When libvterm receives the OSC 52 escape sequence it ignores it because
Nvim does not set any selection callbacks. Install selection callbacks
that forward to the clipboard provider, so that setting the clipboard
with OSC 52 in the embedded terminal writes to the system clipboard
using the configured clipboard provider.
FUNC_ATTR_* should only be used in .c files with generated headers.
Defining FUNC_ATTR_* as empty in headers causes misuses of them to be
silently ignored. Instead don't define them by default, and only define
them as empty after a .c file has included its generated header.
We already have an extensive suite of static analysis tools we use,
which causes a fair bit of redundancy as we get duplicate warnings. PVS
is also prone to give false warnings which creates a lot of work to
identify and disable.
