The c16rtomb implementation has:
// XXX The ISO C 11 spec I have does not say anything about handling
// XXX surrogates in this interface.
The DR#488 resolution, as applied to C2X, requires surrogate pairs to
be handled here (so the first call returns 0 and stores the high
surrogate in the mbstate_t, while the second call combines the
surrogates, produces a multibyte character and returns the number of
bytes written). This patch implements that. (mbrtoc16 already
handled producing surrogates as output.)
Tested for x86_64.
[BZ #23794]
* wcsmbs/c16rtomb.c (c16rtomb): Save first character of surrogate
pair and return 0 in that case, and use saved character to
interpret following character.
* wcsmbs/tst-c16-surrogate.c: New file.
* wcsmbs/Makefile (tests): Add tst-c16-surrogate.c.
[$(run-built-tests) = yes] ($(objpfx)tst-c16-surrogate.out):
Depend on $(gen-locales)
Joseph Myers