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### 1229. `error_code operator=` typo

Section: 19.5.4.3 [syserr.errcode.modifiers] Status: Resolved Submitter: Stephan T. Lavavej Opened: 2009-10-08 Last modified: 2016-01-28

Priority: Not Prioritized

View all issues with Resolved status.

Discussion:

N2960 19.5.4.1 [syserr.errcode.overview] and 19.5.4.3 [syserr.errcode.modifiers] say:

>     template <class ErrorCodeEnum>
>       typename enable_if<is_error_code_enum<ErrorCodeEnum>::value>::type&
>         operator=(ErrorCodeEnum e);

They should say:

>     template <class ErrorCodeEnum>
>       typename enable_if<is_error_code_enum<ErrorCodeEnum>::value, error_code>::type&
>         operator=(ErrorCodeEnum e);

Or (I prefer this form):

>     template <class ErrorCodeEnum>
>       typename enable_if<is_error_code_enum<ErrorCodeEnum>::value, error_code&>::type
>         operator=(ErrorCodeEnum e);

This is because `enable_if` is declared as (21.3.8.7 [meta.trans.other]):

>     template <bool B, class T = void> struct enable_if;

So, the current wording makes `operator=` return `void&`, which is not good.

19.5.4.3 [syserr.errcode.modifiers]/4 says

> Returns: `*this`.

which is correct.

Additionally,

19.5.5.1 [syserr.errcondition.overview]/1 says:

>     template<typename ErrorConditionEnum>
>       typename enable_if<is_error_condition_enum<ErrorConditionEnum>, error_code>::type &
>         operator=( ErrorConditionEnum e );

Which contains several problems (`typename` versus `class` inconsistency, lack of `::value`, `error_code` instead of `error_condition`), while 19.5.5.3 [syserr.errcondition.modifiers] says:

>     template <class ErrorConditionEnum>
>       typename enable_if<is_error_condition_enum<ErrorConditionEnum>::value>::type&
>         operator=(ErrorConditionEnum e);

Which returns `void&`. They should both say:

>     template <class ErrorConditionEnum>
>       typename enable_if<is_error_condition_enum<ErrorConditionEnum>::value,
>       error_condition>::type&
>         operator=(ErrorConditionEnum e);

Or (again, I prefer this form):

>     template <class ErrorConditionEnum>
>       typename enable_if<is_error_condition_enum<ErrorConditionEnum>::value,
>       error_condition&>::type
>         operator=(ErrorConditionEnum e);

Additionally, 19.5.5.3 [syserr.errcondition.modifiers] lacks a "Returns: `*this`." paragraph, which is presumably necessary.

[ 2009-10-18 Beman adds: ]

> The proposed resolution for issue 1237 makes this issue moot, so it should become NAD.

[ 2009-10 Santa Cruz: ]

> NAD Resolved, solved by 1237.

Proposed resolution:

Change 19.5.4.1 [syserr.errcode.overview] and 19.5.4.3 [syserr.errcode.modifiers]:

>     template <class ErrorCodeEnum>
>       typename enable_if<is_error_code_enum<ErrorCodeEnum>::value,
>       error_code&>::type&
>         operator=(ErrorCodeEnum e);

Change 19.5.5.1 [syserr.errcondition.overview]:

>     template<typename class ErrorConditionEnum>
>       typename enable_if<is_error_condition_enum<ErrorConditionEnum>::value,
>       error_conditionde&>::type &
>         operator=( ErrorConditionEnum e );

Change 19.5.5.3 [syserr.errcondition.modifiers]:

>     template <class ErrorConditionEnum>
>       typename enable_if<is_error_condition_enum<ErrorConditionEnum>::value,
>       error_condition&>::type&
>         operator=(ErrorConditionEnum e);

> > Postcondition: `*this == make_error_condition(e)`.

> > Returns: `*this`.

> > Throws: Nothing.