[Bug libstdc++/70893] codecvt incorrectly decodes UTF-16be

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70893

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
If you think there's a bug here please provide a testcase that compiles and
produces an incorrect result.