29 Input/output library [input.output]

29.11 File systems [filesystems]

29.11.8 Class filesystem_error [fs.class.filesystem.error]

namespace std::filesystem {
  class filesystem_error : public system_error {
  public:
    filesystem_error(const string& what_arg, error_code ec);
    filesystem_error(const string& what_arg,
                     const path& p1, error_code ec);
    filesystem_error(const string& what_arg,
                     const path& p1, const path& p2, error_code ec);

    const path& path1() const noexcept;
    const path& path2() const noexcept;
    const char* what() const noexcept override;
  };
}

The class filesystem_error defines the type of objects thrown as exceptions to report file system errors from functions described in subclause [filesystems].

29.11.8.1 Members [fs.filesystem.error.members]

Constructors are provided that store zero, one, or two paths associated with an error.

filesystem_error(const string& what_arg, error_code ec);

Postconditions:

(2.1)
code() == ec,
(2.2)
path1().empty() == true,
(2.3)
path2().empty() == true, and
(2.4)
string_view(what()).find(what_arg.c_str()) != string_view::npos.

filesystem_error(const string& what_arg, const path& p1, error_code ec);

Postconditions:

(3.1)
code() == ec,
(3.2)
path1() returns a reference to the stored copy of p1,
(3.3)
path2().empty() == true, and
(3.4)
string_view(what()).find(what_arg.c_str()) != string_view::npos.

filesystem_error(const string& what_arg, const path& p1, const path& p2, error_code ec);

Postconditions:

(4.1)
code() == ec,
(4.2)
path1() returns a reference to the stored copy of p1,
(4.3)
path2() returns a reference to the stored copy of p2, and
(4.4)
string_view(what()).find(what_arg.c_str()) != string_view::npos.

const path& path1() const noexcept;

Returns: A reference to the copy of p1 stored by the constructor, or, if none, an empty path.

const path& path2() const noexcept;

Returns: A reference to the copy of p2 stored by the constructor, or, if none, an empty path.

const char* what() const noexcept override;

Returns: An ntbs that incorporates the what_arg argument supplied to the constructor.

The exact format is unspecified.

Implementations should include the system_error::what() string and the pathnames of path1 and path2 in the native format in the returned string.