[depr.filesystems]

# Annex D (normative) Compatibility features [[depr]](./#depr)

## D.22 Deprecated file systems [depr.filesystems]

### [D.22.1](#depr.fs.path.factory) Deprecated filesystem path factory functions [[depr.fs.path.factory]](depr.fs.path.factory)

[1](#depr.fs.path.factory-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/future.tex#L793)

The header [<filesystem>](fs.filesystem.syn#header:%3cfilesystem%3e "31.12.4 Header <filesystem> synopsis [fs.filesystem.syn]") has the following additions:

[🔗](#lib:u8path)

`template<class Source>
  path u8path(const Source& source);
template<class InputIterator>
  path u8path(InputIterator first, InputIterator last);
`

[2](#depr.fs.path.factory-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/future.tex#L804)

*Mandates*: The value type of Source and InputIterator ischar or char8_t[.](#depr.fs.path.factory-2.sentence-1)

[3](#depr.fs.path.factory-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/future.tex#L809)

*Preconditions*: The source and [first, last) sequences are UTF-8 encoded[.](#depr.fs.path.factory-3.sentence-1)

Source meets the requirements specified in [[fs.path.req]](fs.path.req "31.12.6.4 Requirements")[.](#depr.fs.path.factory-3.sentence-2)

[4](#depr.fs.path.factory-4)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/future.tex#L814)

*Returns*: 

- [(4.1)](#depr.fs.path.factory-4.1)

If path​::​value_type is char and the current native
 narrow encoding ([[fs.path.type.cvt]](fs.path.type.cvt "31.12.6.3.2 Type and encoding conversions")) is UTF-8,
 return path(source) or path(first, last);
 otherwise,

- [(4.2)](#depr.fs.path.factory-4.2)

if path​::​value_type is wchar_t and the
 native wide encoding is UTF-16, or
 if path​::​value_type is char16_t or char32_t,
 convert source or [first, last)
 to a temporary, tmp, of type path​::​string_type and
 return path(tmp);
 otherwise,

- [(4.3)](#depr.fs.path.factory-4.3)

convert source or [first, last)
 to a temporary, tmp, of type u32string and
 return path(tmp)[.](#depr.fs.path.factory-4.sentence-1)

[5](#depr.fs.path.factory-5)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/future.tex#L833)

*Remarks*: Argument format conversion ([[fs.path.fmt.cvt]](fs.path.fmt.cvt "31.12.6.3.1 Argument format conversions")) applies to the
 arguments for these functions[.](#depr.fs.path.factory-5.sentence-1)

How Unicode encoding conversions are performed is
 unspecified[.](#depr.fs.path.factory-5.sentence-2)

[6](#depr.fs.path.factory-6)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/future.tex#L839)

[*Example [1](#depr.fs.path.factory-example-1)*:

A string is to be read from a database that is encoded in UTF-8, and used
 to create a directory using the native encoding for filenames:namespace fs = std::filesystem;
std::string utf8_string = read_utf8_data();
fs::create_directory(fs::u8path(utf8_string));

For POSIX-based operating systems with the native narrow encoding set
 to UTF-8, no encoding or type conversion occurs[.](#depr.fs.path.factory-6.sentence-2)

For POSIX-based operating systems with the native narrow encoding not
 set to UTF-8, a conversion to UTF-32 occurs, followed by a conversion to the
 current native narrow encoding[.](#depr.fs.path.factory-6.sentence-3)

Some Unicode characters may have no native character
 set representation[.](#depr.fs.path.factory-6.sentence-4)

For Windows-based operating systems a conversion from UTF-8 to
 UTF-16 occurs[.](#depr.fs.path.factory-6.sentence-5)

— *end example*]

[*Note [1](#depr.fs.path.factory-note-1)*:

The example above is representative of
a historical use of filesystem​::​u8path[.](#depr.fs.path.factory-6.sentence-6)

To indicate a UTF-8 encoding,
passing a std​::​u8string to path's constructor is preferred
as it is consistent with path's handling of other encodings[.](#depr.fs.path.factory-6.sentence-7)

— *end note*]

### [D.22.2](#depr.fs.path.obs) Deprecated filesystem path format observers [[depr.fs.path.obs]](depr.fs.path.obs)

[1](#depr.fs.path.obs-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/future.tex#L872)

The following members are declared in addition to those members
specified in [[fs.path.member]](fs.path.member "31.12.6.5 Members"):

namespace std::filesystem {class path {public: std::string string() const;
 std::string generic_string() const; };}

[🔗](#lib:string,path)

`std::string string() const;
`

[2](#depr.fs.path.obs-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/future.tex#L892)

*Returns*: system_encoded_string()[.](#depr.fs.path.obs-2.sentence-1)

[🔗](#lib:generic_string,path)

`std::string generic_string() const;
`

[3](#depr.fs.path.obs-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/future.tex#L903)

*Returns*: generic_system_encoded_string()[.](#depr.fs.path.obs-3.sentence-1)