From 6f8b5fe53b1e28191cbbc17fd8db499890b2abfb Mon Sep 17 00:00:00 2001
From: Mathias Baumann <marenz@supradigital.org>
Date: Wed, 3 Jun 2020 13:53:11 +0200
Subject: [PATCH] Disallow override with non-public state variables

---
 Changelog.md                                             | 1 +
 libsolidity/analysis/OverrideChecker.cpp                 | 5 +++++
 .../inheritance/override/private_state_variable.sol      | 9 +++++++++
 3 files changed, 15 insertions(+)
 create mode 100644 test/libsolidity/syntaxTests/inheritance/override/private_state_variable.sol

diff --git a/Changelog.md b/Changelog.md
index ec12a214b..a1592946b 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -23,6 +23,7 @@ Bugfixes:
  * Type Checker: Fix internal compiler error when trying to decode too large static arrays.
  * Type Checker: Fix wrong compiler error when referencing an overridden function without calling it.
  * Type Checker: Fix internal compiler error when forward referencing non-literal constants from inline assembly.
+ * Type Checker: Disallow usage of override with non-public state variables.
  * NatSpec: DocString block is terminated when encountering an empty line.
  * Scanner: Fix bug when two empty NatSpec comments lead to scanning past EOL.
  * Code Generator: Trigger proper unimplemented errors on certain array copy operations.
diff --git a/libsolidity/analysis/OverrideChecker.cpp b/libsolidity/analysis/OverrideChecker.cpp
index 4b9a3b7f3..89f9a6637 100644
--- a/libsolidity/analysis/OverrideChecker.cpp
+++ b/libsolidity/analysis/OverrideChecker.cpp
@@ -481,7 +481,12 @@ void OverrideChecker::checkIllegalOverrides(ContractDefinition const& _contract)
 	for (auto const* stateVar: _contract.stateVariables())
 	{
 		if (!stateVar->isPublic())
+		{
+			if (stateVar->overrides())
+				m_errorReporter.typeError(8022_error, stateVar->location(), "Override can only be used with public state variables.");
+
 			continue;
+		}
 
 		if (contains_if(inheritedMods, MatchByName{stateVar->name()}))
 			m_errorReporter.typeError(1456_error, stateVar->location(), "Override changes modifier to public state variable.");
diff --git a/test/libsolidity/syntaxTests/inheritance/override/private_state_variable.sol b/test/libsolidity/syntaxTests/inheritance/override/private_state_variable.sol
new file mode 100644
index 000000000..400da4a8e
--- /dev/null
+++ b/test/libsolidity/syntaxTests/inheritance/override/private_state_variable.sol
@@ -0,0 +1,9 @@
+contract C1 {
+  function f() external pure returns(int) { return 42; }
+}
+
+contract C is C1 {
+   int override f;
+}
+// ----
+// TypeError: (96-110): Override can only be used with public state variables.