1372. Adopt recommended practice for standard error categories

Section: 22.5.2.5 [syserr.errcat.objects] Status: C++11 Submitter: BSI Opened: 2010-08-25 Last modified: 2016-02-10

Priority: Not Prioritized

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Discussion:

Addresses GB-76

The C++0x FCD recommends, in a note (see 19.5.1.1/1), that users create a single error_category object for each user defined error category and specifies error_category equality comparsions based on equality of addresses (19.5.1.3). The Draft apparently ignores this when specifying standard error category objects in section 19.5.1.5, by allowing the generic_category() and system_category() functions to return distinct objects for each invocation.

[ Resolved in Rapperswil by a motion to directly apply the words from the ballot comment in N3102. ]

Proposed resolution:

Append a new sentence to 22.5.2.5 [syserr.errcat.objects]/1, and append the same sentence to 19.5.1.5/3.

All calls of this function return references to the same object.