However, this is irrelevant for DMD's purposes, and best practice
protocol for using errno is to treat it as an out parameter, and not
something with state that can be relied on across function calls.
So, we'll ignore it.
extern (C) pure @nogc nothrow pragma(mangle, "realloc") @system
Pure variants of C's memory allocation functions malloc, calloc, and realloc and deallocation function free.
UNIX 98 requires that errno be set to ENOMEM upon failure. https://linux.die.net/man/3/malloc
However, this is irrelevant for DMD's purposes, and best practice protocol for using errno is to treat it as an out parameter, and not something with state that can be relied on across function calls. So, we'll ignore it.