docs(cxx): add a section about std::filesystem limitations

Co-authored-by: Shen Meng Jing <shenmengjing@espressif.com>

docs/en/api-guides/cplusplus.rst

@@ -13,6 +13,7 @@ The following C++ features are supported:
 - :ref:`cplusplus_multithreading`
 - :ref:`cplusplus_rtti`
 - :doc:`thread-local-storage` (``thread_local`` keyword)
+- :ref:`cplusplus_filesystem`
 - All C++ features implemented by GCC, except for some :ref:`cplusplus_limitations`. See `GCC documentation <https://gcc.gnu.org/projects/cxx-status.html>`_ for details on features implemented by GCC.
 
 
@@ -94,6 +95,21 @@ Enabling this option compiles all C++ files with RTTI support enabled, which all
 
 See :example:`cxx/rtti` for an example of using RTTI in ESP-IDF. Specifically, this example demonstrates how to use the RTTI feature in ESP-IDF, enabling compile time support for RTTI, and showing how to print demangled type names of objects and functions, and how dynamic_cast behaves with objects of two classes derived from a common base class.
 
+.. _cplusplus_filesystem:
+
+Filesystem Library
+------------------
+
+C++ Filesystem library (``#include <filesystem>``) features are supported in ESP-IDF, with the following exceptions:
+
+- Since symbolic and hard links are not supported in ESP-IDF, related functions are not implemented.
+- ``std::filesystem::space`` is not implemented.
+- ``std::filesystem::resize_file`` is not implemented.
+- ``std::filesystem::current_path`` always returns ``/``. Setting the current path is not supported.
+- ``std::filesystem::permissions`` doesn't support setting file permissions.
+
+Note that the choice of the filesystem also affects the behavior of the filesystem library. For example, SPIFFS filesystem has limited support for directories, therefore the related std::filesystem functions may not work as they do on a filesystem which does support directories.
+
 Developing in C++
 -----------------
 

docs/zh_CN/api-guides/cplusplus.rst

@@ -13,6 +13,7 @@ ESP-IDF 支持以下 C++ 功能：
 - :ref:`cplusplus_multithreading`
 - :ref:`cplusplus_rtti`
 - :doc:`thread-local-storage` （``thread_local`` 关键字）
+- :ref:`cplusplus_filesystem`
 - 除部分 :ref:`cplusplus_limitations`，所有由 GCC 实现的 C++ 功能均受支持。有关由 GCC 所实现功能的详细信息，请参阅 `GCC 文档 <https://gcc.gnu.org/projects/cxx-status.html>`_。
 
 
@@ -94,6 +95,21 @@ ESP-IDF 默认禁用对 RTTI 的支持，可以用 :ref:`CONFIG_COMPILER_CXX_RTT
 
 有关在 ESP-IDF 中使用 RTTI 的示例，请参阅 :example:`cxx/rtti`。该示例演示了如何在 ESP-IDF 中使用 RTTI 功能，启用编译时对 RTTI 的支持，并展示了如何打印对象和函数的去混淆类型名称，以及 dynamic_cast 在两个继承自同一基类的对象上如何表现。
 
+.. _cplusplus_filesystem:
+
+文件系统库
+----------
+
+ESP-IDF 支持 C++ 文件系统库 (``#include <filesystem>``)，但有部分功能尚未实现：
+
+- 由于 ESP-IDF 不支持符号链接和硬链接，因此相关函数未实现。
+- 未实现 ``std::filesystem::space``。
+- 未实现 ``std::filesystem::resize_file``。
+- ``std::filesystem::current_path`` 只返回 ``/``。不支持设置当前路径。
+- ``std::filesystem::permissions`` 不支持设置文件权限。
+
+请注意，文件系统的选择也会影响文件系统库的行为。例如，SPIFFS 文件系统对目录的支持有限，因此相关的 std::filesystem 函数可能无法像在支持目录的文件系统上那样正常工作。
+
 在 C++ 中进行开发
 -----------------