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### 2599. Library incomplete type permission phrase is unclear

Section: 22.2.6 [declval], 20.3.1 [unique.ptr], 20.3.1.2.1 [unique.ptr.dltr.general], 20.3.2.2 [util.smartptr.shared], 20.3.2.3 [util.smartptr.weak], 20.3.2.5 [util.smartptr.enab] Status: New Submitter: Zhihao Yuan Opened: 2016-03-08 Last modified: 2016-04-16

Priority: 3

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Discussion:

Currently the phrase to grant this permission is:

> The template parameter `T` of `LibraryTemplate` may be an incomplete type.

Two problems:

1. The timing is unclear. We always allow specializations like `LibraryTemplate<Incomp>* p;`

2. To the users of a template, the correct terminology should be "argument" rather than "parameter".

Suggested resolution:

> In an instantiation of `LibraryTemplate`, an incomplete type may be used as the template argument for the template parameter `T`.

as shown here.

Or, to copy N4510's wording:

> An incomplete type `T` may be used when instantiating `LibraryTemplate`.

Proposed resolution: