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3053. Prohibit error_code construction from rvalues of error_category

Section: 19.5.3.1 [syserr.errcode.overview] Status: New Submitter: Antony Polukhin Opened: 2018-01-24 Last modified: 2018-06-19

Priority: 3

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Discussion:

Constructor error_code(int val, const error_category& cat) and member function void assign(int val, const error_category& cat) could be misused if a custom error_category is provided:

error_code ec{1, test_category{}}; // ec holds a pointer/reference to a temporary

[2018-06-18 after reflector discussion]

Priority set to 3

Proposed resolution:

This wording is relative to N4713.

  1. Modify 19.5.3.1 [syserr.errcode.overview] as indicated:

    namespace std {
      class error_code {
      public:
        // 19.5.3.2 [syserr.errcode.constructors], constructors
        […]
        error_code(int val, const error_category& cat) noexcept;
        error_code(int val, const error_category&& cat) = delete;
        […]
        // 19.5.3.3 [syserr.errcode.modifiers], modifiers
        void assign(int val, const error_category& cat) noexcept;
        void assign(int val, const error_category&& cat) = delete;
        […]
      };
      […]
    }