Handle absence of Natspec doc and add option to solc

libsolidity/CompilerStack.cpp

@@ -140,8 +140,12 @@ string const& CompilerStack::getDocumentation()
 		for (FunctionDefinition const* f: exportedFunctions)
 		{
 			Json::Value user;
-			user["user"] = Json::Value(*f->getDocumentation());
-			methods[f->getName()] = user;
+			auto strPtr = f->getDocumentation();
+			if (strPtr)
+			{
+				user["user"] = Json::Value(*strPtr);
+				methods[f->getName()] = user;
+			}
 		}
 		doc["methods"] = methods;
 		m_documentation = writer.write(doc);

solc/main.cpp

@@ -136,6 +136,7 @@ int main(int argc, char** argv)
 	cout << eth::disassemble(compiler.getBytecode()) << endl;
 	cout << "Binary: " << toHex(compiler.getBytecode()) << endl;
 	cout << "Interface specification: " << compiler.getInterface() << endl;
+	cout << "Natspec documentation: " << compiler.getDocumentation() << endl;
 
 	return 0;
 }