Using for with global binding.

libsolidity/ast/AST.h

@@ -641,6 +641,10 @@ private:
  * For version 3, T has to be implicitly convertible to the first parameter type of
  * all functions, and this is checked at the point of the using statement. For versions 1 and
  * 2, this check is only done when a function is called.
+ *
+ * Finally, `using {f1, f2, ..., fn} for T global` is also valid at file level, as long as T is
+ * a user-defined type defined in the same file at file level. In this case, the methods are
+ * attached to all objects of that type regardless of scope.
  */
 class UsingForDirective: public ASTNode
 {
@@ -650,9 +654,14 @@ public:
 		SourceLocation const& _location,
 		std::vector<ASTPointer<IdentifierPath>> _functions,
 		bool _usesBraces,
-		ASTPointer<TypeName> _typeName
+		ASTPointer<TypeName> _typeName,
+		bool _global
 	):
-		ASTNode(_id, _location), m_functions(_functions), m_usesBraces(_usesBraces), m_typeName(std::move(_typeName))
+		ASTNode(_id, _location),
+		m_functions(_functions),
+		m_usesBraces(_usesBraces),
+		m_typeName(std::move(_typeName)),
+		m_global{_global}
 	{
 	}
 
@@ -665,12 +674,14 @@ public:
 	/// @returns a list of functions or the single library.
 	std::vector<ASTPointer<IdentifierPath>> const& functionsOrLibrary() const { return m_functions; }
 	bool usesBraces() const { return m_usesBraces; }
+	bool global() const { return m_global; }
 
 private:
 	/// Either the single library or a list of functions.
 	std::vector<ASTPointer<IdentifierPath>> m_functions;
 	bool m_usesBraces;
 	ASTPointer<TypeName> m_typeName;
+	bool m_global = false;
 };
 
 class StructDefinition: public Declaration, public ScopeOpener

libsolidity/ast/ASTJsonConverter.cpp

@@ -328,6 +328,7 @@ bool ASTJsonConverter::visit(UsingForDirective const& _node)
 	}
 	else
 		attributes.emplace_back("libraryName", toJson(*_node.functionsOrLibrary().front()));
+	attributes.emplace_back("global", _node.global());
 
 	setJsonNode(_node, "UsingForDirective", move(attributes));
 

libsolidity/ast/ASTJsonImporter.cpp

@@ -359,7 +359,8 @@ ASTPointer<UsingForDirective> ASTJsonImporter::createUsingForDirective(Json::Val
 		_node,
 		move(functions),
 		!_node.isMember("libraryName"),
-		_node["typeName"].isNull() ? nullptr  : convertJsonToASTNode<TypeName>(_node["typeName"])
+		_node["typeName"].isNull() ? nullptr  : convertJsonToASTNode<TypeName>(_node["typeName"]),
+		memberAsBool(_node, "global")
 	);
 }
 

libsolidity/ast/Types.cpp

@@ -342,6 +342,13 @@ MemberList::MemberMap Type::boundFunctions(Type const& _type, ASTNode const& _sc
 		solAssert(sourceUnit, "");
 	usingForDirectives += ASTNode::filteredNodes<UsingForDirective>(sourceUnit->nodes());
 
+	if (Declaration const* typeDefinition = _type.typeDefinition())
+		if (auto const* sourceUnit = dynamic_cast<SourceUnit const*>(typeDefinition->scope()))
+			for (auto usingFor: ASTNode::filteredNodes<UsingForDirective>(sourceUnit->nodes()))
+				// We do not yet compare the type name because of normalization.
+				if (usingFor->global() && usingFor->typeName())
+					usingForDirectives.emplace_back(usingFor);
+
 	// Normalise data location of type.
 	DataLocation typeLocation = DataLocation::Storage;
 	if (auto refType = dynamic_cast<ReferenceType const*>(&_type))