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This page is a snapshot from the LWG issues list, see theLibrary Active Issues List for more information and the meaning ofC++20 status.

3014. Morenoexcept issues with filesystem operations

Section: 31.12.13.5[fs.op.copy.file], 31.12.13.7[fs.op.create.directories], 31.12.13.32[fs.op.remove.all]Status:C++20Submitter: Tim SongOpened: 2017-08-23Last modified: 2021-06-06

Priority:Not Prioritized

View all otherissues in [fs.op.copy.file].

View all issues withC++20 status.

Discussion:

create_directories may need to create temporarypaths, andremove_all may need to create temporarypaths and/ordirectory_iterators. These operations may require a potentially throwing memory allocation.

Implementations ofcopy_file may wish to dynamically allocate the buffer used for copying when the underlying OSdoesn't supply a copy API directly. This can happen indirectly, e.g., by using<fstream> facilities toperform the copying without supplying a custom buffer. Unless LWG wishes to prohibit using a dynamically allocated bufferin this manner, thenoexcept should be removed.

[2017-11 Albuquerque Wednesday night issues processing]

Moved to Ready

[2018-3-17 Adopted in Jacksonville]

Proposed resolution:

This wording is relative toN4687.

1. Edit 31.12.4[fs.filesystem.syn], header<filesystem> synopsis, as indicated:

   namespace std::filesystem {  […]  bool copy_file(const path& from, const path& to);  bool copy_file(const path& from, const path& to, error_code& ec)noexcept;  bool copy_file(const path& from, const path& to, copy_options option);  bool copy_file(const path& from, const path& to, copy_options option,                 error_code& ec)noexcept;  […]  bool create_directories(const path& p);  bool create_directories(const path& p, error_code& ec)noexcept;  […]  uintmax_t remove_all(const path& p);  uintmax_t remove_all(const path& p, error_code& ec)noexcept;  […]}

2. Edit [fs.op.copy_file] as indicated:

   bool copy_file(const path& from, const path& to);bool copy_file(const path& from, const path& to, error_code& ec)noexcept;

   -1-Returns: […]

   -2-Throws: […]

   bool copy_file(const path& from, const path& to, copy_options options);bool copy_file(const path& from, const path& to, copy_options options,               error_code& ec)noexcept;

   -3-Requires: […]

   -4-Effects: […]

   -5-Returns: […]

   -6-Throws: […]

   -7-Complexity: […]

3. Edit [fs.op.create_directories] as indicated:

   bool create_directories(const path& p);bool create_directories(const path& p, error_code& ec)noexcept;

   -1-Effects: […]

   -2-Postconditions: […]

   -3-Returns: […]

   -4-Throws: […]

   -5-Complexity: […]

4. Edit [fs.op.remove_all] as indicated:

   uintmax_t remove_all(const path& p);uintmax_t remove_all(const path& p, error_code& ec)noexcept;

   -1-Effects: […]

   -2-Postconditions: […]

   -3-Returns: […]

   -4-Throws: […]