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38. Facet definition incomplete

Section: 28.3.3.2[locale.global.templates]Status:TC1Submitter: Nathan MyersOpened: 1998-08-06Last modified: 2016-01-28

Priority:Not Prioritized

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Discussion:

It has been noticed by Esa Pulkkinen that the definition of"facet" is incomplete. In particular, a class derived fromanother facet, but which does not define a memberid, cannotsafely serve as the argumentF to use_facet<F>(loc),because there is no guarantee that a reference to the facet instancestored inloc is safely convertible toF.

Proposed resolution:

In the definition of std::use_facet<>(), replace the text in paragraph 1 whichreads:

Get a reference to a facet of a locale.

with:

Requires:Facet is a facet class whose definition contains the public static memberid as defined in 28.3.3.1.2.2[locale.facet].

[Kona: strike as overspecification the text "(not inherits)"from the original resolution, which read "... whose definitioncontains (not inherits) the public static memberid..."]