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2719. permissions function should not be noexcept due to narrow contract

Section: 31.12.13.27 [fs.op.permissions] Status: C++17 Submitter: Eric Fiselier Opened: 2016-05-28 Last modified: 2017-07-30

Priority: 0

View all other issues in [fs.op.permissions].

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Discussion:

Currently the signatures for permissions are:

void permissions(const path& p, perms prms);
void permissions(const path& p, perms prms, error_code& ec) noexcept;

However both overloads have a narrow contract since due to the requires clause:

Requires: !((prms & perms::add_perms) != perms::none && (prms & perms::remove_perms) != perms::none).

For this reason I believe the second overload of permissions should not be marked noexcept.

[2016-06 Oulu]

Moved to P0/Ready during issues prioritization.

Friday: status to Immediate

Proposed resolution:

This wording is relative to N4582.

1. Change 31.12.4 [fs.filesystem.syn] as indicated:

   namespace std::filesystem {
     […]
   
     void permissions(const path& p, perms prms);
     void permissions(const path& p, perms prms, error_code& ec) noexcept;
   
     […]
   }
   

2. Change 31.12.13.27 [fs.op.permissions] as indicated:

   void permissions(const path& p, perms prms);
   void permissions(const path& p, perms prms, error_code& ec) noexcept;
   

   -1- Requires: !((prms & perms::add_perms) != perms::none && (prms & perms::remove_perms) != perms::none).