Repository: open-mmlab/mmengine

Issue:
[Bug] Config to_dict() does not convert type recursively.
### Prerequisite

- [X] I have searched [Issues](https://github.com/open-mmlab/mmengine/issues) and [Discussions](https://github.com/open-mmlab/mmengine/discussions) but cannot get the expected help.
- [X] The bug has not been fixed in the latest version(https://github.com/open-mmlab/mmengine).

### Environment


OrderedDict([('sys.platform', 'linux'), ('Python', '3.10.12 | packaged by conda-forge | (main, Jun 23 2023, 22:40:32) [GCC 12.3.0]'), ('CUDA available', True), ('numpy_random_seed', 2147483648), ('GPU 0,1', 'NVIDIA GeForce RTX 2080 Ti'), ('CUDA_HOME', '/usr/local/cuda-12.1'), ('NVCC', 'Cuda compilation tools, release 12.1, V12.1.105'), ('GCC', 'gcc (Ubuntu 9.4.0-1ubuntu1~20.04.2) 9.4.0'), ('PyTorch', '2.1.2+cu121'), ('PyTorch compiling details', 'PyTorch built with:\n  - GCC 9.3\n  - C++ Version: 201703\n  - Intel(R) oneAPI Math Kernel Library Version 2022.2-Product Build 20220804 for Intel(R) 64 architecture applications\n  - Intel(R) MKL-DNN v3.1.1 (Git Hash 64f6bcbcbab628e96f33a62c3e975f8535a7bde4)\n  - OpenMP 201511 (a.k.a. OpenMP 4.5)\n  - LAPACK is enabled (usually provided by MKL)\n  - NNPACK is enabled\n  - CPU capability usage: AVX2\n  - CUDA Runtime 12.1\n  - NVCC architecture flags: -gencode;arch=compute_50,code=sm_50;-gencode;arch=compute_60,code=sm_60;-gencode;arch=compute_70,code=sm_70;-gencode;arch=compute_75,code=sm_75;-gencode;arch=compute_80,code=sm_80;-gencode;arch=compute_86,code=sm_86;-gencode;arch=compute_90,code=sm_90\n  - CuDNN 8.9.2\n  - Magma 2.6.1\n  - Build settings: BLAS_INFO=mkl, BUILD_TYPE=Release, CUDA_VERSION=12.1, CUDNN_VERSION=8.9.2, CXX_COMPILER=/opt/rh/devtoolset-9/root/usr/bin/c++, CXX_FLAGS= -D_GLIBCXX_USE_CXX11_ABI=0 -fabi-version=11 -fvisibility-inlines-hidden -DUSE_PTHREADPOOL -DNDEBUG -DUSE_KINETO -DLIBKINETO_NOROCTRACER -DUSE_FBGEMM -DUSE_QNNPACK -DUSE_PYTORCH_QNNPACK -DUSE_XNNPACK -DSYMBOLICATE_MOBILE_DEBUG_HANDLE -O2 -fPIC -Wall -Wextra -Werror=return-type -Werror=non-virtual-dtor -Werror=bool-operation -Wnarrowing -Wno-missing-field-initializers -Wno-type-limits -Wno-array-bounds -Wno-unknown-pragmas -Wno-unused-parameter -Wno-unused-function -Wno-unused-result -Wno-strict-overflow -Wno-strict-aliasing -Wno-stringop-overflow -Wno-psabi -Wno-error=pedantic -Wno-error=old-style-cast -Wno-invalid-partial-specialization -Wno-unused-private-field -Wno-aligned-allocation-unavailable -Wno-missing-braces -fdiagnostics-color=always -faligned-new -Wno-unused-but-set-variable -Wno-maybe-uninitialized -fno-math-errno -fno-trapping-math -Werror=format -Werror=cast-function-type -Wno-stringop-overflow, LAPACK_INFO=mkl, PERF_WITH_AVX=1, PERF_WITH_AVX2=1, PERF_WITH_AVX512=1, TORCH_DISABLE_GPU_ASSERTS=ON, TORCH_VERSION=2.1.2, USE_CUDA=ON, USE_CUDNN=ON, USE_EXCEPTION_PTR=1, USE_GFLAGS=OFF, USE_GLOG=OFF, USE_MKL=ON, USE_MKLDNN=ON, USE_MPI=OFF, USE_NCCL=1, USE_NNPACK=ON, USE_OPENMP=ON, USE_ROCM=OFF, \n'), ('TorchVision', '0.16.2+cu121'), ('OpenCV', '4.8.1'), ('MMEngine', '0.10.1')])


### Reproduces the problem - code sample

```
In [1]: from mmengine.config import Config

In [2]: cfg = Config.fromfile("mmengine/tests/data/config/py_config/simple_config.py")

In [3]: cfd = cfg.to_dict()

In [4]: type(cfd["item2"])
Out[4]: mmengine.config.config.ConfigDict

In [5]: import mmengine

In [6]: mmengine.__version__
Out[6]: '0.10.2'
```

### Reproduces the problem - command or script

```
In [1]: from mmengine.config import Config

In [2]: cfg = Config.fromfile("mmengine/tests/data/config/py_config/simple_config.py")

In [3]: cfd = cfg.to_dict()

In [4]: type(cfd["item2"])
Out[4]: mmengine.config.config.ConfigDict

In [5]: import mmengine

In [6]: mmengine.__version__
Out[6]: '0.10.2'
```

### Reproduces the problem - error message

```
In [1]: from mmengine.config import Config

In [2]: cfg = Config.fromfile("mmengine/tests/data/config/py_config/simple_config.py")

In [3]: cfd = cfg.to_dict()

In [4]: type(cfd["item2"])
Out[4]: mmengine.config.config.ConfigDict

In [5]: import mmengine

In [6]: mmengine.__version__
Out[6]: '0.10.2'
```

### Additional information

_No response_


Discussion:

Resolving patch:
diff --git a/mmengine/config/config.py b/mmengine/config/config.py
--- a/mmengine/config/config.py
+++ b/mmengine/config/config.py
@@ -48,9 +48,11 @@
 def _lazy2string(cfg_dict, dict_type=None):
     if isinstance(cfg_dict, dict):
         dict_type = dict_type or type(cfg_dict)
-        return dict_type({k: _lazy2string(v) for k, v in dict.items(cfg_dict)})
+        return dict_type(
+            {k: _lazy2string(v, dict_type)
+             for k, v in dict.items(cfg_dict)})
     elif isinstance(cfg_dict, (tuple, list)):
-        return type(cfg_dict)(_lazy2string(v) for v in cfg_dict)
+        return type(cfg_dict)(_lazy2string(v, dict_type) for v in cfg_dict)
     elif isinstance(cfg_dict, (LazyAttr, LazyObject)):
         return f'{cfg_dict.module}.{str(cfg_dict)}'
     else:


Test patch: