[libc] annex K "Runtime-constraint violations" support

[nickdesaulniers]

K.3.1.4 Runtime-constraint violations

Talks about having a callback function invocation when various constraints are violated.

K.3.6 General utilities <stdlib.h>

Talks about the signature of a constraint_handler_t as provided by stdlib.h.

K.3.6.1.1 The set_constraint_handler_s function

Talks about a setter for the callback.

K.3.6.1.2 The abort_handler_s function
K.3.6.1.3 The ignore_handler_s function

Talk about two predefined callbacks that can be set to handle the two most common cases.

We're adding ctime_s support in #110676, but without these callback invocations. ctime_s (and any annex k functions) need to be revisited when set_constraint_handler_s support is added.

[llvmbot]

@llvm/issue-subscribers-libc

Author: Nick Desaulniers (nickdesaulniers)

Details

> K.3.1.4 Runtime-constraint violations

Talks about having a callback function invocation when various constraints are violated.

> K.3.6 General utilities <stdlib.h>

Talks about the signature of a constraint_handler_t as provided by stdlib.h.

> K.3.6.1.1 The set_constraint_handler_s function

Talks about a setter for the callback.

> K.3.6.1.2 The abort_handler_s function
> K.3.6.1.3 The ignore_handler_s function

Talk about two predefined callbacks that can be set to handle the two most common cases.

We're adding ctime_s support in #110676, but without these callback invocations. ctime_s (and any annex k functions) need to be revisited when set_constraint_handler_s support is added.