error_code arguments should be noexceptSection: 15.2 [filesys.ts::fs.op.canonical], 15.11 [filesys.ts::fs.op.current_path], 15.27 [filesys.ts::fs.op.read_symlink], 15.36 [filesys.ts::fs.op.system_complete], 15.37 [filesys.ts::fs.op.temp_dir_path], 99 [filesys.ts::fs.op.unique_path], 8.4 [filesys.ts::path.member] Status: TS Submitter: P.J. Plauger Opened: 2014-01-30 Last modified: 2017-07-30
Priority: Not Prioritized
View all issues with TS status.
Discussion:
Addresses: filesys.ts
all functions with error_code arguments should be noexcept
(see canonical, current_path, read_symlink, system_complete,
temp_directory_path, unique_path, plus member functions).
[2014-02-03: Stephan T. Lavavej comments:]
The declaration and definition of
"recursive_directory_iterator& increment(error_code& ec);" should almost certainly
be marked noexcept.
[2014-02-08: Daniel comments]
All functions that return a path value such as canonical, current_path,
read_symlink, system_complete, temp_directory_path, unique_path,
or any member function returning a path value or basic_string value might legally
throw an exception, if the allocator of the underlying string complains about insufficient
memory. This is an anti-pattern for noexcept, because the exception-specification includes
the return statement of a function and given the fact that the language currently does declare RVO
as an optional action, we cannot rely on it.
noexcept,
if this case can happen, see e.g. std::locale::name(). To the contrary, enforcing them to be
noexcept, would cause a similar problem as the unconditional noexcept specifier of
the value-returning kill_dependency as denoted by LWG 2236.
Basically this requirement conflicts with the section "Adopted Guidelines", second bullet of
N3279.
[Beman Dawes 2014-02-27]
Issues 2637, 2638, 2641, and 2649 are concerned with signatures which should or should not benoexcept. I will provide unified proposed wording for these issues, possibly in a separate paper.
[21 May 2014 Beman Dawes reviewed all functions with error_code& arguments,
and provided proposed wording for the one case found where the above guidelines were not met.
This was the case previously identified by Stephan T. Lavavej.
]
Proposed resolution:
Change 14 Class recursive_directory_iterator [class.rec.dir.itr]:
recursive_directory_iterator& increment(error_code& ec) noexcept;
Change 14.1 recursive_directory_iterator members [rec.dir.itr.members]:
recursive_directory_iterator& increment(error_code& ec) noexcept;