Fixed signed

src/operator/MetaOperator.cpp

@@ -65,7 +65,7 @@ Aidge::MetaOperator_Op::MetaOperator_Op(const char *type, const std::shared_ptr<
         const std::vector<std::vector<std::pair<std::shared_ptr<Node>, IOIndex_t>>> outputNodeoutputs =
             outputNode->outputs();
 
-        for (int outputIdx = 0; outputIdx < outputNodeoutputs.size(); ++outputIdx) {
+        for (size_t outputIdx = 0; outputIdx < outputNodeoutputs.size(); ++outputIdx) {
             mOutputOps.push_back(std::make_pair(outputNode->getOperator(), outputIdx));
         }
     }