Simple aliasing during import.

libsolidity/analysis/NameAndTypeResolver.cpp

@@ -46,14 +46,16 @@ NameAndTypeResolver::NameAndTypeResolver(
 
 bool NameAndTypeResolver::registerDeclarations(SourceUnit& _sourceUnit)
 {
-	solAssert(!m_scopes[&_sourceUnit], "");
-	m_scopes[&_sourceUnit].reset(new DeclarationContainer(nullptr, m_scopes[nullptr].get()));
+	if (!m_scopes[&_sourceUnit])
+		// By importing, it is possible that the container already exists.
+		m_scopes[&_sourceUnit].reset(new DeclarationContainer(nullptr, m_scopes[nullptr].get()));
 	m_currentScope = m_scopes[&_sourceUnit].get();
 
 	// The helper registers all declarations in m_scopes as a side-effect of its construction.
 	try
 	{
 		DeclarationRegistrationHelper registrar(m_scopes, _sourceUnit, m_errors);
+		_sourceUnit.annotation().exportedSymbols = m_scopes[&_sourceUnit]->declarations();
 	}
 	catch (FatalError const&)
 	{
@@ -83,7 +85,7 @@ bool NameAndTypeResolver::performImports(SourceUnit& _sourceUnit, map<string, So
 				);
 				error = true;
 			}
-			else
+			else if (imp->name().empty())
 			{
 				auto scope = m_scopes.find(_sourceUnits.at(path));
 				solAssert(scope != end(m_scopes), "");
@@ -380,7 +382,7 @@ void NameAndTypeResolver::reportFatalTypeError(Error const& _e)
 }
 
 DeclarationRegistrationHelper::DeclarationRegistrationHelper(
-	map<ASTNode const*, unique_ptr<DeclarationContainer>>& _scopes,
+	map<ASTNode const*, shared_ptr<DeclarationContainer>>& _scopes,
 	ASTNode& _astRoot,
 	ErrorList& _errors
 ):
@@ -392,6 +394,17 @@ DeclarationRegistrationHelper::DeclarationRegistrationHelper(
 	_astRoot.accept(*this);
 }
 
+bool DeclarationRegistrationHelper::visit(ImportDirective& _import)
+{
+	SourceUnit const* importee = _import.annotation().sourceUnit;
+	solAssert(!!importee, "");
+	if (!m_scopes[importee])
+		m_scopes[importee].reset(new DeclarationContainer(nullptr, m_scopes[nullptr].get()));
+	m_scopes[&_import] = m_scopes[importee];
+	registerDeclaration(_import, false);
+	return true;
+}
+
 bool DeclarationRegistrationHelper::visit(ContractDefinition& _contract)
 {
 	registerDeclaration(_contract, true);
@@ -489,9 +502,9 @@ void DeclarationRegistrationHelper::endVisit(EventDefinition&)
 
 void DeclarationRegistrationHelper::enterNewSubScope(Declaration const& _declaration)
 {
-	map<ASTNode const*, unique_ptr<DeclarationContainer>>::iterator iter;
+	map<ASTNode const*, shared_ptr<DeclarationContainer>>::iterator iter;
 	bool newlyAdded;
-	unique_ptr<DeclarationContainer> container(new DeclarationContainer(m_currentScope, m_scopes[m_currentScope].get()));
+	shared_ptr<DeclarationContainer> container(new DeclarationContainer(m_currentScope, m_scopes[m_currentScope].get()));
 	tie(iter, newlyAdded) = m_scopes.emplace(&_declaration, move(container));
 	solAssert(newlyAdded, "Unable to add new scope.");
 	m_currentScope = &_declaration;

libsolidity/analysis/NameAndTypeResolver.h

@@ -111,7 +111,8 @@ private:
 	/// Maps nodes declaring a scope to scopes, i.e. ContractDefinition and FunctionDeclaration,
 	/// where nullptr denotes the global scope. Note that structs are not scope since they do
 	/// not contain code.
-	std::map<ASTNode const*, std::unique_ptr<DeclarationContainer>> m_scopes;
+	/// Aliases (for example `import "x" as y;`) create multiple pointers to the same scope.
+	std::map<ASTNode const*, std::shared_ptr<DeclarationContainer>> m_scopes;
 
 	DeclarationContainer* m_currentScope = nullptr;
 	ErrorList& m_errors;
@@ -125,12 +126,13 @@ class DeclarationRegistrationHelper: private ASTVisitor
 {
 public:
 	DeclarationRegistrationHelper(
-		std::map<ASTNode const*, std::unique_ptr<DeclarationContainer>>& _scopes,
+		std::map<ASTNode const*, std::shared_ptr<DeclarationContainer>>& _scopes,
 		ASTNode& _astRoot,
 		ErrorList& _errors
 	);
 
 private:
+	bool visit(ImportDirective& _declaration) override;
 	bool visit(ContractDefinition& _contract) override;
 	void endVisit(ContractDefinition& _contract) override;
 	bool visit(StructDefinition& _struct) override;
@@ -166,7 +168,7 @@ private:
 	// creates the Declaration error and adds it in the errors list and throws FatalError
 	void fatalDeclarationError(SourceLocation _sourceLocation, std::string const& _description);
 
-	std::map<ASTNode const*, std::unique_ptr<DeclarationContainer>>& m_scopes;
+	std::map<ASTNode const*, std::shared_ptr<DeclarationContainer>>& m_scopes;
 	ASTNode const* m_currentScope = nullptr;
 	VariableScope* m_currentFunction = nullptr;
 	ErrorList& m_errors;

libsolidity/ast/AST.cpp

@@ -56,6 +56,13 @@ Error ASTNode::createTypeError(string const& _description) const
 	return Error(Error::Type::TypeError) << errinfo_sourceLocation(location()) << errinfo_comment(_description);
 }
 
+SourceUnitAnnotation& SourceUnit::annotation() const
+{
+	if (!m_annotation)
+		m_annotation = new SourceUnitAnnotation();
+	return static_cast<SourceUnitAnnotation&>(*m_annotation);
+}
+
 ImportAnnotation& ImportDirective::annotation() const
 {
 	if (!m_annotation)
@@ -63,6 +70,12 @@ ImportAnnotation& ImportDirective::annotation() const
 	return static_cast<ImportAnnotation&>(*m_annotation);
 }
 
+TypePointer ImportDirective::type() const
+{
+	solAssert(!!annotation().sourceUnit, "");
+	return make_shared<ModuleType>(*annotation().sourceUnit);
+}
+
 map<FixedHash<4>, FunctionTypePointer> ContractDefinition::interfaceFunctions() const
 {
 	auto exportedFunctionList = interfaceFunctionList();

libsolidity/ast/AST.h

@@ -120,6 +120,7 @@ public:
 
 	virtual void accept(ASTVisitor& _visitor) override;
 	virtual void accept(ASTConstVisitor& _visitor) const override;
+	virtual SourceUnitAnnotation& annotation() const override;
 
 	std::vector<ASTPointer<ASTNode>> nodes() const { return m_nodes; }
 
@@ -128,44 +129,7 @@ private:
 };
 
 /**
- * Import directive for referencing other files / source objects.
- * Example: import "abc.sol" // imports all symbols of "abc.sol" into current scope
- * Source objects are identified by a string which can be a file name but does not have to be.
- * Other ways to use it:
- * import "abc" as x; // creates symbol "x" that contains all symbols in "abc"
- * import * as x from "abc"; // same as above
- * import {a as b, c} from "abc"; // creates new symbols "b" and "c" referencing "a" and "c" in "abc", respectively.
- */
-class ImportDirective: public ASTNode
-{
-public:
-	ImportDirective(
-		SourceLocation const& _location,
-		ASTPointer<ASTString> const& _path,
-			ASTPointer<ASTString> const& _unitAlias,
-			std::vector<std::pair<ASTPointer<Identifier>, ASTPointer<ASTString>>>&& _symbolAliases
-		):
-		ASTNode(_location), m_path(_path), m_unitAlias(_unitAlias), m_symbolAliases(_symbolAliases) {}
-
-	virtual void accept(ASTVisitor& _visitor) override;
-	virtual void accept(ASTConstVisitor& _visitor) const override;
-
-	ASTString const& path() const { return *m_path; }
-	virtual ImportAnnotation& annotation() const override;
-
-private:
-	ASTPointer<ASTString> m_path;
-	/// The alias for the module itself. If present, import the whole unit under that name and
-	/// ignore m_symbolAlias.
-	ASTPointer<ASTString> m_unitAlias;
-	/// The aliases for the specific symbols to import. If non-empty import the specific symbols.
-	/// If the second component is empty, import the identifier unchanged.
-	/// If both m_unitAlias and m_symbolAlias are empty, import all symbols into the current scope.
-	std::vector<std::pair<ASTPointer<Identifier>, ASTPointer<ASTString>>> m_symbolAliases;
-};
-
-/**
- * Abstract AST class for a declaration (contract, function, struct, variable).
+ * Abstract AST class for a declaration (contract, function, struct, variable, import directive).
  */
 class Declaration: public ASTNode
 {
@@ -210,6 +174,45 @@ private:
 	ASTNode const* m_scope;
 };
 
+/**
+ * Import directive for referencing other files / source objects.
+ * Example: import "abc.sol" // imports all symbols of "abc.sol" into current scope
+ * Source objects are identified by a string which can be a file name but does not have to be.
+ * Other ways to use it:
+ * import "abc" as x; // creates symbol "x" that contains all symbols in "abc"
+ * import * as x from "abc"; // same as above
+ * import {a as b, c} from "abc"; // creates new symbols "b" and "c" referencing "a" and "c" in "abc", respectively.
+ */
+class ImportDirective: public Declaration
+{
+public:
+	ImportDirective(
+		SourceLocation const& _location,
+		ASTPointer<ASTString> const& _path,
+		ASTPointer<ASTString> const& _unitAlias,
+		std::vector<std::pair<ASTPointer<Identifier>, ASTPointer<ASTString>>>&& _symbolAliases
+	):
+		Declaration(_location, _unitAlias),
+		m_path(_path),
+		m_symbolAliases(_symbolAliases)
+	{ }
+
+	virtual void accept(ASTVisitor& _visitor) override;
+	virtual void accept(ASTConstVisitor& _visitor) const override;
+
+	ASTString const& path() const { return *m_path; }
+	virtual ImportAnnotation& annotation() const override;
+
+	virtual TypePointer type() const override;
+
+private:
+	ASTPointer<ASTString> m_path;
+	/// The aliases for the specific symbols to import. If non-empty import the specific symbols.
+	/// If the second component is empty, import the identifier unchanged.
+	/// If both m_unitAlias and m_symbolAlias are empty, import all symbols into the current scope.
+	std::vector<std::pair<ASTPointer<Identifier>, ASTPointer<ASTString>>> m_symbolAliases;
+};
+
 /**
  * Abstract class that is added to each AST node that can store local variables.
  */

libsolidity/ast/ASTAnnotations.h

@@ -54,10 +54,20 @@ struct DocumentedAnnotation
 	std::multimap<std::string, DocTag> docTags;
 };
 
+struct SourceUnitAnnotation: ASTAnnotation
+{
+	/// The "absolute" (in the compiler sense) path of this source unit.
+	std::string path;
+	/// The exported symbols (all global symbols).
+	std::map<ASTString, std::vector<Declaration const*>> exportedSymbols;
+};
+
 struct ImportAnnotation: ASTAnnotation
 {
 	/// The absolute path of the source unit to import.
 	std::string absolutePath;
+	/// The actual source unit.
+	SourceUnit const* sourceUnit = nullptr;
 };
 
 struct TypeDeclarationAnnotation: ASTAnnotation

libsolidity/ast/Types.cpp

@@ -1925,9 +1925,25 @@ string ModifierType::toString(bool _short) const
 	return name + ")";
 }
 
-MagicType::MagicType(MagicType::Kind _kind):
-	m_kind(_kind)
+bool ModuleType::operator==(Type const& _other) const
 {
+	if (_other.category() != category())
+		return false;
+	return &m_sourceUnit == &dynamic_cast<ModuleType const&>(_other).m_sourceUnit;
+}
+
+MemberList::MemberMap ModuleType::nativeMembers(ContractDefinition const*) const
+{
+	MemberList::MemberMap symbols;
+	for (auto const& symbolName: m_sourceUnit.annotation().exportedSymbols)
+		for (Declaration const* symbol: symbolName.second)
+			symbols.push_back(MemberList::Member(symbolName.first, symbol->type(), symbol));
+	return symbols;
+}
+
+string ModuleType::toString(bool) const
+{
+	return string("module \"") + m_sourceUnit.annotation().path + string("\"");
 }
 
 bool MagicType::operator==(Type const& _other) const

libsolidity/ast/Types.h

@@ -134,7 +134,7 @@ public:
 	{
 		Integer, IntegerConstant, StringLiteral, Bool, Real, Array,
 		FixedBytes, Contract, Struct, Function, Enum, Tuple,
-		Mapping, TypeType, Modifier, Magic
+		Mapping, TypeType, Modifier, Magic, Module
 	};
 
 	/// @{
@@ -969,6 +969,34 @@ private:
 };
 
 
+
+/**
+ * Special type for imported modules. These mainly give access to their scope via members.
+ */
+class ModuleType: public Type
+{
+public:
+	virtual Category category() const override { return Category::Module; }
+
+	explicit ModuleType(SourceUnit const& _source): m_sourceUnit(_source) {}
+
+	virtual TypePointer binaryOperatorResult(Token::Value, TypePointer const&) const override
+	{
+		return TypePointer();
+	}
+
+	virtual bool operator==(Type const& _other) const override;
+	virtual bool canBeStored() const override { return false; }
+	virtual bool canLiveOutsideStorage() const override { return true; }
+	virtual unsigned sizeOnStack() const override { return 0; }
+	virtual MemberList::MemberMap nativeMembers(ContractDefinition const*) const override;
+
+	virtual std::string toString(bool _short) const override;
+
+private:
+	SourceUnit const& m_sourceUnit;
+};
+
 /**
  * Special type for magic variables (block, msg, tx), similar to a struct but without any reference
  * (it always references a global singleton by name).
@@ -979,7 +1007,7 @@ public:
 	enum class Kind { Block, Message, Transaction };
 	virtual Category category() const override { return Category::Magic; }
 
-	explicit MagicType(Kind _kind);
+	explicit MagicType(Kind _kind): m_kind(_kind) {}
 
 	virtual TypePointer binaryOperatorResult(Token::Value, TypePointer const&) const override
 	{

libsolidity/interface/CompilerStack.cpp

@@ -111,6 +111,8 @@ bool CompilerStack::parse()
 		sourcePair.second.ast = Parser(m_errors).parse(sourcePair.second.scanner);
 		if (!sourcePair.second.ast)
 			solAssert(!Error::containsOnlyWarnings(m_errors), "Parser returned null but did not report error.");
+		else
+			sourcePair.second.ast->annotation().path = sourcePair.first;
 		sourceUnitsByName[sourcePair.first] = sourcePair.second.ast.get();
 	}
 	if (!Error::containsOnlyWarnings(m_errors))
@@ -384,6 +386,7 @@ void CompilerStack::resolveImports()
 							<< errinfo_sourceLocation(import->location())
 							<< errinfo_comment("Source not found.")
 					);
+				import->annotation().sourceUnit = m_sources.at(path).ast.get();
 
 				toposort(path, &m_sources[path]);
 			}

libsolidity/parsing/Parser.cpp

@@ -119,7 +119,7 @@ ASTPointer<ImportDirective> Parser::parseImportDirective()
 	ASTNodeFactory nodeFactory(*this);
 	expectToken(Token::Import);
 	ASTPointer<ASTString> path;
-	ASTPointer<ASTString> unitAlias;
+	ASTPointer<ASTString> unitAlias = make_shared<string>();
 	vector<pair<ASTPointer<Identifier>, ASTPointer<ASTString>>> symbolAliases;
 
 	if (m_scanner->currentToken() == Token::StringLiteral)

test/libsolidity/Imports.cpp

@@ -93,6 +93,14 @@ BOOST_AUTO_TEST_CASE(relative_import_multiplex)
 	BOOST_CHECK(c.compile());
 }
 
+BOOST_AUTO_TEST_CASE(simple_alias)
+{
+	CompilerStack c;
+	c.addSource("a", "contract A {}");
+	c.addSource("dir/a/b/c", "import \"../../.././a\" as x; contract B { function() { x.A r = x.A(20); } }");
+	BOOST_CHECK(c.compile());
+}
+
 BOOST_AUTO_TEST_SUITE_END()
 
 }