+		templ("arrayElementAccess", inMemory ? "mload(srcPtr)" : _from.baseType()->isValueType() ? "sload(srcPtr)" : "srcPtr" );
 		templ("nextArrayElement", nextArrayElementFunction(_from));
 		return templ.render();
 	});
@@ -726,6 +728,122 @@ string ABIFunctions::abiEncodingFunctionCompactStorageArray(
 	});
 }
 
+string ABIFunctions::abiEncodingFunctionStruct(
+	StructType const& _from,
+	StructType const& _to,
+	bool _encodeAsLibraryTypes
+)
+{
+	string functionName =
+		"abi_encode_" +
+		_from.identifier() +
+		"_to_" +
+		_to.identifier() +
+		(_encodeAsLibraryTypes ? "_library" : "");
+
+	solUnimplementedAssert(!_from.dataStoredIn(DataLocation::CallData), "");
+	solAssert(&_from.structDefinition() == &_to.structDefinition(), "");
+
+	return createFunction(functionName, [&]() {
+		bool fromStorage = _from.location() == DataLocation::Storage;
+		bool dynamic = _to.isDynamicallyEncoded();
+		Whiskers templ(R"(
+			function <functionName>(value, pos) <return> {
+				let tail := add(pos, <headSize>)
+				<init>
+				<#members>
+				{
+					// <memberName>
+					<encode>
+				}
+				</members>
+				<assignEnd>
+			}
+		)");
+		templ("functionName", functionName);
+		templ("return", dynamic ? " -> end " : "");
+		templ("assignEnd", dynamic ? "end := tail" : "");
+		// to avoid multiple loads from the same slot for subsequent members
+		templ("init", fromStorage ? "let slotValue := 0" : "");
+		u256 previousSlotOffset(-1);
+		u256 encodingOffset = 0;
+		vector<map<string, string>> members;
+		for (auto const& member: _to.members(nullptr))
+		{
+			solAssert(member.type, "");
+			if (!member.type->canLiveOutsideStorage())
+				continue;
+			solUnimplementedAssert(
+				member.type->mobileType() &&
+				member.type->mobileType()->interfaceType(_encodeAsLibraryTypes) &&
+				member.type->mobileType()->interfaceType(_encodeAsLibraryTypes)->encodingType(),
+				"Encoding type \"" + member.type->toString() + "\" not yet implemented."
+			);
+			auto memberTypeTo = member.type->mobileType()->interfaceType(_encodeAsLibraryTypes)->encodingType();
+			auto memberTypeFrom = _from.memberType(member.name);
+			solAssert(memberTypeFrom, "");
+			bool dynamicMember = memberTypeTo->isDynamicallyEncoded();
+			if (dynamicMember)
+				solAssert(dynamic, "");
+			Whiskers memberTempl(R"(
+				<preprocess>
+				let memberValue := <retrieveValue>
+				)" + (
+					dynamicMember ?
+					string(R"(
+						mstore(add(pos, <encodingOffset>), sub(tail, pos))
+						tail := <abiEncode>(memberValue, tail)
+					)") :
+					string(R"(
+						<abiEncode>(memberValue, add(pos, <encodingOffset>))
+					)")
+				)
+			);
+			if (fromStorage)
+			{
+				solAssert(memberTypeFrom->isValueType() == memberTypeTo->isValueType(), "");
+				u256 storageSlotOffset;
+				size_t intraSlotOffset;
+				tie(storageSlotOffset, intraSlotOffset) = _from.storageOffsetsOfMember(member.name);
+				if (memberTypeFrom->isValueType())
+				{
+					if (storageSlotOffset != previousSlotOffset)
+					{
+						memberTempl("preprocess", "slotValue := sload(add(value, " + toCompactHexWithPrefix(storageSlotOffset) + "))");
+						previousSlotOffset = storageSlotOffset;
+					}
+					else
+						memberTempl("preprocess", "");
+					memberTempl("retrieveValue", shiftRightFunction(intraSlotOffset * 8, false) + "(slotValue)");
+				}
+				else
+				{
+					solAssert(memberTypeFrom->dataStoredIn(DataLocation::Storage), "");
+					solAssert(intraSlotOffset == 0, "");
+					memberTempl("preprocess", "");
+					memberTempl("retrieveValue", "add(value, " + toCompactHexWithPrefix(storageSlotOffset) + ")");
+				}
+			}
+			else
+			{
+				memberTempl("preprocess", "");
+				string sourceOffset = toCompactHexWithPrefix(_from.memoryOffsetOfMember(member.name));
+				memberTempl("retrieveValue", "mload(add(value, " + sourceOffset + "))");
+			}
+			memberTempl("encodingOffset", toCompactHexWithPrefix(encodingOffset));
+			encodingOffset += dynamicMember ? 0x20 : memberTypeTo->calldataEncodedSize();
+			memberTempl("abiEncode", abiEncodingFunction(*memberTypeFrom, *memberTypeTo, _encodeAsLibraryTypes, false));
+
+			members.push_back({});
+			members.back()["encode"] = memberTempl.render();
+			members.back()["memberName"] = member.name;
+		}
+		templ("members", members);
+		templ("headSize", toCompactHexWithPrefix(encodingOffset));
+		return templ.render();
+	});
+}
+
 string ABIFunctions::abiEncodingFunctionStringLiteral(
 	Type const& _from,
 	Type const& _to,
diff --git a/libsolidity/codegen/ABIFunctions.h b/libsolidity/codegen/ABIFunctions.h
index 5bbd842f..de2a140a 100644
--- a/libsolidity/codegen/ABIFunctions.h
+++ b/libsolidity/codegen/ABIFunctions.h
@@ -123,6 +123,13 @@ private:
 		bool _encodeAsLibraryTypes
 	);
 
+	/// Part of @a abiEncodingFunction for struct types.
+	std::string abiEncodingFunctionStruct(
+		StructType const& _givenType,
+		StructType const& _targetType,
+		bool _encodeAsLibraryTypes
+	);
+
 	// @returns the name of the ABI encoding function with the given type
 	// and queues the generation of the function to the requested functions.
 	// Case for _givenType being a string literal
diff --git a/libsolidity/codegen/CompilerUtils.cpp b/libsolidity/codegen/CompilerUtils.cpp
index 1e623357..37aa1aea 100644
--- a/libsolidity/codegen/CompilerUtils.cpp
+++ b/libsolidity/codegen/CompilerUtils.cpp
@@ -121,7 +121,7 @@ void CompilerUtils::storeInMemoryDynamic(Type const& _type, bool _padToWordBound
 {
 	if (auto ref = dynamic_cast<ReferenceType const*>(&_type))
 	{
-		solAssert(ref->location() == DataLocation::Memory, "");
+		solUnimplementedAssert(ref->location() == DataLocation::Memory, "");
 		storeInMemoryDynamic(IntegerType(256), _padToWordBoundaries);
 	}
 	else if (auto str = dynamic_cast<StringLiteralType const*>(&_type))
diff --git a/libsolidity/codegen/ContractCompiler.cpp b/libsolidity/codegen/ContractCompiler.cpp
index 51496368..92782b8d 100644
--- a/libsolidity/codegen/ContractCompiler.cpp
+++ b/libsolidity/codegen/ContractCompiler.cpp
@@ -333,7 +333,7 @@ void ContractCompiler::appendCalldataUnpacker(TypePointers const& _typeParameter
 	{
 		// stack: v1 v2 ... v(k-1) base_offset current_offset
 		TypePointer type = parameterType->decodingType();
-		solAssert(type, "No decoding type found.");
+		solUnimplementedAssert(type, "No decoding type found.");
 		if (type->category() == Type::Category::Array)
 		{
 			auto const& arrayType = dynamic_cast<ArrayType const&>(*type);
diff --git a/libsolidity/interface/ABI.cpp b/libsolidity/interface/ABI.cpp
index 49df843d..aefb34af 100644
--- a/libsolidity/interface/ABI.cpp
+++ b/libsolidity/interface/ABI.cpp
@@ -86,12 +86,12 @@ Json::Value ABI::generate(ContractDefinition const& _contractDef)
 		Json::Value params(Json::arrayValue);
 		for (auto const& p: it->parameters())
 		{
-			solAssert(!!p->annotation().type->interfaceType(false), "");
+			auto type = p->annotation().type->interfaceType(false);
+			solAssert(type, "");
 			Json::Value input;
-			input["name"] = p->name();
-			input["type"] = p->annotation().type->interfaceType(false)->canonicalName(false);
-			input["indexed"] = p->isIndexed();
-			params.append(input);
+			auto param = formatType(p->name(), *type, false);
+			param["indexed"] = p->isIndexed();
+			params.append(param);
 		}
 		event["inputs"] = params;
 		abi.append(event);
@@ -111,10 +111,53 @@ Json::Value ABI::formatTypeList(
 	for (unsigned i = 0; i < _names.size(); ++i)
 	{
 		solAssert(_types[i], "");
-		Json::Value param;
-		param["name"] = _names[i];
-		param["type"] = _types[i]->canonicalName(_forLibrary);
-		params.append(param);
+		params.append(formatType(_names[i], *_types[i], _forLibrary));
 	}
 	return params;
 }
+
+Json::Value ABI::formatType(string const& _name, Type const& _type, bool _forLibrary)
+{
+	Json::Value ret;
+	ret["name"] = _name;
+	string suffix = (_forLibrary && _type.dataStoredIn(DataLocation::Storage)) ? " storage" : "";
+	if (_type.isValueType() || (_forLibrary && _type.dataStoredIn(DataLocation::Storage)))
+		ret["type"] = _type.canonicalName() + suffix;
+	else if (ArrayType const* arrayType = dynamic_cast<ArrayType const*>(&_type))
+	{
+		if (arrayType->isByteArray())
+			ret["type"] = _type.canonicalName() + suffix;
+		else
+		{
+			string suffix;
+			if (arrayType->isDynamicallySized())
+				suffix = "[]";
+			else
+				suffix = string("[") + arrayType->length().str() + "]";
+			solAssert(arrayType->baseType(), "");
+			Json::Value subtype = formatType("", *arrayType->baseType(), _forLibrary);
+			if (subtype.isMember("components"))
+			{
+				ret["type"] = subtype["type"].asString() + suffix;
+				ret["components"] = subtype["components"];
+			}
+			else
+				ret["type"] = subtype["type"].asString() + suffix;
+		}
+	}
+	else if (StructType const* structType = dynamic_cast<StructType const*>(&_type))
+	{
+		ret["type"] = "tuple";
+		ret["components"] = Json::arrayValue;
+		for (auto const& member: structType->members(nullptr))
+		{
+			solAssert(member.type, "");
+			auto t = member.type->interfaceType(_forLibrary);
+			solAssert(t, "");
+			ret["components"].append(formatType(member.name, *t, _forLibrary));
+		}
+	}
+	else
+		solAssert(false, "Invalid type.");
+	return ret;
+}
diff --git a/libsolidity/interface/ABI.h b/libsolidity/interface/ABI.h
index 95b162a9..db70729d 100644
--- a/libsolidity/interface/ABI.h
+++ b/libsolidity/interface/ABI.h
@@ -50,6 +50,10 @@ private:
 		std::vector<TypePointer> const& _types,
 		bool _forLibrary
 	);
+	/// @returns a Json object with "name", "type" and potentially "components" keys, according
+	/// to the ABI specification.
+	/// If it is possible to express the type as a single string, it is allowed to return a single string.
+	static Json::Value formatType(std::string const& _name, Type const& _type, bool _forLibrary);
 };
 
 }
diff --git a/test/libsolidity/ABIEncoderTests.cpp b/test/libsolidity/ABIEncoderTests.cpp
index 4ddf17ce..05158601 100644
--- a/test/libsolidity/ABIEncoderTests.cpp
+++ b/test/libsolidity/ABIEncoderTests.cpp
@@ -424,7 +424,43 @@ BOOST_AUTO_TEST_CASE(function_name_collision)
 	)
 }
 
+BOOST_AUTO_TEST_CASE(structs)
+{
+	string sourceCode = R"(
+		contract C {
+			struct S { uint16 a; uint16 b; T[] sub; uint16 c; }
+			struct T { uint64[2] x; }
+			S s;
+			event e(uint16, S);
+			function f() returns (uint, S) {
+				uint16 x = 7;
+				s.a = 8;
+				s.b = 9;
+				s.c = 10;
+				s.sub.length = 3;
+				s.sub[0].x[0] = 11;
+				s.sub[1].x[0] = 12;
+				s.sub[2].x[1] = 13;
+				e(x, s);
+				return (x, s);
+			}
+		}
+	)";
 
+	NEW_ENCODER(
+		compileAndRun(sourceCode, 0, "C");
+		bytes encoded = encodeArgs(
+			u256(7), 0x40,
+			8, 9, 0x80, 10,
+			3,
+			11, 0,
+			12, 0,
+			0, 13
+		);
+		BOOST_CHECK(callContractFunction("f()") == encoded);
+		REQUIRE_LOG_DATA(encoded);
+	)
+}
 
 BOOST_AUTO_TEST_SUITE_END()
 
diff --git a/test/libsolidity/SolidityABIJSON.cpp b/test/libsolidity/SolidityABIJSON.cpp
index 4b9223de..e5d9e99c 100644
--- a/test/libsolidity/SolidityABIJSON.cpp
+++ b/test/libsolidity/SolidityABIJSON.cpp
@@ -48,7 +48,7 @@ public:
 
 		Json::Value generatedInterface = m_compilerStack.contractABI("");
 		Json::Value expectedInterface;
-		m_reader.parse(_expectedInterfaceString, expectedInterface);
+		BOOST_REQUIRE(m_reader.parse(_expectedInterfaceString, expectedInterface));
 		BOOST_CHECK_MESSAGE(
 			expectedInterface == generatedInterface,
 			"Expected:\n" << expectedInterface.toStyledString() <<
@@ -939,6 +939,217 @@ BOOST_AUTO_TEST_CASE(function_type)
 	checkInterface(sourceCode, interface);
 }
 
+BOOST_AUTO_TEST_CASE(return_structs)
+{
+	char const* text = R"(
+		contract C {
+			struct S { uint a; T[] sub; }
+			struct T { uint[2] x; }
+			function f() returns (uint x, S s) {
+			}
+		}
+	)";
+	char const* interface = R"(
+	[{
+		"constant" : false,
+		"inputs" : [],
+		"name" : "f",
+		"outputs" : [
+			{
+			"name" : "x",
+			"type" : "uint256"
+			},
+			{
+			"components" : [
+				{
+					"name" : "a",
+					"type" : "uint256"
+				},
+				{
+					"components" : [
+						{
+						"name" : "x",
+						"type" : "uint256[2]"
+						}
+					],
+					"name" : "sub",
+					"type" : "tuple[]"
+				}
+			],
+			"name" : "s",
+			"type" : "tuple"
+			}
+		],
+		"payable" : false,
+		"stateMutability" : "nonpayable",
+		"type" : "function"
+	}]
+	)";
+	checkInterface(text, interface);
+}
+
+BOOST_AUTO_TEST_CASE(return_structs_with_contracts)
+{
+	char const* text = R"(
+		contract C {
+			struct S { C[] x; C y; }
+			function f() returns (S s, C c) {
+			}
+		}
+	)";
+	char const* interface = R"(
+	[{
+		"constant": false,
+		"inputs": [],
+		"name": "f",
+		"outputs": [
+			{
+				"components": [
+					{
+						"name": "x",
+						"type": "address[]"
+					},
+					{
+						"name": "y",
+						"type": "address"
+					}
+				],
+				"name": "s",
+				"type": "tuple"
+			},
+			{
+				"name": "c",
+				"type": "address"
+			}
+		],
+		"payable": false,
+		"stateMutability" : "nonpayable",
+		"type": "function"
+	}]
+	)";
+	checkInterface(text, interface);
+}
+
+BOOST_AUTO_TEST_CASE(event_structs)
+{
+	char const* text = R"(
+		contract C {
+			struct S { uint a; T[] sub; bytes b; }
+			struct T { uint[2] x; }
+			event E(T t, S s);
+		}
+	)";
+	char const *interface = R"(
+		[{
+		"anonymous": false,
+		"inputs": [
+			{
+				"components": [
+					{
+						"name": "x",
+						"type": "uint256[2]"
+					}
+				],
+				"indexed": false,
+				"name": "t",
+				"type": "tuple"
+			},
+			{
+				"components": [
+					{
+						"name": "a",
+						"type": "uint256"
+					},
+					{
+						"components": [
+							{
+								"name": "x",
+								"type": "uint256[2]"
+							}
+						],
+						"name": "sub",
+						"type": "tuple[]"
+					},
+					{
+						"name": "b",
+						"type": "bytes"
+					}
+				],
+				"indexed": false,
+				"name": "s",
+				"type": "tuple"
+			}
+		],
+		"name": "E",
+		"type": "event"
+	}]
+	)";
+	checkInterface(text, interface);
+}
+
+BOOST_AUTO_TEST_CASE(structs_in_libraries)
+{
+	char const* text = R"(
+		library L {
+			struct S { uint a; T[] sub; bytes b; }
+			struct T { uint[2] x; }
+			function f(L.S storage s) {}
+			function g(L.S s) {}
+		}
+	)";
+	char const* interface = R"(
+	[{
+		"constant": false,
+		"inputs": [
+			{
+				"components": [
+					{
+						"name": "a",
+						"type": "uint256"
+					},
+					{
+						"components": [
+							{
+								"name": "x",
+								"type": "uint256[2]"
+							}
+						],
+						"name": "sub",
+						"type": "tuple[]"
+					},
+					{
+						"name": "b",
+						"type": "bytes"
+					}
+				],
+				"name": "s",
+				"type": "tuple"
+			}
+		],
+		"name": "g",
+		"outputs": [],
+		"payable": false,
+		"stateMutability": "nonpayable",
+		"type": "function"
+	},
+	{
+		"constant": false,
+		"inputs": [
+			{
+				"name": "s",
+				"type": "L.S storage"
+			}
+		],
+		"name": "f",
+		"outputs": [],
+		"payable": false,
+		"stateMutability": "nonpayable",
+		"type": "function"
+	}]
+	)";
+	checkInterface(text, interface);
+}
+
 BOOST_AUTO_TEST_SUITE_END()
 
 }
diff --git a/test/libsolidity/SolidityEndToEndTest.cpp b/test/libsolidity/SolidityEndToEndTest.cpp
index ea924fcb..f885b0d3 100644
--- a/test/libsolidity/SolidityEndToEndTest.cpp
+++ b/test/libsolidity/SolidityEndToEndTest.cpp
@@ -9682,6 +9682,7 @@ BOOST_AUTO_TEST_CASE(contracts_separated_with_comment)
 	compileAndRun(sourceCode, 0, "C2");
 }
 
+
 BOOST_AUTO_TEST_CASE(include_creation_bytecode_only_once)
 {
 	char const* sourceCode = R"(
diff --git a/test/libsolidity/SolidityNameAndTypeResolution.cpp b/test/libsolidity/SolidityNameAndTypeResolution.cpp
index 8c271fe1..d9e6a63d 100644
--- a/test/libsolidity/SolidityNameAndTypeResolution.cpp
+++ b/test/libsolidity/SolidityNameAndTypeResolution.cpp
@@ -599,6 +599,149 @@ BOOST_AUTO_TEST_CASE(enum_external_type)
 		}
 }
 
+BOOST_AUTO_TEST_CASE(external_structs)
+{
+	char const* text = R"(
+		contract Test {
+			enum ActionChoices { GoLeft, GoRight, GoStraight, Sit }
+			struct Empty {}
+			struct Nested { X[2][] a; uint y; }
+			struct X { bytes32 x; Test t; Empty[] e; }
+			function f(ActionChoices, uint, Empty) external {}
+			function g(Test, Nested) external {}
+			function h(function(Nested) external returns (uint)[]) external {}
+			function i(Nested[]) external {}
+		}
+	)";
+	SourceUnit const* sourceUnit = parseAndAnalyse(text);
+	for (ASTPointer<ASTNode> const& node: sourceUnit->nodes())
+		if (ContractDefinition* contract = dynamic_cast<ContractDefinition*>(node.get()))
+		{
+			auto functions = contract->definedFunctions();
+			BOOST_REQUIRE(!functions.empty());
+			BOOST_CHECK_EQUAL("f(uint8,uint256,())", functions[0]->externalSignature());
+			BOOST_CHECK_EQUAL("g(address,((bytes32,address,()[])[2][],uint256))", functions[1]->externalSignature());
+			BOOST_CHECK_EQUAL("h(function[])", functions[2]->externalSignature());
+			BOOST_CHECK_EQUAL("i(((bytes32,address,()[])[2][],uint256)[])", functions[3]->externalSignature());
+		}
+}
+
+BOOST_AUTO_TEST_CASE(external_structs_in_libraries)
+{
+	char const* text = R"(
+		library Test {
+			enum ActionChoices { GoLeft, GoRight, GoStraight, Sit }
+			struct Empty {}
+			struct Nested { X[2][] a; uint y; }
+			struct X { bytes32 x; Test t; Empty[] e; }
+			function f(ActionChoices, uint, Empty) external {}
+			function g(Test, Nested) external {}
+			function h(function(Nested) external returns (uint)[]) external {}
+			function i(Nested[]) external {}
+		}
+	)";
+	SourceUnit const* sourceUnit = parseAndAnalyse(text);
+	for (ASTPointer<ASTNode> const& node: sourceUnit->nodes())
+		if (ContractDefinition* contract = dynamic_cast<ContractDefinition*>(node.get()))
+		{
+			auto functions = contract->definedFunctions();
+			BOOST_REQUIRE(!functions.empty());
+			BOOST_CHECK_EQUAL("f(Test.ActionChoices,uint256,Test.Empty)", functions[0]->externalSignature());
+			BOOST_CHECK_EQUAL("g(Test,Test.Nested)", functions[1]->externalSignature());
+			BOOST_CHECK_EQUAL("h(function[])", functions[2]->externalSignature());
+			BOOST_CHECK_EQUAL("i(Test.Nested[])", functions[3]->externalSignature());
+		}
+}
+
+BOOST_AUTO_TEST_CASE(struct_with_mapping_in_library)
+{
+	char const* text = R"(
+		library Test {
+			struct Nested { mapping(uint => uint)[2][] a; uint y; }
+			struct X { Nested n; }
+			function f(X storage x) external {}
+		}
+	)";
+	SourceUnit const* sourceUnit = parseAndAnalyse(text);
+	for (ASTPointer<ASTNode> const& node: sourceUnit->nodes())
+		if (ContractDefinition* contract = dynamic_cast<ContractDefinition*>(node.get()))
+		{
+			auto functions = contract->definedFunctions();
+			BOOST_REQUIRE(!functions.empty());
+			BOOST_CHECK_EQUAL("f(Test.X storage)", functions[0]->externalSignature());
+		}
+}
+
+BOOST_AUTO_TEST_CASE(functions_with_identical_structs_in_interface)
+{
+	char const* text = R"(
+		pragma experimental ABIEncoderV2;
+
+		contract C {
+			struct S1 { }
+			struct S2 { }
+			function f(S1) pure {}
+			function f(S2) pure {}
+		}
+	)";
+	CHECK_ERROR(text, TypeError, "Function overload clash during conversion to external types for arguments");
+}
+
+BOOST_AUTO_TEST_CASE(functions_with_different_structs_in_interface)
+{
+	char const* text = R"(
+		pragma experimental ABIEncoderV2;
+
+		contract C {
+			struct S1 { function() external a; }
+			struct S2 { bytes24 a; }
+			function f(S1) pure {}
+			function f(S2) pure {}
+		}
+	)";
+	CHECK_SUCCESS(text);
+}
+
+BOOST_AUTO_TEST_CASE(functions_with_stucts_of_non_external_types_in_interface)
+{
+	char const* text = R"(
+		pragma experimental ABIEncoderV2;
+
+		contract C {
+			struct S { function() internal a; }
+			function f(S) {}
+		}
+	)";
+	CHECK_ERROR(text, TypeError, "Internal or recursive type is not allowed for public or external functions.");
+}
+
+BOOST_AUTO_TEST_CASE(functions_with_stucts_of_non_external_types_in_interface_2)
+{
+	char const* text = R"(
+		pragma experimental ABIEncoderV2;
+
+		contract C {
+			struct S { mapping(uint => uint) a; }
+			function f(S) {}
+		}
+	)";
+	CHECK_ERROR(text, TypeError, "Internal or recursive type is not allowed for public or external functions.");
+}
+
+BOOST_AUTO_TEST_CASE(functions_with_stucts_of_non_external_types_in_interface_nested)
+{
+	char const* text = R"(
+		pragma experimental ABIEncoderV2;
+
+		contract C {
+			struct T { mapping(uint => uint) a; }
+			struct S { T[][2] b; }
+			function f(S) {}
+		}
+	)";
+	CHECK_ERROR(text, TypeError, "Internal or recursive type is not allowed for public or external functions.");
+}
+
 BOOST_AUTO_TEST_CASE(function_external_call_allowed_conversion)
 {
 	char const* text = R"(
@@ -980,24 +1123,24 @@ BOOST_AUTO_TEST_CASE(state_variable_accessors)
 	FunctionTypePointer function = retrieveFunctionBySignature(*contract, "foo()");
 	BOOST_REQUIRE(function && function->hasDeclaration());
 	auto returnParams = function->returnParameterTypes();
-	BOOST_CHECK_EQUAL(returnParams.at(0)->canonicalName(false), "uint256");
+	BOOST_CHECK_EQUAL(returnParams.at(0)->canonicalName(), "uint256");
 	BOOST_CHECK(function->stateMutability() == StateMutability::View);
 
 	function = retrieveFunctionBySignature(*contract, "map(uint256)");
 	BOOST_REQUIRE(function && function->hasDeclaration());
 	auto params = function->parameterTypes();
-	BOOST_CHECK_EQUAL(params.at(0)->canonicalName(false), "uint256");
+	BOOST_CHECK_EQUAL(params.at(0)->canonicalName(), "uint256");
 	returnParams = function->returnParameterTypes();
-	BOOST_CHECK_EQUAL(returnParams.at(0)->canonicalName(false), "bytes4");
+	BOOST_CHECK_EQUAL(returnParams.at(0)->canonicalName(), "bytes4");
 	BOOST_CHECK(function->stateMutability() == StateMutability::View);
 
 	function = retrieveFunctionBySignature(*contract, "multiple_map(uint256,uint256)");
 	BOOST_REQUIRE(function && function->hasDeclaration());
 	params = function->parameterTypes();
-	BOOST_CHECK_EQUAL(params.at(0)->canonicalName(false), "uint256");
-	BOOST_CHECK_EQUAL(params.at(1)->canonicalName(false), "uint256");
+	BOOST_CHECK_EQUAL(params.at(0)->canonicalName(), "uint256");
+	BOOST_CHECK_EQUAL(params.at(1)->canonicalName(), "uint256");
 	returnParams = function->returnParameterTypes();
-	BOOST_CHECK_EQUAL(returnParams.at(0)->canonicalName(false), "bytes4");
+	BOOST_CHECK_EQUAL(returnParams.at(0)->canonicalName(), "bytes4");
 	BOOST_CHECK(function->stateMutability() == StateMutability::View);
 }
 
@@ -1072,7 +1215,7 @@ BOOST_AUTO_TEST_CASE(struct_accessor_one_array_only)
 			Data public data;
 		}
 	)";
-	CHECK_ERROR(sourceCode, TypeError, "Internal type is not allowed for public state variables.");
+	CHECK_ERROR(sourceCode, TypeError, "Internal or recursive type is not allowed for public state variables.");
 }
 
 BOOST_AUTO_TEST_CASE(base_class_state_variable_internal_member)
@@ -3283,7 +3426,7 @@ BOOST_AUTO_TEST_CASE(library_memory_struct)
 			function f() public returns (S ) {}
 		}
 	)";
-	CHECK_ERROR(text, TypeError, "Internal type is not allowed for public or external functions.");
+	CHECK_SUCCESS(text);
 }
 
 BOOST_AUTO_TEST_CASE(using_for_arbitrary_mismatch)
@@ -4874,7 +5017,7 @@ BOOST_AUTO_TEST_CASE(internal_function_as_external_parameter)
 			}
 		}
 	)";
-	CHECK_ERROR(text, TypeError, "Internal type is not allowed for public or external functions.");
+	CHECK_ERROR(text, TypeError, "Internal or recursive type is not allowed for public or external functions.");
 }
 
 BOOST_AUTO_TEST_CASE(internal_function_returned_from_public_function)
@@ -4886,7 +5029,7 @@ BOOST_AUTO_TEST_CASE(internal_function_returned_from_public_function)
 			}
 		}
 	)";
-	CHECK_ERROR(text, TypeError, "Internal type is not allowed for public or external functions.");
+	CHECK_ERROR(text, TypeError, "Internal or recursive type is not allowed for public or external functions.");
 }
 
 BOOST_AUTO_TEST_CASE(internal_function_as_external_parameter_in_library_internal)
@@ -4908,7 +5051,7 @@ BOOST_AUTO_TEST_CASE(internal_function_as_external_parameter_in_library_external
 			}
 		}
 	)";
-	CHECK_ERROR(text, TypeError, "Internal type is not allowed for public or external functions.");
+	CHECK_ERROR(text, TypeError, "Internal or recursive type is not allowed for public or external functions.");
 }
 
 BOOST_AUTO_TEST_CASE(function_type_arrays)
@@ -5396,6 +5539,56 @@ BOOST_AUTO_TEST_CASE(constructible_internal_constructor)
 	success(text);
 }
 
+BOOST_AUTO_TEST_CASE(return_structs)
+{
+	char const* text = R"(
+		contract C {
+			struct S { uint a; T[] sub; }
+			struct T { uint[] x; }
+			function f() returns (uint, S) {
+			}
+		}
+	)";
+	success(text);
+}
+
+BOOST_AUTO_TEST_CASE(return_recursive_structs)
+{
+	char const* text = R"(
+		contract C {
+			struct S { uint a; S[] sub; }
+			function f() returns (uint, S) {
+			}
+		}
+	)";
+	CHECK_ERROR(text, TypeError, "Internal or recursive type is not allowed for public or external functions.");
+}
+
+BOOST_AUTO_TEST_CASE(return_recursive_structs2)
+{
+	char const* text = R"(
+		contract C {
+			struct S { uint a; S[2][] sub; }
+			function f() returns (uint, S) {
+			}
+		}
+	)";
+	CHECK_ERROR(text, TypeError, "Internal or recursive type is not allowed for public or external functions.");
+}
+
+BOOST_AUTO_TEST_CASE(return_recursive_structs3)
+{
+	char const* text = R"(
+		contract C {
+			struct S { uint a; S[][][] sub; }
+			struct T { S s; }
+			function f() returns (uint x, T t) {
+			}
+		}
+	)";
+	CHECK_ERROR(text, TypeError, "Internal or recursive type is not allowed for public or external functions.");
+}
+
 BOOST_AUTO_TEST_CASE(address_checksum_type_deduction)
 {
 	char const* text = R"(