Treat returns with expressions as return param use

There are many cases of code where the return parameters exist mostly
as a form of documentation.  This change ensures that they do not have
to be used in the function body so long as there is a return supplying
values

1 files changed, 12 insertions, 0 deletions

diff --git a/libsolidity/analysis/StaticAnalyzer.cpp b/libsolidity/analysis/StaticAnalyzer.cpp
index 55e7cb59..21c97c3b 100644
--- a/libsolidity/analysis/StaticAnalyzer.cpp
+++ b/libsolidity/analysis/StaticAnalyzer.cpp
@@ -50,6 +50,7 @@ bool StaticAnalyzer::visit(FunctionDefinition const& _function)
 {
 	if (_function.isImplemented())
 		m_inFunction = true;
+	m_currentFunction = &_function;
 	m_localVarUseCount.clear();
 	m_nonPayablePublic = _function.isPublic() && !_function.isPayable();
 	return true;
@@ -96,6 +97,17 @@ bool StaticAnalyzer::visit(VariableDeclaration const& _variable)
 	return true;
 }
 
+bool StaticAnalyzer::visit(Return const& _return)
+{
+	// If the return has an expression, it counts as
+	// a "use" of the return parameters.
+	if (m_inFunction && _return.expression() != NULL)
+		for (auto const& var: m_currentFunction->returnParameterList()->parameters())
+			if (var->name() != "")
+				m_localVarUseCount[var.get()] += 1;
+	return true;
+}
+
 bool StaticAnalyzer::visit(ExpressionStatement const& _statement)
 {
 	if (_statement.expression().annotation().isPure)