No one has proposed making these standard. I doubt they would gain much support as they are similar to the Annex K Bounds Checked Interface functions strcpy_s and strcat_s but not quite as good IMHO.
N2353 2019/03/17 Sebor, Add strdup and strndup to C2X
N2352 2019/03/17 Sebor, Add stpcpy, and stpncpy to C2X
N2351 2019/03/17 Sebor, Add strnlen to C2X
6.33 Sebor, Add strnlen to C2X [N 2351] Result: No consensus on putting N2351 into C2X.
6.34 Sebor, Add stpcpy, and stpncpy to C2X [N 2352] Result: No consensus to put N2352 into C2X.
6.35 Sebor, Add strdup and strndup to C2X [N 2353] Result: N2353 be put into C2X. The committee wants a proposal for the wide character versions of any POSIX functions voted in this meeting.
Err... I thought Annex K is deprecated and dead? Whereas strl* seem very much alive, some compilers even give a "strcpy/strncpy is unsafe, use strlcpy instead" warning.
> Microsoft Visual Studio implements an early version of the APIs. However, the implementation is incomplete and conforms neither to C11 nor to the original TR 24731-1.
> As a result of the numerous deviations from the specification the Microsoft implementation cannot be considered conforming or portable.
> The C Committee has taken two votes on this, and in each case, the committee has been equally divided. Without a consensus to change the standard, the status quo wins.
The fact that it has only survived on status quo is a pretty crass hint that things aren't well with Annex K.
IMO they're a lot more ergonomic than the Annex K functions, and do the thing most programmers think the strncat/strncpy functions do (admittedly, not part of ISO C).
Annex K should be forgotten as the mistake it is and we can move on with existing real-world interfaces instead of inventing features from whole-cloth. I thought that was generally the C standard operating practice.