From 0891b9451b1fab88383c4865ffe861a4a7ffea85 Mon Sep 17 00:00:00 2001
From: Mathias Baumann <git@supradigital.org>
Date: Thu, 14 Nov 2019 12:48:15 +0100
Subject: [PATCH] Disallow variables of library types

---
 Changelog.md                                       |  1 +
 libsolidity/analysis/TypeChecker.cpp               |  3 +++
 test/libsolidity/ABIJson/library_function.sol      | 13 +++++++++----
 .../301_library_instances_cannot_be_used.sol       |  1 +
 .../typeChecking/library_instances.sol             | 14 ++++++++++++++
 5 files changed, 28 insertions(+), 4 deletions(-)
 create mode 100644 test/libsolidity/syntaxTests/nameAndTypeResolution/typeChecking/library_instances.sol

diff --git a/Changelog.md b/Changelog.md
index d3294901f..e61ffff0f 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -12,6 +12,7 @@ Compiler Features:
  * SMTChecker: Support inheritance and function overriding.
  * Standard JSON Interface: Output the storage layout of a contract when artifact ``storageLayout`` is requested.
  * TypeChecker: List possible candidates when overload resolution fails.
+ * TypeChecker: Disallow variables of library types.
 
 
 Bugfixes:
diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index 73bf1b18e..262db9d1d 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -450,6 +450,9 @@ bool TypeChecker::visit(VariableDeclaration const& _variable)
 	TypePointer varType = _variable.annotation().type;
 	solAssert(!!varType, "Variable type not provided.");
 
+	if (auto contractType = dynamic_cast<ContractType const*>(varType))
+		if (contractType->contractDefinition().isLibrary())
+			m_errorReporter.typeError(_variable.location(), "The type of a variable cannot be a library.");
 	if (_variable.value())
 		expectType(*_variable.value(), *varType);
 	if (_variable.isConstant())
diff --git a/test/libsolidity/ABIJson/library_function.sol b/test/libsolidity/ABIJson/library_function.sol
index 2aad8e164..f61a1f8a9 100644
--- a/test/libsolidity/ABIJson/library_function.sol
+++ b/test/libsolidity/ABIJson/library_function.sol
@@ -1,9 +1,14 @@
+contract X {}
 library test {
     struct StructType { uint a; }
-    function f(StructType storage b, uint[] storage c, test d) public returns (uint[] memory e, StructType storage f) { f = f; }
-    function f1(uint[] memory c, test d) public pure returns (uint[] memory e) {  }
+    function f(StructType storage b, uint[] storage c, X d) public returns (uint[] memory e, StructType storage f) { f = f; }
+    function f1(uint[] memory c, X d) public pure returns (uint[] memory e) {  }
 }
 // ----
+//     :X
+// []
+//
+//
 //     :test
 // [
 //   {
@@ -16,9 +21,9 @@ library test {
 //         "type": "uint256[]"
 //       },
 //       {
-//         "internalType": "library test",
+//         "internalType": "contract X",
 //         "name": "d",
-//         "type": "test"
+//         "type": "X"
 //       }
 //     ],
 //     "name": "f1",
diff --git a/test/libsolidity/syntaxTests/nameAndTypeResolution/301_library_instances_cannot_be_used.sol b/test/libsolidity/syntaxTests/nameAndTypeResolution/301_library_instances_cannot_be_used.sol
index dcf11a6e3..3eebc7926 100644
--- a/test/libsolidity/syntaxTests/nameAndTypeResolution/301_library_instances_cannot_be_used.sol
+++ b/test/libsolidity/syntaxTests/nameAndTypeResolution/301_library_instances_cannot_be_used.sol
@@ -6,4 +6,5 @@ contract test {
     }
 }
 // ----
+// TypeError: (87-90): The type of a variable cannot be a library.
 // TypeError: (100-103): Member "l" not found or not visible after argument-dependent lookup in library L.
diff --git a/test/libsolidity/syntaxTests/nameAndTypeResolution/typeChecking/library_instances.sol b/test/libsolidity/syntaxTests/nameAndTypeResolution/typeChecking/library_instances.sol
new file mode 100644
index 000000000..c28bec419
--- /dev/null
+++ b/test/libsolidity/syntaxTests/nameAndTypeResolution/typeChecking/library_instances.sol
@@ -0,0 +1,14 @@
+library X { }
+
+contract Y {
+	X abc;
+	function foo(X param) private view
+	{
+		X ofg;
+		ofg = abc;
+	}
+}
+// ----
+// TypeError: (29-34): The type of a variable cannot be a library.
+// TypeError: (50-57): The type of a variable cannot be a library.
+// TypeError: (77-82): The type of a variable cannot be a library.