On Wed, 7 Feb 2018, Jeff Law wrote:
> Ideally we'd tighten the extension's language so that we could issue an
> error out of the front-end.
It seems to me to be the sort of thing that's only undefined at execution
time - it's perfectly valid to store the address of a label in a global,
and later jump to it if you haven't left the function execution within
which you took the address. I.e., if you detect this case and wish to
diagnose it, it should be a warning plus generating a call to
__builtin_trap, not an error.
Joseph S. Myers