Proposed resolution:

This wording is relative to N4713.

1. Edit [fs.op.copy_file]/4 as indicated:

   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;
   

   -4- Effects: As follows:

   1. (4.1) — Report a file already existsan error as specified in [fs.err.report] if:

   2. 1. (4.1.1) —[…]

   3. (4.2) —[…]

[ 2018-3-17 Adopted in Jacksonville ]

[ 2018-01-23 Moved to Tentatively Ready after 6 positive votes on c++std-lib. ]

[ 2018-01-16, Jonathan comments ]

I said I'd provide updated wording because I wanted to preserve the requirement that the reported error is "file already exists" for some of the error cases. I no longer think that's necessary, so I think the current P/R is fine. Please note that I don't think new wording is needed.

[ 2017-01-27 Telecon ]

Priority 2; Jonathan to provide updated wording.

[fs.op.copy_file]/4 says that copy_file reports "a file already exists error as specified in [fs.err.report] if" any of several error conditions exist.

It's not clear how some of those error conditions, such as !is_regular_file(from), can be sensibly described as "file already exists". Pretty much everywhere else in the filesystem specification just says "an error" without further elaboration.