Move override checks.

1 files changed, 83 insertions, 0 deletions

diff --git a/libsolidity/analysis/ContractLevelChecker.cpp b/libsolidity/analysis/ContractLevelChecker.cpp
index a2e76edf..bf132d63 100644
--- a/libsolidity/analysis/ContractLevelChecker.cpp
+++ b/libsolidity/analysis/ContractLevelChecker.cpp
@@ -35,6 +35,7 @@ bool ContractLevelChecker::check(ContractDefinition const& _contract)
 {
 	checkContractDuplicateFunctions(_contract);
 	checkContractDuplicateEvents(_contract);
+	checkContractIllegalOverrides(_contract);
 
 	return Error::containsOnlyWarnings(m_errorReporter.errors());
 }
@@ -120,3 +121,85 @@ void ContractLevelChecker::findDuplicateDefinitions(map<string, vector<T>> const
 		}
 	}
 }
+
+void ContractLevelChecker::checkContractIllegalOverrides(ContractDefinition const& _contract)
+{
+	// TODO unify this at a later point. for this we need to put the constness and the access specifier
+	// into the types
+	map<string, vector<FunctionDefinition const*>> functions;
+	map<string, ModifierDefinition const*> modifiers;
+
+	// We search from derived to base, so the stored item causes the error.
+	for (ContractDefinition const* contract: _contract.annotation().linearizedBaseContracts)
+	{
+		for (FunctionDefinition const* function: contract->definedFunctions())
+		{
+			if (function->isConstructor())
+				continue; // constructors can neither be overridden nor override anything
+			string const& name = function->name();
+			if (modifiers.count(name))
+				m_errorReporter.typeError(modifiers[name]->location(), "Override changes function to modifier.");
+
+			for (FunctionDefinition const* overriding: functions[name])
+				checkFunctionOverride(*overriding, *function);
+
+			functions[name].push_back(function);
+		}
+		for (ModifierDefinition const* modifier: contract->functionModifiers())
+		{
+			string const& name = modifier->name();
+			ModifierDefinition const*& override = modifiers[name];
+			if (!override)
+				override = modifier;
+			else if (ModifierType(*override) != ModifierType(*modifier))
+				m_errorReporter.typeError(override->location(), "Override changes modifier signature.");
+			if (!functions[name].empty())
+				m_errorReporter.typeError(override->location(), "Override changes modifier to function.");
+		}
+	}
+}
+
+void ContractLevelChecker::checkFunctionOverride(FunctionDefinition const& _function, FunctionDefinition const& _super)
+{
+	FunctionTypePointer functionType = FunctionType(_function).asCallableFunction(false);
+	FunctionTypePointer superType = FunctionType(_super).asCallableFunction(false);
+
+	if (!functionType->hasEqualParameterTypes(*superType))
+		return;
+	if (!functionType->hasEqualReturnTypes(*superType))
+		overrideError(_function, _super, "Overriding function return types differ.");
+
+	if (!_function.annotation().superFunction)
+		_function.annotation().superFunction = &_super;
+
+	if (_function.visibility() != _super.visibility())
+	{
+		// Visibility change from external to public is fine.
+		// Any other change is disallowed.
+		if (!(
+			_super.visibility() == FunctionDefinition::Visibility::External &&
+			_function.visibility() == FunctionDefinition::Visibility::Public
+		))
+			overrideError(_function, _super, "Overriding function visibility differs.");
+	}
+	if (_function.stateMutability() != _super.stateMutability())
+		overrideError(
+			_function,
+			_super,
+			"Overriding function changes state mutability from \"" +
+			stateMutabilityToString(_super.stateMutability()) +
+			"\" to \"" +
+			stateMutabilityToString(_function.stateMutability()) +
+			"\"."
+		);
+}
+
+void ContractLevelChecker::overrideError(FunctionDefinition const& function, FunctionDefinition const& super, string message)
+{
+	m_errorReporter.typeError(
+		function.location(),
+		SecondarySourceLocation().append("Overridden function is here:", super.location()),
+		message
+	);
+}
+