Merge pull request #3875 from ethereum/constructorSelfRef

Stricter check for "this" in constructor.

libsolidity/analysis/StaticAnalyzer.cpp

@@ -206,10 +206,32 @@ bool StaticAnalyzer::visit(MemberAccess const& _memberAccess)
 					);
 			}
 
-	if (m_constructor && m_currentContract)
+	if (m_constructor)
-		if (ContractType const* type = dynamic_cast<ContractType const*>(_memberAccess.expression().annotation().type.get()))
+	{
-			if (type->contractDefinition() == *m_currentContract)
+		auto const* expr = &_memberAccess.expression();
-				m_errorReporter.warning(_memberAccess.location(), "\"this\" used in constructor.");
+		while(expr)
+		{
+			if (auto id = dynamic_cast<Identifier const*>(expr))
+			{
+				if (id->name() == "this")
+					m_errorReporter.warning(
+						id->location(),
+						"\"this\" used in constructor. "
+						"Note that external functions of a contract "
+						"cannot be called while it is being constructed.");
+				break;
+			}
+			else if (auto tuple = dynamic_cast<TupleExpression const*>(expr))
+			{
+				if (tuple->components().size() == 1)
+					expr = tuple->components().front().get();
+				else
+					break;
+			}
+			else
+				break;
+		}
+	}
 
 	return true;
 }

test/libsolidity/syntaxTests/constructor_this.sol

@@ -0,0 +1,12 @@
+contract C {
+    function f() public pure {}
+    constructor() public {
+        C c = this;
+        c.f(); // this does not warn now, but should warn in the future
+        this.f();
+        (this).f();
+    }
+}
+// ----
+// Warning: (172-176): "this" used in constructor. Note that external functions of a contract cannot be called while it is being constructed.
+// Warning: (191-195): "this" used in constructor. Note that external functions of a contract cannot be called while it is being constructed.

test/libsolidity/syntaxTests/parsing/constructor_allowed_this.sol

@@ -0,0 +1,28 @@
+contract A {
+    function a() public pure {
+    }
+}
+contract B {
+    constructor(address) public {
+    }
+    function b(address) public returns (A) {
+        return new A();
+    }
+}
+contract C {
+    B m_b;
+    C m_c;
+    constructor(C other_c) public {
+        m_c = other_c;
+        m_b = new B(this);
+        m_b.b(this).a();
+        g(this).f();
+        other_c.f();
+        m_c.f();
+    }
+    function f() public pure {
+    }
+    function g(C) public view returns (C) {
+        return m_c;
+    }
+}

test/libsolidity/syntaxTests/parsing/constructor_super.sol

@@ -0,0 +1,10 @@
+contract A {
+  function x() pure internal {}
+}
+
+contract B is A {
+  constructor() public {
+    // used to trigger warning about using ``this`` in constructor
+    super.x();
+  }
+}