Merge pull request #24865 from asmorkalov:as/dnn_concat_assert

Normalize axis parameter in DNN Concat to handle negative values

modules/dnn/src/onnx/onnx_importer.cpp

@@ -2617,6 +2617,7 @@ void ONNXImporter::parseConcat(LayerParams& layerParams, const opencv_onnx::Node
 
         // Concat-1 has default value for axis is 1: https://github.com/onnx/onnx/blob/master/docs/Changelog.md#Concat-1
         int axis = layerParams.get<int>("axis", 1);
+        axis = normalize_axis(axis, inputShape.size());
         for (size_t i = 0; i < inputs.size(); ++i)
         {
             MatShape targetShape = inputShape;

modules/dnn/test/test_onnx_conformance_layer_filter_opencv_all_denylist.inl.hpp

@@ -41,7 +41,7 @@
 "test_cast_STRING_to_FLOAT",
 "test_castlike_FLOAT_to_STRING_expanded",
 "test_castlike_STRING_to_FLOAT_expanded",
-"test_concat_1d_axis_negative_1",
+"test_concat_1d_axis_negative_1", // 1d support is required
 "test_div_uint8",  // output type mismatch
 "test_maxpool_2d_dilations",
 "test_maxpool_2d_same_lower",