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Section: 21 [meta] Status: C++17 Submitter: Tim Song Opened: 2016-01-07 Last modified: 2017-07-30
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188.8.131.52 [res.on.functions]/2.5 says that the behavior is undefined "if an incomplete type is used as a template argument when instantiating a template component, unless specifically allowed for that component."This rule should not apply to type traits — a literal application would make is_same<void, void> undefined behavior, since nothing in 21 [meta] (or elsewhere) "specifically allows" instantiating is_same with incomplete types. Traits that require complete types are already explicitly specified as such, so the proposed wording below simply negates 184.108.40.206 [res.on.functions]/2.5 for 21 [meta].
[2016-02, Issues Telecon]
P0; move to Tentatively Ready.
This wording is relative to N4567.
Insert a new paragraph after 21.3.3 [meta.type.synop]/1: