Re: [Qemu-devel] [RFC] error: auto propagated local_err

[Max Reitz <mreitz@redhat.com>]

On 18.09.19 15:02, Vladimir Sementsov-Ogievskiy wrote:
> Hi all!
> 
> Here is a proposal (three of them, actually) of auto propagation for
> local_err, to not call error_propagate on every exit point, when we
> deal with local_err.
> 
> It also may help make Greg's series[1] about error_append_hint smaller.
> 
> See definitions and examples below.
> 
> I'm cc-ing to this RFC everyone from series[1] CC list, as if we like
> it, the idea will touch same code (and may be more).
> 
> [1]: https://lists.gnu.org/archive/html/qemu-devel/2019-09/msg03449.html
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  include/qapi/error.h | 102 +++++++++++++++++++++++++++++++++++++++++++
>  block.c              |  63 ++++++++++++--------------
>  block/backup.c       |   8 +++-
>  block/gluster.c      |   7 +++
>  4 files changed, 144 insertions(+), 36 deletions(-)

If the combination of “if (local_err) { error_propagate(...); ... }” is
what’s cumbersome, can’t this be done simpler by adding an
error_propagate() variant with a return value?

i.e.

bool has_error_then_propagate(Error **errp, Error *err)
{
    if (!err) {
        return false;
    }
    error_propagate(errp, err);
    return true;
}

And then turn all instances of

if (local_err) {
    error_propagate(errp, local_err);
    ...
}

into

if (has_error_then_propagate(errp, local_err)) {
    ...
}

?

Max