[Bug libstdc++/79511] New: Convertation issues in std::codecvt_utf8_utf16

[mikhail at pilin dot name]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79511

            Bug ID: 79511
           Summary: Convertation issues in std::codecvt_utf8_utf16
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mikhail at pilin dot name
  Target Milestone: ---

Hi,

I found two issues in std::codecvt_utf8_utf16 for GCC v5.4 (Clang v3.8 has no
issues here):

1. \xEF\xBF\xBF (UTF8) convered to \xD7FF\xDFFF (UTF16), but should be \xFFFF
(UTF16). (Attention: \xD7FF is not is high surrogate region [D800..DBFF]).
Please see non character representation table in
http://www.unicode.org/faq/private_use.html#noncharacters

2. std::codecvt_utf8_utf16 requires std::little_endian on x86_64. Otherwise big
endian order is used as default!