I tried some artificial example for Plan9 compiler (5c)...

This code is compiled without any problem:

uintptr frst[] = {nil, nil, nil, nil, nil};
uintptr scnd[] = {nil, nil, frst, &frst[0]};

But this one fails:

uintptr frst[] = {nil, nil, nil, nil, nil};
uintptr scnd[] = {nil, nil, frst, &frst[1]};

...with message:

cpu% 5c -p t.c
/usr/pavel/t.c:16[t.c:888] initializer is not a constant: scnd

OTOH, replacement of 'uintptr' by 'void*' is compiled without any problem:

void* frst[] = {nil, nil, nil, nil, nil};
void* scnd[] = {nil, nil, frst, &frst[1]};

Any explanation is appreciated.

Pavel