Proposed resolution:

This wording is relative to N4928.

1. Modify [locale.category], Table 105 ([tab:locale.category.facets]) — "Locale category facets" — and Table 106 ([tab:locale.spec]) "Required specializations" as indicated:

   Table 105: Locale category facets [tab:locale.category.facets]

   Category	Includes facets
   …
   ctype	ctype<char>, ctype<wchar_t> codecvt<char, char, mbstate_t> codecvt<char16_t, char8_t, mbstate_t> codecvt<char32_t, char8_t, mbstate_t> codecvt<wchar_t, char, mbstate_t>
   …

   […]

   Table 106: Required specializations [tab:locale.spec]

   Category	Includes facets
   …
   ctype	ctype_byname<char>, ctype_byname<wchar_t> codecvt_byname<char, char, mbstate_t> codecvt_byname<char16_t, char8_t, mbstate_t> codecvt_byname<char32_t, char8_t, mbstate_t> codecvt_byname<wchar_t, char, mbstate_t>
   …

2. Modify [locale.codecvt.general] as indicated:

   […]

   -3- The specializations required in Table 105 ([locale.category]) convert the implementation-defined native character set. codecvt<char, char, mbstate_t> implements a degenerate conversion; it does not convert at all. The specialization codecvt<char16_t, char8_t, mbstate_t> converts between the UTF-16 and UTF-8 encoding forms, and the specialization codecvt<char32_t, char8_t, mbstate_t> converts between the UTF-32 and UTF-8 encoding forms. codecvt<wchar_t, char, mbstate_t> converts between the native character sets for ordinary and wide characters. Specializations on mbstate_t perform conversion between encodings known to the library implementer. Other encodings can be converted by specializing on a program-defined stateT type. Objects of type stateT can contain any state that is useful to communicate to or from the specialized do_in or do_out members.

3. Modify [depr.locale.category] (Deprecated locale category facets) in Annex D as indicated:

   -1- The ctype locale category includes the following facets as if they were specified in table Table 105 [tab:locale.category.facets] of [locale.codecvt.general].

   codecvt<char16_t, char, mbstate_t>
   codecvt<char32_t, char, mbstate_t>
   codecvt<char16_t, char8_t, mbstate_t>
   codecvt<char32_t, char8_t, mbstate_t>
   

   -1- The ctype locale category includes the following facets as if they were specified in table Table 106 [tab:locale.spec] of [locale.codecvt.general].

   codecvt_byname<char16_t, char, mbstate_t>
   codecvt_byname<char32_t, char, mbstate_t>
   codecvt_byname<char16_t, char8_t, mbstate_t>
   codecvt_byname<char32_t, char8_t, mbstate_t>
   

   -3- The following class template specializations are required in addition to those specified in [locale.codecvt]. The specializations codecvt<char16_t, char, mbstate_t> and codecvt<char16_t, char8_t, mbstate_t> converts between the UTF-16 and UTF-8 encoding forms, and the specializations codecvt<char32_t, char, mbstate_t> and codecvt<char32_t, char8_t, mbstate_t> converts between the UTF-32 and UTF-8 encoding forms.