From 20e227afb543195f2927224e822d4c230298b630 Mon Sep 17 00:00:00 2001
From: Mathias Baumann <git@supradigital.org>
Date: Mon, 16 Sep 2019 12:36:50 +0200
Subject: [PATCH] Ensure list of overrides consists of contracts

---
 libsolidity/analysis/PostTypeChecker.cpp      | 21 +++++++++++++++
 libsolidity/analysis/PostTypeChecker.h        |  2 ++
 .../override/override_type_mismatch.sol       | 26 +++++++++++++++++++
 3 files changed, 49 insertions(+)
 create mode 100644 test/libsolidity/syntaxTests/inheritance/override/override_type_mismatch.sol

diff --git a/libsolidity/analysis/PostTypeChecker.cpp b/libsolidity/analysis/PostTypeChecker.cpp
index 936e133ca..40c4f22d8 100644
--- a/libsolidity/analysis/PostTypeChecker.cpp
+++ b/libsolidity/analysis/PostTypeChecker.cpp
@@ -60,6 +60,27 @@ void PostTypeChecker::endVisit(ContractDefinition const&)
 	m_constVariableDependencies.clear();
 }
 
+void PostTypeChecker::endVisit(OverrideSpecifier const& _overrideSpecifier)
+{
+	for (ASTPointer<UserDefinedTypeName> const& override: _overrideSpecifier.overrides())
+	{
+		Declaration const* decl  = override->annotation().referencedDeclaration;
+		solAssert(decl, "Expected declaration to be resolved.");
+
+		if (dynamic_cast<ContractDefinition const*>(decl))
+			continue;
+
+		TypeType const* actualTypeType = dynamic_cast<TypeType const*>(decl->type());
+
+		m_errorReporter.typeError(
+			override->location(),
+			"Expected contract but got " +
+			actualTypeType->actualType()->toString(true) +
+			"."
+		);
+	}
+}
+
 bool PostTypeChecker::visit(VariableDeclaration const& _variable)
 {
 	solAssert(!m_currentConstVariable, "");
diff --git a/libsolidity/analysis/PostTypeChecker.h b/libsolidity/analysis/PostTypeChecker.h
index e428b81ae..b4441b395 100644
--- a/libsolidity/analysis/PostTypeChecker.h
+++ b/libsolidity/analysis/PostTypeChecker.h
@@ -37,6 +37,7 @@ namespace solidity
 /**
  * This module performs analyses on the AST that are done after type checking and assignments of types:
  *  - whether there are circular references in constant state variables
+ *  - whether override specifiers are actually contracts
  * @TODO factor out each use-case into an individual class (but do the traversal only once)
  */
 class PostTypeChecker: private ASTConstVisitor
@@ -53,6 +54,7 @@ private:
 
 	bool visit(ContractDefinition const& _contract) override;
 	void endVisit(ContractDefinition const& _contract) override;
+	void endVisit(OverrideSpecifier const& _overrideSpecifier) override;
 
 	bool visit(VariableDeclaration const& _variable) override;
 	void endVisit(VariableDeclaration const& _variable) override;
diff --git a/test/libsolidity/syntaxTests/inheritance/override/override_type_mismatch.sol b/test/libsolidity/syntaxTests/inheritance/override/override_type_mismatch.sol
new file mode 100644
index 000000000..c7b120a4e
--- /dev/null
+++ b/test/libsolidity/syntaxTests/inheritance/override/override_type_mismatch.sol
@@ -0,0 +1,26 @@
+contract A {
+	int public testvar;
+	function foo() internal returns (uint256);
+	function test(uint8 _a) internal returns (uint256);
+}
+contract B {
+	function foo() internal returns (uint256);
+	function test() internal returns (uint256);
+}
+contract C {
+	function foo() internal returns (uint256);
+}
+contract D {
+	function foo() internal returns (uint256);
+}
+contract X is A, B, C, D {
+	struct MyStruct { int abc; }
+	enum ENUM { F,G,H }
+
+	int public override testvar;
+	function test() internal override returns (uint256);
+	function foo() internal override(MyStruct, ENUM, A, B, C, D) returns (uint256);
+}
+// ----
+// TypeError: (552-560): Expected contract but got struct X.MyStruct.
+// TypeError: (562-566): Expected contract but got enum X.ENUM.