Improve failure message when generating getter.

Author: mejsiej

libsolidity/analysis/TypeChecker.cpp

@@ -592,7 +592,14 @@ bool TypeChecker::visit(VariableDeclaration const& _variable)
 				);
 		}
 		if (!getter.interfaceFunctionType())
-			m_errorReporter.typeError(6744_error, _variable.location(), "Internal or recursive type is not allowed for public state variables.");
+		{
+			solAssert(getter.returnParameterNames().size() == getter.returnParameterTypes().size());
+			solAssert(getter.parameterNames().size() == getter.parameterTypes().size());
+			if (getter.returnParameterTypes().empty() && getter.parameterTypes().empty())
+				m_errorReporter.typeError(5359_error, _variable.location(), "The struct has all its members omitted, therefore the getter cannot return any values.");
+			else
+				m_errorReporter.typeError(6744_error, _variable.location(), "Internal or recursive type is not allowed for public state variables.");
+		}
 	}
 
 	bool isStructMemberDeclaration = dynamic_cast<StructDefinition const*>(_variable.scope()) != nullptr;

test/libsolidity/syntaxTests/nameAndTypeResolution/070_struct_accessor_one_array_only.sol

@@ -3,4 +3,4 @@ contract test {
     Data public data;
 }
 // ----
-// TypeError 6744: (58-74): Internal or recursive type is not allowed for public state variables.
+// TypeError 5359: (58-74): The struct has all its members omitted, therefore the getter cannot return any values.